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Archean crustal evolution constrained by strontium isotopes in apatite and uranium-lead geochronology… Emo, Robert Bernard 2018

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ARCHEAN CRUSTAL EVOLUTION CONSTRAINED BY STRONTIUM ISOTOPES IN APATITE AND URANIUM-LEAD GEOCHRONOLOGY AND TRACE ELEMENT GEOCHEMISTRY OF ZIRCONbyROBERT BERNARD EMOB.A. with Honors, Trinity College Dublin, 2015A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCEinTHE FACULTY OF GRADUATE AND POSTDOCTORAL STUDIES(Geological Sciences)THE UNIVERSITY OF BRITISH COLUMBIA(Vancouver)April 2018© Robert Bernard Emo, 2018iiAbstractArchean continents were the nuclei for crustal growth and large volumes of continental crust appear to have been produced during the Archean. Much of the preserved Archean crust is of tonalite-trondhjemite-granodiorite (TTG) composition and it is argued that this made up the bulk of Earth’s earliest crust. Other models involve a bulk mafic crust that was very different to the modern crust. New data are therefore needed to test and refine these models and determine how continents were first formed. The Rb-Sr isotopic system provides a potentially powerful proxy for crustal composition yet it has thus far been underutilized in studies on early crustal evolution due to its susceptibility to re-equilibration. Overcoming this issue requires new analytical approaches to micro-sample ancient Sr-rich minerals, such as apatite, that may retain primary 87Sr/86Sr signatures. In this thesis, a novel method in laser-ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) was applied to apatite from TTG complexes of different Archean age. The first area of focus was the Acasta Gneiss Complex, Northwest Territories, which contains the oldest known terrestrial rocks. Apatite inclusions within ca. 3.7 Ga zircon host grains were subjected to Sr isotope analysis by LA-MC-ICPMS. The initial 87Sr/86Sr values of these inclusions are identical within error and are different from values obtained from altered matrix apatite. Combining the 87Sr/86Sr results with information on the protolith and source-extraction age yields estimates for the range of source Rb/Sr and suggests that an evolved Hadean source was involved in the formation of the Acasta Gneiss Complex. The Sr isotope LA-MC-ICPMS method was also applied to matrix apatite from TTG of the ca. 3.6 Ga Bastar Craton, India, and the 3.0-2.8 Ga Kvanefjord Block, Greenland. The radiogenic 87Sr/86Sr signatures from these apatite grains also require a high Rb/Sr crustal source. This suggests that enriched crustal vestiges played a role in the formation of TTG crust. iiiLay SummaryThe key goals of this research work were to investigate the composition of Earth’s oldest crust and to contribute to the timeframe for when Earth began to resemble the modern crustal compositon and structure. This was conducted by obtaining ages for the mineral zircon and geochemical data for the mineral apatite from some of Earth’s oldest known rocks covering a timespan of approximately one billion years. The main conclusion of this work is that enriched, ancient pockets of crust could survive for long timescales (at least several hundred million years) in the early Earth without being recycled into the mantle. This idea fits into previously proposed models for stagnant plate movements in the ancient Earth compared to more mobile plate movements that operate in the present day. ivPrefaceThis thesis contains two research chapters (Chapter 2 and Chapter 3) that have been written for submission to peer-reviewed geoscience journals and include co-authors who contributed to their development. I am the lead author and investigator on both chapters and my supervisor Dr. Matthijs Smit is a co-author on both studies and provided extensive feedback and editing for the chapters. Details of the work conducted by all coauthors for the research in these chapters are outlined below.Chapter 2Evidence for evolved Hadean crust from Sr isotopes in apatite within Eoarchean zircon from the Acasta Gneiss ComplexAuthors: Robert B. Emo, Matthijs A. Smit, Melanie Schmitt, Ellen Kooijman, Erik E. Scherer, Peter Sprung, Wouter Bleeker & Klaus MezgerM. A. Smit and myself designed and conducted the LA-ICPMS U-Pb zircon and trace element analytical sessions. M. Schmitt and E. Kooijman designed the analytical routine for the Rb-Sr apatite analysis and conducted the analyses along with myself. E. E. Scherer, P. Sprung and W. Bleeker obtained the Acasta Gneiss Complex samples and provided mineral separates. All co-authors contributed to the editing of the manuscript. vChapter 3The longevity and fate of ancient evolved crust during the Archean from Sr isotopes in apatiteAuthors: Robert B. Emo, Matthijs A. Smit, Melanie Schmitt, Ellen Kooijman, Anders Scherstén, Alessandro Maltese & Klaus MezgerM. A. Smit and myself designed and conducted the LA-ICPMS U-Pb zircon and trace element analytical sessions of the Kvanefjord block samples. M. Schmitt and E. Kooijman designed the analytical routine for the Rb-Sr analysis and conducted the analyses along with myself. A. Scherstén provided the Kvanefjord block samples and I processed these samples (sample crushing and mineral separation). A. Maltese and K. Mezger obtained the Bastar Craton samples and provided mineral separates.viTable of ContentsAbstract                                                                                            iiLay Summary                                                                                     iiiPreface                                                                                             ivTable of Contents                                                                                  viList of Tables                                                                                       xList of Figures                                                                                     xiList of Abbreviations                                                                            xivAcknowledgements                                                                               xviDedication                                                                                        xvii1  Introduction                                                                                  11.1.  Introduction and scope of the project   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  11.2.  The Hadean-Archean crust . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41.2.1. Overview of Hadean-Archean crustal evolution . . . . . . . . . . . . . . . . 41.2.2. Hadean-Archean zircon studies   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  61.2.3. Sr isotopes and crustal evolution . . . . . . . . . . . . . . . . . . . . . . . . 71.3.  Apatite geochemistry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101.4.  Sample availability . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 121.5.  Regional geological backgrounds  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 121.5.1. Overview of the Acasta Gneiss Complex   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 121.5.2. Overview of the Bastar Craton . . . . . . . . . . . . . . . . . . . . . . . . . 131.5.3. Overview of the Kvanefjord block . . . . . . . . . . . . . . . . . . . . . . . 131.6.  Overview of the thesis  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14vii2  Evidence for evolved Hadean crust from Sr isotopes in apatite within Eoarchean zircon from the Acasta Gneiss Complex                                                         172.1.  Introduction   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 172.2.  Geological Background   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 192.2.1. The Slave Province . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 192.2.2. Geological setting of the Acasta Gneiss Complex . . . . . . . . . . . . . . . 212.3.  Analytical Methods   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 232.3.1. LA-ICPMS U-Pb zircon dating   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 232.3.2. Zircon trace elements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 262.3.3. Sr isotopes of matrix apatite and apatite inclusions in zircon  . . . . . . . . . 272.4.  Results  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 342.4.1. Zircon.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 342.4.2. Apatite Sr isotopes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382.5.  Discussion  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 392.5.1. The Rb-Sr record of apatite  . . . . . . . . . . . . . . . . . . . . . . . . . . 392.5.2. Source and crustal evolution .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 412.6.  Conclusions   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 453  The longevity and fate of ancient evolved crust during the Archean from Sr isotopes in apatite                                                                                           463.1.  Introduction   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 463.2.  Geological setting and sample descriptions  . . . . . . . . . . . . . . . . . . . . . . 493.2.1. Bastar Craton . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 493.2.2. Kvanefjord block . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52viii3.3.  Analytical Methods   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 543.3.1. Zircon U-Pb analyses.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 543.3.2. Zircon trace element analyses  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 553.3.3. Apatite Sr isotope analyses . . . . . . . . . . . . . . . . . . . . . . . . . . . 553.4.  Results  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 563.4.1. Textures of zircon and apatite in the Kvanefjord block  .  .  .  .  .  .  .  .  .  .  .  . 563.4.2. Kvanefjord block zircon U-Pb and trace element results  . . . . . . . . . . . 593.4.3. Matrix apatite Sr isotope results  . . . . . . . . . . . . . . . . . . . . . . . . 613.5.  Discussion  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 623.5.1. Exploring possible alteration of apatite Sr isotope signatures  . . . . . . . . . 623.5.2. Investigation of possible sources to the TTG samples . . . . . . . . . . . . . 663.6.  Conclusions   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 704  Conclusions                                                                                  724.1.  The evolution of the Acasta Gneiss Complex  . . . . . . . . . . . . . . . . . . . . . 734.2.  The evolution of Archean crust   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 754.3.  Future developments   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 77Bibliography                                                                                       80Appendices                                                                                        94Appendix A  LA-ICPMS U-Pb results for the secondary zircon standard FC-1 . . . . . . . . . 94Appendix B  Complete U-Pb analyses of zircon from the Acasta Gneiss Complex, Northwest Territories, Canada, determined by LA-ICPMS   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 96Appendix C  Zircon U-Pb Wetherill concordia plots and age histograms for additional Acasta Gneiss Complex samples  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 115ixAppendix D  Major and minor element oxides of zircon from the Acasta Gneiss Complex and the Kvanefjord Block determined by EPMA . . . . . . . . . . . . . . . . . . . . . . . . . . 118Appendix E  Complete trace element analyses of zircon from the Acasta Gneiss Complex, Northwest Territories, Canada, determined by LA-ICPMS . . . . . . . . . . . . . . . . . . . 123Appendix F  Cathodoluminescence images of zircon grains from the Acasta Gneiss Complex 125Appendix G  Thin section scans of samples from the Kvanefjord block   .  .  .  .  .  .  .  .  .  .  . 166Appendix H  Complete U-Pb analyses of zircon from the Kvanefjord block, Greenland . . . 170Appendix I  Complete trace element analyses of zircon from the Kvanefjord block, determined by LA-ICPMS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 172Appendix J  Cathodoluminescence images of zircon from the Kvanefjord block analysed by LA-ICPMS  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 176Appendix K  Optical microscopy images for Kvanefjord Block and Bastar Craton apatite grains analysed by LA-MC-ICPMS  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 182Appendix L  Apatite Sr isotope data of samples from the Kvanefjord block, Greenland, and the Baster Craton, India, determined by LA-MC-ICPMS  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 184xList of TablesTable 1 1  Summary of Appendix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16Table 2 1  Summary of Acasta Gneiss Complex samples analysed in this study . . . . . . . . . 23Table 2 2  Apatite Rb-Sr analysis instrument setup   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 31Table 2 3  Isobaric interferences and Faraday cup configuration for Rb-Sr isotopic analyses . . 31Table 2 4  LA-MC-ICPMS Rb-Sr isotopic compositions for  apatite from the Acasta Gneiss Complex . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33Table 3 1  Summary of samples analysed in this study . . . . . . . . . . . . . . . . . . . . . . 51Table A 1  Complete LA-ICPMS U-Pb data for FC-1  . . . . . . . . . . . . . . . . . . . . . . 94Table B 1  Zircon LA-ICPMS U-Pb data for Acasta Gneiss samples  .  .  .  .  .  .  .  .  .  .  .  .  .  . 96Table D 1  Major and minor element oxides in zircon from the Acasta Gneiss Complex  . . . 118Table D 2  Major and minor element oxides in zircon from the Kvanefjord Block  . . . . . . 122Table E 1  Trace element concentrations of zircon from the Acasta Gneiss Complex measured by LA-ICPMS  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 123Table H 1  Zircon LA-ICPMS U-Pb data for the Kvanefjord block samples   .  .  .  .  .  .  .  .  . 170Table I 1  Trace element concentrations of zircon from the Kvanefjord block measured by LA-ICPMS.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 172Table L 1  LA-MC-ICPMS Sr isotope data for Kvanefjord block apatite  . . . . . . . . . . . 184Table L 2  LA-MC-ICPMS Sr isotope data for Bastar Craton apatite  . . . . . . . . . . . . . 185xiList of FiguresFigure 1 1  World map showing the approximate distribution of Phanerozoic, Proterozoic and Archean rocks and the location of the areas of focus of this study, modified from Furnes et al. (2014).   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  3Figure 1 2  Geological timeline of the Hadean and Archean eons (modified from Cohen et al., 2013) with the timing of important events with regard to Hadean-Archean crustal evolution and the tonalite-trondhjemite-granodiorite suites analysed in this thesis. . 6Figure 1 3  Strontium isotope composition of carbonate rocks with time (modified from Shields and Vezier, 2002; Vezier and Mackenzie, 2014). . . . . . . . . . . . . . . . . . . . 10Figure 1 4  Summary of the physical properties, important substitutions and geochemical applications of apatite, based on Pan and Fleet (2002) and Hughes and Rakovan (2015).   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 11Figure 2 1  Geological setting of the Slave Province and the Acasta Gneiss Complex. . . . . . 21Figure 2 2  U-Pb systematics for the secondary zircon standard FC-1 measured by LA-ICPMS during this study: (a) Wetherill concordia plot for FC-1 analyses; (b) Weighted mean 207Pb/206Pb age for FC-1 analyses.   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 26Figure 2 3  Fractionation corrections for U-Pb analysis AMS030C_083 conducted with (a) the linear intercept method with an Excel macro using the protocol of Kooijman et al. (2012) and (b) the exponential curve method with Iolite v3 using the protocol in Paton et al. (2010).  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26Figure 2 4  Cathodoluminescence images of Acasta Gneiss Complex zircon grains containing apatite inclusions from samples AMS027 (a)-(e) and AMS013 (f)-(g).  . . . . . . . 28Figure 2 5  Examples of individual peaks for the Sr isotope analysis of apatite by LA-MC-ICPMS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30Figure 2 6  The 87Sr/86Sr values obtained for repeated LA-MC-ICPMS analysis of the Holly Springs secondary apatite standard (TIMS 87Sr/86Sr = 0.718926 ± 0.000014) during the course of the analytical session.   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 32xiiFigure 2 7  Results from MC-ICPMS analyses of a 25 ppb solution of the NBS-987 Sr standard reference material spiked with varying concentrations of Rb (2.5 ppt, 25 ppt, 0.1 ppb; 0.25 ppb; 6 analyses per solution). . . . . . . . . . . . . . . . . . . . . . . . . . . 32Figure 2 8  Examples of cathodoluminescence images for zircon grains from samples AMS027 (a)-(c) and AMS013 (d)-(f).   .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 35Figure 2 9  U-Pb zircon age systematics for samples AMS013 and AMS027 from the Acasta Gneiss Complex.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36Figure 2 10  Th/U versus 207Pb/206Pb date for >90% concordant zircon grains from sample AMS027, with higher Th/U for grains from the 3.7 Ga population. . . . . . . . . . 37Figure 2 11  Chondrite normalised rare earth element (REE) plots for zircon grains from samples AMS027 and AMS013 from the Acasta Gneiss Complex. . . . . . . . . . . . . . . 37Figure 2 12  Sr isotopes results for all apatite inclusions and grains from samples AMS027 (squares) and AMS013 (circles). . . . . . . . . . . . . . . . . . . . . . . . . . . . 38Figure 2 13  Rb-Sr isotopic results and evolution diagram for apatite inclusions from the Acasta Gneiss Complex.  . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41Figure 3 1  Simplified geological map of the Bastar Craton, India, with sample locations shown (modified after Meert et al., 2010). . . . . . . . . . . . . . . . . . . . . . . . . . . 50Figure 3 2  LaN/YbN versus YbN plot of whole rock samples from the Acasta Gneiss Complex, Kvanefjord block and Bastar Craton (from Smit et al., in review).  .  .  .  .  .  .  .  .  . 51Figure 3 3  Simplified geological map of the Kvanefjord block, southwest Greenland, with sample locations shown (modified after Windley and Garde, 2009).   .  .  .  .  .  .  .  . 53Figure 3 4  Examples of cathodoluminescence images for zircon grains from Kvanefjord block TTG samples. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 58Figure 3 5  Examples of optical microscopy images of apatite grains from the four Kvanefjord block samples.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 59Figure 3 6  Wetherill concordia plots for Kvanefjord block U-Pb zircon analyses.  . . . . . . . 60Figure 3 7  Chondrite-normalised rare earth element (REE) patterns for zircon crystals from the Kvanefjord block TTG samples. Normalisation values after McDonough and Sun (1995) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 61xiiiFigure 3 8  Initial 87Sr/86Sr values of matrix apatite from Archean TTG rocks measured by LA-MC-ICPMS. The Acasta values are of apatite inclusions in zircon from Chapter 2. 62Figure 3 9  Photomicrographs of apatite grains from samples 508281 (left) and 468623 (right) from the Kvanefjord block. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 63Figure 3 10  Measured 87Sr/86Sr versus the ratio between Rb/Sr of each apatite grain and the whole rock Rb/Sr (F) of the respective sample.  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  .  . 65Figure 3 11  Possible source ages and compositions for TTG samples.  . . . . . . . . . . . . . 67Figure 4 1  Schematic diagram of how ancient crust evolved from the Hadean to Archean based evidence presented in Chapters 2 and 3, and proposals from Kamber et al. (2005) and Kamber (2015). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 77xivList of AbbreviationsAnalytical:CL: cathodoluminescenceEPMA: electron probe micro-analyserGa: billion yearsLA-ICPMS: laser ablation-inductively coupled plasma-mass spectrometryLASS: laser ablation split streamMa: million yearsMC-ICPMS: multicollector-inductively coupled plasma-mass spectrometryMSWD: mean squared weighted deviationNIST SRM 612: National Institute of Standards and Technology Standard Reference Material 612 (glass)ppb: parts per billionppm: parts per millionSEM: scanning electron microscopyTIMS: thermal ionisation mass spectrometryμm: micronGeological:AGC: Acasta Gneiss Complexap: apatiteBSE: bulk silicate Earthbt: biotiteep: epidotegrt: garnethbl: hornblendeHREE: heavy rare earth elements (Gd-Lu)ilm: ilmenitekfs: K-feldsparLREE: light rare earth elements (La-Eu)LILE: large ion lithophile elementms: muscoviteplag: plagioclaseqtz: quartzxvREE: rare earth element (La-Lu)ttn: titaniteTTG: tonalite-trondhjemite-granodioritezrn: zirconxviAcknowledgementsI would first and foremost like to thank my supervisor, Dr. Matthijs Smit, for his enduring support, fruitful discussions and vital feedback throughout this project. I am also very grateful to my committee members, Drs James Scoates and Dominique Weis for their advice and help. I thank all the graduate students and postdocs in the PCIGR group, past and present, for their support and friendship throughout my time here.  I am deeply grateful to my family back in Ireland, particularly my mom, who have supported me from afar throughout this project. I am very thankful to Chris Cottier for all of his assistance during my time in Vancouver.I am grateful to Dr. Mati Raudsepp, Edith Czech, Elisabetta Pani, Lan Kato, Jenni Lai from the Electron Microbeam and X-Ray Diffraction Facility for their assistance with the SEM and electron microprobe. I thank Vivian Lai for providing her help and expertise with the zircon LA-ICPMS work at PCIGR. Many thanks also go to Melanie Schmitt and Dr. Ellen Kooijman at the Swedish Museum of Natural History for their assistance with the LA-MC-ICPMS Sr isotope analysis. xviiDedicationTo dad,Who will always be my inspiration11  Introduction1 1   Introduction and scope of the projectThe composition and evolution of Earth’s ancient crust are vigorously debated subjects in the geoscience community (e.g., Harrison, 2009; Kamber, 2015). This is an area of research with implications that relate to a variety of broader topics, such as the beginning of life on Earth (Mojzsis et al., 2001; Wilde et al., 2001) and the start of modern style plate tectonics (Harrison et al., 2005; Næraa et al., 2012; Dhuime et al., 2015; Kamber, 2015; Tang et al., 2016). The lack of consensus on the subject of early crustal evolution is primarily due to the poor preservation of Hadean-Archean crust and the propensity for geochemical signatures of ancient rocks to be altered during later metamorphic events. Establishing primary geochemical and isotopic signatures from those that have been affected by secondary events is required to unravel the evolution of Earth’s ancient crust (e.g., Mojzsis et al., 2014). The mineral zircon has been at the centre of many studies focused on the early Earth (e.g., Harrison, 2009; Kemp et al., 2010; Reimink et al., 2016; Bauer et al., 2017), as it is a robust mineral that can be dated through U-Pb geochronology. Zircon can also be used to study the composition and evolution of crustal sources via Hf and O isotope analyses (e.g., Mojzsis et al., 2001; Kemp et al., 2010; Næraa et al., 2012; Reimink et al., 2016b). Recently, several studies have focused on analysing mineral inclusions within zircon crystals (Bell et al., 2015; Delavault et al., 2016) and developments in this area may provide important breakthroughs in crustal evolution research. In situ geochemical and isotopic analyses of inclusions in zircon may provide either corroborative evidence to the zircon record or new insights into crustal evolution that may not have been recorded in zircon. This thesis focuses on the use of laser ablation-multicollector-inductively coupled plasma-mass spectrometry (LA-MC-ICPMS) Sr isotope analysis of apatite, a method developed as part of this 2study, to investigate the formation and composition of some of Earth’s oldest crustal fragments. The thesis contains two research chapters that utilise the Rb-Sr isotopic system in apatite and U-Pb zircon geochronology and trace element geochemistry of Archean tonalite-trondhjemite-granodiorite (TTG) rocks. The first chapter provides the results of Sr isotope analysis of apatite inclusions in zircon from the Acasta Gneiss Complex, Northwest Territories, with the aim of reconstructing the Eoarchean initial 87Sr/86Sr record and using this to investigate the composition of possible sources to the Acasta Gneiss Complex protolith rocks. The Acasta Gneiss Complex contains the oldest known terrestrial rocks with protolith ages of up to 4.03 Ga (Bowring and Williams, 1999; Iizuka et al., 2007; Mojzsis et al., 2014; Reimink et al., 2016a) and therefore provides a window into the earliest history of our planet. However, this region is also known for its complex geological history, with numerous metamorphic and alteration events potentially obscuring the original formation and source history. Primary apatite inclusions found within zircon crystals may provide a solution to this issue; these inclusions can preserve initial Sr isotope signatures of the host rock as they could be shielded within the zircon from post-magmatic alteration and can therefore yield insights into how this ancient crust formed. Recent developments in LA-MC-ICPMS now allow small (~30 μm) apatite inclusions to be analysed. Combining these Sr isotope compositions with U-Pb zircon geochronology provides a time-resolved record of the composition of the Acasta Gneiss Complex and its ancient source. The second research chapter focuses on Sr isotopes of matrix apatite from well-preserved TTG rocks from the ca 3.0 Ga Kvanefjord block, west Greenland, and the ca. 3.5 Ga Bastar Craton, central India. Several studies have proposed that there was a secular change in the composition of Earth’s crust from more mafic compositions to more felsic at approximately 3 Ga (Næraa et al., 2012; Dhuime et al., 2015; Tang et al., 2016; Smit and Mezger, 2017) and this change has been 3linked to the onset of modern-style plate tectonic mechanisms (Næraa et al., 2012; Dhuime et al., 2015; Tang et al., 2016). The Kvanefjord and Bastar rocks, combined with the AGC rocks from Chapter 2, cover much of the timeline of the Archean Eon, and thus allow time-resolved insight into TTG source compositions throughout the Archean.The introduction chapter contains background information on ancient crustal evolution, with insight into the various models that have been proposed for Hadean-Archean crust. It provides an overview on how Sr isotopic compositions may be useful in crustal evolution studies and a background to the methods used to analyse Sr isotopes in apatite. This introduction chapter also provides sample availability and basic geological background information on the complexes that contain the TTG samples analysed in this study: the Acasta Gneiss Complex, Northwest Territories, the Bastar Craton, India, and the Kvanefjord block, West Greenland (Figure 1.1). Figure 1 1  World map showing the approximate distribution of Phanerozoic, Proterozoic and Archean rocks and the location of the areas of focus of this study, modified from Furnes et al. (2014).41 2   The Hadean-Archean crust1 2 1  Overview of Hadean-Archean crustal evolutionEarly studies in the 1960s and 1970s on crustal evolution used the available whole rock Pb and Sr isotopic evidence to investigate crustal growth (Hurley et al., 1962; Armstrong, 1968; Hurley and Rand, 1969; Moorbath and Pankhurst, 1976; Moorbath, 1977). However, the lack of discovered rock samples >3 Ga limited the interpretations that could be presented to broad inferences about the growth of continental crust with time (e,g, Hurley et al., 1962). Other studies have argued against crustal growth over time, instead proposing a steady state model of crustal evolution (Armstrong, 1968). As analytical methods have developed and more ancient rocks have been discovered, crustal growth curves have become better constrained (McLennan and Taylor, 1982; Dhuime et al., 2012). However, the major limitation of these growth curves, particularly with regard to Archean crustal evolution, is that they only apply to the preserved crust (Kemp and Hawkesworth, 2014).The scarcity of intact crust >3.85 Ga on Earth creates great difficulty when investigating the nature of Earth’s earliest crust. Some studies have proposed a uniformitarian model early in Earth’s history (>4.3 Ga) with large continents and modern-style plate tectonics operating (Wilde et al., 2001; Harrison et al., 2005), whereas others have suggested that Earth’s earliest crust was dominantly mafic in composition and that any emerged crust geochemically resembled oceanic plateaux rather than present-day continental crust (Kamber, 2010). Non-uniformitarian tectonic models include sluggish plate tectonics, in which the hotter mantle resulted in stiff, buoyant lithospheric plates that were difficult to subduct (Caro et al., 2017); or the similar stagnant lid tectonic model involving episodic periods of subduction (O’Neill and Debaille, 2014). Studying Earth’s earliest crust relies strongly on geochemical analyses of the few 5Eoarchean rocks that have been preserved at the Earth’s surface (e.g. the Acasta Gneiss Complex, Northwest Territories, and Nuvvuagittuq Greenstone Belt, Québec), as well as detrital Hadean zircon found in younger sedimentary rocks, such as the Jack Hills zircon (Harrison, 2009). The Hadean-Eoarchean boundary at 4 Ga approximately corresponds to the first known appearance of preserved terrestrial rocks in the geological record, the Acasta Gneiss Complex (Figure 1.2)(Van Kranendonk et al., 2012). Detrital Hadean zircon grains provide valuable geochemical constraints on the composition of the Hadean crust (e.g., the abundance of muscovite inclusions may suggest an aluminous protolith; Bell et al., 2015), however, the information that can be derived from them is limited by the lack of a preserved host. Further evidence for the nature of the Hadean crust and mantle is provided by radioactive isotopes with relatively short-lived half-lives on a geological timescale. The 146Sm-142Nd system (half-life of t1/2 = 103 Ma; Meissner et al., 1987) shows that differentiation must have occurred in the first few hundred million years of Earth’s history to produce the anomalous 142Nd/144Nd, relative to the modern terrestrial standard, observed in several Archean complexes as young as 2.7 Ga (Debaille et al., 2013; Roth et al., 2014; Caro et al., 2017; O’Neil and Carlson, 2017). These anomalies demonstrate that enriched Hadean reservoirs existed and were reworked to form Archean crust. However, there is debate as to whether Hadean crust itself contributed to the formation of the Archean crust, which would mean parts of this crust survived in some form for >1 billion years (O’Neil et al., 2017), or the anomalies are derived from enriched mantle reservoirs formed during the Hadean that could be preserved due to inefficient mantle mixing (Bennett et al., 2007; Rizo et al., 2012; Debaille et al., 2013).61 2 2  Hadean-Archean zircon PaleoarcheanEoarcheanMesoarcheanNeoarcheanHadeanArchean456840003600320028004404, oldest detrital Jack Hills zircon a4030, oldest Acasta Gneiss protolith  c, doldest Bastar Craton granitoid e, f ~3000, global crustal change from mafic to felsic compositions g, h, i, j4200, Acasta Gneiss zircon xenocryst b2940, oldest Kvanefjord block TTG protolith kEraEon2500MaFigure 1 2  Geological timeline of the Hadean and Archean eons (modified from Cohen et al., 2013) with the timing of important events with regard to Hadean-Archean crustal evolution and the tonalite-trondhjemite-granodiorite suites analysed in this thesis. References are indicated by superscript letters: (a) Wilde et al. (2001); (b) Iizuka et al. (2006); (c) Bowring and Williams (1999); (d) Reimink et al. (2016a); (e) Ghosh et al. (2004); (f) Rajesh et al. (2009); (g) Næraa et al. (2012); (h) Dhuime et al. (2015); (i) Tang et al. (2016); (j) Smit and Mezger (2017); (k) Friend and  Nutman (2001).studiesThe mineral zircon (ZrSiO4) has been the focus of many early Earth studies as it is a robust mineral that can be easily dated using the U-Pb method (Fryer et al., 1993; Košler and Sylvester, 2003; Jackson et al., 2004). Zircon crystals found in a 3 Ga conglomerate from the 7Jack Hills, Australia, have been dated to as old as 4.404 ± 0.008 Ga and represent the oldest terrestrial material thus far found (Wilde et al., 2001). U-Pb zircon geochronology has also been used to date some lithologies in the Acasta Gneiss Complex to 4.03 Ga (Bowring and Williams, 1999; Iizuka et al., 2007; Mojzsis et al., 2014; Reimink et al., 2016a). Lu-Hf zircon isotope data, typically obtained through LA-MC-ICPMS, combined with U-Pb geochronology data can be used to study crust-mantle evolution (Kemp and Hawkesworth, 2013; Reimink et al., 2016; Vervoort and Kemp, 2016; Bauer et al., 2017). Oxygen isotope studies of the Jack Hills zircon have been used to argue for recycling of continental crust under low-temperature, water-rich conditions in the Hadean (Mojzsis et al., 2001; Wilde et al., 2001). However, due to the complex nature of these zircon crystals, the robustness of the geochronologic results for the Hadean zircon crystals from the Jack Hills analysed in this study, and the Hf and O isotope data, has recently been called into question (Whitehouse et al., 2017; Bellucci et al., 2018). This highlights the need to develop other isotope methods to corroborate with the ancient zircon record. Recently, there has been a focus on mineral inclusion assemblages within zircon crystals to investigate the Hadean-Archean crustal record. Thus far these studies have mainly focused on textural information and bulk percentages of inclusions along with major and minor element geochemistry for certain inclusions (e.g., muscovite; Hopkins et al., 2010; Rasmussen et al., 2011; Bell et al., 2015). The next logical advance is to target inclusions for isotopic and trace element analyses (e.g., Sr isotopes in apatite inclusions), provided the inclusions are primary and large enough to perform such analyses at sufficient analytical resolution.1 2 3  Sr isotopes and crustal evolutionShort-lived radioisotopes such as 146Sm, as well as the more commonly used 177Lu-176Hf 8and 147Sm-144Nd systems, hold important information for ancient earth studies, however, they do have issues. In both systems, the parent and daughter elements (Sm/Nd, Lu/Hf)  have relatively similar partitioning behaviour to each other, and therefore the deviations produced through chemical differentiation events are relatively small (Kemp et al., 2010; Dhuime et al., 2015). This results in the differences between potential source reservoirs for Archean rocks being obscured or overlapping within the error of the measured 176Hf/177Hf or 143Nd/144Nd of a given sample. The Rb-Sr system generally does not have this issue. Rubidium is a highly incompatible, large ion lithophile element (LILE), and is therefore concentrated in more evolved crust. Strontium is also an incompatible element, however, it is more compatible than Rb during crustal differentiation. As 87Rb decays through β-decay to 87Sr (λ87Rb = 1.393 x 10-11 yr-1; Nebel et al., 2011), the analysed 87Sr/86Sr can be used to study the nature of the crust: evolved crust will generally have higher 87Sr/86Sr values while more mafic or juvenile material will have lower 87Sr/86Sr values. Early isotopic studies demonstrated the importance of the Rb-Sr system with regards to crustal evolution (Hurley et al., 1962; Hurley and Rand, 1969; Moorbath and Pankhurst, 1976). These studies used available 87Sr/86Sr whole rock data to generally show the formation and distribution of continental crust with time. The 87Sr/86Sr of carbonate rocks can constrain the isotopic evolution of the oceans, which is controlled by mantle input (low 87Sr/86Sr ~0.700) and riverine input derived from the continental crust (high 87Sr/86Sr~0.730) (Shields and Veizer, 2002; Veizer and Mackenzie, 2014). As the continental crust evolved to its present composition and volume, the 87Sr/86Sr composition of the oceans, preserved in the carbonate rock record, has transitioned from “mantle-buffered” in the Archean to river-buffered from the Proterozoic onwards (Figure 1.3)(Veizer et al., 1982; Veizer and Mackenzie, 2014). The limitation of these studies with regard to Archean crustal evolution is the lack of preserved Archean carbonate 9rocks and the poor age constraints on the few examples that are preserved. A recent study by Dhuime et al. (2015) combined 87Sr/86Sr and Nd model ages of over 13,000 magmatic rocks to estimate Rb/Sr values of juvenile crust that correlate with wt % SiO2. They found there was a change from low Rb/Sr before ca. 3 Ga, to higher values after 3 Ga, indicating a change from dominantly mafic crust to more evolved, thick crust. This change was interpreted to represent a shift to modern-style plate tectonics. Other studies have reached a similar conclusion with other methods (e.g., zircon Hf isotopic compositions, Næraa et al., 2012), yet there are some problems with the approach used in the study of Dhuime et al. (2015). Firstly, there are few analyses for rocks older than 3.6 Ga and those that do exist may have been affected by later alteration, which is common in such ancient rocks and can particularly affect Rb due its high mobility. Therefore these may not represent primary Rb-Sr or Sm-Nd isotopic systematics. Another issue is the discrepancy between some crystallisation ages and Nd model ages, which are interpreted to represent crustal residence times (Dhuime et al., 2015). Several samples in the large dataset have crystallisation ages up to the present day and unrealistically long crustal residence times from the Nd model ages (as old as 4 Ga), which skews the oldest juvenile Rb/Sr data to very low values and therefore more mafic crust. Different approaches to acquire new Sr isotope data are required for Archean rocks to fully assess the accurate 87Sr/86Sr of rocks of Archean age.1087Sr/ 86 Sr0.7000.7020.7040.7060.7080.710Age (Ga)3.5 3.0 2.5 2.0 1.5 1.0 0.5 0Seawater evolutionMantle contributionFigure 1 3  Strontium isotope composition of carbonate rocks with time (modified from Shields and Vezier, 2002; Vezier and Mackenzie, 2014). Minimum  87Sr/86Sr values for a given time provide an estimate for the 87Sr/86Sr of seawater, with values generally increasing from the Archean to the present due to an increase in more radiogenic riverine input derived from continental crust. Open circles represent samples with poor age constraints (errors >50 Ma; Shields and Vezier, 2002).1 3   Apatite geochemistryAnalysing Sr isotopes in apatite provides an alternative to relying on bulk-rock Rb/Sr and 87Sr/86Sr for Archean crustal evolution studies. Apatite (Ca5(PO4)3(F,Cl,OH)) is a phosphate mineral group that commonly occurs as an accessory mineral in magmatic rocks (Figure 1.4). It is a useful mineral in geochronology and thermochronology studies, as it can be dated through several methods that each have a different closure temperature: U-Pb (350-550°C) (Chew et al., 2014; Chew and Spikings, 2015), fission track (60-110°C) (Gallagher et al., 1998; Donelick et al., 2005), (U-Th)/He (40-80°C) (Zeitler et al., 1987; Shuster et al., 2006). Apatite can also be used as a low Rb/Sr isochron anchor in Rb-Sr geochronology (e.g. Kruger et al., 1998), and may, if primary, provide an accurate estimate of the initial 87Sr/86Sr ratio (87Sr/86Sr0) of the rock. This is 11due to the fact that Sr is easily substituted as Sr2+ for the cation Ca2+, forming an extensive solid solution series, whereas Rb is highly incompatible in the apatite structure (Pan and Fleet, 2002). Sr concentrations in apatite are typically >400 ppm (Yang et al., 2014). Primary apatite grains have very low Rb/Sr values so internal 87Rb decay to 87Sr is usually negligible within the apatite grain and the measured 87Sr/86Sr ratio of the apatite provides an accurate estimate of 87Sr/86Sr0. Primary apatite can be identified through textural settings (in the whole rock as matrix apatite or in a zircon host grain as inclusions) and geochemical characteristics (e.g., post-magmatic alteration may result in higher Rb/Sr). There is evidence that even under conditions in which the whole rock Sr isotope record has been modified, apatite crystals may still preserve 87Sr/86Sr0 (Creaser and Gray, 1992; Kruger et al., 1998; Tsuboi, 2005). This makes apatite an ideal mineral for Archean crustal evolution studies as 87Sr/86Sr0 can be used in conjunction with U-Pb age data from a rock to evaluate the nature and evolution of the magmatic source.ApatiteFormula Ca5(PO4)3(F,Cl,OH)System hexagonalHardness 5Specific Gravity 3.16-3.22Cell Parameters a = 9.4-9.6 Å, c = 6.8-6.9 ÅBirefringence first orderRelief moderate-highImportant substitutions and geochemical applicationsSr2+→ Ca2+ 87Sr/86Sr, crustal evolution, Rb-Sr isochron anchorREE2+,3+→ Ca2+ (1) Provenance indicator & fingerprinting magmatic processesU4+,Th4+→ Ca2+ (1) U-Pb geochronologyFigure 1 4  Summary of the physical properties, important substitutions and geochemical applications of apatite, based on Pan and Fleet (2002) and Hughes and Rakovan (2015). (1) Substitutions shown are simplified because there are multiple, complex possible substitutions that are not fully understood. Right: Photomicrograph of a prismatic apatite crystal from sample 468623 of the Kvanefjord block, southwest Greenland, showing first-order gray interference colours (XPL = cross-polarised light).121 4   Sample availabilityZircon mineral separates from nine rock samples from the Acasta Gneiss Complex, Northwest Territories, were provided for this study. Apatite mineral separates were also made available for one of these samples (AMS013). Apatite mineral separates were provided for two rock samples from the Bastar Craton, India. Four tonalite rock samples from the Kvanefjord block, Southwest Greenland, were supplied for this study.1 5   Regional geological backgroundsThe three tonalite-trondhjemite-granodiorite (TTG) Archean complexes studied in this thesis (Acasta Gneiss Complex, Bastar Craton, Kvanefjord block) cover most of the timespan of the Archean (4.0-2.8 Ga), therefore providing a window into the evolution of initial 87Sr/86Sr of TTG crust with time. The TTG samples were chosen as they are relatively pristine, with little evidence for post-magmatic alteration in most samples. They are therefore more likely to retain the primary geochemical and isotopic signatures of the protolith. 1 5 1  Overview of the Acasta Gneiss ComplexThe Acasta Gneiss Complex (AGC) is an area of basement gneisses exposed in the westernmost part of the Slave Craton in the Northwest Territories, Canada (Figure 1.1) (Bowring et al., 1989; Iizuka et al., 2007). It is composed of gneisses of variable composition, ranging from mafic to felsic. A northeast-trending fault divides the complex into high strain gneisses to the west of this fault and low-strain gneisses to the east (Iizuka et al., 2007). Uranium-lead zircon dating of rocks from the AGC yield protolith ages of 4.03-3.94, 3.75-3.72 and 3.6 Ga (Bowring et al., 1989; Stern and Bleeker, 1998; Bowring and Williams, 1999; Iizuka et al., 2007; 13Mojzsis et al., 2014; Reimink et al., 2014; Reimink et al., 2016a), with a single zircon xenocryst dated to 4.2 Ga (Iizuka et al., 2006). Hafnium isotope studies of zircon indicate the involvement of Hadean mafic crust in the formation of the AGC (Amelin et al., 2000; Iizuka et al., 2009; Reimink et al., 2016b; Bauer et al., 2017). Pooled whole rock Sm-Nd isotopic compositions from different AGC lithologies of the whole complex give an Sm-Nd resetting age of ca. 3.4 Ga (Bowring and Housh, 1995; Moorbath et al., 1997; Mojzsis et al., 2014), although the geological significance of this age has been disputed and older Sm-Nd ages similar to the oldest zircon ages have been presented (Sprung et al., 2016; Reimink et al., 2016b). 1 5 2  Overview of the Bastar CratonThe Bastar Craton (also known as the Bastar-Bandara Craton) is located in central India (Figure 1.1) and is one of four Archean cratons found on the Indian peninsula (Sarkar et al., 1993). The basement of the craton consists of variably deformed TTG, which, based on zircon U-Pb studies, include domains as old 3.6 Ga (Sarkar et al., 1993; Ghosh, 2004; Rajesh et al., 2009). Trace element geochemistry and Pb isotopic signatures of the TTG have suggested a major input of juvenile material at ca. 3.5 Ga that was reworked at 2.5 Ga (Maltese et al., 2017). Supracrustal greenstone belts containing metasedimentary and metavolcanic rocks are also found associated with the TTG gneisses (Rajesh et al., 2009; Saha and Patranabis-Deb, 2014).1 5 3  Overview of the Kvanefjord blockThe Mesoarchean Kvanefjord block, West Greenland, consists of a 130-km long crustal segment of the North Atlantic Craton that extends towards the Greenland ice sheet (Windley and Garde, 2009). The block was initially interpreted to consist of several separate tectonothermal 14terranes (McGregor and Friend, 1997; Friend and Nutman, 2001), although more recently it has been proposed to be a contiguous crustal segment overlain by the Neria Nappe (Windley and Garde, 2009). The block consists of variably deformed orthogneisses and associated metavolcanic rocks, including those belonging to the Tartoq Group. Previously dated gneisses from the Kvanefjord block have protolith ages between 3.0 and 2.8 Ga (Windley and Garde, 2009; Szilas et al., 2013).1 6   Overview of the thesisThe research in this thesis, presented in Chapters 2 and 3, utilises Sr isotope signatures in apatite measured by LA-MC-ICPMS to investigate the composition and evolution of the Archean crust. This study aims to answer the question of what the initial 87Sr/86Sr record of Archean tonalite-trondhjemite-granodiorite (TTG) was and how this can be used to put constraints on the possible sources to Archean TTG crust. The first chapter focuses on the Acasta Gneiss Complex, Northwest Territories, with the goal of using Sr isotope analysis of apatite inclusions within zircon host grains from TTG to investigate the composition of the source material to this ancient crust. The second chapter combines these data with Sr isotope results from apatite from TTG of the Paleoarchean Bastar Craton, India, and Mesoarchean Kvanefjord block, West Greenland, to investigate the evolution of the Archean crust with time and to test whether there are any discernible differences in Sr isotope composition of apatite from Archean TTG with age. The research of these two chapters aims to answer several key questions with regard to early Earth crustal evolution: 1) what were the crustal source compositions of the Archean TTG complexes analysed in this thesis; 2) do these source compositions change or evolve throughout the Archean; 3) does the initial 87Sr/86Sr record of Archean apatite grains corroborate with other 15geochemical indicators of secular crustal evolution in the Archean (e.g. Dhuime et al., 2015; Næraa et al., 2012)? The main conclusions from the two research chapters are summarised in Chapter 4 along with ideas on the direction of future research. The Appendix to this thesis provides a catalogue of additional imagery, data and figures that supports the research presented in Chapters 2 and 3. The contents of the Appendix are summarised in Table 1.1.16Table 1 1  Summary of AppendixAppendix Appendix titleAppendix A LA-ICPMS U-Pb results for the secondary zircon standard FC-1Appendix B Complete U-Pb analyses of zircon from the Acasta Gneiss Complex, Northwest Territories, Canada, determined by LA-ICPMSAppendix C Zircon U-Pb Wetherill concordia plots and age histograms for additional Acasta Gneiss Complex samplesAppendix D Major and minor element oxides of zircon from the Acasta Gneiss Complex and the Kvanefjord Block determined by EPMAAppendix E Complete trace element analyses of zircon from the Acasta Gneiss Complex, Northwest Territories, Canada, determined by LA-ICPMSAppendix F Cathodoluminescence images of zircon grains from the Acasta Gneiss ComplexAppendix G Thin section scans of samples from the Kvanefjord blockAppendix H Complete U-Pb analyses of zircon from the Kvanefjord block, GreenlandAppendix I Complete trace element analyses of zircon from the Kvanefjord block, determined by LA-ICPMSAppendix J Cathodoluminescence images of zircon from the Kvanefjord block analysed by LA-ICPMSAppendix K Optical microscopy images for Kvanefjord Block and Bastar Craton apatite grains analysed by LA-MC-ICPMSAppendix L Apatite Sr isotope data of samples from the Kvanefjord block, Greenland, and the Baster Craton, India, determined by LA-MC-ICPMS 172  Evidence for evolved Hadean crust from Sr isotopes in apatite within Eoarchean zircon from the Acasta Gneiss Complex2 1   IntroductionModels for the development, composition, and evolution of Earth’s earliest continental crust largely rely on the analysis of Eoarchean and Hadean rocks. However, such rocks are exceedingly rare in the geologic record. One of the very few occurrences is found within the Acasta Gneiss Complex (AGC) of the westernmost Slave Province, Northwest Territories, Canada (Bowring et al., 1989; Bleeker and Davis, 1999; Bleeker et al., 1999; Bowring and Williams, 1999; Bleeker, 2002). Geochemical research on tonalite-trondhjemite-granodiorite (TTG) rocks from the AGC, including Nd, Hf and O isotope analysis, and extensive U-Pb dating, have yielded valuable insights into early crust formation (Bowring et al., 1989; Stern and Bleeker, 1998; Bowring and Williams, 1999; Iizuka et al., 2007; Mojzsis et al., 2014; Reimink et al., 2014, 2016b; Roth et al., 2014). Nevertheless, the nature and composition of the source of the AGC, and of Hadean and Eoarchean crust in general, is still subject to debate. New data and approaches are needed to advance knowledge on this matter. To contribute to this effort, this study focuses on using in situ Rb/Sr and Sr isotope analysis. This method provides an opportunity to characterise crustal composition, as well as the nature of the source (Hurley et al., 1962; Hurley and Rand, 1969; Dhuime et al., 2015). The approach is based on the premise that Rb—a highly incompatible, large ion lithophile element—is enriched in felsic, differentiated reservoirs, which consequently develop higher 87Sr/86Sr with time through the β- decay of 87Rb to 87Sr (λ87Rb = 1.393 ± 0.004 x 10-11 yr-1; Nebel et al., 2011). Due to the large differences in 18partitioning behaviour of Rb and Sr, 87Sr/86Sr values provide a more useful proxy for crustal evolution compared to the 176Hf/177Hf and 143Nd/144Nd systems typically analysed in ancient rocks. This is because their respective parent-daughter elements (Lu-Hf, Sm-Nd) have relatively similar incompatibility characteristics and thus produce a much more restricted range of ratios for different source materials (Kemp et al., 2010; Dhuime et al., 2015).In spite of the potential of the Rb-Sr isotopic system, it has so far been underexploited in research on early crustal evolution. The reconstruction of the initial 87Sr/86Sr of bulk rocks is challenging because of post-magmatic alteration and modification of the primary mineral assemblage and disturbance of Rb-Sr systematics. In such cases, initial 87Sr/86Sr may be estimated from minerals such as apatite, which contain Sr, but essentially no Rb. Primary isotopic signatures from this mineral may, however, also be compromised by alteration, metamorphic recrystallisation, or re-melting of the host rock. Such problems may be expected for polymetamorphic rocks of the AGC, the history of which is notably complex (Bowring et al., 1989; Stern and Bleeker, 1998; Bowring and Williams, 1999; Sano et al., 1999; Iizuka et al., 2007; Mojzsis et al., 2014; Reimink et al., 2014, 2016a; Roth et al., 2014). This limits the proper targets in apatite Rb-Sr analysis to microscopic apatite inclusions trapped in relict magmatic minerals.Recent advances provide a new approach in making such analyses possible as laser-ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) now enables 87Sr/86Sr analysis of small spots (30-90 μm) in apatite. A particularly powerful approach is the micro-analysis of apatite inclusions in zircon. Zircon can provide a robust inclusion host if not affected by radiation damage and fracturing (Harrison, 2009). In addition, zircon has the advantage of allowing U-Pb dating, thus providing minimum ages of its apatite inclusions. This 19age information is needed to accurately correct for 87Sr produced by internal 87Rb decay, yet is otherwise difficult to obtain. Apatite U/Pb is typically low and U-Pb dating of such material requires multiple analyses with different U/Pb (Chew et al., 2014). Considering that apatite inclusions are typically small (<50 μm), performing both Rb-Sr analysis and reliable U-Pb dating of the same material is analytically challenging, if not currently impossible. Combining apatite Rb-Sr analysis with age dating of a zircon host provides a useful analytical compromise that still permits reliable estimates of 87Sr/86Sr0, the 87Sr/86Sr value of apatite when it crystallized.Combining zircon U-Pb dating with Rb-Sr analysis of apatite inclusions provides an exciting new approach for the investigation of the Sr isotope record of crustal evolution in deep time. Because the required analytical developments are recent, the method is not yet widely applied and its full potential is yet to be explored. In this study, the use of LA-MC-ICPMS in apatite Rb-Sr micro-analysis is explored by applying this method to apatite inclusions in primary igneous zircon from Eoarchean TTG samples from the Acasta Gneiss Complex. The results are combined with U-Pb geochronology and published information on the development of this complex to investigate the Sr isotope signatures of these rocks and to assess the nature of their source. The apatite Sr isotope results are also compared to Hf isotope signatures in zircon from the Acasta Gneiss Complex (Bauer et al., 2017). While this may not be a direct comparison for investigating possible source reservoirs, most of the evidence for a Hadean source for the Acasta Gneiss Complex is from Hf isotope analysis of zircon. Therefore, until further research is conducted, the Hf isotope record provides the only comparison for the apatite Sr isotope record of possible Hadean sources.202 2   Geological Background2 2 1  The Slave ProvinceThe Slave Province is a well-exposed Archean craton covering an area of approximately 213,000 km2 in the northwestern part of the Canadian Shield (Figure 2.1) (Hoffman, 1989; Padgham and Fyson, 1992). The craton is divided by a well-defined Pb- and Nd-isotopic boundary that shows evidence for the contribution of older, more evolved crust to the west and less evolved compositions to the east (Davis and Hegner, 1992; Davis et al., 1996). The main components of the Slave Province include a 4.0-2.9 Ga basement complex overlain by a 2.9-2.85 Ga cover sequence, the 2.72-2.65 Ga supracrustal rocks of the Yellowknife Supergroup and 2.62-2.58 Ga granitic to tonalitic plutons (Van Breemen et al., 1992; Bleeker et al., 1999; Sircombe et al., 2001). The 4.0-2.9 Ga basement complex is only found in the western Slave Province and mainly consists of deformed granitoids and gneisses (Isachsen and Bowring, 1994). The Yellowknife Supergroup is dominated by sedimentary rocks interlayered with volcanic rocks. The final stage of the Slave craton formation was the intrusion of 2.62-2.58 Ga granitic to tonalitic plutons.21NWopmay OrogenCoronation GulfGreat Slave LakeN. AmericaPhanerozoic rocksProterozoic rocksMetavolcanic rocks100 kmNAcasta River10 km1 kmN115˚35’115˚35’65˚10’ 65˚10’QuaternaryMetasedimentary rocksLayered gneissFelsic gneissMafic-intermediate gneissAMS027AMS013Metasedimentary rocksGranitoidsBasement gneissa bcFaultInferred faultFigure 2 1  Geological setting of the Slave Province and the Acasta Gneiss Complex: (a) Simplified geological map of the Slave Province modified after Hoffman (1989) and Bleeker et al. (1999). (b) Closeup of the basement gneisses that include the Acasta Gneiss Complex. (c) Simplified geological map of the Acasta Gneiss Complex showing the two key samples analysed in this study, modified after Iizuka et al. (2007).2 2 2  Geological setting of the Acasta Gneiss ComplexThe AGC forms a basement block of gneisses exposed along the Acasta River in the western margin of the Slave Province (Figure 2.1). Mapping and U-Pb zircon dating of samples from the area in the 1980s first revealed the presence of very ancient rocks (St-Onge et al., 1988; Bowring et al., 1989). The complex is divided by a northeast-trending fault that juxtaposes different lithologies and strain (Bowring and Williams, 1999; Iizuka et al., 2007). Areas of high strain dominate to the west of the fault, with lithologies primarily consisting of highly deformed interlayered gneisses with mafic and felsic components. The rocks to the east of the fault consist of lower strain tonalitic to granitic gneisses containing enclaves of a mafic-intermediate gneiss series (Iizuka et al., 2007). 22U-Pb zircon analyses for the AGC have yielded a 4.2 Ga component (Iizuka et al., 2006), protolith ages indicating crystallisation at 4.03-3.94, 3.75-3.72 and 3.6 Ga, and Paleo- and Mesoarchean ages related to repeated metamorphism, alteration and metasomatism (Bowring et al., 1989; Stern and Bleeker, 1998; Bowring and Williams, 1999; Iizuka et al., 2007; Mojzsis et al., 2014; Reimink et al., 2014, 2016a). Recent mapping of the area to the north of the original discovery outcrops has revealed the presence of a well-preserved intermediate tonalite, referred to as the Idiwhaa unit, with a crystallization age of 4.02 Ga (Reimink et al., 2014, 2016a). Based on geochemical characteristics of the tonalites, these studies have proposed that the oldest AGC crust formed through shallow melting of hydrous basaltic crust, in a setting analogous to modern Iceland (Reimink et al., 2014, 2016a). However, while the samples may show geochemical similarities to Icelandic felsic rocks, there is debate as to how applicable the analogy is due to the unusual tectonic setting of Iceland, with the coincidental occurrence of a mantle plume and mid-ocean ridge (Kamber, 2015). Several AGC zircon Lu-Hf studies have shown relatively unradiogenic 176Hf/177Hf, with initial εHf ranging from -2 to -10 (Amelin et al., 2000; Iizuka et al., 2007; Reimink et al., 2016b; Bauer et al., 2017). These studies indicate that a Hadean crustal component was involved in the formation of Eoarchean AGC rocks, while a recent study proposes a shift to a more juvenile source at ca. 3.6 Ga to explain more radiogenic 176Hf/177Hf values for the AGC (Bauer et al., 2017). Significantly, these studies show little evidence for a strongly depleted mantle source for the AGC and Bauer et al. (2017) suggest from this that a complementary, extensive continental crust in the Hadean was unlikely to be present. Some studies have indicated complete resetting of 147Sm-143Nd systematics for rocks at ca. 3.4 Ga (Moorbath et al., 1997; Mojzsis et al., 2014; Roth et al., 2014), although this age may be the result of pooling unrelated rock units with different 23reset ages and older 147Sm-143Nd ages have been identified (Mojzsis et al., 2014; Reimink et al., 2014). Roth et al. (2014) used coupled 147,146Sm-143,142Nd systematics to propose a ca. 4.35 Ga model extraction age from Bulk Silicate Earth (BSE), yet this model age relies on the assumption that the 3.4 Ga resetting age is a geologically significant event. Nine TTG samples from the AGC were screened for the presence of apatite (Table 2.1). Two samples were found to contain abundant apatite and reflect relatively minor hydrothermal alteration. These samples are a biotite-bearing granodiorite from the western part of the AGC (AMS027; Figure 2.1c) and a foliated biotite-bearing granodiorite from the eastern part (AMS013). The rocks consist of quartz, plagioclase, K-feldspar, biotite and muscovite in different modal abundances, and both contain zircon and apatite as main accessory minerals. Sample AMS027 shows a pristine igneous texture and contains abundant zircon grains with large apatite inclusions (>20 μm). Inclusions of apatite in zircon in AMS013 were typically smaller than 10 μm in length, although several inclusions were identified. Rare calcite and plagioclase inclusions were found in zircon from AMS027 and AMS013, however they were typically small (~5 μm) and associated with secondary inclusions such as chlorite. As a result, the calcite and plagioclase inclusions would not be suitable targets for Sr isotope analysis.24Table 2 1  Summary of Acasta Gneiss Complex samples analysed in this studySample name Sampling date Latitude Longitude Major mineral phasesAccessory phases Field descriptionAMS027 26 Aug 06 65°9.893N 115°36.083W qtz, pl, kfs, bt, ms zrn, ap foliated granodiorite AMS013 23 Aug 06 65°10.212N 115°33.762W qtz, pl, kfs, bt, ms zrn, ap foliated granodioriteAMS030AA 26 Aug 06 65°10.177N 115°35.278W qtz, pl, kfs, bt, ms zrn, ap tonalitic layer of layered gneissAMS030B 26 Aug 06 65°10.177N 115°35.278W qtz, pl, bt zrn tonalitic layer of layered gneissAMS030C 26 Aug 06 65°10.177N 115°35.278W qtz, pl, kfs, bt zrn, ttn tonalitic layer of layered gneissAMS031A 26 Aug 06 65°10.177N 115°35.278W pl, bt, hbl, qtz ap, ttn, ilm, zrn dioritic layer of layered gneissAMS001 22 Aug 06 65°10.118N 115°33.551W qtz, pl, bt, grt zrn, ap meta-tonaliteAMS008 23 Aug 06 65°10.118N 115°33.551W qtz, pl, bt zrn, ap light meta-tonaliteAMS039 27 Aug 06 65°9.770N 115°32.847W pl, qtz, bt, hbl zrn, ap dark meta-tonaliteqtz = quartz; pl = plagioclase; kfs = K-feldspar; bt = biotite; ms = muscovite; hbl = hornblende; zrn = zircon; ap = apatite; ttn = titanite; ilm = ilmenite2 3   Analytical Methods2 3 1  LA-ICPMS U-Pb zircon datingZircon crystals were recovered using standard crushing, heavy liquid (CH3I) and magnetic separation techniques. They were mounted in epoxy and polished to expose the mid-sections of the grains. Cathodoluminescence imaging was conducted with a Philips XL30 electron microscope equipped with a Robinson cathodoluminescence detector at the Electron Microbeam and X-Ray Diffraction Facility at the University of British Columbia to reveal internal zoning of the zircon crystals. The U-Pb analyses were conducted using a Thermo Finnigan ELEMENT2 high-resolution inductively coupled plasma mass spectrometry (ICPMS) instrument connected to an ESI NWR193UC laser ablation (LA) system at the Pacific Centre for Isotopic and Geochemical Research (PCIGR), the University of British Columbia. Spot sizes of 25 μm were used at a laser 25fluence of ~4.5 J cm-2, a repetition rate of 6 Hz, an ablation time of 30 s, and a washout period of 22 s. Measurements were conducted on the masses 202Hg (to correct for 204Hg interfering on 204Pb), 204Pb, 206Pb, 207Pb, 232Th, 235U and 238U. The zircon reference material GJ-1 was used as a primary standard (Jackson et al., 2004) with standard-sample bracketing employed and FC-1 zircon was used as a secondary standard (Paces and Miller, 1993). Repeated analysis of FC-1 during the course of the analytical sessions provided a weighted mean 207Pb/206Pb age of 1104 ± 17 Ma for this material (n = 41; Figure 2.2 and Appendix A), which is in agreement with the age obtained using ID-TIMS (1099 ± 0.6 Ma; Paces and Miller, 1993)All data reduction, including static and time-dependent fractionation, uncertainty calculations and error propagation, was carried out offline using an Excel-based macro (Kooijman et al., 2012), with analysis integrations chosen based on stable U-Pb signals. As 206Pb/238U was linear for most analyses, time-dependent fractionation was corrected for using  the linear intercept method. For each analysis, a least squares linear regression was applied to 206Pb/238U and this was extrapolated back to time zero (laser shutter on). This method avoids the pitfalls of exponential curve corrections based on the downhole behaviour of the primary zircon standard (e.g. Paton et al., 2010) as finding a matrix-matched zircon standard that has similar time-dependent fractionation behaviour to the old, high-U zircons from the AGC would be difficult (Ver Hoeve et al., 2018). This is highlighted by the fact that when data reduction is conducted using an exponential curve correction method in the Iolite v3 software package, the unknown analyses from the AGC commonly have residual or overcorrected slopes when viewing the “corrected” 206Pb/238U (Figure 2.3). Some zircon crystals contained a significant amount of common Pb, as indicated by anomalously low 206Pb/204Pb (Appendix B; calculated after 204Hg correction). Common Pb was corrected for assuming the composition of terrestrial common Pb 26at the approximate age of the sample (Stacey and Kramers, 1975) and subtracting this from the baseline- and 204Hg-corrected signals. Error propagation was calculated by quadratic addition of the external reproducibility (from repeated bracketed measurements of the primary standard GJ-1) and the precision of each individual analysis. Concordia plots for additional AGC samples (aside from AMS027 and AMS013) are presented in Appendix C. Figure 2 2  U-Pb systematics for the secondary zircon standard FC-1 measured by LA-ICPMS during this study: (a) Wetherill concordia plot for FC-1 analyses; (b) Weighted mean 207Pb/206Pb age for FC-1 analyses.206 Pb/238 U0.60.81.01.21.41.61.82.02.2Runs since laser on0 10 20 30 40 50 60 70 80Runs since laser on10 20 30 40 50 60 70 80a bFigure 2 3  Fractionation corrections for U-Pb analysis AMS030C_083 conducted with (a) the linear intercept method with an Excel macro using the protocol of Kooijman et al. (2012) and (b) the exponential curve method with Iolite v3 using the protocol in Paton et al. (2010). The black circles show the raw, uncorrected ratios and the blue circles show the fractionation-corrected only ratios using the intercept method (i.e. not yet normalised to the primary standard). The purple circles show the final, fully corrected ratios from Iolite. Note the difference in slopes between the blue and purple lines, highlighting the effectiveness of the linear intercept method over the exponential curve approach.272 3 2  Zircon trace elementsTrace element concentrations of representative zircon grains from several AGC samples were analysed using a similar LA-ICPMS set up as for the U-Pb analyses, with a Thermo Finnigan ELEMENT2 connected to an ESI NWR193UC laser ablation system. Ablation spot sizes between 25-50 μm were placed in the same CL zone as the U-Pb spot analyses. A laser fluence of ~4.5 J cm-2, a repetition rate of 6 Hz, a dwell time of 40 s and a washout period of 30 s. Measurements were conducted on masses 49Ti, 139La, 140Ce, 141Pr, 146Nd, 147Sm, 153Eu, 157Gd, 160Gd, 159Tb, 163Dy, 165Ho, 166Er, 169Tm, 172Yb, 175Lu, 178Hf, 208Pb, 232Th and 238U. Analyses were internally standardized using Hf concentrations obtained using a Cameca SX-50 electron probe micro-analyser (EPMA; data in Appendix D) with EPMA spots placed in the same CL zone as the laser ablation spot. The zircon reference 91500 was used as a primary calibration standard (Wiedenbeck et al., 2004; Liu et al., 2010) and GJ-1 was used as a secondary zircon standard to monitor for accuracy (Liu et al., 2010). Data reduction was conducted offline using the Iolite v3 software and complete results are shown in Appendix E.2 3 3  Sr isotopes of matrix apatite and apatite inclusions in zircon Apatite Rb-Sr isotopic analysis was done on inclusions found in the mounted zircon crystals in samples AMS013 and AMS027, and in matrix apatite grains from AMS013. Apatite inclusions were identified by subjecting the inclusions in zircon to confocal Raman spectroscopy using a Horiba XploRA PLUS Raman system. Numerous apatite inclusions were found in the (sub-)surface of mounted zircon grains, however, apatite inclusions large enough to analyse by LA-MC-ICPMS proved extremely rare. Careful screening of 1,000+ zircon grains per sample provided six large and properly exposed apatite inclusions in sample AMS027. Another two were 28found in zircon from AMS013. The textures of the rare inclusions and their zircon hosts were carefully examined. Only one of the inclusions showed clear signs of alteration; the inclusion was cut by fractures. Cathodoluminesce images of host zircon and apatite inclusions are shown in Figure 2.4.a b cfd e 3728 ± 84 Ma (D = 5 %)87Sr/86Sr = 0.7025 ± 16  3356 ± 61 Ma (D = 33 %)87Sr/86Sr = 0.7019 ± 19 87Sr/86Sr = 0.7046 ± 19  3643 ± 79 Ma (D = 57 %)87Sr/86Sr = 0.7010 ± 38  3562 ± 85 Ma (D = 10 %) 3236 ± 62 Ma (D = 43 %)87Sr/86Sr = 0.7026 ± 18 87Sr/86Sr = 0.7039 ± 22  3232 ± 93 Ma (D = 48 %)3546 ± 58 Ma(D = 16 %)87Sr/86Sr = 0.7136 ± 38 gFigure 2 4  Cathodoluminescence images of Acasta Gneiss Complex zircon grains containing apatite inclusions from samples AMS027 (a)-(e) and AMS013 (f)-(g). (a) Bright zircon with large apatite inclusion in zircon core; (b),(c) Dark zircon crystals with faint oscillatory zoning and apatite inclusions in the zircon cores; (d) Zircon crystal with strong oscillatory zoning and an apatite inclusion overlapping with the zircon core and mantle; (e) Apatite inclusion on the rim of the zircon host; (f) Apatite inclusion between the zircon core and mantle; (g) Zircon host grain with fractures permeating through the zircon towards the apatite inclusion in the core. White circles represent 25 μm ablation spots for LA-ICPMS zircon U-Pb analyses and 207Pb/206Pb dates are given (D = discordance). Scale bars are 70 μm. 29The Rb-Sr isotopic analyses of apatite were conducted by LA-MC-ICPMS using a Nu Instruments Plasma II MC-ICPMS connected to an ESI NWR193UC laser ablation system at the Vegacenter, Swedish Museum of Natural History, Stockholm. Apatite grains were analysed at spot sizes between 30-90 μm (30 μm for inclusion analyses) using a laser fluence of 2.7 J cm-2, a repetition rate of 15 Hz, an ablation time of 40 s and a baseline measurement of 50 s (parameters outlined in Table 2.2). The latter allowed precise correction of Kr+ isobaric interferences introduced by the Ar gas. Other potential isobaric interferences and Faraday cup configuration are outlined in Table 2.3 and examples of accurate interference corrections for individual analyses are shown in Figure 2.5. The interferences were corrected for (ratio-by-ratio) in the following order: 1) Kr+ gas blank, 2) doubly charged rare earth elements (Er2+ and Yb2+, corrected by measuring m/z corresponding to 166Er2+, and 171Yb2+ and 173Yb2+ at half mass), 3) Ca dimers and argides, 4) 87Rb+ on 87Sr+ by measuring 85Rb+, applying mass bias based on measured 86Sr/88Sr and assuming the exponential law as with Sr. Durango apatite was used as a primary reference material (Yang et al., 2014). Accuracy was monitored through repeat analyses of the in-house hydroxyl-apatite Holly Springs standard, the 87Sr/86Sr value of which is determined at 0.718926 ± 0.000014 by thermal ionization mass spectrometry. A weighted mean 87Sr/86Sr value of 0.71882 ± 0.00021 (MSWD = 1.6, n = 10; Table 2.4) was obtained during the course of this study (Figure 2.6a), indicating accuracy and robustness of the interference corrections made.  The latter is further demonstrated by the absence of a correlation between 174Yb2+/86Sr and 87Sr/86Sr (Figure 2.6b). The robustness of the REE2+ corrections is also shown by the accuracy of the corrected 84Sr/86Sr ratios compared to the natural ratio (84Sr/86Sr = 0.565). Due to the low abundance of 84Sr, the interference by doubly charged 168Er on 84Sr is stronger than that of 172,174Yb on 86,87Sr. The fact that 84Sr/86Sr values (Table 2.4) are accurate indicates the efficacy of the REE2+ correction 30protocol for Sr isotopes. The effectiveness of the 87Rb correction was tested through analysis of a 25 ppb solution of the Sr Standard Reference Material NBS-987 spiked with different concentrations of Rb (up to 0.25 ppb). These tests show that the correction of 87Rb+ on total m/z corresponding to mass 87 is robust, even for large interferences that are at least several orders of magnitude larger than a typical apatite analysis would exhibit (Figure 2.7).0.700.710.720.730.51.01.52.02.53.03.5m/z – 88 (V) 0.00300.00250.00200.00150.00100.000582CaAr+, 87Rb+, 173Yb2+ (V)87Sr/ 86SrTime (s)10 20 30 40 50 600.00250.00200.00150.00100.000500.700.710.720.730.7410 20 30 40 50 6087Sr/ 86Srm8887Rb+173Yb2+82CaAr+87Sr/ 86Sr uncorr.87Sr/ 86Sr corr.84Sr/ 86Sr corr.m8887Rb+173Yb2+82CaAr+a0.040.060.080.1084Sr/ 86 Sr84Sr/ 86 Sr0.040.060.080.12 0.10 0.14 87Sr/ 86Sr uncorr.87Sr/ 86Sr corr.84Sr/ 86Sr uncorr.84Sr/ 86Sr corr.cbdTime (s)00.20.40.60.81.01.21.4m/z – 88 (V) 82CaAr+, 87Rb+, 173Yb2+ (V) Figure 2 5  Examples of individual peaks for the Sr isotope analysis of apatite by LA-MC-ICPMS: (a) and (b) show a spike in 87Rb that is seen to be accurately corrected for in the 87Sr/86Sr ratio. (c) and (d) show accurate interference corrections, mainly for the Yb2+ interference in this example, on 84Sr/86Sr and 87Sr/86Sr. The axes of the left panel indicate the signal in Volts (V) for that particular mass to charge ratio (m/z) or interference. 31Table 2 2  Apatite Rb-Sr analysis instrument setupMass spectrometer Nu plasma (II) MC-ICP-MSCooling gas flow rate 13 L/minAuxiliary gas flow rate 0.90 L/minMass resolution lowCones common Ni conesTorch glass  Laser ablation ESI NWR193 ArF excimer laser ablation systemAr flow rate (mix gas) 0.81 L/minHe flow rate 0.32  L/minAblation    Frequency 15 Hz  Spot size 30 - 90 µm  Fluence 2.7 J/cm2Data collection    Washout time 50 s  Ablation time 40 s  Integration 0.5 sTable 2 3  Isobaric interferences and Faraday cup configuration for Rb-Sr isotopic analysesm/z1 81.5 82 83 84 85 85.5 86 86.5 87 88Sr 84Sr+ 86Sr+ 87Sr+ 88Sr+Kr 82Kr+ 83Kr+ 84Kr+ 86Kr+REE2+ 164Er2+ 166Er2+ 168Er2+ 170Er2+ 171Yb2+ 172Yb2+ 174Yb2+ 176Yb2+(168Yb2+) (170Yb2+) 173Yb2+163Dy2+ 164Dy2+Ca dimers 42Ca40Ca+ (43Ca40Ca+) 44Ca40Ca+ 42Ca43Ca+ (46Ca40Ca+) (48Ca40Ca+)Ca argides 42Ca40Ar+ (43Ca40Ar+) 44Ca40Ar+ (46Ca40Ar+) 48Ca40Ar+Rb 85Rb+ 87Rb+Ca-P-O 40(Ca,Ar)31P16O+1m/z = mass to charge ratio320.7160.7170.7180.7190.7200.72187Sr / 86SrMean = 0.71882 ± 0.00016MSWD = 1.8, n = 100.7160.7170.7180.7190.7200.7210.003 0.004 0.005 0.006 0.007 0.00887Sr / 86Sr174Yb2+ / 86Sra bFigure 2 6  The 87Sr/86Sr values obtained for repeated LA-MC-ICPMS analysis of the Holly Springs secondary apatite standard (TIMS 87Sr/86Sr = 0.718926 ± 0.000014) during the course of the analytical session. (a) The data demonstrate accuracy of 87Sr/86Sr within the uncertainty of the method. (b) Absence of a correlation between 87Sr/86Sr and the interference monitor 174Yb2+/86Sr indicate that corrections for doubly charged REE are reliable.87Sr/86Sr mass bias  + Rb correction87Sr/86Sr mass bias correction0.700.710.720.730.740.750.760.770.780.7985Rb+ / Σ 8#Sr +  (V)0 0.005 0.010 0.01587Sr / 86SrFigure 2 7  Results from MC-ICPMS analyses of a 25 ppb solution of the NBS-987 Sr standard reference material spiked with varying concentrations of Rb (2.5 ppt, 25 ppt, 0.1 ppb; 0.25 ppb; 6 analyses per solution). This shows the accuracy of the 87Rb interference correction and the linear correlation between Rb concentration and the 87Sr/86Sr ratio when only corrected for mass bias. The x-axis is the ratio between the signal of 85Rb+ and the total Sr beam (Σ8#Sr+).33Table 2 4  LA-MC-ICPMS Rb-Sr isotopic compositions for  apatite from the Acasta Gneiss ComplexSample name Sampling time (sec)87Sr/86Sr 2 S.D. 84Sr/86Sr 2 S.E. 87Rb/86Sr2 2 S.E. 174Yb(2+)/ 86Sr3 2 S.E. Total Sr-Beam (V)Initial 87Sr/86Sr4InclusionsAMS027_1 18.8 0.7030 0.0012 0.0570 0.0015 0.00045 0.00017 0.0071 0.0006 0.46 0.7029AMS027_2 32.8 0.7039 0.0022 0.0587 0.0037 0.00471 0.00055 0.0847 0.0068 0.14 0.7038AMS027_3 10.8 0.7025 0.0016 0.0543 0.0024 0.0013 0.00025 0.0108 0.0009 0.48 0.7025AMS027_4 13.9 0.7019 0.0019 0.0584 0.0025 0.00261 0.00068 0.0181 0.0018 0.40 0.7018AMS027_5 11.6 0.7046 0.0019 0.0538 0.0036 0.00190 0.00049 0.0261 0.0041 0.36 0.7045AMS027_6 17.9 0.7026 0.0018 0.0561 0.0023 0.00195 0.00039 0.0202 0.0025 0.05 0.7026AMS013_1 14.3 0.7010 0.0038 0.0541 0.0059 0.0068 0.0022 0.0428 0.0071 0.13 0.7009AMS013_2 8.5 0.7136 0.0038 0.0529 0.0076 0.0028 0.0017 0.0306 0.0036 0.16 0.7135Matrix apatite1 30 0.70949 0.00032 0.05552 0.00041 0.000761 0.000045 0.01121 0.00039 1.76 0.709492 35.5 0.71198 0.00026 0.05576 0.00036 0.00137 0.00012 0.01519 0.00058 1.63 0.711983 20.6 0.7100 0.0011 0.0552 0.0016 0.00123 0.00019 0.0203 0.0011 0.54 0.71004 27.5 0.7102 0.0010 0.0567 0.0015 0.00049 0.00013 0.00894 0.00055 0.49 0.71025 31.7 0.7140 0.0011 0.055 0.0018 0.00231 0.00017 0.04238 0.00118 0.37 0.71406 17.1 0.7135 0.0016 0.0583 0.0024 0.00284 0.00045 0.0518 0.0068 0.37 0.71347 35.7 0.71220 0.00086 0.0555 0.0015 0.00092 0.00011 0.01476 0.00093 0.45 0.71228 23.3 0.7157 0.0011 0.0549 0.0019 0.00154 0.00020 0.0343 0.0015 0.36 0.71579 33.4 0.70761 0.00065 0.0554 0.0013 0.00096 0.00011 0.01300 0.00054 0.50 0.7076110 33.5 0.70777 0.00078 0.0567 0.0012 0.00086 0.00014 0.01388 0.00065 0.49 0.70777Holly Springs apatite11 33 0.71913 0.00030 0.05631 0.00046 0.000271 0.000041 0.004787 0.000232 1.572 32 0.71872 0.00026 0.05622 0.00037 0.000314 0.000038 0.004778 0.000170 1.633 34.5 0.71909 0.00030 0.05626 0.00036 0.00024 0.000032 0.005512 0.000233 2.014 32.5 0.71866 0.00027 0.05646 0.00036 0.000286 0.00004 0.004378 0.000143 1.785 33 0.71865 0.00024 0.05628 0.00033 0.000318 0.000029 0.005047 0.00015 1.946 34 0.71916 0.00070 0.0569 0.0011 0.00035 0.00010 0.00483 0.00041 0.517 33.5 0.71891 0.00056 0.0560 0.0011 0.00018 0.00013 0.00521 0.00037 0.498 33.5 0.71836 0.00077 0.0568 0.0011 0.00038 0.00012 0.00590 0.00042 0.509 33.2 0.7186 0.0021 0.0579 0.0034 0.00036 0.00028 0.0063 0.0012 0.1910 32.9 0.7192 0.0018 0.0582 0.0031 0.00031 0.00026 0.0055 0.0012 0.201 In-house hydroxyl-apatite, TIMS value: 87Sr/86Sr = 0.718926 ± 0.000014; 2 87Rb was calculated from 85Rb (Rb-factor = 0.3861); 3 From 173Yb(2+) measured on m/z = 86.5; 4 87Rb decay constant = 1.393x10-11 yr-1 (Nebel et al., 2011)342 4   Results2 4 1  ZirconZircon crystals from AMS027 are typically brown and range in size with most grains being 50-200 μm in length (Figure 2.8a-c). Zircon grains are generally prismatic, elongate and euhedral to subhedral (Figure 2.8a-b), with a sub-population of smaller, round grains (Figure 2.8c). Many grains have a low CL response (Figure 2.8b), and appear to be metamict with porous textures. Relict oscillatory zoning is present in many of these CL-inactive crystals. Apatite inclusions are common in zircon from this sample and can be up to 100 μm long. Many zircon grains contain substantial amounts of common Pb (Appendix B), possibly due to fluid infiltration after metamictisation. Zircon crystals from AMS013 are commonly colourless, with few brown or pink crystals. They are generally elongate and euhedral and mostly between 200 and 400 μm in length, although crystals up to 800 μm occur (Figure 2.8d-f). Most crystals exhibit primary oscillatory zoning although dark, porous grains exist (Figure 2.8e). Some crystal cores have been resorbed and are surrounded by a dark mantle, which is then surrounded by a thin, CL-bright rim. The large size of many of these crystals, along with their oscillatory zoning suggests that many of them are of primary igneous origin. Apatite inclusions are rare in zircon grains from this sample; inclusions mostly comprise quartz, biotite, and K-feldspar (Figure 2.8f). 35Figure 2 8  Examples of cathodoluminescence images for zircon grains from samples AMS027 (a)-(c) and AMS013 (d)-(f). (a) A bright core surrounded by a dark, U-rich rim; (b) A dark, metamict zircon with high U contents; (c) Small, round zircon grain; (d) Large, elongate zircon grain; (e) Dark zircon grain with a metamict zircon core surrounded by a lower U-mantle; (f) Large, elongate zircon grain with quartz and K-feldspar inclusions present. 25 μm ablation spots for LA-ICPMS U-Pb zircon analyses are indicated by white circles with 207Pb/206Pb dates (D = discordance) and Uranium concentrations in ppm given. As is typical for rocks of the AGC (Bowring et al., 1989; Stern and Bleeker, 1998; Bowring and Williams, 1999; Iizuka et al., 2006, 2007; Mojzsis et al., 2014; Reimink et al., 2014, 2016a), the U-Pb data for zircon from the samples analysed in this study are complex and yield several populations of 207Pb/206Pb dates for analyses that are more than 90% concordant (Figure 2.9 and Appendix B). For sample AMS027, the main concordant age population clusters at approximately 3.7 Ga, with a weighted mean average 207Pb/206Pb age of 3.717 ± 0.021 Ga (n = 12; uncertainty here and elsewhere is external 2 s.d.). Several discordant results show the same upper intercept age and appear to reflect Pb loss from this oldest age component. Zircon from this population typically has bright CL responses, shows strong oscillatory zoning to no zoning (Figure 2.4 and Appendix F), and exhibits high Th/U (0.75-1.78; Figure 2.10). In contrast to the 3.7 Ga zircon grains, the younger zircon (3.5 Ga or younger) typically shows limited CL 36response, porous textures and low Th/U (0.15-0.77). The REE patterns for AMS027, which has high total REE concentrations, show only slight enrichment of HREE relative to LREE (Figure 2.11 and Appendix E). The U-Pb data for zircon from sample AMS013 have a smaller degree of dispersion compared to AMS027 and have a Wetherill concordia upper intercept age of 3.620 ± 0.027 Ga, although older components of up to 3.8 Ga are also present. With the exception of a single analysis, La/Yb values are low (<0.05; Figure 2.11 and Appendix E), corresponding to those obtained from high-Th/U zircon in AMS027. Figure 2 9  U-Pb zircon age systematics for samples AMS013 and AMS027 from the Acasta Gneiss Complex. Histogram and probability distributions (right panels) show 207Pb/206Pb ages with >90% concordance which are represented by the coloured ellipses in the Wetherill concordia plots (left panels).37Th/U00.40.81.21.62.0207Pb/206Pb date (Ma)3000 3200 3400 3600 3800 4000Figure 2 10  Th/U versus 207Pb/206Pb date for >90% concordant zircon grains from sample AMS027, with higher Th/U for grains from the 3.7 Ga population.Figure 2 11  Chondrite-normalised rare earth element (REE) patterns for zircon grains from samples AMS027 and AMS013 from the Acasta Gneiss Complex. Normalisation values are after McDonough and Sun (1995).382 4 2  Apatite Sr isotopesThe apatite inclusions that were analysed occur in zircon that either yielded 207Pb/206Pb ages identical to the oldest age component (3.717 ± 0.021 Ga) or in zircon that initially crystallised at this age, but lost Pb at a later stage. All but one inclusion yielded consistent 87Sr/86Sr values, with a weighted mean 87Sr/86Sr of 0.70290 ± 0.00066 (n = 7; MSWD = 1.06)(Table 2.4; Figure 2.12 and Figure 2.13). When corrected for the minor amount of internal 87Rb decay, these values provide an estimate of 87Sr/86Sr0 = 0.70289 ± 0.00066. The one inclusion in AMS013 that was visibly intersected by fractures has substantially higher 87Sr/86Sr (0.7136 ± 0.0038; 87Sr/86Sr0 = 0.7135 ± 0.0038). Matrix apatite in sample AMS013 have high 87Sr/86Sr = 0.7076-0.7157 (Table 2.4), which yields the same 87Sr/86Sr0 due to insignificant corrections for radiogenic 87Sr. These values bracket the value that was obtained for the seemingly altered inclusion in this sample (0.7136 ± 0.0024).Figure 2 12  Sr isotopes results for all apatite inclusions and grains from samples AMS027 (squares) and AMS013 (circles). Primary apatite grains from AMS027 and AMS013 have lower 87Sr/86Sr than the secondary apatite inclusion and matrix apatite grains from AMS013.392 5   Discussion 2 5 1  The Rb-Sr record of apatite The U-Pb data obtained from zircon of the AGC samples analysed in this study indicate a main population at 3.7-3.6 Ga, a common feature of many samples from this complex (e.g., Bowring and Williams, 1999). The textural features and high Th/U of zircon that yielded such ages indicates that these grains were part of a primary mineral assemblage that crystallized as part of the igneous protolith. Younger age components, which were typically obtained from overgrowth and recrystallised zones of zircon with low Th/U, appear to represent secondary processes such as metamorphism or (partial) re-melting of the rock.The 87Sr/86Sr values (0.7010-0.7046) of the apatite inclusions in the ca. 3.7 Ga zircon are distinctly lower than those for matrix apatite and show a much smaller degree of dispersion. With a MSWD value of 1.06, the apatite inclusions define a single population of 87Sr/86Sr values with limited or no resolvable geological scatter. The one apatite inclusion intersected by fractures, has the substantially more radiogenic 87Sr/86Sr (0.7136 ± 0.0038), which is similar to the high values obtained for apatite that occur in the altered matrix of AMS013 (87Sr/86Sr = 0.7076-0.7157). The apatite inclusions in zircon appear to have been mostly shielded from the metamorphism, metasomatism and alteration that affected the matrix and that produced the high 87Sr/86Sr values for the apatite grains in the matrix. No textural evidence for possible apatite alteration—particularly (healed) fractures in the zircon host—were found for the inclusion population that yielded consistently low 87Sr/86Sr values. It is possible that fractures were subsurface in all cases and that the apatite with a seemingly homogeneous single population of 87Sr/86Sr values still harbours some effect of re-equilibration. As the data population is small, this model is difficult to test (Figure 2.13). Most 40of the analyses, including those that are relatively precise (<2 ‰ RSD), show a relatively normal distribution around the mean. If these values were skewed upward by alteration from an initially low 87Sr/86Sr, this would set very specific limits to the relative degree of alteration and the 87Sr/86Sr values of the fluids involved in this process. A simpler and more plausible explanation is that the consistently low 87Sr/86Sr values represents the true time-integrated 87Sr/86Sr value of primary apatite in samples AMS027 and AMS013 and, thus, the resultant 87Sr/86Sr0 provides a reasonable estimate for the primary mineral assemblages that the apatite were part of. The elevated 87Sr/86Sr values of the matrix apatite grains and the altered apatite inclusion in AMS013 likely record interaction between these grains and a fluid or melt that was relatively enriched in 87Sr. This component may have been exotic to the samples or could have been produced within the rock itself. The rocks were repeatedly metamorphosed and partially re-melted (Iizuka et al., 2007; Mojzsis et al., 2014). The latter likely involved dehydration melting of micas, which have a low solidus temperature, and variably high Rb/Sr and 87Sr/86Sr. This process could have locally released isotopically heterogeneous Sr to the re-equilibrating matrix.41BSE     DMM0.7000.7020.7040.7060.708Age (Ga)3.4 3.6 3.8 4.0 4.2 4.4 87Sr/ 86 SrRb/Sr = 0.21-0. 32 (SiO2  ~64-68 %)Rb/Sr = 0.14-0. 20 (SiO2  ~61-64 %)0.6960.7000.7040.708 87Sr/ 86SrW. M. 87Sr/86Sr00.70289 ± 0.00066AMS027AMS013Figure 2 13  Rb-Sr isotopic results and evolution diagram for apatite inclusions from the Acasta Gneiss Complex. The ellipse represents the 87Sr/86Sr of primary apatite inclusions and age of the zircon host grains (± external 2 s.d.). The enveloping fans show extraction from Bulk Silicate Earth (BSE) at different ages (starting at 4.2 Ga) and the implied Rb/Sr and SiO2 of the youngest and oldest model sources. Depleted MORB mantle evolution is shown for reference (Workman & Hart, 2005). Inset: 87Sr/86Sr values of primary apatite inclusions from samples AMS027 and AMS013. 2 5 2  Source and crustal evolution The estimate of 87Sr/86Sr0 = 0.70289 ± 0.00066 provides the first direct measurement of the initial Sr isotopic composition of Eoarchean (3.717 ± 0.021 Ga) crustal rocks. Crustal differentiation within the Acasta Gneiss Complex can be investigated by considering possible source extraction ages between 4.2 and 4.0 Ga (Figure 2.13). The upper limit of this range is defined by the oldest zircon date (4,203 ± 58 Ma; Iizuka et al., 2006) and a plausible source age for the Acasta Gneiss Complex from a Lu-Hf isotope systematics in zircon (Iizuka et al., 2009; Bauer et al., 2017). The youngest limit is defined by the age of tonalitic gneiss within the Idiwhaa 42unit (4,020 ± 2 Ma) and banded gneisses elsewhere in the Acasta Gneiss Complex (Reimink et al., 2014; Reimink et al., 2016a; Sprung et al., 2016; Reimink et al., 2016b). This range is assumed to include all plausible possibilities of source extraction ages for the main Acasta Gneiss lithologies. Models for source composition were based on extraction from bulk silicate earth (BSE). The 87Sr/86Sr of BSE was calculated at a given time using the best initial value for basaltic achondrite (87Sr/86Sr = 0.69897 at 4.56 Ga) (Papanastassiou and Wasserburg, 1968) and a modern BSE value (87Sr/86Sr = 0.7045) (Workman and Hart, 2005). Extraction from BSE at 4.2 Ga would require a Rb/Sr of ~0.17 for the source to produce the 87Sr/86Sr of the primary apatite inclusions. This is similar to the Rb/Sr of ‘generic’ felsic crust (0.15; Dhuime et al., 2015) and indicative of intermediate-felsic compositions (~62 wt% SiO2; based on the correlation between Rb/Sr and SiO2 in magmatic rocks presented by Dhuime et al., 2015) during the proposed time of source isolation. This value resembles estimates of Rb/Sr for Archean TTG crust (mean Rb/Sr = 0.16; n = 280; GEOROC database, n.d.). These results indicate that a relatively felsic segregation of TTG-type composition resided in the source from which the Acasta Gneiss Complex was extracted. Such a source would explain inheritance of a 4.2 Ga zircon xenocryst in the Acasta Gneiss Complex (Iizuka et al., 2006), which demonstrates that at least one Hadean source was, or became, evolved enough to form zircon-saturated magmas.A ‘younger source’ model for the enriched source of the Acasta Gneiss Complex , involving extraction at 4.0 Ga from BSE or an isotopically similar mafic reservoir as suggested for the Idiwhaa tonalite (Reimink et al., 2016b), is consistent with the extremely rare occurrence of >4.03 Ga zircon xenocrysts. Hf isotope geochemistry of the 4.02 Ga mafic tonalite indicates that at least portions of the Acasta Gneiss Complex were sourced from an enriched mafic reservoir that had little or no interaction with an evolved Hadean component (Reimink et al., 432016b). For a 4.0 Ga extraction age to be viable, the initial 87Sr/86Sr values for apatite from samples AMS027 and AMS013 require that the source had an extreme Rb/Sr of ~0.27. This is at the upper end of the range of Rb/Sr values observed within Archean TTG (0.12-0.22; ± 50%; Martin et al., 2005; Moyen, 2011). The Rb/Sr, and by extension SiO2 content (Dhuime et al., 2015), of a melt is typically higher than that of the source, so any TTG extracted from a source with Rb/Sr = 0.27 would have a Rb/Sr value that is not consistent with the typical Archean TTG record. Although the “younger source” model cannot be fully excluded, the above considerations of TTG geochemistry would indicate source extraction at 4.2 Ga is more plausible than at 4 Ga. This older source age, thus, sets a more reliable lower age limit for the emergence of evolved sources within the proto-continental Hadean crust.The nature of the source to the Acasta Gneiss Complex is enigmatic and there are several possibilities that may account for the apparently high-Rb/Sr signature. One possibility is that the samples represent shallow partial melting of hydrothermally altered seafloor rocks and that the high-Rb/Sr signature of the source reflects the altered, Rb-enriched nature of those rocks. This model is analogous to that proposed for the older, more mafic lithologies of the Acasta Gneiss Complex that have high heavy rare earth element (HREE) concentrations indicative of shallow melting (Reimink et al., 2014; Reimink et al., 2016a). For the samples analysed here, however, this model may not apply. Low-temperature alteration of oceanic crust will generally increase Rb concentrations (and Sr to a lesser extent), however, the Rb that is introduced into the rocks during alteration is typically leached when these become buried and heated (Staudigel, 2014). The low-HREE content of samples AMS027 and AMS013 (Sprung et al., 2016) requires melting of a deeply seated garnet-bearing source. Secondary Rb-enrichment, if present, would not have survived burial towards the high pressure and temperature conditions of this source. 44The implication of deep burial, in conjunction with the distinctly high Rb/Sr values, indicates that the source of the 3.7 Ga TTG in the Acasta Gneiss Complex requires a different setting and formation process than the 4.02 Ga Idiwhaa tonalite (Reimink et al., 2014; Reimink et al., 2016a). The evolved source of the Acasta Gneiss Complex may represent differentiated melts extracted from an older mafic crust—possibly of the kind that formed the source of the mafic-intermediate Idiwhaa tonalites (58-62 wt% SiO2; Reimink et al. 2014). The 3.7 Ga TTG record of deep-seated anatectic differentiation of Idiwhaa-like mafic crust occurred when the Acasta proto-continent had become more mature and in part buried to depths at which garnet form. The initial 87Sr/86Sr values of apatite inclusions from the Acasta Gneiss Complex indicate that the complex was not derived exclusively from an enriched mantle reservoir or mafic crustal source during the Hadean. Instead, it appears to have had multiple sources, one of which involved an evolved Hadean crustal component enriched in incompatible elements, including Rb. This enriched source would likely have been volumetrically minor. This is indicated by the lack of evidence for a depleted mantle component in the gneisses of the Acasta Gneiss Complex from the Hf isotope zircon record (Amelin et al., 2000; Iizuka et al., 2009; Reimink et al., 2016b; Bauer et al., 2017). The bulk Hadean crust likely remained intermediate or mafic in composition at least until the Meso- or Neoarchean (Dhuime et al., 2015; Kamber, 2015; Smit and Mezger, 2017). Its more felsic components may have contributed disproportionately strongly to crustal melts due to their much higher melt fertility (Watkins et al., 2007). The more felsic vestiges could thus represent an under-appreciated low-Sm/Nd and low-Lu/Hf component of the Hadean Earth, which may have contributed to the unradiogenic 142,143Nd/144Nd and 176Hf/177Hf observed for some of Earth’s oldest rocks (Boyet et al., 2003; Caro et al., 2003; Harrison et al., 2005; Bennett et al., 2007).452 6   ConclusionsAnalytical developments in LA-MC-ICPMS now enable accurate in situ measurement of 87Rb/86Sr and 87Sr/86Sr in apatite at a precision that is sufficient to resolve early Sr isotope heterogeneity at the levels that are expected in the early crust-mantle system. This approach was applied to primary apatite inclusions in 3.7 Ga zircon from the Acasta Gneiss Complex to investigate the nature and composition of its Hadean source. The 87Sr/86Sr values of the inclusions were mostly similar, with a weighted mean value of 0.70289 ± 0.00066, and was distinctly lower than the 87Sr/86Sr obtained from apatite in the altered matrix of the samples. When corrected for radiogenic 87Sr ingrowth, the inclusion data provide an estimate of the initial 87Sr/86Sr value of the melt from which the grains and their zircon hosts may have crystallized. This result and other data from the Acasta Gneiss Complex indicate that the magmatic source was relatively evolved and had formed by approximately 4.2 Ga. The Hadean crust was compositionally heterogeneous and, although dominated by mafic rocks, included vestiges of relatively felsic material. Although likely volumetrically minor, this felsic source component would have contributed disproportionately strongly to the isotope composition of newly formed crust in the Hadean.463  The longevity and fate of ancient evolved crust during the Archean from Sr isotopes in apatite3 1   IntroductionThe physical rock record on Earth reaches back to the Hadean and includes relics of some of the earliest continents (Mojzsis et al., 2001; Wilde et al., 2001; Iizuka et al., 2006; Reimink et al., 2014). Uncovering how these first continents formed and developed during the Archean has been an important geoscientific endeavour and has led to the development of various models for Hadean and Archean crustal evolution and tectonics. The ancient crust may have been more mafic than the present day (Dhuime et al., 2015; Kamber, 2015; Tang et al., 2016; Smit and Mezger, 2017), although alternative models have been proposed (e.g., Harrison, 2009). The Sr isotope data for apatite inclusions in zircon from the Acasta Gneiss Complex presented in Chapter 2 suggest that vestiges of ancient crust had relatively evolved compositions. It appears that the early crust was largely comprised of intermediate to basaltic rocks mixed with sedimentary rocks in an upward younging stratigraphic sequence that can be interpreted as differentiated oceanic plateaux (Bédard et al., 2003, 2013; Kamber, 2010, 2015). Various proxies constrain the transition from these proto-continents to a continental crust with modern, more evolved compositions and volume to the period between 3.5 and 2.5 Ga (Konhauser et al., 2009; Næraa et al., 2012; Dhuime et al., 2012, 2015; Smit and Mezger, 2017). The rapid rise of juvenile tonalite-trondhjemite-granodiorite (TTG) crust during this period marks a major secular change in the dynamics of the Earth’s crust and mantle. The driving mechanisms are, however, still largely unconstrained. Several models interpret this change as an indicator for the start of plate tectonics (Cawood et al., 2013; Dhuime et al., 2015; Tang et al., 2016). Others argue that 47this apparent change in crustal composition and growth rates may relate to enhanced mantle heat flow produced by the removal of a thermal boundary layer or peeling-away of the lower crust (Kamber, 2015). Testing of these models requires improved time-resolved constraints of the processes that produced TTG complexes and the sources that were involved.The Rb-Sr isotopic system provides an opportunity to investigate the processes and geodynamic setting of Archean crust formation. The Rb/Sr values of rocks and reservoirs show strong and predictable differences depending on composition (Dhuime et al., 2015). This allows compositionally distinct reservoirs in the crust and mantle to develop characteristic 87Sr/86Sr signatures with time through the β-decay of 87Rb to 87Sr (λ87Rb = 1.393 ± 0.004 x 10-11 yr-1; Nebel et al., 2011) and, therefore, the 87Sr/86Sr can be used to trace magmatic sources. Likewise, initial 87Sr/86Sr values of igneous rocks can be used to constrain the Rb/Sr of the source if estimates of its age are known. These features make the Rb-Sr system an indicator of the nature of juvenile crust and the material it was sourced from (Dhuime et al., 2015). The main problem limiting the efficacy of this method is the susceptibility of Rb/Sr and 87Sr/86Sr to re-equilibration. Both Rb and Sr are relatively fluid-mobile and thus the Rb-Sr system can be affected by aqueous alteration (Tatsumi et al., 1986). This is particularly problematic for Archean TTG rocks, as they commonly show evidence for repeated deformation, metamorphism and alteration (e.g., Mojzsis et al., 2014). Apatite Rb-Sr isotopic analysis may provide an alternative to bulk rock Rb/Sr and 87Sr/86Sr measurements to constrain initial Rb-Sr signatures. Apatite Rb/Sr values are typically very low (<0.001), so analysis of primary apatite crystals allows estimates of initial 87Sr/86Sr without requiring substantial correction for the ingrowth of radiogenic 87Sr (87Sr*) from internal 87Rb decay. Given the relatively low diffusivity of Sr in apatite (Watson et al., 1985; Cherniak 48and Ryerson, 1993), diffusive re-equilibration of Sr isotopes in apatite is unlikely to occur even during high-temperature overprinting and re-melting. Modification of primary Rb-Sr systematics may occur by interaction with aqueous fluids. However, this process typically produces elevated apatite Rb/Sr and can hence be monitored through assessment of this ratio. In this study, a novel method in laser ablation multi-collector inductively coupled plasma mass spectrometry (LA-MC-ICPMS) was used to perform Rb-Sr isotopic analysis of individual apatite grains from Archean TTG. This method provides a new perspective in Archean lithosphere research and can be combined with zircon U-Pb dating to provide a time-resolved record of crustal evolution.The focus of this study is on two occurrences of relatively pristine Archean TTG rocks of different Archean age: the Kvanefjord block of southwest Greenland and the Bastar Craton of central India. The Kvanefjord block consists of a crustal segment containing TTG complexes with protolith ages between ca. 3.0-2.8 Ga (McGregor and Friend, 1997; Windley and Garde, 2009; Polat et al., 2016). The Bastar Craton of central India is a relatively underexplored Archean craton that consists of Paleo- and Neoarchean TTG and associated greenstone belts (Saha and Patranabis-Deb, 2014). Several zircon U-Pb studies have revealed the presence of ca. 3.6-3.5 Ga TTG and granites in central and southern areas of the Bastar Craton (Sarkar et al., 1993; Ghosh, 2004; Rajesh et al., 2009). The Rb-Sr isotope data from the Kvanefjord block and Bastar Craton are compared with apatite Rb-Sr data obtained from TTG samples from the Acasta Gneiss Complex (Chapter 2). Collectively, the results provide a time-resolved record of TTG crust formation that can be used to explore possible changes in the Rb/Sr record produced by the secular evolution of Archean lithosphere dynamics.493 2   Geological setting and sample descriptions3 2 1  Bastar CratonThe Bastar Craton (also known as the Bastar-Bandara Craton) of central India is one of four Archean cratons found on the Indian peninsula. It covers an area of ~200,000 km2, yet it is relatively unexplored compared to the other Indian cratons (Dharwar, Singhbhum and Arvalli-Bundelkhand) (Ghosh, 2004; Saha and Patranabis-Deb, 2014). Upper Paleozoic-Mesozoic rift basins demarcate the craton to the northeast (Mahanadi graben) and southwest (Pranhita-Godavari rift) (Figure 3.1). It is bounded by the Central Indian Tectonic Zone and the Satpura mobile belt to the northwest and the Eastern Ghats Mobile Belt to the southeast. The Bastar Craton consists primarily of variably deformed TTG gneisses and associated supracrustal greenstone belts, which consist of metamorphosed sedimentary and volcanic rocks (Rajesh et al., 2009; Saha and Patranabis-Deb, 2014). U-Pb zircon studies of the Bastar TTG have revealed the presence of ca. 3.6-3.5 Ga basement within the craton (Sarkar et al., 1993; Ghosh, 2004; Rajesh et al., 2009). Granite emplacement in the Neoarchean-Paleoproterozoic is linked to the final stabilisation of the craton (Saha and Patranabis-Deb, 2014). Mafic dyke swarms emplaced in the Neoarchean-Paleoproterozoic are found throughout the Bastar Craton (Rajesh et al., 2009; Srivastava and Gautam, 2009). Two TTG samples from the Bastar Craton were analysed in this study (Figure 3.1) (AMA-01 and AMA-04; Table 3.1). The samples are Paleoarchean tonalite gneiss and contain plagioclase, K-feldspar, quartz, biotite and muscovite with accessory zircon and apatite. Zircon from these samples were analysed by LA-ICPMS for U-Pb geochronology and yielded ages of 3582 ± 43 Ma for AMA-04 and 3503 ± 9 Ma for AMA-01 (Maltese et al., 2017). Bulk rock trace-element concentrations for these samples are presented by Smit et al. (in review). With chondrite-normalised YbN values of 0.77 (AMA-04) and 0.97 (AMA-01A), both 50samples are of the low-YbN variety and plot at the moderate-to-low end of the Archean TTG field of the classification of Moyen and Martin (2012) (Figure 3.2).Granitoids and gneiss80°N82°82°80°19°100 km84°84°21° 21°19°Supracrustal rocksProterozoic basinsGranulite BeltGondwana rocksDeccan TrapsMahanadi RiftAMA01-AAMA01-A Eastern Ghats Mobile BeltPrahnita-GodavariFigure 3 1  Simplified geological map of the Bastar Craton, India, with sample locations shown (modified after Meert et al., 2010).51Figure 3 2  LaN/YbN versus YbN plot of whole rock samples from the Acasta Gneiss Complex, Kvanefjord block and Bastar Craton (from Smit et al., in review). Archean TTG and <2.5 Ga granitoid fields after Moyen and Martin (2012). Sample 468623 is the only sample that plots towards the <2.5 Ga granitoid high YbN field. Chondrite normalisation values after Masuda et al. (1973). Table 3 1  Summary of samples analysed in this studySample Rock type Age (Ma) Latitude Longitude Main minerals AccessoriesBastar CratonAMA-01A Granodiorite gneiss 3503 ± 9 20°04.970 80°41.020 pl, kfs, qtz, bt, ms zrn, apAMA-04 Granodiorite gneiss 3582 ± 43 20°06.680 80°41.480 pl, kfs, qtz, bt, ms zrn, apKvanefjord Block518001 Tonalite gneiss 2937 ± 29 61°49.065 -49°16.487 pl, qtz, kfs, bt, hbl zrn, ap518006 Tonalite gneiss 2866 ± 34 61°49.223 -49°15.919 pl, qtz, kfs, bt, ms zrn, ap468623 Tonalite gneiss 2855 ± 34 64°11.081 -50°16.376 pl, qtz, kfs, bt, grt zrn, ap508281 Tonalite gneiss 2868 ± 31 62°8.415 -49°31.765 pl, qtz, kfs, bt, ep zrn, appl = plagioclase; kfs = K-feldspar; qtz = quartz; bt = biotite; ms = muscovite; hbl = hornblende; grt = garnet; ep = epidote; zrn = zircon; ap = apatite523 2 2  Kvanefjord blockThe Kvanefjord block of West Greenland represents a 130-km long Mesoarchean crustal segment of the North Atlantic Craton that extends to the Greenland Ice Sheet (Figure 3.3)(Windley and Garde, 2009). Initial studies proposed that the block consisted of several separate tectonothermal terranes (McGregor and Friend, 1997; Friend and Nutman, 2001). However, it has also been interpreted as a contiguous crustal segment overlain by a major nappe, called the Neria Nappe (Windley and Garde, 2009). The Kvanefjord block generally consists of orthogneisses, which have undergone variable degrees of metamorphism under greenschist- to granulite-facies conditions. The Tartôq Greenstone Belt is a supracrustal belt in the southern area of the Kvanefjord block, located next to Sermiligaarsuk Fjord. It consists of slivers of greenschist facies metavolcanic and metasedimentary rocks, which were intruded by ca. 3 Ga TTG rocks (Kisters et al., 2012; Szilas et al., 2013; Polat et al., 2016). Recent geochemical evidence from mafic and ultramafic rocks of the belt indicate that they may represent oceanic crust that formed a subduction-accretion complex (Szilas et al., 2013; Polat et al., 2016). Four Mesoarchean tonalite gneiss samples from the Kvanefjord block were investigated (Table 3.1, Figure 3.3 and Appendix G). These were collected from the areas of the Neria fjord (518001 and 518006), Kvanefjord (508281) and the Fredikshåb Isblink glacier (468623). 53PaamiutFrederikshåb IsblinkKvanefjordSermilikNeriaSermiligaarsukIvittuutblock62° N49° W62° N49° WN518001518006508281468623OrthogneissGranitic rocksMetavolcanic rocksAnorthosite IceTerrane boundary25 kmNertusoqFigure 3 3  Simplified geological map of the Kvanefjord block, southwest Greenland, with sample locations shown (modified after Windley and Garde, 2009). Sample 518006 is a foliated tonalite consisting mostly of quartz, plagioclase, K-feldspar and biotite, with minor muscovite also present. Sample 518001 is a foliated tonalite consisting mainly of quartz, plagioclase and biotite, with accessory zircon and apatite. Sample 508281 is a weakly foliated tonalite consisting mostly of quartz, plagioclase and biotite with minor K-feldspar and epidote, and accessory zircon and apatite. The presence of secondary epidote indicates that this sample was metamorphosed at upper greenschist to lower amphibolite conditions. Sample 468623 is a pristine tonalite consisting mainly of quartz and plagioclase, with minor K-feldspar, biotite and minor peritectic garnet. The samples are classified as high-Yb 54TTG with chondrite-normalized Yb (YbN) of 4.0-4.8 (468623, 518001) or low-Yb TTG (518006, 508281; YbN between 0.39-1.2) (Figure 3.2). These compositional differences are attributed to variable amounts of garnet in the residue—and by extension different depth of melting—with high-Yb samples representing garnet-absent melting (Moyen and Martin, 2012). All samples plot on the low-LaN/LuN end of Archean TTG field in the classification diagram of Moyen and Martin (2012). 3 3   Analytical MethodsMatrix apatite grains from all samples, and zircon from the Kvanefjord TTG rocks, were recovered using standard crushing, heavy liquid (CH3I) and magnetic separation techniques. The grains were mounted in epoxy and polished to expose the mid-sections of the grains. Cathodoluminescence (CL) imaging was conducted on the zircon grains at the Electron Microbeam and X-Ray Diffraction Facility at the University of British Columbia with a Philips XL30 scanning electron microscope equipped with a Robinson CL detector to reveal internal zoning of the zircon crystals. 3 3 1  Zircon U-Pb analysesThe zircon U-Pb analyses were conducted using a Thermo Finnigan ELEMENT2 high-resolution ICPMS instrument connected to an ESI NWR193UC laser ablation system at the Pacific Centre for Isotopic and Geochemical Research (PCIGR), University of British Columbia. Spot sizes of 25 μm were used at a laser fluence of ~4.5 J cm-2, a repetition rate of 6 Hz, an ablation time of 30 s, and a washout period of 22 s. The zircon reference material GJ-1 was used as a primary standard (Jackson et al., 2004) with standard-sample bracketing employed. The 55zircon standard FC-1 was used to monitor accuracy. Repeated analysis of this standard during the course of the analytical sessions provided a Wetherill concordia upper intercept age of 1103 ± 17 Ma for this material (n = 41; Figure 2.2 and Appendix A), which is in agreement with the age obtained using isotope dilution thermal ionization mass spectrometry (1099.0 ± 0.6 Ma; Paces and Miller, 1993). All data reduction was conducted offline using an Excel-based macro (Kooijman et al., 2012) and the complete data are presented in Appendix H. 3 3 2  Zircon trace element analysesTrace element concentrations in zircon grains from the Kvanefjord samples were analysed using the same LA-ICPMS system. Ablation spot sizes from 25-50 μm were placed in the same CL zone as the U-Pb spot analyses. A laser fluence of ~4.5 J cm-2, a repetition rate of 6 Hz, an ablation time of 40 s, and a washout period of 30 s were used. Analyses were internally standardized using Hf concentrations obtained using a CAMECA SX-50 electron probe micro-analyser at the Electron Microbeam and X-Ray Diffraction Facility at the University of British Columbia, with spots placed in the same CL zone as the laser ablation spot (results presented in Appendix D). The NIST SRM 612 glass was used as a primary calibration standard (Pearce et al., 1997) and zircon 91500 was used as a secondary zircon to monitor for accuracy (Wiedenbeck et al., 2004; Liu et al., 2010). The concentrations of the rare earth elements (REE) in zircon are precise to ~10%. Data reduction was conducted using Iolite the v. 3 software. The complete data are presented in Appendix I.3 3 3  Apatite Sr isotope analysesApatite grains from the Kvanefjord and Bastar samples were analysed for Rb-Sr 56isotopes by LA-MC-ICPMS using the same method applied to the apatite inclusions from the Acasta Gneiss Complex in Chapter 2 at the Vegacenter, Swedish Museum of Natural History, Stockholm. Apatite grains were analysed using a Nu Instruments Plasma II MC-ICPMS connected to an ESI NWR193UC laser ablation system with spot sizes 30, 50 or 90 μm using a laser fluence of 2.7 J cm-2, a repetition rate of 15 Hz, and an ablation time of 40 s. Baseline was measured for 50 s to allow for sufficiently precise correction of Kr+ isobaric interferences introduced with the Ar gas. Accuracy was monitored through replicate analyses of the in-house Holly Springs hydroxyl-apatite standard, which was determined by TIMS at the Swedish Museum of Natural History, Stockholm, to have an 87Sr/86Sr value of 0.718926 ± 0.000014. A weighted mean 87Sr/86Sr value of 0.71882 ± 0.00021 (MSWD = 1.6, n = 10; Figure 2.6) was obtained during the course of this study, indicating accuracy and robustness of the interference corrections made.3 4   Results3 4 1  Textures of zircon and apatite in the Kvanefjord blockZircon and apatite grains are found as accessory minerals in all four Kvaenfjord block samples. Zircon grains from all samples are typically clear or pink in colour. CL images of representative zircon grains from the samples are shown in Figure 3.4 and images for all grains analysed in this study are found in Appendix J. Grains from sample 468623 are between 120 and 240 μm in length, equant and euhedral to subhedral and have a low CL response with weak oscillatory zoning present in most grains (Figure 3.4a,b). Sample 508281 contains elongate, euhedral to subhedral zircon grains that are between 80 and 150 μm in length. Most grains from this sample have a high CL response and strong oscillatory zoning (Figure 3.4c,d). Zircon grains 57from sample 518001 are between 120 and 200 μm in length and most grains are elongate and subhedral with dark CL responses and weak zoning (Figure 3.4e,f). Grains from sample 518006 are between 80 and 250 μm in length. Most grains are round and equant (Figure 3.4g), although elongate, euhedral grains are also present (Figure 3.4h). The grains have low CL responses and either weak or no zoning.  Apatite crystals from the four samples are typically colourless, prismatic, stubby and between 100-200 μm. Examples of optical microscopy images of apatite grains with laser ablation spots are shown in Figure 3.5 and all grains are shown in Appendix K.58Figure 3 4  Examples of cathodoluminescence images for zircon grains from Kvanefjord block TTG samples. (a) An equant zircon with no zoning from sample 468623; (b) A zircon grain from sample 468623 with weak oscillatory zoning; (c), (d) Euhedral zircon grains with oscillatory zoning from sample 508281; (e), (f) Elongate zircon grains from sample 518001; (g) Round zircon grain with oscillatory zoning from sample 518006; (h) Elongate zircon grain from sample 518006. 25 μm ablation spots for LA-ICPMS U-Pb zircon analyses are indicated by white circles with 207Pb/206Pb dates (D = discordance) and uranium concentrations in ppm given.59Figure 3 5  Examples of optical microscopy images of apatite grains from the four Kvanefjord block samples. Ablation spots (50-90 μm) for LA-MC-ICPMS Sr isotope analyses are indicated by white circles with the 87Sr/86Sr indicated (± 2σ). Scale bars are 200 μm.3 4 2  Kvanefjord block zircon U-Pb and trace element results The analyses of zircon from the Kvanefjord samples yielded U-Pb results with single populations for each sample and concordia upper intercept ages between 2.94 and 2.85 Ga (Figure 3.6; Appendix H) that are in agreement with protolith ages for other gneisses in the area (Windley and Garde, 2009). The rare earth element (REE) concentrations and chondrite-normalised patterns for the Kvanefjord zircon are shown in Figure 3.7 and Appendix I. The patterns generally show enrichment of heavy REE relative to light REE and positive Ce anomalies (Ce/Ce* = 6.1–83.1) and negative Eu anomalies (Eu/Eu* = 0.02–0.29) of variable magnitude.60Figure 3 6  Wetherill concordia plots for Kvanefjord block U-Pb zircon analyses. The U-Pb results show relatively simple age systematics exhibited by the well-constrained upper intercept ages. 61Figure 3 7  Chondrite-normalised rare earth element (REE) patterns for zircon crystals from the Kvanefjord block TTG samples. Normalisation values after McDonough and Sun (1995)3 4 3  Matrix apatite Sr isotope resultsApatite grains from the two Bastar tonalites show similar Rb-Sr isotopic systematics and yield identical estimates of initial 87Sr/86Sr within uncertainty: 0.7020 ± 0.0017 for sample AMA-01 and 0.7028 ± 0.0024 for sample AMA-04 (Figure 3.8 and Appendix L). Apatite crystals in both samples are also characterised by low 87Rb/86Sr (0.0003-0.0020). Although there is variability between the Kvanefjord samples, individual samples generally show a restricted range of initial 87Sr/86Sr ratios, with scatter of the population being about 4.4 times the average uncertainty of individual points. The one exception is sample 508281 which shows large differences in 87Sr/86Sr from grain-to-grain. The sample with the most 62radiogenic 87Sr/86Sr (468623) has an initial 87Sr/86Sr mean of 0.7241 ± 0.0038 (2 s.d; n = 4; Figure 3.8 and Appendix L), whereas 518001 has the least radiogenic apatite 87Sr/86Sr, with a mean of 0.7039 ± 0.0012 (n = 13). The 87Rb/86Sr values of Kvanefjord apatite are between 0.00005 and 0.00872, and are highest for apatite from 468623.Figure 3 8  Initial 87Sr/86Sr values of matrix apatite from Archean TTG rocks measured by LA-MC-ICPMS. The Acasta values are of apatite inclusions in zircon from Chapter 2.3 5   Discussion3 5 1  Exploring possible alteration of apatite Sr isotope signatures The apatite 87Sr/86Sr results must be evaluated for any effects that could be attributed to alteration. Low-grade metamorphism and fluid-rock interaction typically involve Rb-rich fluids (Tatsumi et al., 1986; Glodny and Gauert, 2009), which could also carry Sr that is isotopically distinct from that incorporated into apatite during magmatic crystallization. This process may either lead to partial or full re-equilibration of apatite Rb-Sr systematics. Apatite grains that occurred in the altered matrix of the Acasta Gneiss Complex rocks analysed in Chapter 2 showed 63spurious 87Sr/86Sr values that were distinctly more radiogenic that the 87Sr/86Sr values determined for microscopic apatite inclusions trapped in zircon. The latter defined a homogeneous population of 87Sr/86Sr data (weighted mean = 0.70289 ± 0.00066), which was related to the igneous formation of the Eoarchean or Hadean protolith. The Rb-Sr isotopic systematics of the matrix apatite crystals in the Acasta samples reflect fluid-rock interaction and a high degree of disequilibrium. Different crystals were affected to different degrees depending on their textural setting and proximity to the channels affected by reactive fluid flow. Alteration may indeed be reflected in at least one of the samples from Kvanefjord. Sample 508281 shows inter-grain variability in 87Sr/86Sr that is well outside of the analytical uncertainty of individual spots. This is not unexpected based on the textural evidence from this sample for low-grade metamorphism, presumably at greenschist-facies conditions considering the occurrence of the indicator mineral epidote replacing biotite (Figure 3.9), which is typical for rocks from this area of the Kvanefjord block (Windley and Garde, 2009). Figure 3 9  Photomicrographs of apatite grains from samples 508281 (left) and 468623 (right) from the Kvanefjord block. Left: Secondary epidote replaced biotite and encloses the apatite grain. Right: Apatite grain appears to be primary with well-developed crystal faces and grain boundaries with quartz. Scale bars are 100 μm. Abbreviations: ap, apatite; bt. biotite; ep, epidote; plag, plagioclase; qtz; quartz; XPL, cross-polarised light.64The degree of 87Sr/86Sr dispersion observed in apatite from sample 508281 is not found in other samples, which also lack textural evidence for overprinting and alteration (Figure 3.9). These samples do not have secondary replacement minerals, such as epidote, in significant abundance and the apatite grains appear to be texturally primary (Figure 3.9). Although less obvious, alteration still has to be considered as a mechanism controlling the 87Sr/86Sr signatures of these samples. Dissolution and reprecipitation at low-grade conditions may cause replacement of igneous minerals with products that are difficult to distinguish from their precursors (Putnis and Austrheim, 2010). While textural evidence for such alteration may be lacking, or otherwise difficult to recover, the process is nevertheless expected to leave a chemical trace. Low-grade metamorphism and fluid-rock interaction typically causes apatite to become enriched in Rb and have high 87Sr/86Sr (Glodny and Grauert, 2009). This modification presumably reflects the composition of the fluid phase, which is generally enriched in incompatible Rb, and may show high 87Sr/86Sr if it interacted locally or distally with high-Rb/Sr minerals such as biotite. Alteration during fluid-rock interaction may be reflected in the data for apatite from sample 468623, which has relatively high Rb/Sr and high 87Sr/86Sr (Figure 3.8). This sample also has the highest bulk rock Rb concentrations (146.9 ppm) (Smit et al., in review) and is the most felsic (SiO2 = 73.5 wt%). It is therefore possible that the Rb enrichment in apatite from this sample merely reflects the felsic nature of the rock. To test this, the ratio of apatite Rb/Sr over whole-rock Rb/Sr was investigated, defined here as the ratio F (Figure 3.10). Fluid-rock interaction causes Rb enrichment in both rock and apatite, but typically results in leaching and removal of Sr (Glodny and Grauert, 2009), possibly due to the replacement of feldspars (Plümper and Putnis, 2009). This Sr removal affects the bulk rock more strongly than apatite, causing Rb/Sr of the bulk rock to increase more strongly than Rb/Sr of apatite in the same rock volume. 65Reactive fluid flow is expected to cause low F, and F for different grains should correlate with 87Sr/86Sr if there is any heterogeneity in the extent of alteration. This systematic is not observed in the samples. Although there is substantial scatter in F as calculated for different apatite grains per sample, the values of F are essentially overlapping for all samples and show no correlation with 87Sr/86Sr, neither between samples nor between grains within given a sample. This leaves two options: all samples are similarly affected by alteration and alteration did not affect 87Sr/86Sr or none of the samples show substantial effects of fluid-rock interaction. We suggest that the age-corrected initial apatite 87Sr/86Sr values are representative of the magmatic initial 87Sr/86Sr in the grains and their TTG host rocks, which do not show textural evidence for alteration. Figure 3 10  Measured 87Sr/86Sr versus the ratio between Rb/Sr of each apatite grain and the whole rock Rb/Sr (F) of the respective sample. The lack of a correlation between the two indicate that alteration by high-Rb/Sr fluids is not controlling the high 87Sr/86Sr observed.663 5 2  Investigation of possible sources to the TTG samplesThe initial 87Sr/86Sr apatite data from the TTG samples from the Kvanefjord block and Bastar Craton can be used to evaluate the sources that contributed to the formation of these rocks. The time-integrated 87Sr/86Sr value of a source may be estimated and, if the age of that source is known, its Rb/Sr can be constrained. The Rb/Sr may provide a proxy for the SiO2 content of these sources (Dhuime et al., 2015) and thus provide useful insight into the composition of the source. As an alternative approach, initial 87Sr/86Sr can be used as a tracer for individual components that may have contributed to forming the rocks. The average result of mixing several sources with different ages and Rb/Sr can then be used to make predictions about the range of Rb/Sr and ages that these sources may have had. A first-order observation from the results is that the 87Sr/86Sr values for apatite from the Bastar Craton are relatively low and are characterised by little internal scatter. The values are similar to those obtained for ca. 3.7 Ga apatite inclusions from the Acasta Gneiss Complex (Chapter 2). These 87Sr/86Sr values may represent a Rb/Sr signature of a single source or a mixture between a relatively radiogenic source component and juvenile melt extracted from the mantle. The 87Sr/86Sr values require a source component that developed such values, or higher in the case of mixed sources, in the time between its formation and the crystallization of the Bastar TTG rocks. Assuming a single source component, the Bastar TTG could have formed from an ancient source of moderate Rb/Sr (e.g., mantle extraction at 4 Ga with a Rb/Sr between 0.12-0.15; Figure 3.11) or from a highly evolved, high Rb/Sr source that formed more recently (e.g. 3.6 Ga with a Rb/Sr between 0.55-0.73). A single source could not have been more evolved than the TTG themselves and, considering the correlation between Rb/Sr and SiO2 (Dhuime et al., 2015) and the relatively low Rb/Sr of these rocks (~0.15), it appears more likely that 67these samples formed from ancient crust that formed in the Hadean-Eoarchean. Regardless of whether the TTG formed from a single or mixed source, the 87Sr/86Sr indicates the involvement of an evolved and/or ancient source. This is the first evidence for the involvement of an evolved or ancient crustal source in the formation of Bastar Paleoarchean TTG. Previous studies have suggested input of juvenile material at ca. 3.5 Ga (Sarkar et al., 1993; Maltese et al., 2017) and this may have triggered partial melting of the evolved source in the lower crust. Figure 3 11  Possible source ages and compositions for TTG samples. The curves show the required Rb/Sr and source age (Δt) to reach the 87Sr/86Sr of apatite for TTG samples. Unrealistically high Rb/Sr is required for younger extraction ages. The blue interval shows the typical range of Rb/Sr (0.12-0.22) found in Archean TTG rocks (Moyen, 2011).In contrast, the Sr isotope results determined for apatite from the Kvanefjord block are relatively heterogeneous. Sample 468623 in particular shows very high 87Sr/86Sr values that are significantly more radiogenic than what may be expected for evolution from a typical felsic source even if it formed during the Hadean. These results are the opposite of what is expected on the basis of Hf isotopic compositions of zircon from supracrustal rocks in the same region 68that indicate an input of juvenile material since 3.2 Ga (Næraa et al., 2012). Irrespective of whether there was a single source or whether a source component with an even higher 87Sr/86Sr than those measured here was present, the radiogenic 87Sr/86Sr values require recycling of material that was highly evolved by 3.0 Ga. If a source is considered that is as old as some of the basement rocks in the region (3.8 Ga; Nutman et al., 1999; Næraa et al., 2012), the most radiogenic Kvanefjord apatite would still require such a source to have had a very high Rb/Sr (~0.60; Figure 3.11). The correlation between Rb/Sr and SiO2 would indicate that these values are typical for felsic rocks with SiO2 over 70 wt% (Dhuime et al., 2015). Younger extraction ages would require unrealistically high Rb/Sr and SiO2 contents that are uncommon even in modern settings of highly evolved crust. The presence of high 87Sr/86Sr apatite from the Kvanefjord TTG thus is best explained by a model in which the TTG source included crustal material that was compositionally evolved and aged at least 0.5 Ga at the time of magmatism. Apatite from the other samples from the Kvanefjord block has less radiogenic 87Sr/86Sr (e.g. sample 518001, 87Sr/86Sr0 = 0.70311-0.70562). This indicates that there is at least one other source component contributing to the formation of the Kvanefjord TTG that was less evolved that the source that produced the highly radiogenic apatite from sample 468623. The high-Rb/Sr crustal component of the Kvanfjord block may have formed as enriched reservoirs buried within an overall mafic Archean crust (Kamber, 2015), where it evolved to very high 87Sr/86Sr before being tapped as a source during TTG crust formation ca. 2.9 Ga. These evolved reservoirs may be similar to those that sourced at least part of the Acasta Gneiss Complex TTG (Chapter 2). The survival of these evolved reservoirs was likely aided by sluggish mantle geodynamics and a more quiescent tectonic regime in the Archean (Caro et al., 2017; O’Neil and Carlson, 2017), which would decrease the likelihood of wholesale crustal remelting 69or recycling back into the mantle. The formation of the highly radiogenic Kvanefjord TTG could be related to the beginning of widespread re-melting of these evolved sources as a result of secular changes within the Earth’s crust in the Mesoarchean. This process occurred at a time when modern continental crust with intermediate to felsic compositions appears to have first emerged (Næraa et al., 2012; Dhuime et al., 2015; Smit and Mezger, 2017) and trace element signatures indicate a change in how new evolved crust formed (Moyen and Martin, 2012). Typical Archean TTG crust has low Yb and high La/Y, which reflect highly fractionated REE caused by melting of deep crust with garnet in the residue (Moyen and Martin, 2012) (Figure 3.2). Conversely, modern granitoids (<2.5 Ga) have higher Yb and lower La/Yb, indicating melting at shallower crustal levels. Of the samples analysed in this study, the highly radiogenic apatite from 468623 is the only sample that chemically resembles the modern granitoid field (Figure 3.2) and could indicate shallower melting in the crust. More extensive melting at mid-crustal levels could reflect overall thickening and maturation of continental crust at ca. 3 Ga, perhaps aided or forced by the start of more modern-style plate tectonics (Dhuime et al., 2012, 2015; Cawood et al., 2013). This melting was an anatectic process in which vestiges of older felsic crust, once trapped at shallow sub-solidus conditions, was buried to depths that melting could occur. This may have given rise to granitoids with higher Rb/Sr and 87Sr/86Sr, and lower La/Yb, than those that had previously formed by differentiation at the base of an overall mafic crust (Van Kranendonk, 2010; Kamber, 2015). Various lines of evidence place this secular tectonic change in the Mesoarchean (Næraa et al., 2012; Dhuime et al., 2015; Tang et al., 2016) or perhaps even earlier (Greber et al., 2017). The emergence of more potassic granitoids and sanukitoids between 2.9-2.7 Ga may also mark this the tectonic change (Smithies et al., 2009; Moyen, 2011). All models place the secular change before or during the crystallization of the 70Kvanefjord TTG suite, thus supporting a possible link between the 87Sr/86Sr apatite results and the establishment of a new, more modern tectonic regime. It is expected that future apatite Rb-Sr analysis on other TTG complexes of different locations and Archean age will further unravel the timing of this change and whether or not it was globally diachronous.The Sr isotope geochemistry of apatite grains in this study provides important evidence for the composition of source reservoirs to Archean TTG and how the earliest continental crust formed. The results reveal a compositionally heterogeneous crust in which old, enriched reservoirs could survive long periods of time without being reworked or destroyed. While studies have shown that the bulk Archean crust may have been mafic (Dhuime et al., 2015; Tang et al., 2016; Smit and Mezger, 2017) and the surface mostly covered in mafic-ultramafic lavas (Kamber et al., 2005), the Sr isotopic signatures of evolved source material suggests ancient enriched crust played a key role in the formation of TTG crust relative to more abundant mafic crust. Some studies have proposed that the Meso-Neoarchean TTG from southwest Greenland were sourced exclusively from a juvenile mafic source with little to no involvement of ancient evolved crust (Moorbath and Pankhurst, 1976; Huang et al., 2013) and Hf isotope studies of Archean TTG generally show the presence of an ancient mafic source (e.g. Bauer et al., 2017). The Rb-Sr systematics of the Kvanefjord and Bastar apatite provide complementary compositional information for the Archean continental crust and suggest that vestiges of evolved crust were present.3 6   ConclusionsIn this study, Sr isotope results of apatite from Archean tonalite-trondhjemite-granodiorite (TTG) from the Kvanefjord block and the Bastar Craton were combined with zircon U-Pb 71data to explore the evolution of Archean crustal sources and how they could have changed with time. The 87Sr/86Sr of apatite from the two Bastar Craton samples (initial 87Sr/86Sr mean of 0.7020 ± 0.0017 for AMA-01 and 0.7028 ± 0.0024 AMA-04) are similar to the 87Sr/86Sr of apatite inclusions in zircon from the Acasta Gneiss Complex presented in Chapter 2. Sample 468623 from the Kvanefjord block contains the most radiogenic apatite analysed in this study (initial 87Sr/86Sr mean = 0.7241 ± 0.0038), although other samples have less radiogenic apatite similar to the Bastar Craton and Acasra Gneiss Complex (sample 518001 initial 87Sr/86Sr mean = 0.7039 ± 0.0012). The results reveal an ancient heterogeneous crust with evolved felsic vestiges that could survive over one billion years. The source rocks were remelted and taken up into the geochemical cycle as the Mesoarchean crust thickened and anatectic differentiation occurred, resulting in the radiogenic 87Sr/86Sr signatures observed in the TTG from the Kvanefjord block. Similarly, the Sr isotope compositions of apatite grains from the Bastar Craton suggest an ancient, evolved source was involved in the formation of these TTG. Enriched source reservoirs could be a common component in tonalite-trondhjemite-granodiorite crust formation.724  ConclusionsThis chapter summarises the main findings of the two research chapters in this thesis and provides an overall outlook on future developments on Archean crustal evolution research and in situ Sr isotope analyses of apatite. The first research chapter (Chapter 2) focused on the evolution of the Acasta Gneiss Complex through in situ Sr isotope analysis of apatite inclusions within zircon hosts via laser ablation-multicollector-inductively coupled plasma mass spectrometry (LA-MC-ICPMS). The Acasta Gneiss Complex hosts the oldest known terrestrial rocks (Bowring and Williams, 1999; Reimink, et al., 2016a); therefore, investigating the evolution of this complex and constraining the composition of its possible Hadean sources can aid in our understanding of the evolution of the Earth’s earliest crust. The second chapter (Chapter 3)presented a study of Archean crustal evolution through Sr isotope analysis of apatite grains from three key Archean tonalite-trondhjemite-granodiorite (TTG) complexes by LA-MC-ICPMS. The two intertwined topics of the research chapters in this thesis lead to an overall picture of what Earth’s ancient crust might have looked like and how it evolved throughout the Archean. The LA-MC-ICPMS method used in this study to investigate the Sr isotope composition of apatite from Archean TTG provides an exciting development in crustal evolution research. This method allows for rapid, relatively precise measurements of the 87Sr/86Sr values of apatite grains and inclusions that can be combined with zircon U-Pb dating to constrain the initial 87Sr/86Sr of the sample. Further developments of the method (e.g., laser ablation split stream), as well as expanding the number of Archean TTG complexes targeted by the method could greatly enhance our insight into how Earth’s earliest crust evolved.734 1   The evolution of the Acasta Gneiss ComplexThe Acasta Gneiss Complex, Northwest Territories, Canada, is considered to contain the oldest known terrestrial rocks (Bowring and Williams, 1999; Reimink et al., 2016a). In this research chapter, LA-MC-ICPMS Sr isotope analysis was conducted on apatite inclusions in Acasta Gneiss Complex zircon host grains in ca. 3.7 Ga granodiorites. Through recent analytical developments, this method allows for small apatite inclusions (~30 μm) and grains to be measured at a precision sufficient to resolve 87Sr/86Sr signatures for crustal evolution studies (typically 2σ ≤ 3 ‰ for individual inclusions). The initial 87Sr/86Sr values of apatite inclusions that were identified to be primary show that an ancient source of Hadean age (>4.0 Ga), with a relatively evolved composition (SiO2 ≥ 61 %), was involved in the formation of the Acasta Gneiss Complex. While a mafic Hadean source has previously been suggested for the Acasta Gneiss Complex on the basis of 176Hf/177Hf analysis of zircon (Amelin et al., 2000; Reimink et al., 2016; Bauer et al., 2017), this study provides some of the first evidence for an evolved Hadean source. Based on the apatite inclusion data and results from Lu-Hf isotope studies, as well as evidence from a zircon xenocryst found in a granodiorite from the Acasta Gneiss Complex (Iizuka et al., 2006), this evolved source may have formed by 4.2 Ga. This has important implications for studies on the composition of the Hadean-Eoarchean crust as thus far most evidence for evolved Hadean crust comes from a single locality, the detrital Jack Hills zircon from Australia (Harrison et al., 2005; Harrison, 2009). The Acasta Gneiss Complex Sr isotope record yields information that can be used, alongside other lines of indirect evidence for Hadean crust (e.g., 142Nd anomalies that were produced in the first few hundred million years of Earth’s history; O’Neil and Carlson, 2017), producing models for Hadean crustal evolution. The subchondritic Hf isotope signatures in some Acasta Gneiss Complex rocks (Amelin et al., 2000; 74Reimink et al., 2016; Bauer et al., 2017), suggest the presence of Hadean mafic source, which when combined with the 87Sr/86Sr isotope evidence for a more enriched Hadean source from the Chapter 2 study, indicates that at least two sources were involved in the formation of the Acasta Gneiss Complex. This leads to the conclusion that the Hadean crust was heterogeneous with both mafic and more evolved (intermediate-felsic) compositions present. Geothermal considerations for Hadean-Eoarchean crust suggest that, due to the higher radioactive heat production from Th, U and K (particularly 235U, which had a much higher abundance in the early Earth than today as it has a relatively short half-life, λ235U = 9.8485 x 10-10 yr-1; Steiger & Jäger, 1977), large volumes of felsic crust, which concentrate these elements, would be unstable. Evolved compositions could, therefore, only be present as subordinate components in an overall mafic Hadean crust (Kamber et al., 2005; Kamber, 2015). This indicates that the high-Rb/Sr vestiges that produced the 87Sr/86Sr signatures in the Acasta Gneiss Complex inclusions may have only formed as voluminously minor pockets within a crust that was dominantly mafic. This mafic crust would have produced the subchondritic Hf isotopic signatures in the Acasta Gneiss Complex (Amelin et al., 2000; Reimink et al., 2016; Bauer et al., 2017).The main limitation of the study presented in Chapter 2 lies in the scarcity of large apatite inclusions within zircon crystals from the Acasta Gneiss Complex. Even though several Acasta Gneiss Complex samples from this study contain zircon grains that host apatite inclusions and >1000 zircon grains were picked, only seven primary inclusions yielded sufficient signal during the LA-MC-ICPMS analysis to provide reliable data. This highlights the common problem of preservation in studies involving Hadean-Eoarchean rocks. If further Sr isotope analyses of Acasta Gneiss Complex (or other Eoarchean complexes) apatite inclusions in zircon grains are to be conducted, it is recommended that large rock samples are collected and a large number 75of zircon grains are picked and mounted (at least several hundred grains per sample). It is also possible that future developments and improvements in LA-MC-ICPMS methodology (e.g., reduction of the Kr background interference) could produce relatively precise 87Sr/86Sr data from even smaller apatite inclusions than those that were analysed in this study (~30 μm). It also may be of benefit for future studies to conduct a comprehensive analysis of matrix apatite grains from Acasta Gneiss Complex samples, including geochronology, trace element geochemistry and Sr isotope signatures to further set the 87Sr/86Sr values of the apatite inclusions into context. 4 2   The evolution of Archean crustThe 87Sr/86Sr isotope systematics of the apatite grains from TTG of the Kvanefjord block, Greenland, and the Bastar Craton, India, provide a complementary picture to the results from the Acasta Gneiss Complex apatite inclusions that were used to study the evolution of Archean crust. Similar to the Acasta Gneiss Complex, the radiogenic 87Sr/86Sr values of these apatite grains show that an evolved, ancient source was involved in the formation of these TTG. This implies that enriched sources played an important role in the formation of Archean TTG crust. Previous studies have suggested that a secular change in crustal composition occurred at around 3 Ga (Næraa et al., 2012; Dhuime et al., 2015; Tang et al., 2016; Smit and Mezger, 2017) and the highly radiogenic 87Sr/86Sr signatures from the ca. 2.9 Ga Kvanefjord TTG could be an indication of this. The nature of this change could be further constrained in future studies by conducting Sr isotope analysis of apatite grains from 3.5-2.9 Ga TTG, such as those associated with the Barberton greenstone belt (Clemens et al., 2006). This would lead to the formation of a larger database of initial 87Sr/86Sr for apatite grains from Archean TTG that could be plotted versus age, similar to what is now done for zircon Hf isotope studies (e.g. Figure 5 from Bauer et al., 762017). This database could test whether the whole rock Archean Sr isotope record investigated by Dhuime et al. (2015) does in fact reflect a major change in crustal composition at ca. 3 Ga. While Dhuime et al. (2015), along with other studies (Næraa et al., 2012; Tang et al., 2016), have suggested that this compositional change marks the onset of plate tectonics, others claim that non-subduction related mechanisms can produce similar geochemical signatures (Kamber, 2015). It could therefore be argued that the secular change from thin, mafic crust to thick, felsic crust at ca. 3 Ga could have been the cause of the onset of plate tectonics rather than the result of the beginning of modern-style subduction. This issue needs to be further investigated. Generally, models of the Hadean-Archean crust combine geological and geochemical observations with geothermal and geophysical considerations to create plausible scenarios for the evolution of Earth’s oldest crust (Kamber et al., 2005; O’Neill et al., 2013; Kamber, 2015). Setting the radiogenic Sr isotope signatures of the magmatic apatite analysed in Chapters 2 and 3 in the framework of these models (e.g., Kamber et al., 2005; Debaille et al., 2013; O’Neill et al., 2013), it can be postulated that vestiges of high-Rb/Sr crust could survive for long periods of time during the Hadean-Archean in a stagnant lid regime with inefficient mixing (O’Neill et al., 2013). Stagnant lid tectonic mechanisms with only episodic subduction have been proposed based on 142Nd isotopic deviations (from the modern terrestrial standard) in Archean rocks that could only have been produced in the Hadean, as well as numerical models (Debaille et al., 2013; O’Neill et al., 2013). The high-Rb/Sr pockets could later contribute to the formation of new TTG crust through intracrustal melting and TTG/continental crust eventually came to dominate the crustal record, possibly as a result, or cause, of the onset of plate tectonics in the Mesoarchean (Figure 4.1).774 3   Figure 4 1  Schematic diagram of how ancient crust evolved from the Hadean to Archean based evidence presented in Chapters 2 and 3, and proposals from Kamber et al. (2005) and Kamber (2015). The Hadean-Eoarchean panels show a relatively thin mafic crust with vestiges of enriched material that may have been the source of the high initial 87Sr/86Sr identified in the apatite grains from this study. The Meso-Neoarchean panel shows a more modern-style crust with thick, more evolved crust and a lower, dense mafic crust with eclogitic drip features.Future developments Analysing Sr isotopes in apatite inclusions and matrix grains by LA-MC-ICPMS provides a new geochemical tool that can contribute significantly to elucidating the time-resolved record of a changing continental crust, and providing constraints on its origin and the development of global tectonics. Application of this approach to TTG complexes of different location and Archean age would be needed to achieve this overarching research goal. Identifying the promising prospects of apatite research, several groups are now developing the analytical approach used in this thesis in their labs. Areas that are known to contain Hadean-Eoarchean zircon grains, such as Jack Hills, Western Australia (Harrison, 2009) and the Nuvvuagittuq Greenstone Belt (O’Neil et al., 2012), are being targeted for apatite inclusions and subjected to the same LA-MC-ICPMS method applied here to the Acasta Gneiss Complex inclusions. Apatite inclusions in >4 Ga Jack Hills zircon grains have been identified (Hopkins et al., 2010; 78Rasmussen et al., 2011; Bell et al., 2015), although they may be affected by alteration or are too small to be analysed by the LA-MC-ICPMS method used in Chapter 2. It might be expected that apatite inclusions within Jack Hills zircon would have highly radiogenic Sr isotope signatures based on O isotope, trace element and inclusion assemblage evidence (Wilde et al., 2001; Bell et al., 2015). The Nuvvuagittuq zircon may include apatite that has less radiogenic 87Sr/86Sr signatures derived from a more mafic source (O’Neil et al., 2012). Combining Sr isotope analysis of apatite inclusions within Acasta Gneiss Complex zircon (or other ancient zircon grains such as the Jack Hills zircon) with Lu-Hf analysis of the zircon host grains by LA-MC-ICPMS could help to verify the apatite Sr isotope record, as radiogenic 87Sr/86Sr apatite inclusions would be expected to be enclosed in low-176Hf/177Hf zircon host grains (i.e., Lu/Hf is lower in more evolved rocks and 176Lu decays to 176Hf, resulting in lower 176Hf/177Hf). Future developments with respect to the LA-MC-ICPMS methodology used in this study (e.g. reduced spot size or increased sensitivity would allow smaller apatite grains or inclusions to be analysed) could also lead to greater insight into the significance of the Sr isotope record of apatite grains. Laser-ablation split-stream (LASS) analysis (Kylander-Clark et al., 2013) could be used to combine Sr isotope analysis with either U-Pb dating or trace element analysis to better constrain the age of a single apatite grain and the conditions under which it formed (i.e., whether alteration or recrystallisation occurred). LASS analysis may not be feasible for apatite inclusions in zircon grains as they would likely be too small to obtain a high enough signal. The method would be useful in studies of matrix apatite grains from regions where metamorphic overprinting is expected as this could be identified through trace element signatures of the apatite grains. In conclusion, the research in this thesis provides an important contribution in Archean crustal evolution research through the analysis of apatite Sr isotope signatures in Archean TTG by 79LA-MC-ICPMS. 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(%)e 206Pb/204Pb 204Pb < DL?f ƒ206%gFC-1-01 337 1.8 0.1 0.175 0.007 5.71 0.22 0.076 0.002 0.78 1040 37 3.6 1059 33 3.1 1098 63 5.7 5.2 yesFC-1-02 340 1.9 0.1 0.184 0.007 5.44 0.22 0.077 0.002 0.81 1088 40 3.7 1098 34 3.1 1119 59 5.2 2.7 yesFC-1-03 327 1.8 0.1 0.181 0.008 5.52 0.25 0.073 0.002 0.82 1074 45 4.2 1058 36 3.5 1025 64 6.2 -4.8 yesFC-1-04 237 1.9 0.1 0.183 0.010 5.48 0.30 0.077 0.004 0.73 1081 55 5.1 1096 51 4.6 1124 104 9.2 3.8 8478 no 0.04FC-1-05 190 2.3 0.1 0.213 0.007 4.70 0.15 0.078 0.004 0.56 1244 35 2.8 1210 40 3.3 1150 93 8.1 -8.2 12472 no 0.04FC-1-06 185 2.3 0.1 0.212 0.007 4.71 0.15 0.079 0.004 0.52 1241 37 3.0 1218 45 3.7 1178 107 9.1 -5.4 yesFC-1-07 216 2.1 0.2 0.195 0.012 5.13 0.32 0.078 0.004 0.75 1148 66 5.8 1150 58 5.0 1154 111 9.6 0.6 2446 no 0.11FC-1-08 187 2.0 0.1 0.197 0.009 5.09 0.22 0.076 0.004 0.61 1157 47 4.0 1132 49 4.3 1084 114 10.5 -6.8 2199 no 0.22FC-1-09 183 2.0 0.2 0.181 0.011 5.52 0.33 0.080 0.005 0.71 1074 60 5.5 1113 58 5.2 1191 119 10.0 9.8 26526 no 0.02FC-1-10 188 1.8 0.2 0.173 0.014 5.77 0.48 0.075 0.005 0.79 1031 79 7.6 1038 68 6.6 1055 131 12.4 2.3 yesFC-1-11 194 2.0 0.1 0.189 0.011 5.29 0.30 0.076 0.003 0.83 1116 58 5.2 1109 46 4.2 1096 77 7.0 -1.8 2233 no 0.24FC-1-12 165 2.0 0.2 0.188 0.011 5.32 0.31 0.076 0.004 0.75 1109 59 5.3 1105 52 4.7 1097 101 9.2 -1.2 5250 no 0.07FC-1-13 182 2.0 0.1 0.1928 0.0071 5.19 0.19 0.076 0.004 0.55 1137 38 3.4 1120 45 4.1 1088 112 10.3 -4.5 2237 no 0.08FC-1-14 156 2.1 0.1 0.1990 0.0067 5.02 0.17 0.075 0.004 0.51 1170 36 3.1 1133 45 4.0 1062 114 10.7 -10.1 1964 no 0.21FC-1-15 146 1.9 0.1 0.1802 0.0093 5.55 0.29 0.077 0.005 0.66 1068 51 4.8 1083 52 4.8 1112 118 10.6 4 yesFC-1-16 179 1.9 0.2 0.1867 0.0093 5.36 0.27 0.073 0.005 0.62 1104 50 4.6 1074 53 4.9 1013 128 12.6 -8.9 yesFC-1-17 171 2.1 0.2 0.1901 0.0073 5.26 0.20 0.080 0.006 0.47 1122 40 3.5 1148 56 4.9 1199 143 11.9 6.4 yesFC-1-18 175 2.0 0.1 0.1865 0.0050 5.36 0.14 0.076 0.004 0.48 1103 27 2.5 1101 38 3.4 1099 99 9.0 -0.3 2355 no 0.28FC-1-19 251 1.9 0.2 0.177 0.011 5.65 0.34 0.076 0.005 0.66 1051 59 5.6 1065 61 5.8 1093 141 12.9 3.9 1479 no 0.44FC-1-20 248 1.7 0.2 0.171 0.014 5.85 0.48 0.074 0.004 0.81 1018 78 7.6 1026 66 6.4 1044 122 11.7 2.5 yesFC-1-21 260 1.8 0.2 0.182 0.011 5.49 0.34 0.070 0.004 0.72 1079 62 5.7 1031 56 5.5 931 125 13.4 -15.9 yesFC-1-22 246 1.7 0.1 0.1635 0.0043 6.12 0.16 0.075 0.004 0.44 976 24 2.4 1005 38 3.8 1068 108 10.1 8.6 1209 no 0.70FC-1-23 349 1.9 0.1 0.1766 0.0055 5.66 0.18 0.079 0.004 0.55 1048 30 2.9 1093 38 3.5 1182 93 7.9 11.3 yesFC-1-24 307 1.9 0.2 0.1736 0.0080 5.76 0.26 0.080 0.005 0.57 1032 44 4.2 1088 54 4.9 1202 131 10.9 14.2 yesFC-1-25 369 1.9 0.2 0.178 0.014 5.63 0.46 0.076 0.006 0.74 1054 79 7.5 1065 72 6.8 1087 147 13.6 3 yesFC-1-26 349 1.9 0.1 0.1855 0.0067 5.39 0.19 0.076 0.004 0.61 1097 36 3.3 1097 39 3.6 1098 93 8.5 0.1 4212 no 0.15FC-1-27 270 2.0 0.2 0.194 0.012 5.16 0.32 0.076 0.004 0.78 1141 66 5.7 1121 55 4.9 1083 102 9.4 -5.4 8516 no 0.08FC-1-28 283 2.0 0.2 0.1902 0.0054 5.26 0.15 0.076 0.005 0.37 1122 29 2.6 1114 52 4.6 1098 142 12.9 -2.2 yesFC-1-29 280 2.0 0.1 0.1831 0.0086 5.46 0.26 0.079 0.003 0.81 1084 47 4.3 1116 39 3.5 1180 68 5.8 8.1 yesFC-1-30 259 1.9 0.1 0.1795 0.0071 5.57 0.22 0.076 0.004 0.63 1064 39 3.6 1078 41 3.8 1105 96 8.7 3.7 yesFC-1-31 369 2.0 0.2 0.190 0.014 5.26 0.38 0.076 0.004 0.80 1123 74 6.6 1112 61 5.5 1092 109 10.0 -2.8 yesFC-1-32 244 1.9 0.2 0.189 0.020 5.28 0.57 0.073 0.005 0.86 1118 110 9.9 1086 84 7.7 1021 130 12.7 -9.5 yesFC-1-33 256 2.1 0.3 0.202 0.016 4.95 0.40 0.077 0.008 0.62 1185 87 7.3 1162 90 7.7 1121 203 18.1 -5.8 15541 no 0.03FC-1-34 230 2.1 0.2 0.197 0.012 5.07 0.30 0.077 0.004 0.74 1161 62 5.4 1149 54 4.7 1125 106 9.4 -3.2 3099 no 0.12Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))x100; f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)Appendices95Table A 1. (continued) Complete LA-ICPMS U-Pb data for FC-1Ratios b Dates (Ma)d Common PbNumber U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb < DL?f ƒ206%gFC-1-35 276 2.0 0.2 0.1957 0.0087 5.11 0.23 0.073 0.005 0.57 1152 47 4.1 1101 53 4.8 1001 132 13.2 -15.1 5852 no 0.14FC-1-36 282 2.1 0.1 0.2041 0.0092 4.90 0.22 0.075 0.003 0.69 1197 49 4.1 1148 45 3.9 1056 94 8.9 -13.4 yesFC-1-37 364 1.9 0.2 0.180 0.014 5.57 0.42 0.076 0.004 0.83 1065 75 7.0 1079 61 5.6 1106 101 9.1 3.7 yesFC-1-38 230 1.6 0.1 0.1592 0.0052 6.28 0.21 0.074 0.003 0.58 952 29 3.1 983 36 3.6 1051 92 8.8 9.4 yesFC-1-39 202 1.9 0.2 0.1697 0.0091 5.89 0.32 0.080 0.005 0.66 1011 50 5.0 1075 54 5.0 1209 121 10.0 16.4 1604 no 0.62FC-1-40 216 2.0 0.1 0.1912 0.0080 5.23 0.22 0.076 0.004 0.65 1128 43 3.8 1117 44 3.9 1096 99 9.1 -2.9 9585 no 0.07FC-1-41 312 1.9 0.1 0.1780 0.0059 5.62 0.19 0.079 0.003 0.67 1056 32 3.1 1094 33 3.1 1169 74 6.3 9.7 38119 no 0.01Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100;      f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)96Appendix B  Complete U-Pb analyses of zircon from the Acasta Gneiss Complex, Northwest Territories, Canada, determined by LA-ICPMSTable B 1  Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS027_BG3MT_001a 1070 13.4 0.8 0.407 0.017 2.46 0.10 0.240 0.010 0.70 2199 79 3.6 2711 58 2.1 3118 70 2.2 29.5 85 no 13AMS027_BG3MT_001b 1010 6.3 0.4 0.182 0.009 5.49 0.27 0.2509 0.0088 0.81 1078 48 4.5 2018 53 2.6 3191 56 1.7 66.2 83 no 13.39AMS027_BG3MT_002 567 22.1 1.2 0.567 0.023 1.76 0.07 0.283 0.010 0.75 2895 96 3.3 3189 53 1.7 3380 56 1.7 14.4 88 no 12.51AMS027_BG3MT_003a 59 26.1 1.6 0.559 0.027 1.79 0.08 0.339 0.014 0.76 2862 110 3.8 3352 61 1.8 3660 62 1.7 21.8 739 no 1.45AMS027_BG3MT_003b 82 23.4 1.5 0.55 0.02 1.82 0.07 0.309 0.016 0.57 2826 83 2.9 3244 62 1.9 3514 80 2.3 19.6 134 no 8.22AMS027_BG3MT_003c 691 7.7 0.5 0.212 0.007 4.72 0.16 0.265 0.013 0.55 1238 38 3.1 2200 55 2.5 3275 80 2.4 62.2 52 no 21.17AMS027_BG3MT_005 715 29.0 0.8 0.681 0.015 1.47 0.03 0.309 0.006 0.77 3348 58 1.7 3455 28 0.8 3517 29 0.8 4.8 989 no 1.12AMS027_BG3MT_006 436 15.0 1.6 0.379 0.022 2.64 0.15 0.287 0.027 0.53 2072 101 4.9 2816 104 3.7 3402 145 4.3 39.1 47 no 23.43AMS027_BG3MT_007 523 16.1 1.1 0.411 0.018 2.43 0.11 0.285 0.014 0.67 2220 84 3.8 2885 63 2.2 3389 76 2.2 34.5 43 no 25.65AMS027_BG3MT_009 342 24.2 1.3 0.580 0.025 1.72 0.07 0.303 0.010 0.78 2948 102 3.4 3277 54 1.6 3485 53 1.5 15.4 91 no 12.16AMS027_BG3MT_011 249 25.9 1.3 0.614 0.025 1.63 0.07 0.3060 0.0085 0.83 3084 100 3.3 3342 48 1.4 3501 43 1.2 11.9 208 no 5.32AMS027_BG3MT_013a 26 24.6 1.9 0.626 0.032 1.60 0.08 0.285 0.016 0.68 3132 128 4.1 3291 74 2.2 3389 86 2.5 7.6 141 no 7.84AMS027_BG3MT_013b 804 15.8 0.8 0.449 0.018 2.23 0.09 0.256 0.008 0.79 2389 80 3.4 2867 49 1.7 3223 49 1.5 25.9 78 no 14.15AMS027_BG3MT_014 278 28.3 2.6 0.655 0.042 1.53 0.10 0.313 0.020 0.70 3247 164 5.1 3429 90 2.6 3537 100 2.8 8.2 1110 no 1AMS027_BG3MT_015 615 8.2 1.1 0.172 0.013 5.82 0.44 0.345 0.037 0.57 1021 71 6.9 2250 120 5.3 3686 166 4.5 72.3 19 no 57.74AMS027_BG3MT_018a 532 9.0 0.9 0.219 0.017 4.56 0.35 0.298 0.019 0.77 1279 88 6.9 2341 90 3.8 3462 97 2.8 63.1 1184 no 0.93AMS027_BG3MT_018b 667 4.4 0.4 0.1350 0.0083 7.41 0.46 0.238 0.017 0.65 816 47 5.8 1716 79 4.6 3104 116 3.7 73.7 69 no 16.12AMS027_BG3MT_019 1110 18.3 1.7 0.442 0.024 2.26 0.12 0.300 0.023 0.57 2359 106 4.5 3004 92 3.0 3470 122 3.5 32 54 no 20.44AMS027_BG3MT_020 1450 11.1 1.0 0.321 0.019 3.11 0.18 0.250 0.018 0.62 1795 91 5.1 2529 88 3.5 3185 117 3.7 43.6 96 no 11.55AMS027_BG3MT_021a 334 26.7 2.4 0.637 0.034 1.57 0.08 0.304 0.022 0.59 3178 136 4.3 3373 90 2.7 3491 114 3.3 9 95 no 11.69AMS027_BG3MT_021b 1230 6.7 0.6 0.202 0.011 4.96 0.27 0.242 0.019 0.58 1184 60 5.0 2076 84 4.1 3132 123 3.9 62.2 57 no 19.36AMS027_BG3MT_022 1890 8.5 0.8 0.282 0.015 3.55 0.19 0.218 0.016 0.59 1600 76 4.7 2284 82 3.6 2969 118 4.0 46.1 285 no 3.88AMS027_BG3MT_024 704 15.1 1.5 0.390 0.032 2.57 0.21 0.280 0.015 0.84 2121 148 7.0 2819 93 3.3 3365 82 2.4 37 39 no 28.09AMS027_BG3MT_025a 844 22.4 2.2 0.532 0.047 1.88 0.17 0.305 0.013 0.90 2750 199 7.2 3200 96 3.0 3496 67 1.9 21.4 1285 no 0.86AMS027_BG3MT_025b 1610 9.1 0.8 0.280 0.023 3.58 0.29 0.236 0.010 0.89 1590 116 7.3 2350 85 3.6 3096 68 2.2 48.7 148 no 7.45AMS027_BG3MT_026a 423 19.6 1.9 0.469 0.040 2.13 0.18 0.302 0.013 0.89 2481 174 7.0 3070 92 3.0 3481 68 1.9 28.7 115 no 9.62AMS027_BG3MT_028 486 24.6 2.4 0.649 0.057 1.54 0.14 0.275 0.012 0.89 3223 223 6.9 3291 97 2.9 3333 70 2.1 3.3 103 no 10.72AMS027_BG3MT_029 1380 25.2 2.5 0.644 0.058 1.55 0.14 0.284 0.012 0.91 3204 229 7.1 3316 98 3.0 3384 66 2.0 5.3 43100 no 0.03AMS027_BG3MT_030 283 27.4 2.7 0.699 0.062 1.43 0.13 0.285 0.012 0.90 3417 234 6.8 3399 96 2.8 3388 65 1.9 -0.9 3622 no 0.23AMS027_BG3MT_031 205 26.2 2.8 0.627 0.060 1.59 0.15 0.302 0.014 0.90 3139 239 7.6 3353 105 3.1 3483 74 2.1 9.9 96 no 11.47AMS027_BG3MT_032 489 20.7 1.8 0.559 0.036 1.79 0.11 0.268 0.016 0.74 2862 148 5.2 3124 84 2.7 3297 92 2.8 13.2 78 no 14.20AMS027_BG3MT_035 488 16.6 1.6 0.395 0.028 2.53 0.18 0.304 0.021 0.71 2145 128 6.0 2910 94 3.2 3491 107 3.1 38.5 28 no 38.93Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100) 97Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS027_BG3MT_036a 288 20.3 1.8 0.499 0.034 2.00 0.13 0.295 0.017 0.77 2611 144 5.5 3107 85 2.7 3445 88 2.5 24.2 260 no 4.25AMS027_BG3MT_036b 1450 15.2 1.3 0.420 0.027 2.38 0.15 0.262 0.015 0.74 2262 122 5.4 2827 82 2.9 3259 91 2.8 30.6 82 no 13.49AMS027_BG3MT_037 613 22.3 1.5 0.528 0.030 1.89 0.11 0.306 0.011 0.84 2734 126 4.6 3196 65 2.0 3500 56 1.6 21.9 43 no 25.43AMS027_BG3MT_038a 520 15.4 1.0 0.421 0.023 2.37 0.13 0.2658 0.0093 0.84 2266 105 4.6 2843 62 2.2 3282 55 1.7 31 43 no 25.65AMS027_BG3MT_038b 532 7.8 0.6 0.204 0.013 4.9 0.3 0.276 0.011 0.84 1198 68 5.7 2205 66 3.0 3340 62 1.9 64.1 38 no 28.75AMS027_BG3MT_039a 707 19.6 1.1 0.538 0.029 1.86 0.10 0.2642 0.0050 0.94 2777 122 4.4 3072 56 1.8 3272 30 0.9 15.1 417 no 2.65AMS027_BG3MT_039b 1200 9.8 0.6 0.311 0.017 3.21 0.18 0.2292 0.0051 0.93 1747 85 4.9 2420 55 2.3 3047 36 1.2 42.7 160 no 6.93AMS027_BG3MT_040 771 8.8 0.6 0.210 0.009 4.76 0.20 0.304 0.018 0.58 1229 47 3.8 2317 67 2.9 3489 92 2.6 64.8 27 no 40.97AMS027_BG3MT_042 478 37.1 2.0 0.864 0.022 1.16 0.03 0.311 0.015 0.47 4014 76 1.9 3696 53 1.4 3528 73 2.1 -13.8 56 no 19.76AMS027_BG3MT_045 617 28.6 1.5 0.651 0.018 1.54 0.04 0.319 0.014 0.55 3232 72 2.2 3440 51 1.5 3564 66 1.9 9.3 408 no 2.71AMS027_BG3MT_046a 40 24.5 1.5 0.528 0.017 1.89 0.06 0.337 0.018 0.52 2733 72 2.6 3290 60 1.8 3649 81 2.2 25.1 4983 no 0.13AMS027_BG3MT_046b 347 18.0 0.9 0.433 0.012 2.31 0.06 0.301 0.013 0.53 2318 53 2.3 2988 49 1.7 3477 68 1.9 33.3 67 no 16.47AMS027_BG3MT_048a 83 33.2 1.7 0.776 0.018 1.29 0.03 0.310 0.015 0.44 3701 64 1.7 3586 51 1.4 3523 72 2.1 -5.1 195 no 5.66AMS027_BG3MT_048b 1790 10.7 0.5 0.3363 0.0071 2.97 0.06 0.2301 0.0092 0.47 1869 34 1.8 2495 42 1.7 3053 64 2.1 38.8 544 no 2.03AMS027_BG3MT_051 695 16.4 1.0 0.381 0.011 2.63 0.08 0.312 0.016 0.49 2080 52 2.5 2899 57 2.0 3530 81 2.3 41.1 40 no 27.55AMS027_PRMT4_002 921 17.7 1.7 0.542 0.038 1.85 0.13 0.237 0.014 0.76 2791 160 5.7 2972 90 3.0 3097 98 3.2 9.9 3079 no 0.36AMS027_PRMT4_005 1600 8.5 0.6 0.261 0.016 3.83 0.23 0.235 0.011 0.80 1496 82 5.5 2282 70 3.0 3086 73 2.4 51.5 1212 no 0.94AMS027_PRMT4_009 712 14.7 1.3 0.364 0.027 2.75 0.20 0.293 0.016 0.80 2002 127 6.3 2795 87 3.1 3431 85 2.5 41.7 78 no 14.09AMS027_PRMT4_010 891 24.2 2.0 0.626 0.044 1.60 0.11 0.280 0.013 0.85 3132 176 5.6 3275 82 2.5 3364 70 2.1 6.9 3610 no 0.31AMS027_PRMT4_013 664 39.4 3.3 0.834 0.059 1.20 0.08 0.342 0.015 0.84 3910 207 5.3 3755 83 2.2 3672 68 1.9 -6.5 1306 no 0.85AMS027_PRMT4_016 1480 20.0 1.7 0.565 0.040 1.77 0.13 0.257 0.012 0.83 2888 165 5.7 3094 82 2.7 3230 74 2.3 10.6 1776 no 0.62AMS027_PRMT4_017 731 26.2 1.3 0.669 0.021 1.5 0.1 0.285 0.011 0.62 3301 80 2.4 3355 49 1.5 3388 61 1.8 2.6 13563 no 0.04AMS027_PRMT4_018 1500 12.6 0.7 0.406 0.014 2.46 0.08 0.224 0.009 0.65 2199 64 2.9 2647 50 1.9 3010 65 2.2 27 8381 no 0.13AMS027_PRMT4_020 1210 15.0 0.9 0.480 0.016 2.08 0.07 0.227 0.011 0.57 2527 69 2.7 2815 55 2.0 3028 76 2.5 16.5 114 no 9.68AMS027_PRMT4_021 1030 8.5 0.6 0.250 0.008 4.00 0.14 0.246 0.014 0.52 1437 44 3.0 2282 60 2.6 3158 90 2.8 54.5 46 no 23.78AMS027_PRMT4_022 220 21.7 1.1 0.549 0.017 1.82 0.06 0.287 0.011 0.62 2820 72 2.6 3170 49 1.6 3399 62 1.8 17 2025 no 0.55AMS027_PRMT4_023 704 11.4 1.3 0.339 0.035 2.95 0.31 0.244 0.010 0.93 1884 169 9.0 2559 105 4.1 3147 66 2.1 40.1 53 no 20.79AMS027_PRMT4_024 563 25.0 2.7 0.619 0.064 1.61 0.17 0.293 0.010 0.95 3107 255 8.2 3309 107 3.2 3433 53 1.6 9.5 1272 no 0.87AMS027_PRMT4_028 744 8.0 0.9 0.242 0.025 4.13 0.43 0.240 0.010 0.93 1398 131 9.4 2233 101 4.5 3121 63 2.0 55.2 95 no 11.61AMS027_PRMT4_031 1200 20.9 2.3 0.617 0.064 1.62 0.17 0.2452 0.0089 0.94 3099 257 8.3 3132 107 3.4 3154 57 1.8 1.8 5623 no 0.20AMS027_SMMT4_003 327 37.9 2.6 0.777 0.045 1.29 0.07 0.354 0.013 0.83 3705 162 4.4 3717 68 1.8 3724 58 1.6 0.5 6467 no 0.12AMS027_SMMT4_006 780 37.5 3.2 0.755 0.049 1.32 0.09 0.360 0.020 0.76 3626 178 4.9 3706 84 2.3 3750 84 2.2 3.3 14071 no 0.06AMS027_SMMT4_009 255 31.0 2.6 0.693 0.045 1.44 0.09 0.324 0.018 0.76 3396 172 5.1 3518 84 2.4 3589 85 2.4 5.4 15192 no 0.05AMS027_SMMT4_012 255 35.2 3.0 0.720 0.048 1.39 0.09 0.354 0.020 0.77 3495 179 5.1 3643 86 2.3 3726 84 2.3 6.2 14347 no 0.04AMS027_SMMT4_020 416 34.0 2.8 0.720 0.044 1.39 0.09 0.342 0.018 0.75 3496 166 4.8 3609 81 2.2 3672 82 2.2 4.8 yesAMS027_SMMT4_027 237 33.8 2.8 0.689 0.044 1.45 0.09 0.356 0.019 0.76 3380 169 5.0 3604 83 2.3 3732 82 2.2 9.4 6863 no 0.12Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100) 98Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS027_SMMT4_028 548 35.1 2.3 0.728 0.031 1.37 0.06 0.349 0.018 0.65 3527 117 3.3 3641 65 1.8 3704 77 2.1 4.8 36101 no 0.02AMS027_SMMT4_029 234 37.2 2.5 0.753 0.033 1.33 0.06 0.359 0.018 0.66 3617 120 3.3 3700 65 1.8 3746 76 2.0 3.4 11360 no 0.05AMS027_SMMT4_031 272 27.5 1.9 0.573 0.026 1.75 0.08 0.348 0.018 0.66 2919 106 3.6 3400 67 2.0 3696 78 2.1 21 2263 no 0.49AMS027_SMMT4_032 314 38.0 2.5 0.775 0.032 1.29 0.05 0.356 0.018 0.63 3698 115 3.1 3720 65 1.7 3733 77 2.1 0.9 9726 no 0.04AMS027_SMMT4_034 320 40.0 2.2 0.830 0.029 1.20 0.04 0.349 0.015 0.64 3895 103 2.6 3770 54 1.4 3703 64 1.7 -5.2 7531 no 0.08AMS027_SMMT4_035 346 30.5 1.7 0.651 0.025 1.54 0.06 0.339 0.014 0.67 3233 97 3.0 3502 56 1.6 3660 65 1.8 11.7 44534 no 0.01AMS027_ApMT1_03a 879 10.6 0.7 0.297 0.010 3.36 0.11 0.258 0.015 0.48 1677 48 2.9 2484 62 2.5 3232 93 2.9 48.1 55 no 19.94AMS027_ApMT1_03b 1540 6.8 0.5 0.196 0.006 5.10 0.16 0.253 0.015 0.48 1155 34 2.9 2090 60 2.9 3201 94 2.9 63.9 43 no 25.67AMS027_ApMT1_04a 260 35.6 2.3 0.728 0.024 1.37 0.05 0.355 0.020 0.51 3525 90 2.5 3656 64 1.7 3728 84 2.3 5.5 8233 no 0.13AMS027_ApMT1_04b 382 34.7 2.2 0.705 0.022 1.42 0.04 0.357 0.019 0.50 3439 83 2.4 3630 61 1.7 3736 82 2.2 8 1136 no 0.13AMS027_ApMT1_05a 583 18.6 1.2 0.502 0.025 2.0 0.1 0.268 0.011 0.77 2623 107 4.1 3019 62 2.0 3295 64 1.9 20.4 110 no 10.05AMS027_ApMT1_05b 672 15.9 1.0 0.413 0.020 2.42 0.12 0.279 0.011 0.77 2230 90 4.0 2870 59 2.0 3356 61 1.8 33.5 64 no 17.16AMS027_ApMT1_06a 483 10.7 0.9 0.248 0.014 4.03 0.23 0.313 0.020 0.67 1430 72 5.1 2498 79 3.1 3535 97 2.7 59.6 27 no 40.33AMS027_ApMT1_06b 863 12.6 0.9 0.272 0.013 3.68 0.18 0.336 0.017 0.69 1551 68 4.4 2649 67 2.5 3643 79 2.2 57.4 37 no 29.90AMS027_ApMT1_06c 494 8.2 0.6 0.198 0.010 5.05 0.26 0.302 0.014 0.73 1164 54 4.6 2257 63 2.8 3478 73 2.1 66.5 28 no 39.08AMS027_ApMT1_08a 884 11.8 0.7 0.332 0.016 3.01 0.14 0.258 0.010 0.77 1848 76 4.1 2590 58 2.2 3236 62 1.9 42.9 94 no 11.81AMS027_ApMT1_08b 1050 9.1 0.6 0.263 0.012 3.80 0.18 0.251 0.010 0.77 1505 63 4.2 2350 56 2.4 3193 62 1.9 52.9 89 no 12.39AMS027_ApMT2_01a 499 28.1 1.3 0.674 0.020 1.48 0.04 0.302 0.010 0.67 3322 78 2.3 3421 44 1.3 3480 51 1.5 4.5 1861 no 0.59AMS027_ApMT2_01b 451 16.0 1.0 0.379 0.012 2.64 0.08 0.306 0.016 0.53 2072 57 2.7 2878 57 2.0 3502 78 2.2 40.8 34 no 32.43AMS027_Pk5_bt37a 532 17.7 1.0 0.415 0.017 2.41 0.10 0.310 0.012 0.74 2239 79 3.5 2976 54 1.8 3521 58 1.7 36.4 9550 no 0.12AMS027_Pk5_bt37b 257 29.5 1.6 0.634 0.025 1.58 0.06 0.337 0.012 0.73 3166 98 3.1 3469 52 1.5 3649 56 1.5 13.2 5755 no 0.17Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100) 99Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS013_BG3MT_001a 603 26.3 1.8 0.608 0.039 1.64 0.11 0.3134 0.0085 0.92 3062 158 5.2 3357 69 2.1 3538 42 1.2 13.5 25144 no 0.03AMS013_BG3MT_001b 68 31.1 2.4 0.708 0.047 1.41 0.09 0.319 0.012 0.87 3450 176 5.1 3523 75 2.1 3565 58 1.6 3.2 yesAMS013_BG3MT_002a 98 26.2 1.9 0.585 0.037 1.71 0.11 0.326 0.011 0.89 2968 149 5.0 3356 69 2.1 3596 50 1.4 17.5 yesAMS013_BG3MT_002b 208 26.3 2.0 0.634 0.039 1.58 0.10 0.301 0.014 0.79 3166 152 4.8 3358 76 2.3 3474 74 2.1 8.9 yesAMS013_BG3MT_003 124 28.2 2.1 0.630 0.037 1.59 0.09 0.324 0.015 0.78 3151 146 4.6 3425 73 2.1 3590 71 2.0 12.2 yesAMS013_BG3MT_004 105 26.2 1.9 0.588 0.034 1.7 0.1 0.324 0.015 0.79 2982 140 4.7 3356 72 2.2 3587 69 1.9 16.9 8489 no 0.08AMS013_BG3MT_005a 863 14.5 1.1 0.429 0.025 2.33 0.14 0.245 0.011 0.79 2303 114 4.9 2785 71 2.5 3156 72 2.3 27 7325 no 0.14AMS013_BG3MT_005b 241 26.2 1.9 0.615 0.034 1.63 0.09 0.309 0.015 0.76 3089 135 4.4 3352 71 2.1 3514 74 2.1 12.1 6712 no 0.14AMS013_BG3MT_005c 64 28.5 2.1 0.683 0.037 1.46 0.08 0.303 0.015 0.74 3357 142 4.2 3437 73 2.1 3484 77 2.2 3.6 yesAMS013_BG3MT_006 102 30.5 2.2 0.658 0.035 1.52 0.08 0.336 0.016 0.74 3261 138 4.2 3504 72 2.0 3646 75 2.0 10.6 yesAMS013_BG3MT_009 49 25.0 1.9 0.576 0.032 1.74 0.10 0.316 0.017 0.72 2931 132 4.5 3310 76 2.3 3549 83 2.3 17.4 4764 no 0.10AMS013_BG3MT_010a 213 30.2 2.2 0.660 0.035 1.51 0.08 0.332 0.016 0.74 3267 136 4.2 3495 70 2.0 3628 73 2.0 9.9 4161 no 0.16AMS013_BG3MT_010b 74 20.9 1.2 0.553 0.023 1.81 0.07 0.274 0.012 0.69 2839 94 3.3 3133 58 1.8 3326 68 2.0 14.6 5105 no 0.15AMS013_BG3MT_011 854 33.5 1.9 0.704 0.029 1.42 0.06 0.345 0.014 0.72 3434 109 3.2 3596 56 1.6 3687 61 1.6 6.9 13808 no 0.06AMS013_BG3MT_012a 89 34.9 2.0 0.796 0.031 1.26 0.05 0.318 0.013 0.69 3775 112 3.0 3635 56 1.6 3559 64 1.8 -6 3136 no 0.11AMS013_BG3MT_012b 283 31.4 1.8 0.709 0.030 1.41 0.06 0.321 0.013 0.73 3453 114 3.3 3531 57 1.6 3575 61 1.7 3.4 yesAMS013_BG3MT_013a 169 33.9 2.0 0.757 0.026 1.32 0.04 0.325 0.015 0.59 3633 95 2.6 3609 57 1.6 3595 72 2.0 -1.1 14342 no 0.03AMS013_BG3MT_013b 272 22.6 1.3 0.585 0.020 1.71 0.06 0.280 0.012 0.62 2971 81 2.7 3211 54 1.7 3364 68 2.0 11.7 yesAMS013_BG3MT_014 121 33.5 2.0 0.741 0.027 1.35 0.05 0.328 0.015 0.61 3575 98 2.7 3596 58 1.6 3608 71 2.0 0.9 yesAMS013_BG3MT_015 106 29.7 1.8 0.654 0.028 1.53 0.06 0.330 0.015 0.69 3242 107 3.3 3478 60 1.7 3616 68 1.9 10.3 5085 no 0.10AMS013_BG3MT_016 95 30.8 2.0 0.704 0.032 1.42 0.06 0.318 0.015 0.70 3436 121 3.5 3514 64 1.8 3559 71 2.0 3.4 yesAMS013_BG3MT_017a 1780 18.1 1.1 0.504 0.023 1.98 0.09 0.260 0.011 0.73 2631 97 3.7 2995 60 2.0 3250 68 2.1 19 31355 no 0.02AMS013_BG3MT_017b 445 14.0 0.9 0.391 0.017 2.55 0.11 0.259 0.013 0.66 2129 81 3.8 2750 64 2.3 3243 80 2.5 34.3 1140 no 0.82AMS013_BG3MT_017c 187 28.3 2.0 0.673 0.035 1.49 0.08 0.305 0.015 0.73 3318 136 4.1 3429 70 2.1 3494 75 2.2 5 yesAMS013_BG3MT_018a 108 29.8 1.9 0.703 0.031 1.42 0.06 0.308 0.015 0.68 3430 117 3.4 3481 64 1.8 3510 74 2.1 2.3 8193 no 0.02AMS013_BG3MT_018b 217 27.5 2.0 0.605 0.025 1.65 0.07 0.329 0.020 0.56 3051 99 3.3 3401 71 2.1 3614 92 2.6 15.6 yesAMS013_BG3MT_020a 1760 15.1 1.0 0.500 0.015 2.00 0.06 0.219 0.014 0.45 2613 66 2.5 2823 66 2.3 2976 100 3.4 12.2 yesAMS013_BG3MT_020b 162 17.9 1.4 0.405 0.019 2.47 0.12 0.320 0.020 0.60 2193 88 4.0 2984 76 2.5 3572 97 2.7 38.6 795 no 0.88AMS013_BG3MT_021a 111 28.1 1.9 0.614 0.019 1.63 0.05 0.332 0.020 0.46 3085 75 2.4 3424 65 1.9 3628 90 2.5 15 yesAMS013_BG3MT_021b 136 21.1 1.5 0.543 0.020 1.84 0.07 0.281 0.018 0.49 2798 82 2.9 3142 71 2.3 3370 100 3.0 17 1849 no 0.35AMS013_BG3MT_022 78 26.5 2.0 0.608 0.034 1.64 0.09 0.316 0.015 0.75 3063 137 4.5 3366 73 2.2 3552 75 2.1 13.8 1894 no 0.36AMS013_BG3MT_023a 137 26.7 2.0 0.592 0.034 1.69 0.10 0.327 0.016 0.76 2997 139 4.6 3371 74 2.2 3601 75 2.1 16.8 3508 no 0.18AMS013_BG3MT_023b 219 24.0 1.7 0.630 0.035 1.59 0.09 0.277 0.013 0.77 3149 139 4.4 3270 71 2.2 3345 73 2.2 5.9 4018 no 0.11AMS013_BG3MT_024 82 31.8 2.2 0.717 0.038 1.39 0.07 0.321 0.015 0.75 3485 143 4.1 3543 70 2.0 3576 72 2.0 2.5 yesAMS013_BG3MT_025 610 24.5 1.5 0.644 0.023 1.55 0.06 0.276 0.014 0.57 3203 90 2.8 3288 61 1.9 3339 81 2.4 4.1 yesAMS013_BG3MT_026a 187 26.5 1.7 0.589 0.022 1.70 0.06 0.326 0.017 0.59 2987 90 3.0 3364 62 1.8 3597 78 2.2 17 yesRaw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)100Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS013_BG3MT_026b 196 24.4 1.5 0.636 0.023 1.57 0.06 0.278 0.014 0.56 3174 89 2.8 3284 61 1.9 3351 81 2.4 5.3 yesAMS013_BG3MT_028a 104 31.9 2.0 0.715 0.025 1.40 0.05 0.324 0.017 0.56 3479 95 2.7 3549 62 1.8 3588 81 2.2 3.0 2559 no 0.17AMS013_BG3MT_028b 220 22.6 1.6 0.566 0.027 1.77 0.08 0.290 0.015 0.67 2891 110 3.8 3211 69 2.1 3418 82 2.4 15.4 yesAMS013_BG3MT_029a 97 17.6 2.2 0.405 0.045 2.47 0.28 0.314 0.020 0.87 2193 208 9.5 2966 123 4.2 3543 96 2.7 38.1 yesAMS013_BG3MT_029b 221 31.6 2.5 0.764 0.042 1.31 0.07 0.300 0.017 0.70 3658 154 4.2 3537 78 2.2 3469 87 2.5 -5.4 149942 no 0.00AMS013_BG3MT_030a 55 27.6 2.5 0.608 0.040 1.64 0.11 0.330 0.020 0.73 3063 161 5.3 3407 89 2.6 3615 95 2.6 15.3 6671 no 0.09AMS013_BG3MT_030b 193 27.3 2.2 0.619 0.037 1.62 0.10 0.321 0.018 0.73 3104 146 4.7 3396 79 2.3 3573 85 2.4 13.1 10619 no 0.06AMS013_BG3MT_031a 74 28.8 2.6 0.654 0.026 1.53 0.06 0.319 0.026 0.43 3245 99 3.1 3446 88 2.6 3565 125 3.5 9.0 9863 no 0.06AMS013_BG3MT_032b 177 34.1 2.9 0.783 0.029 1.28 0.05 0.316 0.025 0.43 3727 105 2.8 3613 85 2.4 3550 121 3.4 -5.0 3433 no 0.15AMS013_BG3MT_032 125 29.5 2.7 0.651 0.030 1.54 0.07 0.329 0.026 0.50 3232 117 3.6 3470 90 2.6 3611 121 3.4 10.5 43529 no 0.01AMS013_BG3MT_033 822 22.3 1.9 0.574 0.020 1.74 0.06 0.282 0.022 0.41 2925 83 2.8 3198 84 2.6 3375 123 3.6 13.3 15181 no 0.04AMS013_BG3MT_034 37 38.9 3.4 0.852 0.027 1.17 0.04 0.331 0.027 0.35 3974 93 2.3 3743 88 2.3 3622 127 3.5 -9.7 766 no 0.91AMS013_BG3MT_035a 61 31.1 2.5 0.687 0.032 1.46 0.07 0.328 0.021 0.60 3372 124 3.7 3522 78 2.2 3609 97 2.7 6.6 yesAMS013_BG3MT_035b 167 32.2 2.6 0.732 0.036 1.37 0.07 0.319 0.021 0.61 3540 136 3.8 3555 81 2.3 3564 100 2.8 0.7 32000 no 0.02AMS013_BG3MT_036 153 27.3 2.3 0.586 0.031 1.71 0.09 0.338 0.022 0.63 2974 124 4.2 3396 81 2.4 3655 98 2.7 18.6 1924 no 0.22AMS013_BG3MT_037a 41 27.3 2.5 0.645 0.038 1.55 0.09 0.307 0.022 0.64 3208 148 4.6 3394 90 2.7 3506 110 3.1 8.5 1799 no 0.34AMS013_BG3MT_037b 234 32.8 2.0 0.730 0.036 1.37 0.07 0.326 0.011 0.83 3534 136 3.8 3574 59 1.7 3596 52 1.4 1.7 yesAMS013_RouP4_001 99 33.6 2.3 0.762 0.033 1.31 0.06 0.320 0.017 0.64 3652 122 3.3 3598 68 1.9 3568 82 2.3 -2.4 3096 no 0.25AMS013_RouP4_002 75 29.5 1.8 0.665 0.030 1.50 0.07 0.322 0.014 0.72 3287 114 3.5 3472 60 1.7 3580 65 1.8 8.2 13731 no 0.04AMS013_RouP4_004a 398 35.7 1.7 0.793 0.032 1.26 0.05 0.3268 0.0085 0.84 3765 114 3.0 3660 47 1.3 3602 40 1.1 -4.5 yesAMS013_RouP4_004b 298 23.5 1.1 0.537 0.020 1.86 0.07 0.3177 0.0093 0.79 2770 85 3.1 3248 46 1.4 3559 45 1.3 22.2 7509 no 0.11AMS013_RouP4_005a 57 29.6 1.8 0.674 0.023 1.48 0.05 0.319 0.017 0.55 3319 88 2.7 3473 61 1.8 3563 80 2.2 6.8 yesAMS013_RouP4_005b 345 29.7 1.5 0.671 0.018 1.49 0.04 0.322 0.014 0.51 3309 68 2.1 3479 51 1.5 3578 68 1.9 7.5 yesAMS013_RouP4_006 116 28.1 1.8 0.627 0.024 1.60 0.06 0.325 0.016 0.62 3136 97 3.1 3421 61 1.8 3593 75 2.1 12.7 yesAMS013_RouP4_007a 145 28.3 1.6 0.631 0.019 1.59 0.05 0.326 0.015 0.54 3152 75 2.4 3430 55 1.6 3597 73 2.0 12.4 3063 no 0.24AMS013_RouP4_007b 230 28.0 1.6 0.628 0.020 1.59 0.05 0.323 0.015 0.57 3141 79 2.5 3419 55 1.6 3586 70 2.0 12.4 yesAMS013_RouP4_008 1860 9.8 0.7 0.311 0.020 3.22 0.20 0.229 0.010 0.83 1743 97 5.6 2418 70 2.9 3048 67 2.2 42.8 13086 no 0.08AMS013_RouP4_009 116 15.8 1.4 0.358 0.026 2.79 0.20 0.319 0.015 0.83 1973 123 6.2 2863 83 2.9 3566 74 2.1 44.7 1456 no 0.67AMS013_RouP4_012 288 33.6 2.6 0.741 0.047 1.35 0.08 0.329 0.014 0.83 3574 173 4.8 3598 75 2.1 3612 66 1.8 1.1 yesAMS013_RouP4_014 111 33.6 2.6 0.730 0.045 1.37 0.08 0.334 0.016 0.80 3535 169 4.8 3598 77 2.1 3634 72 2.0 2.7 16452 no 0.03AMS013_RouP4_017 81 36.5 1.6 0.798 0.026 1.25 0.04 0.332 0.009 0.76 3782 93 2.5 3681 42 1.2 3626 43 1.2 -4.3 yesAMS013_RouP4_018 247 26.7 1.6 0.597 0.030 1.68 0.09 0.324 0.010 0.85 3017 122 4.1 3371 58 1.7 3590 48 1.3 16.0 yesAMS013_RouP4_020 123 28.5 1.4 0.626 0.024 1.60 0.06 0.330 0.010 0.79 3136 93 3.0 3436 47 1.4 3616 45 1.2 13.3 yesAMS013_RouP4_022 440 28.9 1.6 0.634 0.029 1.58 0.07 0.331 0.010 0.83 3166 114 3.6 3451 54 1.6 3621 46 1.3 12.6 9310 no 0.07AMS013_RouP4_023 103 35.5 1.8 0.729 0.028 1.37 0.05 0.353 0.012 0.74 3528 104 2.9 3652 51 1.4 3720 54 1.4 5.1 79990 no 0.01AMS013_RouP4_029 118 31.1 2.5 0.697 0.027 1.44 0.06 0.324 0.023 0.48 3408 103 3.0 3523 80 2.3 3588 109 3.0 5.0 yesRaw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)101Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS013_RouP4_030 90 37.1 3.0 0.808 0.033 1.24 0.05 0.333 0.024 0.49 3818 116 3.0 3697 81 2.2 3632 110 3.0 -5.1 yesAMS013_RouP4_032 746 40.4 3.1 0.780 0.028 1.28 0.05 0.376 0.026 0.47 3717 103 2.8 3781 77 2.0 3815 104 2.7 2.6 20773 no 0.05AMS013_RouP4_036 233 37.1 3.0 0.809 0.033 1.24 0.05 0.333 0.023 0.50 3822 116 3.0 3697 80 2.2 3631 108 3.0 -5.3 3186 no 0.25AMS013_RouP4_038 47 30.0 2.4 0.673 0.038 1.49 0.08 0.323 0.019 0.70 3318 148 4.5 3486 80 2.3 3584 89 2.5 7.4 yesAMS013_RouP4_039 1070 36.4 2.8 0.765 0.042 1.31 0.07 0.345 0.019 0.71 3662 154 4.2 3677 77 2.1 3685 84 2.3 0.6 48418 no 0.02AMS013_PRMT4_003 398 31.5 2.8 0.613 0.039 1.63 0.10 0.373 0.023 0.72 3081 157 5.1 3535 87 2.5 3804 92 2.4 19.0 4955 no 0.18AMS013_PRMT4_008 398 31.5 2.3 0.740 0.038 1.35 0.07 0.309 0.016 0.70 3569 139 3.9 3535 71 2.0 3516 79 2.3 -1.5 42222 no 0.01AMS013_PRMT4_010 203 24.8 1.6 0.555 0.031 1.8 0.1 0.323 0.010 0.88 2848 127 4.5 3299 62 1.9 3585 47 1.3 20.6 24543 no 0.03AMS013_PRMT4_011 239 36.1 3.5 0.757 0.062 1.32 0.11 0.346 0.018 0.85 3632 229 6.3 3669 96 2.6 3689 78 2.1 1.5 yesAMS013_PRMT4_012 170 25.7 1.5 0.599 0.030 1.67 0.08 0.312 0.010 0.84 3024 120 4.0 3336 58 1.7 3530 49 1.4 14.3 yesAMS013_PRMT4_013 551 19.7 1.4 0.470 0.029 2.13 0.13 0.3047 0.0091 0.90 2482 129 5.2 3078 67 2.2 3494 46 1.3 29.0 35194 no 0.02AMS013_PRMT4_015 413 31.4 2.0 0.705 0.041 1.42 0.08 0.3227 0.0076 0.93 3440 157 4.6 3531 62 1.8 3583 36 1.0 4.0 15342 no 0.04AMS013_PRMT4_016 206 37.1 2.2 0.802 0.043 1.25 0.07 0.3352 0.0093 0.89 3796 154 4.1 3695 60 1.6 3641 43 1.2 -4.3 10902 no 0.06AMS013_PRMT4_017 307 29.2 1.9 0.666 0.038 1.50 0.08 0.318 0.010 0.88 3291 146 4.4 3460 63 1.8 3559 48 1.3 7.5 yesAMS013_PRMT4_018 448 27.6 1.8 0.621 0.037 1.61 0.09 0.322 0.010 0.88 3116 145 4.7 3404 65 1.9 3579 48 1.3 12.9 20740 no 0.04AMS013_PRMT4_021 174 32.4 2.0 0.694 0.039 1.44 0.08 0.3390 0.0086 0.91 3396 150 4.4 3563 61 1.7 3658 39 1.1 7.2 yesAMS013_PRMT4_022 500 30 2 0.690 0.028 1.45 0.06 0.315 0.013 0.68 3383 106 3.1 3486 58 1.7 3545 66 1.9 4.6 18009 no 0.04AMS013_PRMT4_023 166 32.5 2.2 0.705 0.032 1.42 0.06 0.334 0.017 0.67 3440 120 3.5 3565 67 1.9 3636 78 2.1 5.4 1486 no 0.77AMS013_PRMT4_030 774 35.9 2.1 0.720 0.029 1.39 0.06 0.362 0.015 0.69 3494 109 3.1 3665 58 1.6 3759 65 1.7 7.0 35399 no 0.01AMS013_PRMT4_037 302 33.6 2.1 0.673 0.029 1.49 0.06 0.363 0.016 0.69 3317 111 3.3 3600 61 1.7 3761 68 1.8 11.8 5425 no 0.14AMS013_PRMT4_038 151 29.1 2.2 0.685 0.042 1.46 0.09 0.308 0.014 0.80 3362 159 4.7 3457 75 2.2 3513 70 2.0 4.3 yesAMS013_PRMT4_039 574 15.8 1.4 0.410 0.029 2.44 0.17 0.279 0.014 0.81 2216 132 5.9 2863 83 2.9 3356 79 2.4 34.0 15428 no 0.07AMS013_PRMT4_040 850 29.0 2.2 0.720 0.043 1.39 0.08 0.292 0.014 0.79 3495 163 4.7 3454 75 2.2 3430 72 2.1 -1.9 81405 no 0.01AMS013_ApMT2_01a 68 27.1 1.2 0.601 0.017 1.66 0.05 0.327 0.011 0.64 3032 70 2.3 3386 44 1.3 3603 53 1.5 15.8 yesAMS013_ApMT2_01b 86 31.1 1.5 0.707 0.022 1.41 0.04 0.319 0.012 0.64 3447 84 2.4 3522 48 1.4 3566 58 1.6 3.3 4406 no 0.21AMS013_ApMT2_01c 38 30.4 1.5 0.692 0.023 1.44 0.05 0.318 0.012 0.67 3392 89 2.6 3498 50 1.4 3560 58 1.6 4.7 906 no 0.87AMS013_ApMT2_06a 155 25.6 1.4 0.589 0.022 1.70 0.06 0.315 0.012 0.70 2986 89 3.0 3331 52 1.5 3546 58 1.6 15.8 yesAMS013_ApMT2_06b 150 29.6 1.4 0.662 0.020 1.51 0.05 0.324 0.012 0.65 3273 78 2.4 3472 47 1.3 3589 56 1.5 8.8 yesAMS013_ApMT1_01a 66 28.4 1.8 0.647 0.021 1.55 0.05 0.318 0.018 0.51 3217 82 2.5 3433 63 1.8 3562 85 2.4 9.7 8790 no 0.09AMS013_ApMT1_01b 74 20.2 1.3 0.530 0.017 1.89 0.06 0.276 0.015 0.49 2741 70 2.6 3101 62 2.0 3343 87 2.6 18.0 yesRaw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)102Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS030AA_001 317 36.3 1.8 0.772 0.035 1.29 0.06 0.3413 0.0082 0.88 3689 126 3.4 3676 50 1.4 3669 37 1.0 -0.6 2187 no 0.52AMS030AA_003 1150 29.6 1.5 0.703 0.032 1.42 0.07 0.3049 0.0071 0.89 3433 122 3.6 3473 51 1.5 3496 36 1.0 1.8 10552 no 0.11AMS030AA_004 1220 25.9 1.3 0.603 0.027 1.66 0.07 0.3121 0.0072 0.89 3040 108 3.5 3344 49 1.5 3531 35 1.0 13.9 536 no 2.13AMS030AA_005 1040 36.3 2.0 0.847 0.030 1.18 0.04 0.311 0.013 0.63 3956 105 2.7 3675 55 1.5 3525 67 1.9 -12.2 yesAMS030AA_007 1440 26.3 1.5 0.700 0.025 1.43 0.05 0.272 0.012 0.61 3420 93 2.7 3358 56 1.7 3320 71 2.1 -3.0 20597 no 0.05AMS030AA_008 1720 15.3 0.9 0.543 0.020 1.84 0.07 0.205 0.010 0.63 2794 85 3.0 2835 57 2.0 2865 76 2.7 2.5 16185 no 0.07AMS030AA_012 1520 24.9 1.5 0.665 0.025 1.50 0.06 0.272 0.012 0.65 3285 98 3.0 3306 58 1.7 3319 70 2.1 1.0 13037 no 0.09AMS030AA_013 2160 36.8 3.3 0.772 0.047 1.29 0.08 0.346 0.023 0.66 3689 169 4.6 3689 90 2.4 3688 104 2.8 0.0 7732 no 0.15AMS030AA_014 1180 25.8 3.0 0.595 0.056 1.68 0.16 0.314 0.021 0.81 3011 225 7.5 3337 114 3.4 3540 105 3.0 14.9 49135 no 0.02AMS030AA_021 2220 23.1 2.2 0.641 0.039 1.56 0.09 0.262 0.019 0.65 3194 152 4.7 3232 91 2.8 3256 112 3.4 1.9 2397 no 0.48AMS030AA_024 1390 22.3 1.5 0.640 0.029 1.56 0.07 0.252 0.013 0.67 3190 114 3.6 3196 66 2.1 3200 80 2.5 0.3 98955 no 0.01AMS030AA_025 1440 20.1 1.4 0.612 0.029 1.63 0.08 0.238 0.012 0.68 3080 117 3.8 3098 68 2.2 3110 81 2.6 1.0 2826 no 0.40AMS030AA_026a 1860 19.2 1.4 0.536 0.027 1.87 0.09 0.259 0.014 0.69 2767 112 4.1 3051 70 2.3 3244 83 2.6 14.7 7482 no 0.15AMS030AA_026b 390 33.3 2.3 0.708 0.034 1.41 0.07 0.341 0.018 0.68 3451 127 3.7 3591 69 1.9 3669 78 2.1 5.9 2402 no 0.48AMS030AA_028a 1490 15.7 1.0 0.483 0.020 2.07 0.09 0.235 0.012 0.65 2540 88 3.5 2856 62 2.2 3088 79 2.5 17.8 635 no 1.80AMS030AA_028b 137 27.3 1.8 0.624 0.026 1.60 0.07 0.318 0.016 0.65 3125 105 3.4 3396 64 1.9 3560 76 2.1 12.2 2544 no 0.37AMS030AA_030a 1220 27.3 2.9 0.595 0.046 1.68 0.13 0.333 0.024 0.73 3011 187 6.2 3396 104 3.1 3631 111 3.1 17.1 yesAMS030AA_030b 346 26.3 1.4 0.653 0.019 1.53 0.05 0.292 0.013 0.56 3240 76 2.3 3358 52 1.6 3430 69 2.0 5.6 9775 no 0.12AMS030AA_031 1150 34.8 4.0 0.706 0.041 1.42 0.08 0.358 0.036 0.51 3442 156 4.5 3633 115 3.2 3740 153 4.1 8.0 23645 no 0.05AMS030AA_032 973 32.5 1.4 0.729 0.020 1.37 0.04 0.323 0.011 0.62 3528 73 2.1 3565 43 1.2 3586 53 1.5 1.6 683 no 1.67AMS030AA_033 1120 12.3 0.7 0.373 0.017 2.68 0.12 0.2400 0.0085 0.79 2043 81 3.9 2631 55 2.1 3120 57 1.8 34.5 2087 no 0.55AMS030AA_034 1240 34.3 2.9 0.723 0.032 1.38 0.06 0.344 0.024 0.53 3507 121 3.5 3619 83 2.3 3682 108 2.9 4.7 38212 no 0.03AMS030AA_037 1000 27.0 1.6 0.639 0.022 1.56 0.05 0.306 0.014 0.60 3186 88 2.8 3383 57 1.7 3503 72 2.1 9.0 9937 no 0.11AMS030AA_038 1960 15 1 0.522 0.018 1.92 0.07 0.209 0.012 0.52 2706 76 2.8 2818 63 2.2 2899 92 3.2 6.7 4584 no 0.25AMS030AA_040 825 35.7 2.1 0.786 0.027 1.27 0.04 0.330 0.015 0.59 3738 97 2.6 3658 57 1.6 3615 71 2.0 -3.4 3317 no 0.34AMS030AA_041 1760 16.4 1.2 0.471 0.024 2.12 0.11 0.253 0.014 0.67 2490 104 4.2 2902 72 2.5 3202 89 2.8 22.2 5790 no 0.20AMS030AA_042 1830 14.8 1.5 0.426 0.027 2.35 0.15 0.251 0.019 0.63 2289 122 5.3 2799 95 3.4 3191 122 3.8 28.3 3581 no 0.32AMS030AA_043 632 38.7 2.8 0.745 0.038 1.34 0.07 0.377 0.019 0.71 3590 142 3.9 3739 72 1.9 3819 77 2.0 6.0 8470 no 0.13AMS030AA_044 1360 12.1 0.9 0.350 0.020 2.85 0.16 0.250 0.014 0.72 1937 94 4.9 2612 73 2.8 3187 86 2.7 39.2 729 no 1.57AMS030AA_045 699 38.8 3.0 0.815 0.044 1.23 0.07 0.345 0.019 0.70 3844 155 4.0 3741 76 2.0 3686 84 2.3 -4.3 83034 no 0.01AMS030AA_046 1560 30.0 2.5 0.626 0.044 1.60 0.11 0.348 0.017 0.83 3133 174 5.5 3488 83 2.4 3699 73 2.0 15.3 yesAMS030AA_049 593 36.4 3.0 0.734 0.049 1.36 0.09 0.360 0.017 0.81 3548 181 5.1 3678 81 2.2 3749 73 1.9 5.4 51732 no 0.01AMS030AA_051 2130 14.3 1.1 0.451 0.029 2.22 0.14 0.231 0.011 0.80 2398 127 5.3 2773 75 2.7 3058 76 2.5 21.6 6404 no 0.18AMS030AA_052 1820 17.8 1.4 0.517 0.032 1.93 0.12 0.250 0.011 0.81 2687 136 5.1 2981 74 2.5 3187 72 2.3 15.7 17499 no 0.06AMS030AA_055a 558 14.4 1.1 0.390 0.026 2.56 0.17 0.267 0.010 0.87 2124 120 5.7 2774 72 2.6 3289 58 1.8 35.4 129 no 8.86AMS030AA_055b 259 26.0 1.9 0.585 0.037 1.71 0.11 0.322 0.010 0.89 2970 152 5.1 3346 70 2.1 3580 49 1.4 17.1 6503 no 0.14Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)103Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS030AA_056 954 34.4 2.4 0.723 0.045 1.38 0.09 0.345 0.011 0.89 3509 168 4.8 3623 69 1.9 3687 49 1.3 4.8 9696 no 0.10AMS030AA_059 688 31.3 2.1 0.662 0.040 1.51 0.09 0.342 0.010 0.90 3276 155 4.7 3527 66 1.9 3673 45 1.2 10.8 7698 no 0.15AMS030AA_063 376 33.8 2.3 0.699 0.042 1.43 0.09 0.351 0.011 0.89 3415 158 4.6 3604 66 1.8 3711 47 1.3 8.0 4382 no 0.26AMS030AA_068 394 32.1 2.1 0.717 0.033 1.40 0.06 0.325 0.016 0.69 3483 125 3.6 3554 66 1.8 3595 74 2.0 3.1 yesAMS030AA_071 646 37.9 2.5 0.770 0.036 1.30 0.06 0.357 0.016 0.71 3682 131 3.5 3717 65 1.7 3736 70 1.9 1.5 1607 no 0.71AMS030AA_074 236 37.9 2.5 0.752 0.034 1.33 0.06 0.366 0.018 0.68 3616 123 3.4 3718 65 1.8 3774 74 2.0 4.2 808 no 1.41AMS030AA_086 1630 13.0 0.9 0.394 0.019 2.54 0.12 0.239 0.011 0.71 2141 86 4.0 2678 62 2.3 3112 74 2.4 31.2 14306 no 0.08AMS030AA_088 268 36.5 2.5 0.687 0.019 1.46 0.04 0.385 0.024 0.42 3372 74 2.2 3680 67 1.8 3852 92 2.4 12.5 1441675 no 0.00AMS030AA_093 465 23.5 1.6 0.567 0.018 1.76 0.06 0.300 0.018 0.47 2896 74 2.6 3247 66 2.0 3471 92 2.7 16.6 9056 no 0.10AMS030AA_097 626 32.0 2.1 0.687 0.019 1.46 0.04 0.338 0.020 0.41 3372 71 2.1 3551 65 1.8 3655 93 2.5 7.7 2006 no 0.53AMS030AA_098 453 29.7 2.2 0.616 0.024 1.62 0.06 0.349 0.022 0.52 3095 94 3.0 3476 72 2.1 3704 95 2.6 16.4 400 no 2.86AMS030AA_099 202 36.6 2.5 0.730 0.023 1.37 0.04 0.364 0.022 0.46 3534 87 2.4 3683 68 1.9 3766 93 2.5 6.2 yesAMS030AA_102 379 32.5 2.7 0.673 0.040 1.49 0.09 0.351 0.020 0.72 3317 155 4.7 3567 82 2.3 3710 88 2.4 10.6 2230 no 0.51AMS030AA_108 75 47.7 4.2 0.828 0.054 1.21 0.08 0.418 0.025 0.74 3889 191 4.9 3945 89 2.3 3974 91 2.3 2.2 yesAMS030AA_bt01a 1020 16.2 1.1 0.389 0.021 2.57 0.14 0.303 0.013 0.78 2117 99 4.7 2891 67 2.3 3486 68 2.0 39.3 2097 no 0.53AMS030AA_bt01b 908 23.1 1.5 0.591 0.026 1.69 0.07 0.283 0.013 0.69 2993 103 3.5 3231 61 1.9 3381 71 2.1 11.5 15336 no 0.07AMS030AA_bt02a 717 9.1 0.5 0.275 0.011 3.63 0.15 0.239 0.009 0.73 1568 57 3.6 2345 51 2.2 3113 61 2.0 49.6 846 no 1.31AMS030AA_bt02b 138 20.6 1.8 0.525 0.031 1.91 0.11 0.285 0.019 0.68 2718 132 4.9 3120 86 2.7 3389 102 3.0 19.8 757 no 1.46AMS030AA_bt02c 190 17.6 1.3 0.439 0.018 2.28 0.09 0.291 0.017 0.56 2347 80 3.4 2968 69 2.3 3422 93 2.7 31.4 2453 no 0.41AMS030AA_bt03a 725 12.4 1.0 0.370 0.016 2.70 0.12 0.244 0.015 0.57 2029 77 3.8 2638 72 2.7 3145 100 3.2 35.5 1008 no 1.10AMS030AA_bt03b 309 29.0 2.0 0.643 0.025 1.55 0.06 0.326 0.019 0.56 3202 98 3.1 3452 68 2.0 3601 87 2.4 11.1 1591 no 0.69AMS030AA_bt03c 276 21.2 1.6 0.477 0.023 2.1 0.1 0.322 0.019 0.63 2513 100 4.0 3146 75 2.4 3579 92 2.6 29.8 2360 no 0.47AMS030AA_bt81a 367 31.3 1.8 0.663 0.028 1.51 0.06 0.343 0.013 0.74 3278 110 3.4 3530 57 1.6 3676 59 1.6 10.8 2211 no 0.50AMS030AA_bt81b 429 38.9 2.4 0.734 0.035 1.36 0.06 0.384 0.015 0.76 3549 129 3.6 3743 61 1.6 3848 61 1.6 7.8 2100 no 0.47AMS030AA_bt20a 1350 20.9 0.9 0.539 0.016 1.86 0.05 0.281 0.008 0.72 2779 66 2.4 3133 40 1.3 3368 45 1.3 17.5 9080 no 0.12AMS030AA_bt20b 767 15.0 0.6 0.401 0.011 2.49 0.07 0.2718 0.0067 0.75 2173 52 2.4 2817 36 1.3 3316 39 1.2 34.5 3846 no 0.29AMS030AA_bt20c 1580 13.1 0.6 0.367 0.014 2.73 0.10 0.2588 0.0072 0.81 2013 66 3.3 2685 45 1.7 3239 44 1.3 37.9 2888 no 0.38AMS030AA_ApMT2_03a 807 32.4 1.9 0.690 0.033 1.45 0.07 0.340 0.012 0.80 3383 125 3.7 3562 58 1.6 3665 54 1.5 7.7 yesAMS030AA_ApMT2_03b 199 14.6 0.9 0.365 0.019 2.74 0.14 0.291 0.011 0.80 2004 88 4.4 2791 61 2.2 3423 60 1.7 41.4 481 no 2.30AMS030AA_ApMT2_04a 569 23.5 1.0 0.569 0.016 1.76 0.05 0.300 0.010 0.66 2904 66 2.3 3249 42 1.3 3469 49 1.4 16.3 48784 no 0.01AMS030AA_ApMT2_04b 537 30.0 1.3 0.633 0.018 1.58 0.04 0.344 0.011 0.65 3162 69 2.2 3486 42 1.2 3679 49 1.3 14.1 5792 no 0.19Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)104Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS030B_004 1656 21.3 1.9 0.624 0.043 1.60 0.11 0.248 0.014 0.77 3126 172 5.5 3152 88 2.8 3169 92 2.9 1.4 51917 no 0.02AMS030B_006 600 25.6 2.4 0.572 0.048 1.75 0.15 0.325 0.015 0.88 2915 195 6.7 3333 93 2.8 3595 71 2.0 18.9 27465 no 0.03AMS030B_007 1329 33.2 3.1 0.741 0.061 1.35 0.11 0.325 0.014 0.89 3575 226 6.3 3587 91 2.5 3593 65 1.8 0.5 38926 no 0.02AMS030B_008 1088 28.5 2.8 0.638 0.056 1.57 0.14 0.325 0.014 0.90 3180 221 6.9 3438 96 2.8 3592 66 1.8 11.5 492312 no 0.00AMS030B_009 619 40.8 3.9 0.870 0.069 1.15 0.09 0.340 0.018 0.83 4034 239 5.9 3791 95 2.5 3664 82 2.2 -10.1 3477 no 0.33AMS030B_010 672 42.7 3.9 0.821 0.067 1.22 0.10 0.377 0.016 0.89 3863 236 6.1 3835 91 2.4 3820 65 1.7 -1.1 77592 no 0.01AMS030B_011 3852 9.98 0.53 0.440 0.017 2.27 0.09 0.1644 0.0063 0.70 2352 74 3.1 2433 49 2.0 2502 64 2.6 6.0 42471 no 0.02AMS030B_013 325 39.9 2.4 0.798 0.036 1.25 0.06 0.362 0.015 0.74 3783 128 3.4 3767 60 1.6 3759 63 1.7 -0.6 yesAMS030B_014 953 28.5 1.7 0.703 0.029 1.42 0.06 0.294 0.012 0.72 3430 111 3.2 3435 57 1.7 3438 63 1.8 0.2 40593 no 0.00AMS030B_016 480 32.4 2.0 0.704 0.033 1.42 0.07 0.334 0.013 0.76 3437 126 3.7 3562 61 1.7 3634 61 1.7 5.4 54340 no 0.01AMS030B_017 239 28.9 1.8 0.683 0.036 1.46 0.08 0.307 0.009 0.87 3356 138 4.1 3450 60 1.7 3504 46 1.3 4.2 22080 no 0.01AMS030B_022 1336 29.2 2.3 0.679 0.047 1.47 0.10 0.312 0.011 0.89 3341 180 5.4 3462 76 2.2 3532 55 1.5 5.4 31541 no 0.01AMS030B_024 615 38.8 2.6 0.779 0.048 1.28 0.08 0.361 0.011 0.90 3715 173 4.6 3740 68 1.8 3753 46 1.2 1.0 4644 no 0.22AMS030B_026 828 36.2 2.3 0.810 0.047 1.23 0.07 0.3241 0.0079 0.92 3826 166 4.3 3672 62 1.7 3590 38 1.0 -6.6 yesAMS030B_030 2215 29.5 1.9 0.753 0.044 1.33 0.08 0.2847 0.0080 0.90 3617 162 4.5 3472 64 1.8 3389 44 1.3 -6.7 162621 no 0.00AMS030B_031 247 27.7 2.1 0.637 0.045 1.57 0.11 0.3153 0.0093 0.92 3179 179 5.6 3409 76 2.2 3547 45 1.3 10.4 3755 no 0.26AMS030B_032 348 33.9 2.6 0.728 0.052 1.37 0.10 0.3381 0.0096 0.93 3526 196 5.6 3608 77 2.1 3654 43 1.2 3.5 7632 no 0.12AMS030B_033 245 45.3 3.4 0.843 0.059 1.19 0.08 0.390 0.011 0.93 3940 206 5.2 3894 75 1.9 3871 43 1.1 -1.8 12474 no 0.04AMS030B_034 541 26.1 2.0 0.662 0.046 1.51 0.10 0.2860 0.0084 0.92 3275 178 5.4 3351 74 2.2 3396 46 1.3 3.6 4895 no 0.21AMS030B_035 363 42.1 3.3 0.782 0.051 1.28 0.08 0.390 0.017 0.83 3725 185 5.0 3820 78 2.0 3871 66 1.7 3.8 17142 no 0.04AMS030B_040 448 50.2 3.8 0.917 0.058 1.09 0.07 0.397 0.017 0.84 4196 196 4.7 3996 76 1.9 3898 63 1.6 -7.6 13357 no 0.02AMS030B_041 1979 22.9 1.7 0.674 0.041 1.48 0.09 0.2464 0.0096 0.84 3320 159 4.8 3222 71 2.2 3162 62 1.9 -5.0 132716 no 0.01AMS030B_042 882 18.3 1.3 0.541 0.032 1.85 0.11 0.2450 0.0095 0.84 2789 134 4.8 3005 68 2.3 3153 62 2.0 11.5 1936 no 0.59AMS030B_043 223 31.5 2.3 0.758 0.046 1.32 0.08 0.301 0.012 0.83 3637 169 4.6 3535 72 2.0 3478 64 1.8 -4.6 yesAMS030B_047 415 31.6 2.9 0.776 0.049 1.29 0.08 0.295 0.020 0.68 3704 177 4.8 3538 92 2.6 3445 107 3.1 -7.5 8588 no 0.11AMS030B_048 423 36.4 3.2 0.787 0.046 1.27 0.07 0.335 0.022 0.66 3744 166 4.4 3678 88 2.4 3642 102 2.8 -2.8 yesAMS030B_050 386 47.2 4.2 0.864 0.051 1.16 0.07 0.396 0.027 0.66 4014 176 4.4 3934 90 2.3 3893 102 2.6 -3.1 yesAMS030B_054 780 37.5 3.4 0.794 0.049 1.26 0.08 0.342 0.023 0.67 3767 175 4.6 3706 90 2.4 3673 103 2.8 -2.5 5337 no 0.20AMS030B_057 477 25.3 2.0 0.600 0.026 1.67 0.07 0.306 0.019 0.57 3032 105 3.5 3321 75 2.3 3501 98 2.8 13.4 4165 no 0.25AMS030B_058 547 50.0 3.9 0.966 0.043 1.04 0.05 0.375 0.024 0.57 4358 141 3.2 3992 78 2.0 3813 97 2.6 -14.3 1949 no 0.59AMS030B_065 715 45.7 3.6 0.898 0.042 1.11 0.05 0.369 0.024 0.59 4132 143 3.5 3903 79 2.0 3786 98 2.6 -9.1 42066 no 0.01AMS030B_066 235 33.7 3.0 0.747 0.041 1.34 0.07 0.328 0.023 0.63 3596 153 4.3 3602 87 2.4 3606 106 2.9 0.3 yesAMS030B_067 597 30.0 2.6 0.693 0.038 1.44 0.08 0.314 0.021 0.63 3393 143 4.2 3485 85 2.4 3539 103 2.9 4.1 68354 no 0.01AMS030B_069 735 32.5 2.5 0.729 0.050 1.37 0.09 0.323 0.010 0.91 3530 188 5.3 3565 75 2.1 3585 50 1.4 1.5 55287 no 0.01AMS030B_070 1246 29.5 2.3 0.722 0.050 1.39 0.10 0.2963 0.0096 0.91 3502 188 5.4 3470 76 2.2 3451 51 1.5 -1.5 42681 no 0.02AMS030B_073 1251 28.3 2.3 0.709 0.050 1.41 0.10 0.290 0.011 0.88 3453 190 5.5 3430 80 2.3 3416 60 1.8 -1.1 1588 no 0.70Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)105Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS030B_074 738 42.5 2.9 0.872 0.055 1.15 0.07 0.3538 0.0099 0.91 4042 190 4.7 3832 69 1.8 3724 43 1.1 -8.5 287710 no 0.00AMS030B_075 689 39.4 3.8 0.814 0.069 1.23 0.10 0.351 0.016 0.88 3841 245 6.4 3756 96 2.6 3711 71 1.9 -3.5 19499 no 0.03AMS030B_078 136 37.6 3.6 0.876 0.073 1.14 0.09 0.311 0.015 0.86 4056 250 6.2 3709 96 2.6 3527 76 2.2 -15.0 yesAMS030B_080 639 43.0 3.9 0.840 0.068 1.19 0.10 0.371 0.016 0.88 3932 239 6.1 3842 91 2.4 3796 65 1.7 -3.6 5800 no 0.19AMS030B_082 900 27.4 2.5 0.735 0.058 1.36 0.11 0.270 0.012 0.88 3552 217 6.1 3398 89 2.6 3308 68 2.1 -7.4 13653 no 0.08AMS030B_083 1414 13.8 1.3 0.542 0.043 1.85 0.15 0.1846 0.0080 0.88 2790 181 6.5 2735 86 3.2 2695 72 2.7 -3.5 2359 no 0.47AMS030B_088 615 34.0 2.6 0.856 0.049 1.17 0.07 0.288 0.015 0.74 3985 169 4.2 3611 76 2.1 3409 80 2.4 -16.9 73120 no 0.01AMS030B_089 1339 37.9 2.8 0.902 0.050 1.11 0.06 0.305 0.015 0.75 4144 170 4.1 3716 74 2.0 3494 76 2.2 -18.6 152020 no 0.00AMS030B_091 506 35.8 2.7 0.842 0.046 1.19 0.07 0.309 0.016 0.73 3936 161 4.1 3661 74 2.0 3514 79 2.2 -12.0 5698 no 0.18AMS030B_093 877 24.9 1.9 0.554 0.032 1.81 0.10 0.327 0.016 0.75 2842 133 4.7 3306 75 2.3 3601 78 2.2 21.1 11231 no 0.10AMS030B_095 317 31.0 1.9 0.705 0.028 1.42 0.06 0.319 0.015 0.65 3438 107 3.1 3518 61 1.7 3564 72 2.0 3.5 yesAMS030B_097 744 33.9 2.0 0.821 0.031 1.22 0.05 0.300 0.014 0.62 3864 108 2.8 3607 59 1.6 3468 73 2.1 -11.4 yesAMS030B_100 633 24.4 1.5 0.619 0.024 1.61 0.06 0.286 0.013 0.64 3108 94 3.0 3285 59 1.8 3396 72 2.1 8.5 1608 no 0.69AMS030B_101 357 35.0 2.2 0.752 0.029 1.33 0.05 0.338 0.016 0.63 3616 107 3.0 3639 61 1.7 3652 73 2.0 1.0 1717 no 0.64Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)106Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS030C_002 680 30.5 2.0 0.708 0.031 1.41 0.06 0.312 0.016 0.66 3449 118 3.4 3502 66 1.9 3532 78 2.2 2.4 107517 no 0.01AMS030C_004 432 25 1 0.537 0.017 1.86 0.06 0.338 0.014 0.60 2771 70 2.5 3308 51 1.5 3653 63 1.7 24.1 3622 no 0.31AMS030C_005 935 22.3 1.1 0.561 0.016 1.78 0.05 0.288 0.012 0.56 2872 64 2.2 3198 48 1.5 3409 64 1.9 15.8 yesAMS030C_006 553 28.0 1.4 0.643 0.019 1.56 0.05 0.316 0.013 0.60 3200 75 2.4 3419 49 1.4 3549 61 1.7 9.8 9501 no 0.05AMS030C_012 1887 12.5 0.7 0.434 0.013 2.31 0.07 0.208 0.009 0.56 2323 57 2.5 2640 50 1.9 2892 71 2.5 19.7 6322 no 0.17AMS030C_013 754 29.6 1.5 0.636 0.022 1.57 0.05 0.338 0.012 0.71 3174 88 2.8 3474 49 1.4 3652 53 1.5 13.1 3600 no 0.31AMS030C_014 1316 21.8 1.0 0.561 0.015 1.78 0.05 0.282 0.011 0.55 2870 61 2.1 3176 46 1.4 3376 62 1.8 15.0 yesAMS030C_015 508 22.8 1.1 0.586 0.020 1.71 0.06 0.282 0.010 0.70 2972 83 2.8 3218 48 1.5 3376 56 1.6 11.9 2913 no 0.35AMS030C_016 1564 28.4 1.5 0.680 0.026 1.47 0.06 0.303 0.010 0.75 3343 102 3.0 3431 51 1.5 3484 53 1.5 4.0 37064 no 0.01AMS030C_018 780 26.4 1.3 0.624 0.020 1.60 0.05 0.307 0.011 0.66 3127 79 2.5 3363 47 1.4 3507 56 1.6 10.8 23009 no 0.03AMS030C_020 691 22.1 1.8 0.628 0.037 1.59 0.09 0.255 0.014 0.74 3142 147 4.7 3188 78 2.5 3217 86 2.7 2.3 5388 no 0.20AMS030C_021 303 34.3 2.8 0.772 0.047 1.30 0.08 0.322 0.017 0.76 3687 171 4.6 3618 80 2.2 3580 81 2.3 -3.0 5317 no 0.13AMS030C_022 447 31.2 2.5 0.704 0.042 1.42 0.08 0.321 0.017 0.75 3436 158 4.6 3525 78 2.2 3576 80 2.2 3.9 11870 no 0.05AMS030C_024 1433 27.3 2.1 0.759 0.044 1.32 0.08 0.261 0.013 0.75 3639 160 4.4 3393 76 2.2 3251 81 2.5 -11.9 108838 no 0.01AMS030C_025 386 31.6 1.8 0.719 0.026 1.39 0.05 0.319 0.013 0.65 3491 98 2.8 3538 55 1.6 3564 65 1.8 2.1 6495 no 0.12AMS030C_026 563 30.6 1.6 0.697 0.022 1.43 0.05 0.318 0.014 0.60 3410 85 2.5 3506 53 1.5 3561 67 1.9 4.2 yesAMS030C_027 698 29.3 1.4 0.716 0.019 1.40 0.04 0.297 0.011 0.57 3479 72 2.1 3463 46 1.3 3454 59 1.7 -0.7 4222 no 0.26AMS030C_029 1782 26.6 2.0 0.716 0.034 1.40 0.07 0.269 0.016 0.63 3480 128 3.7 3367 74 2.2 3301 93 2.8 -5.4 9580 no 0.12AMS030C_032 435 30.5 1.4 0.697 0.018 1.44 0.04 0.318 0.012 0.56 3408 69 2.0 3503 46 1.3 3558 60 1.7 4.2 6390 no 0.15AMS030C_033 243 30.2 1.7 0.689 0.027 1.45 0.06 0.318 0.013 0.69 3377 103 3.1 3495 56 1.6 3562 63 1.8 5.2 7055 no 0.09AMS030C_034 1031 20.3 1.1 0.582 0.022 1.72 0.07 0.253 0.010 0.69 2958 92 3.1 3105 54 1.7 3201 64 2.0 7.6 4144 no 0.27AMS030C_035 1270 22 1 0.562 0.026 1.78 0.08 0.284 0.011 0.75 2876 106 3.7 3183 59 1.8 3383 62 1.8 15.0 54567 no 0.01AMS030C_037 1950 21 1 0.575 0.032 1.7 0.1 0.264 0.012 0.77 2930 130 4.4 3136 69 2.2 3271 71 2.2 10.4 15777 no 0.07AMS030C_038a 548 22.3 1.4 0.547 0.024 1.83 0.08 0.296 0.014 0.68 2814 99 3.5 3199 62 1.9 3450 73 2.1 18.4 yesAMS030C_038b 77 23.9 2.0 0.547 0.030 1.83 0.10 0.317 0.019 0.68 2811 126 4.5 3263 80 2.4 3555 93 2.6 20.9 602 no 1.8AMS030C_039 2080 10.6 0.8 0.382 0.021 2.61 0.14 0.200 0.012 0.68 2088 96 4.6 2485 73 3.0 2829 94 3.3 26.2 20840 no 0.05AMS030C_041 571 30.3 1.9 0.639 0.027 1.56 0.07 0.344 0.016 0.68 3186 106 3.3 3497 61 1.8 3681 70 1.9 13.4 5832 no 0.17AMS030C_045 292 34.5 2.1 0.741 0.029 1.35 0.05 0.338 0.016 0.64 3574 107 3.0 3625 60 1.6 3653 71 1.9 2.2 7114 no 0.12AMS030C_046 2740 16.3 1.2 0.517 0.026 1.93 0.10 0.228 0.012 0.70 2686 112 4.2 2892 69 2.4 3039 82 2.7 11.6 26005 no 0.04AMS030C_056 89 22.5 2.3 0.368 0.032 2.71 0.24 0.443 0.022 0.86 2022 151 7.5 3207 98 3.1 4063 75 1.9 50.2 1531 no 0.58AMS030C_061 646 23.3 2.3 0.580 0.044 1.73 0.13 0.292 0.019 0.76 2947 181 6.1 3241 98 3.0 3428 101 2.9 14.0 yesAMS030C_067 236 37.8 2.8 0.683 0.037 1.46 0.08 0.401 0.020 0.74 3357 143 4.3 3715 74 2.0 3915 76 1.9 14.2 yesAMS030C_069 357 26.1 1.8 0.632 0.033 1.58 0.08 0.299 0.014 0.74 3159 131 4.2 3349 69 2.1 3464 73 2.1 8.8 3473 no 0.32AMS030C_070 145 44.3 3.0 0.769 0.040 1.30 0.07 0.418 0.019 0.75 3679 144 3.9 3872 68 1.7 3974 67 1.7 7.4 yesAMS030C_071 226 35.1 2.5 0.676 0.037 1.48 0.08 0.376 0.017 0.77 3330 141 4.2 3640 70 1.9 3816 69 1.8 12.7 61089 no 0.01AMS030C_076 268 30.2 2.1 0.576 0.032 1.74 0.10 0.380 0.017 0.78 2931 131 4.5 3492 70 2.0 3832 67 1.8 23.5 20631 no 0.02Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)107Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS030C_077 296 34.0 2.4 0.725 0.040 1.38 0.08 0.340 0.015 0.78 3514 149 4.2 3610 70 1.9 3663 68 1.9 4.1 31879 no 0.02AMS030C_080 569 30.8 3.2 0.635 0.054 1.58 0.13 0.352 0.021 0.82 3168 211 6.7 3514 101 2.9 3717 89 2.4 14.8 5323 no 0.21AMS030C_081 475 25.5 2.6 0.618 0.053 1.62 0.14 0.299 0.017 0.83 3100 211 6.8 3327 102 3.1 3467 90 2.6 10.6 7754 no 0.15AMS030C_083 232 39.5 4.1 0.714 0.061 1.40 0.12 0.402 0.023 0.82 3472 228 6.6 3759 102 2.7 3916 88 2.2 11.3 4874 no 0.20AMS030C_084 566 30.2 3.1 0.657 0.056 1.52 0.13 0.334 0.019 0.83 3255 218 6.7 3494 102 2.9 3634 89 2.4 10.4 5529 no 0.21AMS030C_085 824 30.4 2.1 0.647 0.036 1.55 0.09 0.341 0.014 0.81 3215 142 4.4 3500 68 1.9 3667 61 1.7 12.3 2487 no 0.46AMS030C_090 345 41.0 2.8 0.782 0.044 1.28 0.07 0.380 0.014 0.83 3725 160 4.3 3795 68 1.8 3832 58 1.5 2.8 5114240 no 0.00AMS030C_091 426 29.5 2.0 0.648 0.037 1.54 0.09 0.330 0.013 0.83 3221 143 4.5 3470 67 1.9 3617 58 1.6 11.0 10293 no 0.10AMS030C_092 287 33.4 2.3 0.708 0.040 1.41 0.08 0.342 0.013 0.83 3451 152 4.4 3591 68 1.9 3671 58 1.6 6.0 21821 no 0.02AMS030C_095 589 41.8 2.8 0.777 0.043 1.29 0.07 0.391 0.014 0.84 3706 157 4.2 3815 66 1.7 3873 54 1.4 4.3 113484 no 0.00AMS030C_097a 483 10.3 0.8 0.317 0.019 3.16 0.19 0.236 0.011 0.79 1774 93 5.2 2461 70 2.9 3091 75 2.4 42.6 40 no 28.6AMS030C_097b 146 24.9 1.6 0.608 0.035 1.64 0.10 0.2972 0.0072 0.92 3062 141 4.6 3305 61 1.9 3456 37 1.1 11.4 551 no 2.07AMS030C_099 485 30.2 2.0 0.678 0.041 1.47 0.09 0.3230 0.0086 0.91 3338 157 4.7 3493 65 1.9 3584 41 1.1 6.9 69921 no 0.01AMS030C_101 290 35.5 2.3 0.726 0.043 1.38 0.08 0.3546 0.0095 0.91 3520 160 4.5 3653 64 1.8 3727 41 1.1 5.6 5317 no 0.20AMS030C_104 231 32.7 2.2 0.696 0.042 1.44 0.09 0.341 0.010 0.91 3406 160 4.7 3572 66 1.9 3666 43 1.2 7.1 yesAMS030C_105 460 40 2 0.877 0.051 1.14 0.07 0.3305 0.0064 0.95 4059 176 4.3 3770 61 1.6 3619 30 0.8 -12.2 yesAMS030c_bt65a 203 37.5 2.9 0.658 0.028 1.52 0.06 0.414 0.026 0.55 3258 107 3.3 3707 76 2.0 3960 96 2.4 17.7 70666 no 0.01AMS030c_bt65b 329 38.5 3.0 0.686 0.028 1.46 0.06 0.408 0.027 0.53 3365 108 3.2 3734 77 2.1 3938 98 2.5 14.5 yesRaw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)108Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS031A4Pr_BG2_001 660 34.1 2.4 0.732 0.050 1.37 0.09 0.338 0.006 0.97 3541 187 5.3 3613 70 1.9 3653 26 0.7 3.1 29231 no 0.02AMS031A4Pr_BG2_002 642 34.3 2.4 0.728 0.050 1.37 0.09 0.342 0.006 0.97 3528 186 5.3 3620 69 1.9 3671 25 0.7 3.9 12029 no 0.08AMS031A4Pr_BG2_004 774 34.4 2.5 0.745 0.051 1.34 0.09 0.335 0.007 0.96 3589 189 5.3 3622 71 2.0 3640 31 0.8 1.4 yesAMS031A4Pr_BG2_005 592 36.2 2.0 0.769 0.038 1.30 0.06 0.341 0.008 0.89 3679 137 3.7 3673 54 1.5 3669 37 1.0 -0.3 73065 no 0.01AMS031A4Pr_BG2_006 206 32.6 1.9 0.673 0.035 1.49 0.08 0.351 0.010 0.88 3318 133 4.0 3568 58 1.6 3712 43 1.2 10.6 82691 no 0.01AMS031A4Pr_BG2_007 606 38.6 2.1 0.830 0.041 1.20 0.06 0.3376 0.0083 0.90 3896 144 3.7 3737 55 1.5 3652 38 1.0 -6.7 320423 no 0.00AMS031A4Pr_BG2_009 516 34.3 1.8 0.775 0.038 1.29 0.06 0.3212 0.0074 0.90 3700 137 3.7 3619 53 1.5 3575 35 1.0 -3.5 15944 no 0.04AMS031A4Pr_BG2_010 82 34.7 2.1 0.728 0.037 1.37 0.07 0.346 0.010 0.86 3524 139 3.9 3629 59 1.6 3688 46 1.2 4.4 yesAMS031A4Pr_BG2_012 647 32.2 1.5 0.695 0.022 1.44 0.05 0.336 0.011 0.71 3402 85 2.5 3556 45 1.3 3644 49 1.3 6.7 41137 no 0.02AMS031A4Pr_BG2_015 615 35.7 1.7 0.766 0.025 1.31 0.04 0.338 0.011 0.70 3665 91 2.5 3657 46 1.3 3652 51 1.4 -0.3 23411 no 0.04AMS031A4Pr_BG2_017 704 35.1 1.7 0.781 0.026 1.28 0.04 0.326 0.011 0.70 3721 93 2.5 3642 47 1.3 3598 52 1.4 -3.4 30778 no 0.02AMS031A4Pr_BG2_018 545 39.5 1.8 0.834 0.026 1.20 0.04 0.343 0.011 0.69 3909 92 2.3 3758 45 1.2 3678 49 1.3 -6.3 yesAMS031A4Pr_BG2_019 547 27.4 1.8 0.670 0.030 1.49 0.07 0.296 0.015 0.67 3305 115 3.5 3396 65 1.9 3451 76 2.2 4.2 10931 no 0.06AMS031A4Pr_BG2_024 618 35.8 2.5 0.759 0.036 1.32 0.06 0.342 0.017 0.68 3640 130 3.6 3662 68 1.9 3673 77 2.1 0.9 yesAMS031A4Pr_BG2_026 971 38.2 2.7 0.811 0.040 1.23 0.06 0.341 0.017 0.70 3830 141 3.7 3725 69 1.9 3669 77 2.1 -4.4 127796 no 0.00AMS031A4Pr_BG2_027 447 34.6 2.4 0.711 0.036 1.41 0.07 0.353 0.017 0.71 3463 134 3.9 3627 69 1.9 3718 75 2.0 6.9 yesAMS031A4Pr_BG2_028 421 24.1 1.7 0.593 0.028 1.69 0.08 0.295 0.015 0.68 3003 113 3.8 3273 68 2.1 3444 79 2.3 12.8 yesAMS031A4Pr_BG2_029 397 37.8 2.0 0.811 0.028 1.23 0.04 0.338 0.014 0.65 3828 101 2.6 3715 53 1.4 3654 62 1.7 -4.7 yesAMS031A4Pr_BG2_031 436 32.4 1.7 0.688 0.025 1.45 0.05 0.341 0.012 0.71 3377 97 2.9 3562 51 1.4 3668 55 1.5 7.9 yesAMS031A4Pr_BG2_032 556 30.5 1.7 0.630 0.025 1.59 0.06 0.352 0.014 0.71 3148 99 3.1 3504 55 1.6 3715 60 1.6 15.3 43862 no 0.01AMS031A4Pr_BG2_033 518 32.6 1.9 0.655 0.028 1.53 0.06 0.361 0.015 0.72 3248 108 3.3 3569 58 1.6 3754 61 1.6 13.5 10759 no 0.07AMS031A4Pr_BG2_036 589 26.5 1.6 0.564 0.025 1.77 0.08 0.341 0.013 0.76 2883 104 3.6 3366 58 1.7 3667 58 1.6 21.4 18901 no 0.03AMS031A4Pr_BG2_037 577 28.1 1.7 0.566 0.026 1.77 0.08 0.360 0.014 0.75 2892 106 3.7 3422 59 1.7 3749 60 1.6 22.9 yesAMS031A4Brou_BG2_003 69 28.6 2.3 0.580 0.033 1.72 0.10 0.358 0.021 0.70 2948 135 4.6 3441 80 2.3 3742 88 2.4 21.2 yesAMS031A4Brou_BG2_004 111 22.1 1.4 0.490 0.022 2.04 0.09 0.328 0.014 0.73 2569 96 3.7 3190 60 1.9 3608 64 1.8 28.8 1953 no 0.52AMS031A4Brou_BG2_005a 45 22.0 1.4 0.443 0.021 2.26 0.11 0.360 0.015 0.74 2364 93 3.9 3183 62 1.9 3750 65 1.7 37.0 yesAMS031A4Brou_BG2_005b 243 16.8 1.4 0.374 0.026 2.67 0.18 0.325 0.014 0.84 2050 120 5.9 2923 78 2.7 3595 67 1.9 43.0 12113 no 0.05AMS031A4Brou_BG2_010a 544 24.5 1.2 0.523 0.019 1.91 0.07 0.340 0.012 0.72 2713 79 2.9 3289 48 1.5 3661 53 1.4 25.9 17550 no 0.04AMS031A4Brou_BG2_010b 62 25.9 1.6 0.511 0.023 1.96 0.09 0.367 0.015 0.76 2662 99 3.7 3342 59 1.8 3779 60 1.6 29.5 2726 no 0.25AMS031A4Brou_BG2_011 371 14.67 0.84 0.404 0.018 2.47 0.11 0.263 0.009 0.78 2188 83 3.8 2794 55 2.0 3266 56 1.7 33.0 17540 no 0.04AMS031A4Brou_BG2_012 604 21.1 1.4 0.442 0.019 2.26 0.10 0.346 0.017 0.68 2358 87 3.7 3141 63 2.0 3689 73 2.0 36.1 63808 no 0.00AMS031A4Brou_BG2_015 392 21.8 1.6 0.443 0.025 2.26 0.13 0.357 0.018 0.74 2363 110 4.6 3175 73 2.3 3738 77 2.1 36.8 112286 no 0.00AMS031A4Brou_BG2_016 51 25.6 1.7 0.528 0.024 1.89 0.08 0.352 0.017 0.68 2735 99 3.6 3332 64 1.9 3715 73 2.0 26.4 yesAMS031A4Brou_BG2_020 68 22.5 1.4 0.536 0.019 1.87 0.06 0.304 0.015 0.57 2767 78 2.8 3205 59 1.8 3492 77 2.2 20.8 5535 no 0.05AMS031A4Brou_BG2_021 682 20.6 1.4 0.447 0.019 2.24 0.10 0.334 0.017 0.66 2381 86 3.6 3119 64 2.0 3636 76 2.1 34.5 yesAMS031A4Brou_BG2_023 60 23.6 2.0 0.481 0.033 2.08 0.14 0.356 0.019 0.79 2533 143 5.6 3252 85 2.6 3732 81 2.2 32.1 2413 no 0.25Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)109Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS031A4Brou_BG2_034 54 25.7 1.8 0.525 0.026 1.91 0.10 0.356 0.018 0.71 2719 111 4.1 3337 69 2.1 3732 76 2.0 27.1 1027 no 0.80AMS031A4Brou_BG2_035 200 12.55 0.91 0.407 0.022 2.46 0.13 0.224 0.011 0.75 2202 101 4.6 2647 68 2.6 3007 78 2.6 26.8 10288 no 0.05AMS031A4Brou_BG2_039 54 21.9 1.8 0.444 0.029 2.25 0.15 0.357 0.019 0.78 2370 130 5.5 3180 81 2.6 3739 79 2.1 36.6 yesAMS031A4Brou_BG2_040 683 27.1 1.5 0.551 0.027 1.82 0.09 0.356 0.009 0.90 2829 113 4.0 3386 54 1.6 3735 37 1.0 24.3 yesAMS031A4Brou_BG2_045 65 23.3 1.3 0.469 0.023 2.13 0.10 0.360 0.008 0.90 2481 100 4.0 3240 53 1.6 3750 36 1.0 33.8 yesAMS031A8Med_P5_001 542 38.6 2.8 0.805 0.044 1.24 0.07 0.347 0.016 0.75 3809 156 4.1 3735 72 1.9 3695 72 2.0 -3.1 78838 no 0.01AMS031A8Med_P5_002 483 35.8 2.5 0.761 0.041 1.31 0.07 0.342 0.015 0.77 3647 150 4.1 3662 69 1.9 3670 69 1.9 0.6 yesAMS031A8Med_P5_004 415 39.5 2.8 0.832 0.045 1.20 0.07 0.344 0.016 0.77 3902 159 4.1 3758 70 1.9 3682 70 1.9 -6.0 9185 no 0.11AMS031A8Med_P5_006 126 37.7 2.7 0.793 0.043 1.26 0.07 0.345 0.016 0.76 3764 154 4.1 3712 70 1.9 3685 70 1.9 -2.2 1943 no 0.22AMS031A8Med_P5_008 594 31.7 2.3 0.679 0.039 1.47 0.08 0.339 0.015 0.78 3339 149 4.5 3542 72 2.0 3659 70 1.9 8.7 129423 no 0.00AMS031A8Med_P5_014 612 37.7 1.6 0.768 0.024 1.30 0.04 0.356 0.011 0.72 3673 89 2.4 3712 43 1.2 3733 46 1.2 1.6 6390 no 0.15AMS031A8Med_P5_020 359 36.3 1.4 0.755 0.022 1.32 0.04 0.349 0.009 0.74 3625 80 2.2 3675 38 1.0 3703 40 1.1 2.1 12485 no 0.06AMS031A8Med_P5_021 398 34.4 1.3 0.713 0.020 1.40 0.04 0.350 0.009 0.73 3468 77 2.2 3621 39 1.1 3706 41 1.1 6.4 7435 no 0.09AMS031A8Brou_BG1_002 162 28.0 2.1 0.618 0.035 1.62 0.09 0.328 0.015 0.77 3104 141 4.5 3419 73 2.1 3610 72 2.0 14.0 yesAMS031A8Brou_BG1_003 300 27.7 2.0 0.635 0.035 1.58 0.09 0.316 0.014 0.77 3168 140 4.4 3407 71 2.1 3551 70 2.0 10.8 122375 no 0.00AMS031A8Brou_BG1_007 57 28.1 2.1 0.614 0.036 1.63 0.10 0.332 0.016 0.78 3086 145 4.7 3421 74 2.2 3624 72 2.0 14.8 yesAMS031A8Brou_BG1_008 424 32.2 2.0 0.685 0.028 1.46 0.06 0.342 0.016 0.66 3362 105 3.1 3558 60 1.7 3670 70 1.9 8.4 31048 no 0.02AMS031A8Brou_BG1_009 919 32.5 2.1 0.737 0.030 1.36 0.06 0.319 0.016 0.62 3560 113 3.2 3564 65 1.8 3567 79 2.2 0.2 5692 no 0.19AMS031A8Brou_BG1_013 238 26.6 1.7 0.637 0.026 1.57 0.06 0.303 0.014 0.65 3177 101 3.2 3370 61 1.8 3487 73 2.1 8.9 yesAMS031A8Brou_BG1_014 47 30.8 2.0 0.659 0.029 1.52 0.07 0.339 0.016 0.67 3264 111 3.4 3512 64 1.8 3657 74 2.0 10.7 1208 no 0.39AMS031A8Brou_BG1_017 168 28.5 1.9 0.611 0.028 1.64 0.08 0.339 0.017 0.69 3073 114 3.7 3438 67 1.9 3658 75 2.1 16.0 7019 no 0.12AMS031A8Brou_BG1_022 265 28.2 2.6 0.612 0.043 1.63 0.12 0.334 0.020 0.76 3077 173 5.6 3425 91 2.7 3635 93 2.6 15.4 yesAMS031A8Brou_BG1_023 85 22.9 2.1 0.544 0.038 1.84 0.13 0.306 0.019 0.76 2800 160 5.7 3223 91 2.8 3499 94 2.7 20.0 yesAMS031A8Brou_BG1_026a 876 26.6 2.5 0.626 0.044 1.60 0.11 0.308 0.019 0.75 3133 174 5.6 3368 91 2.7 3511 94 2.7 10.8 20503 no 0.04AMS031A8Brou_BG1_026b 61 24.7 2.3 0.578 0.040 1.73 0.12 0.310 0.019 0.75 2939 166 5.6 3297 92 2.8 3522 97 2.8 16.6 yesAMS031A8Brou_BG1_027 563 30.9 3.0 0.666 0.052 1.50 0.12 0.337 0.020 0.80 3290 201 6.1 3516 97 2.8 3648 91 2.5 9.8 yesAMS031A8Brou_BG1_028 131 28.6 2.7 0.636 0.048 1.57 0.12 0.326 0.019 0.80 3172 191 6.0 3440 94 2.7 3599 89 2.5 11.9 yesAMS031A8Brou_BG1_030 165 28.2 2.8 0.607 0.048 1.65 0.13 0.337 0.020 0.80 3059 191 6.2 3427 96 2.8 3650 89 2.4 16.2 2868 no 0.39AMS031A8Brou_BG1_032 46 30.5 2.9 0.647 0.049 1.55 0.12 0.342 0.020 0.79 3215 193 6.0 3502 95 2.7 3671 89 2.4 12.4 1466 no 0.31AMS031A8Brou_BG1_033 172 30.0 2.9 0.648 0.050 1.54 0.12 0.335 0.020 0.80 3222 197 6.1 3486 96 2.7 3642 89 2.5 11.6 4596 no 0.19AMS031A8Pr_BG1_001 438 25.0 1.6 0.545 0.019 1.83 0.06 0.333 0.018 0.53 2805 78 2.8 3309 63 1.9 3630 84 2.3 22.7 20423 no 0.04AMS031A8Pr_BG1_003 405 30.8 2.0 0.645 0.018 1.55 0.04 0.347 0.020 0.45 3209 72 2.2 3514 63 1.8 3692 87 2.4 13.1 16665 no 0.06AMS031A8Pr_BG1_005 453 26.5 1.7 0.578 0.017 1.73 0.05 0.332 0.019 0.46 2939 69 2.3 3364 62 1.8 3627 86 2.4 19.0 17640 no 0.03AMS031A8Pr_BG1_006 482 35.9 2.4 0.756 0.026 1.32 0.04 0.345 0.019 0.52 3629 94 2.6 3665 65 1.8 3685 86 2.3 1.5 115039 no 0.01AMS031A8Pr_BG1_007 40 28.2 2.2 0.574 0.037 1.74 0.11 0.356 0.016 0.83 2924 151 5.2 3427 76 2.2 3735 67 1.8 21.7 12433 no 0.04Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)110Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS031A8Pr_BG1_008 478 29.8 2.2 0.605 0.038 1.65 0.10 0.357 0.015 0.84 3050 153 5.0 3479 74 2.1 3736 62 1.7 18.4 yesAMS031A8Pr_BG1_010 72 31.6 2.4 0.654 0.042 1.53 0.10 0.351 0.014 0.85 3245 163 5.0 3539 75 2.1 3710 62 1.7 12.5 yesAMS031A8Pr_BG1_011 467 23.7 1.7 0.554 0.034 1.80 0.11 0.311 0.012 0.85 2842 143 5.0 3258 72 2.2 3525 60 1.7 19.4 42639 no 0.01AMS031A8Pr_BG1_014 544 28.9 2.2 0.669 0.041 1.49 0.09 0.313 0.013 0.83 3303 160 4.8 3451 73 2.1 3537 64 1.8 6.6 30877 no 0.02AMS031A8Pr_BG1_014 81 29.3 2.0 0.604 0.020 1.66 0.06 0.352 0.021 0.49 3045 82 2.7 3465 67 1.9 3718 91 2.5 18.1 yesAMS031A8Pr_BG1_015 619 36.4 2.4 0.787 0.027 1.27 0.04 0.335 0.019 0.51 3742 97 2.6 3677 66 1.8 3642 88 2.4 -2.8 yesAMS031A8Pr_BG1_019 44 30.3 2.1 0.658 0.021 1.52 0.05 0.334 0.020 0.47 3259 82 2.5 3497 67 1.9 3637 92 2.5 10.4 1942 no 0.34AMS031A8Pr_BG1_020 692 33.0 2.1 0.715 0.022 1.40 0.04 0.335 0.019 0.48 3479 84 2.4 3581 64 1.8 3638 87 2.4 4.4 22588 no 0.03AMS031A8Pr_BG1_021 452 30.9 2.3 0.660 0.040 1.52 0.09 0.340 0.015 0.81 3265 155 4.7 3516 73 2.1 3662 66 1.8 10.8 4807 no 0.23AMS031A8Pr_BG1_022 377 32.5 2.6 0.679 0.044 1.47 0.09 0.347 0.016 0.81 3342 168 5.0 3564 79 2.2 3692 72 1.9 9.5 yesAMS031A8Pr_BG1_026 541 33.4 2.5 0.732 0.045 1.37 0.08 0.331 0.015 0.81 3541 168 4.7 3593 75 2.1 3622 68 1.9 2.2 6209165 no 0.00AMS031A8Pr_BG1_027 426 23.3 1.8 0.582 0.036 1.72 0.11 0.291 0.013 0.81 2956 146 4.9 3241 74 2.3 3423 70 2.0 13.6 yesAMS031A8Pr_BG1_029 458 32.7 2.4 0.711 0.043 1.41 0.09 0.334 0.014 0.81 3462 163 4.7 3573 74 2.1 3636 66 1.8 4.8 21835 no 0.05AMS031A8Pr_BG1_030 552 33.3 2.4 0.726 0.050 1.38 0.09 0.332 0.007 0.95 3519 187 5.3 3589 71 2.0 3628 34 0.9 3.0 yesAMS031A8_bt25a 467 28.6 1.7 0.649 0.030 1.54 0.07 0.319 0.012 0.78 3224 116 3.6 3439 58 1.7 3567 57 1.6 9.6 yesAMS031A8_bt25b 464 31.1 2.1 0.720 0.022 1.39 0.04 0.313 0.019 0.44 3497 81 2.3 3521 66 1.9 3535 93 2.6 1.1 yesRaw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)111Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS001Big_BG2_001 820 25.2 1.3 0.557 0.024 1.80 0.08 0.328 0.009 0.85 2854 101 3.5 3315 50 1.5 3607 41 1.1 20.9 41721 no 0.02AMS001Big_BG2_002 551 27.9 1.6 0.556 0.029 1.80 0.09 0.364 0.010 0.89 2850 121 4.2 3415 58 1.7 3766 40 1.1 24.3 yesAMS001Big_BG2_003 400 29.4 1.5 0.557 0.025 1.80 0.08 0.383 0.009 0.89 2853 102 3.6 3468 49 1.4 3845 34 0.9 25.8 4375 no 0.25AMS001Big_BG2_004 967 12.4 2.9 0.360 0.084 2.77 0.65 0.250 0.007 0.99 1984 401 20 2638 225 8.5 3187 44 1.4 37.7 23387 no 0.04AMS001Big_BG2_005 687 22.5 5.3 0.52 0.12 1.91 0.45 0.311 0.010 0.99 2716 520 19 3205 234 7.3 3528 50 1.4 23.0 147993 no 0.004AMS001Big_BG2_006 1972 6.9 1.7 0.229 0.054 4.4 1.0 0.2194 0.0068 0.99 1327 286 22 2100 216 10 2976 50 1.7 55.4 20553 no 0.05AMS001Big_BG2_008 1454 8.9 2.1 0.284 0.067 3.52 0.83 0.2282 0.0068 0.99 1611 337 21 2331 221 9.5 3039 48 1.6 47.0 9598 no 0.11AMS001Big_BG2_009 1067 13.3 2.2 0.349 0.058 2.86 0.48 0.2757 0.0075 0.99 1931 277 14 2699 160 5.9 3339 43 1.3 42.2 yesAMS001Big_BG2_012 368 32.4 5.4 0.575 0.095 1.74 0.29 0.408 0.011 0.99 2929 391 13 3562 167 4.7 3941 40 1.0 25.7 1575 no 0.70AMS001Big_BG2_013 1042 19.8 3.3 0.447 0.075 2.24 0.37 0.322 0.008 0.99 2381 333 14 3082 165 5.3 3578 39 1.1 33.5 16377 no 0.06AMS001Big_BG2_014 466 20.7 3.5 0.442 0.073 2.26 0.38 0.340 0.010 0.99 2358 328 14 3126 164 5.3 3664 43 1.2 35.7 2354 no 0.47AMS001Big_BG2_015 472 22.3 3.8 0.485 0.082 2.06 0.35 0.333 0.010 0.98 2551 358 14 3195 169 5.3 3629 48 1.3 29.7 13447 no 0.06AMS001Big_BG2_016 1195 18.3 1.0 0.472 0.018 2.12 0.08 0.282 0.010 0.72 2492 78 3.1 3008 50 1.7 3373 56 1.7 26.1 24509 no 0.03AMS001Big_BG2_020 1316 8.39 0.48 0.242 0.011 4.13 0.19 0.252 0.009 0.79 1397 57 4.1 2274 52 2.3 3195 57 1.8 56.3 2356 no 0.47AMS001Big_BG2_021 1247 13.54 0.68 0.420 0.015 2.38 0.09 0.234 0.008 0.72 2259 69 3.1 2718 47 1.7 3080 55 1.8 26.7 4189 no 0.26AMS001Big_BG2_022 1008 12.30 0.69 0.386 0.016 2.59 0.10 0.231 0.009 0.72 2106 73 3.5 2628 53 2.0 3058 63 2.1 31.1 20822 no 0.04AMS001Big_BG2_024 1583 12.9 1.3 0.355 0.029 2.81 0.23 0.263 0.014 0.85 1960 140 7.1 2673 92 3.5 3267 82 2.5 40.0 9395 no 0.11AMS001Big_BG2_025 925 18.0 1.8 0.455 0.038 2.20 0.18 0.287 0.015 0.85 2417 170 7.0 2991 95 3.2 3404 81 2.4 29.0 6490 no 0.17AMS001Big_BG2_029 660 21.2 2.2 0.456 0.039 2.19 0.19 0.337 0.019 0.84 2422 172 7.1 3147 99 3.1 3650 85 2.3 33.7 9684 no 0.11AMS001Big_BG2_030 580 33.0 3.4 0.594 0.052 1.68 0.15 0.403 0.023 0.84 3007 208 6.9 3581 102 2.9 3919 85 2.2 23.3 9318 no 0.10AMS001Big_BG2_031 1257 28.5 2.8 0.619 0.052 1.62 0.14 0.334 0.018 0.84 3105 206 6.6 3436 98 2.8 3635 81 2.2 14.6 17645 no 0.05AMS001Big_BG2_032 371 14.7 1.6 0.436 0.043 2.30 0.23 0.244 0.012 0.90 2331 195 8.4 2794 105 3.8 3147 75 2.4 25.9 5164 no 0.11AMS001Big_BG2_033 668 28.9 3.1 0.620 0.061 1.61 0.16 0.338 0.015 0.91 3110 242 7.8 3448 106 3.1 3652 67 1.8 14.8 3171 no 0.35AMS001Big_BG2_034 979 14.8 1.7 0.367 0.038 2.73 0.28 0.293 0.013 0.92 2013 180 8.9 2802 108 3.9 3432 69 2.0 41.3 9824 no 0.11AMS001Big_BG2_036 1072 16.0 1.7 0.401 0.040 2.49 0.25 0.290 0.012 0.92 2174 183 8.4 2879 103 3.6 3418 66 1.9 36.4 9350 no 0.12AMS001Big_BG2_037 836 15.5 1.2 0.399 0.029 2.51 0.18 0.283 0.010 0.90 2163 132 6.1 2849 76 2.7 3378 53 1.6 36.0 8297 no 0.13AMS001Big_BG2_038 1043 24.9 1.9 0.558 0.039 1.79 0.13 0.323 0.010 0.92 2859 163 5.7 3304 75 2.3 3586 47 1.3 20.3 8177 no 0.12AMS001Big_BG2_039 734 16.4 1.5 0.344 0.027 2.90 0.23 0.346 0.013 0.90 1907 132 6.9 2903 85 2.9 3692 58 1.6 48.3 14300 no 0.07AMS001Big_BG2_040 764 23.2 1.8 0.499 0.035 2.00 0.14 0.338 0.012 0.90 2609 151 5.8 3237 76 2.4 3654 53 1.5 28.6 8287 no 0.12AMS001Big_BG2_042 1674 12.8 1.0 0.356 0.026 2.81 0.20 0.260 0.008 0.91 1964 122 6.2 2665 74 2.8 3250 50 1.5 39.6 43889 no 0.01AMS001Med_P5_001 1013 16.7 0.9 0.409 0.015 2.45 0.09 0.297 0.011 0.72 2209 69 3.1 2918 49 1.7 3452 56 1.6 36.0 11160 no 0.09AMS001Med_P5_002 386 26.0 1.2 0.574 0.016 1.74 0.05 0.328 0.013 0.58 2925 66 2.2 3345 47 1.4 3607 60 1.7 18.9 536994 no 0.002AMS001Med_P5_003 535 32.6 1.4 0.713 0.018 1.40 0.03 0.332 0.012 0.56 3471 66 1.9 3570 43 1.2 3626 56 1.5 4.3 793972 no 0.001AMS001Med_P5_006 612 29.1 1.3 0.629 0.016 1.59 0.04 0.336 0.013 0.54 3145 62 2.0 3459 45 1.3 3646 60 1.6 13.8 49200 no 0.01AMS001Med_P5_008 877 23.2 1.0 0.554 0.014 1.81 0.05 0.304 0.011 0.57 2840 58 2.0 3236 43 1.3 3491 57 1.6 18.7 4583 no 0.24Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)112Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS001Med_P5_009 529 35.6 1.6 0.694 0.019 1.44 0.04 0.371 0.014 0.60 3399 73 2.1 3654 45 1.2 3798 55 1.5 10.5 15019 no 0.04AMS001Med_P5_010 804 29.2 1.9 0.625 0.027 1.60 0.07 0.339 0.016 0.66 3131 107 3.4 3461 64 1.8 3658 74 2.0 14.4 10270 no 0.07AMS001Med_P5_023 502 22.2 1.4 0.530 0.023 1.89 0.08 0.303 0.015 0.67 2743 98 3.6 3192 63 2.0 3488 74 2.1 21.4 5660 no 0.16AMS001Med_P5_024 1154 23.6 1.5 0.603 0.025 1.66 0.07 0.283 0.013 0.66 3043 100 3.3 3251 61 1.9 3382 74 2.2 10.0 58788 no 0.01AMS001Med_P5_025 1099 20.2 1.3 0.483 0.021 2.07 0.09 0.303 0.015 0.66 2541 91 3.6 3100 63 2.0 3486 75 2.2 27.1 23559 no 0.04AMS001Med_P5_026 978 20.1 1.0 0.460 0.020 2.17 0.09 0.316 0.007 0.89 2439 88 3.6 3094 47 1.5 3553 34 1.0 31.4 6120 no 0.14AMS001Med_P5_027 1278 19.9 1.0 0.514 0.022 1.94 0.08 0.281 0.006 0.90 2675 95 3.5 3088 47 1.5 3370 33 1.0 20.6 5355 no 0.21AMS001Sm_P5_001 784 38.9 1.9 0.716 0.031 1.40 0.06 0.394 0.009 0.88 3482 117 3.4 3743 49 1.3 3886 36 0.9 10.4 1567 no 0.71AMS001Rou_P5_001 933 24.6 1.2 0.589 0.026 1.70 0.07 0.302 0.006 0.90 2985 104 3.5 3291 47 1.4 3483 32 0.9 14.3 yesAMS001Rou_P5_002 1547 19.8 1.0 0.513 0.023 1.95 0.09 0.280 0.006 0.89 2668 96 3.6 3083 48 1.6 3366 36 1.1 20.7 32269 no 0.03AMS001Rou_P5_006 1253 14.91 0.47 0.438 0.011 2.28 0.06 0.247 0.004 0.83 2342 51 2.2 2809 30 1.1 3164 27 0.9 26.0 8150 no 0.13AMS001Rou_P5_015 1099 20.84 0.58 0.545 0.011 1.84 0.04 0.278 0.005 0.72 2802 46 1.6 3131 27 0.9 3350 30 0.9 16.3 14065 no 0.07AMS001Rou_P5_017 617 28.60 0.86 0.597 0.012 1.68 0.03 0.348 0.008 0.67 3017 48 1.6 3440 29 0.9 3697 34 0.9 18.4 yesAMS001Rou_P5_021 837 31.9 1.1 0.724 0.014 1.38 0.03 0.320 0.008 0.59 3510 53 1.5 3548 32 0.9 3570 41 1.1 1.7 488116 no 0.001AMS001Rou_P5_023 1211 21.0 0.7 0.559 0.013 1.79 0.04 0.272 0.007 0.68 2864 55 1.9 3139 34 1.1 3320 41 1.2 13.8 5521 no 0.20AMS001Rou_P5_028 779 39.1 1.0 0.716 0.014 1.40 0.03 0.396 0.007 0.75 3481 54 1.5 3748 26 0.7 3894 27 0.7 10.6 yesAMS001_bt13a 1013 27.5 2.1 0.562 0.034 1.78 0.11 0.354 0.016 0.80 2876 141 4.9 3400 75 2.2 3725 70 1.9 22.8 3000 no 0.34AMS001_bt13b 1101 37.2 2.5 0.846 0.045 1.18 0.06 0.319 0.013 0.79 3951 158 4.0 3700 67 1.8 3567 65 1.8 -10.8 15581 no 0.07AMS001_bt13c 1407 21.0 1.5 0.415 0.024 2.41 0.14 0.367 0.015 0.81 2235 109 4.9 3139 69 2.2 3781 64 1.7 40.9 979 no 1.13AMS001_bt13d 635 40.4 3.0 0.745 0.044 1.34 0.08 0.394 0.017 0.81 3587 164 4.6 3782 73 1.9 3887 65 1.7 7.7 2894 no 0.38AMS001_bt12a 358 32.1 2.6 0.599 0.040 1.67 0.11 0.388 0.017 0.83 3026 162 5.4 3553 79 2.2 3865 67 1.7 21.7 5123 no 0.20AMS001_bt12b 1261 29.6 2.0 0.695 0.036 1.44 0.08 0.309 0.013 0.78 3400 138 4.1 3474 66 1.9 3517 64 1.8 3.3 6622 no 0.17AMS001_bt12c 1369 25.1 2.0 0.495 0.032 2.02 0.13 0.367 0.016 0.83 2592 139 5.4 3311 76 2.3 3780 65 1.7 31.4 12503 no 0.07AMS001_bt12d 799 35.5 2.4 0.660 0.036 1.52 0.08 0.390 0.016 0.81 3265 139 4.3 3653 67 1.8 3872 60 1.5 15.7 1817 no 0.61AMS001_bt11a 921 23.6 1.6 0.557 0.030 1.79 0.10 0.307 0.013 0.79 2856 123 4.3 3253 66 2.0 3508 64 1.8 18.6 yesAMS001_bt11b 275 33.5 2.1 0.547 0.027 1.83 0.09 0.443 0.017 0.80 2814 114 4.1 3594 62 1.7 4063 56 1.4 30.7 1469 no 0.75AMS001_bt11c 393 21.8 1.4 0.420 0.023 2.38 0.13 0.376 0.013 0.85 2261 105 4.7 3174 63 2.0 3817 53 1.4 40.8 2514 no 0.44AMS001_bt10a 421 29.2 1.7 0.562 0.027 1.78 0.08 0.377 0.013 0.80 2873 110 3.8 3460 59 1.7 3820 54 1.4 24.8 1214 no 0.91AMS001_bt10b 492 18.3 1.0 0.425 0.020 2.36 0.11 0.313 0.010 0.81 2281 89 3.9 3008 55 1.8 3537 51 1.5 35.5 1234 no 0.90AMS001_bt10c 764 19.8 1.2 0.492 0.023 2.03 0.09 0.292 0.011 0.78 2581 99 3.8 3081 58 1.9 3426 58 1.7 24.7 341 no 3.24AMS001_bt10d 786 19.7 1.1 0.479 0.021 2.09 0.09 0.299 0.010 0.79 2522 91 3.6 3079 54 1.7 3465 53 1.5 27.2 712 no 1.55AMS001_bt09a 743 25.4 1.5 0.543 0.026 1.84 0.09 0.340 0.011 0.82 2797 108 3.8 3325 57 1.7 3661 51 1.4 23.6 yesAMS001_bt09b 866 25.8 1.5 0.576 0.026 1.74 0.08 0.325 0.012 0.79 2932 108 3.7 3338 57 1.7 3592 56 1.5 18.4 22013 no 0.05AMS001_bt09c 279 30.5 1.7 0.596 0.027 1.68 0.08 0.371 0.011 0.84 3013 110 3.7 3503 54 1.5 3796 45 1.2 20.6 16408 no 0.06AMS001_bt05a 605 20.2 1.0 0.513 0.021 1.95 0.08 0.286 0.009 0.79 2668 89 3.3 3102 50 1.6 3397 49 1.4 21.5 108529 no 0.003Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)113Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS001_bt05b 578 26.8 1.8 0.496 0.025 2.02 0.10 0.392 0.017 0.77 2595 110 4.2 3375 65 1.9 3878 64 1.6 33.1 23058 no 0.03AMS001_bt15a 918 11.8 0.9 0.325 0.018 3.07 0.17 0.262 0.015 0.69 1816 87 4.8 2586 74 2.9 3260 90 2.8 44.3 1720 no 0.64AMS001_bt15b 214 31.8 1.9 0.753 0.026 1.33 0.05 0.307 0.015 0.58 3617 96 2.7 3545 59 1.7 3505 75 2.1 -3.2 2414 no 0.42AMS001_bt15c 235 28.3 1.8 0.558 0.026 1.79 0.08 0.368 0.015 0.74 2858 107 3.8 3429 61 1.8 3782 63 1.7 24.4 6362 no 0.14AMS001_bt16a 612 13.58 0.78 0.383 0.015 2.61 0.10 0.257 0.011 0.67 2091 69 3.3 2721 55 2.0 3229 68 2.1 35.2 9960 no 0.06AMS001_bt16b 1790 11.22 0.60 0.351 0.013 2.85 0.11 0.232 0.009 0.70 1938 63 3.2 2541 50 2.0 3066 62 2.0 36.8 40790 no 0.02Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)114Table B 1  (continued) Zircon LA-ICPMS U-Pb data for Acasta Gneiss samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gAMS008_001 603 31.2 2.4 0.752 0.043 1.33 0.08 0.301 0.016 0.73 3614 157 4.3 3525 76 2.2 3474 81 2.3 -4.0 4129 no 0.27AMS008_002 335 23.1 1.8 0.544 0.030 1.84 0.10 0.308 0.016 0.73 2799 127 4.5 3232 75 2.3 3513 82 2.3 20.3 313 no 3.53AMS008_005 959 34.6 2.6 0.792 0.044 1.26 0.07 0.317 0.016 0.74 3761 158 4.2 3629 74 2.0 3556 78 2.2 -5.8 yesAMS008_008 633 34.1 2.4 0.785 0.041 1.27 0.07 0.315 0.015 0.73 3736 148 4.0 3612 71 2.0 3544 76 2.1 -5.4 2994 no 0.37AMS008_009 850 29.7 2.4 0.733 0.049 1.36 0.09 0.294 0.013 0.83 3545 181 5.1 3477 79 2.3 3438 69 2.0 -3.1 12019 no 0.08AMS008_011 527 30.4 2.3 0.712 0.047 1.40 0.09 0.310 0.012 0.86 3465 176 5.1 3500 76 2.2 3520 61 1.7 1.6 2988 no 0.37AMS008_012 975 25.9 2.0 0.707 0.048 1.41 0.10 0.266 0.010 0.88 3448 181 5.2 3344 75 2.2 3282 57 1.7 -5.0 7876 no 0.13AMS008_017 665 27.7 2.1 0.689 0.046 1.45 0.10 0.292 0.011 0.87 3381 175 5.2 3410 75 2.2 3428 60 1.7 1.4 23218 no 0.02AMS008_019 803 24.6 1.9 0.614 0.041 1.63 0.11 0.291 0.011 0.87 3085 162 5.3 3293 75 2.3 3422 59 1.7 9.8 4140 no 0.27AMS008_020 508 27.2 1.8 0.656 0.036 1.53 0.08 0.301 0.012 0.82 3250 140 4.3 3390 66 1.9 3474 60 1.7 6.5 471 no 2.35AMS008_022 781 19.5 1.4 0.509 0.029 1.97 0.11 0.278 0.011 0.82 2652 125 4.7 3068 68 2.2 3354 64 1.9 20.9 1737 no 0.64AMS008_023 128 27.3 2.0 0.634 0.037 1.58 0.09 0.313 0.013 0.81 3165 145 4.6 3395 70 2.1 3534 65 1.8 10.5 3580 no 0.10AMS008_024 503 27.0 2.0 0.637 0.039 1.57 0.10 0.308 0.012 0.84 3177 154 4.9 3385 72 2.1 3510 62 1.8 9.5 6899 no 0.16AMS008_025 219 29.1 2.0 0.676 0.027 1.48 0.06 0.312 0.018 0.58 3329 106 3.2 3457 69 2.0 3532 88 2.5 5.8 5456 no 0.11AMS008_026 618 33.4 2.4 0.645 0.028 1.55 0.07 0.376 0.021 0.62 3207 110 3.4 3593 70 1.9 3815 84 2.2 15.9 16154 no 0.07AMS008_027 586 22.3 1.6 0.536 0.022 1.87 0.08 0.303 0.017 0.60 2765 94 3.4 3199 68 2.1 3483 86 2.5 20.6 1753 no 0.63AMS008_028 360 27.2 1.9 0.655 0.024 1.53 0.06 0.302 0.017 0.54 3246 94 2.9 3392 67 2.0 3479 89 2.6 6.7 1280 no 0.86AMS008_029 588 25.4 1.7 0.613 0.024 1.63 0.06 0.301 0.017 0.57 3081 95 3.1 3324 66 2.0 3474 86 2.5 11.3 361775 no 0.00AMS008_030 553 29.5 2.0 0.689 0.026 1.45 0.05 0.310 0.018 0.55 3381 99 2.9 3469 67 1.9 3521 87 2.5 4.0 148653 no 0.00AMS008_031 488 19.4 1.3 0.562 0.020 1.78 0.06 0.250 0.014 0.53 2874 83 2.9 3061 65 2.1 3186 90 2.8 9.8 yesAMS008_033 699 27.1 1.9 0.637 0.023 1.57 0.06 0.309 0.018 0.53 3176 90 2.8 3388 67 2.0 3515 90 2.6 9.6 6243 no 0.17AMS008_034 1490 21.8 1.4 0.643 0.018 1.56 0.04 0.246 0.014 0.44 3199 72 2.3 3176 63 2.0 3162 93 2.9 -1.2 9167 no 0.12AMS008_035 614 23.8 1.2 0.558 0.022 1.79 0.07 0.3094 0.0093 0.80 2859 91 3.2 3261 48 1.5 3518 46 1.3 18.8 2485 no 0.44AMS008_036 586 23.2 1.1 0.594 0.024 1.68 0.07 0.2828 0.0077 0.83 3005 98 3.3 3234 48 1.5 3379 43 1.3 11.0 14154 no 0.04AMS008_037 384 26.6 1.3 0.647 0.026 1.55 0.06 0.2987 0.0089 0.80 3216 102 3.2 3370 49 1.5 3463 46 1.3 7.1 3833 no 0.29AMS008_038 552 31.0 1.6 0.739 0.032 1.35 0.06 0.3041 0.0088 0.83 3565 118 3.3 3518 51 1.5 3491 45 1.3 -2.1 4075 no 0.25AMS008_041 539 24.5 1.8 0.585 0.035 1.71 0.10 0.304 0.014 0.80 2970 143 4.8 3289 73 2.2 3490 70 2.0 14.9 11881 no 0.09AMS008_042 221 33.4 1.6 0.766 0.032 1.31 0.05 0.3169 0.0076 0.87 3664 116 3.2 3594 47 1.3 3555 37 1.0 -3.1 2356 no 0.48AMS008_044 357 24.5 1.2 0.564 0.022 1.77 0.07 0.3152 0.0082 0.83 2883 92 3.2 3289 46 1.4 3547 40 1.1 18.7 6892 no 0.10AMS008_047 1423 13.5 1.6 0.366 0.035 2.73 0.27 0.268 0.018 0.82 2010 167 8.3 2717 112 4.1 3295 107 3.2 39.0 213 no 5.36AMS008_049 435 27.2 1.3 0.666 0.026 1.50 0.06 0.2960 0.0076 0.83 3291 100 3.0 3390 46 1.3 3450 40 1.2 4.6 60016 no 0.01AMS008_055 333 26.3 1.7 0.639 0.036 1.57 0.09 0.2986 0.0085 0.89 3184 143 4.5 3358 62 1.9 3463 44 1.3 8.1 4396 no 0.25AMS008_060 387 32.3 2.0 0.751 0.041 1.33 0.07 0.3115 0.0088 0.89 3611 152 4.2 3558 61 1.7 3529 43 1.2 -2.3 9563 no 0.06AMS008_062 360 27.6 1.7 0.658 0.037 1.52 0.08 0.3039 0.0079 0.91 3259 142 4.4 3404 60 1.8 3490 40 1.2 6.6 3224 no 0.35AMS008_064 455 27.3 1.7 0.663 0.037 1.51 0.08 0.2980 0.0076 0.91 3280 143 4.4 3393 60 1.8 3460 40 1.1 5.2 4444 no 0.26AMS008_065 401 29.2 1.8 0.714 0.040 1.40 0.08 0.2962 0.0084 0.89 3474 151 4.3 3459 62 1.8 3451 44 1.3 -0.7 11988 no 0.06Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))*100. f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)115Appendix C   Zircon U-Pb Wetherill concordia plots and age histograms for additional Acasta Gneiss Complex samplesNotes:Coloured ellipses represent results that are <10 % discordant. Grey ellipses represent results that are >10 % discordant. Filled elipses represent results used for weighted mean calculations. For complex samples with numerous age populations (either primary igneous or metamorphic/alteration related), protolith ages are based on weighted mean (WM) of the oldest, distinct cluster of concordant 207Pb/206Pb ages. Otherwise protolith ages are based on the upper intercept age. Histograms are only shown for samples that have >7 U-Pb zircon analyses with <10 % discordance. 0.1 0.3 0.5 0.7 0.9 0 10 20 30 40 50    0 2 4 6 8 3100 3500 3900 Number 207Pb/206Pb age (Ma)n=28207Pb/235U206 Pb/238 UAMS030AAWM 207Pb/ 206Pb age: 3.694 ± 0.033 Ga (n = 19)0.3 0.5 0.7 0.9 1.1 0 20 40 60 80  4200 2800 3200 3600 4000 Number 2 4 6 8 10 0207Pb/235U206 Pb/238 U207Pb/206Pb Age (Ma)3800 3400 3000 n = 37AMS030BWM 207Pb/ 206Pb age: 3.853 ± 0.038 Ga (n = 7)1160.2 0.4 0.6 0.8 1.0 0 10 20 30 40 50  207Pb/235U206 Pb/238 U4000 3600 3200 2800 2400 2 4 6 8 10 3100 3200 3300 3400 3500 3600 3700 Number 207Pb/206Pb Age (Ma)AMS008 n = 33WM 207Pb/ 206Pb age: 3.509 ± 0.013 Ga (n = 18)0.2 0.4 0.6 0.8 1.0 0 10 20 30 40 50 AMS030C207Pb/235U206 Pb/238 U2 4 6 8 3200 3400 3600 3800 4000 4200 Number 207Pb/206Pb Age (Ma)n = 23WM 207Pb/ 206Pb age: 3.89 ± 0.17 Ga (n = 3)4000 3600 3200 2800 2400 0.2 0.4 0.6 0.8 1.0 0 10 20 30 40 50 4000 3600 3200 2800 2400  3400 3500 3600 3700 3800 3900 Number2 4 6 8 10 12 14 207Pb/235U206 Pb/238 U207Pb/206Pb Age (Ma)AMS031A n = 42Upper Intercept: 3.654 ± 0.019 Gan = 88; MSWD = 5.71170.1 0.3 0.5 0.7 0.9 0 10 20 30 40 50 60  207Pb/235U206 Pb/238 UAMS039Upper intercept = 3.764 ± 0.027 Gan = 37; MSWD = 2.13800 3400 3000 2600 2200 0.1 0.3 0.5 0.7 0.9 0 20 40 60 80 4200 3800 3400 3000 2600 207Pb/235U206 Pb/238 UAMS001118Appendix D  Major and minor element oxides of zircon from the Acasta Gneiss Complex and the Kvanefjord Block determined by EPMATable D 1  Major and minor element oxides in zircon from the Acasta Gneiss ComplexSample SiO2 CaO2 ZrO2 HfO2 TotalOxide (wt. %) wt. %AMS027_BG3MT_5 31.58 0.01 65.30 1.54 98.44AMS027_BG3MT_6 32.03 0.02 66.76 1.17 99.98AMS027_BG3MT_14 31.94 0.05 66.13 1.58 99.70AMS027_BG3MT_18a 30.99 0.19 63.70 1.51 96.38AMS027_BG3MT_21 31.24 0.20 64.57 1.56 97.58AMS027_BG3MT_25 31.64 0.04 65.01 1.78 98.48AMS027_BG3MT_30 32.35 0.01 66.00 1.59 99.94AMS027_BG3MT_36a 32.31 - 66.62 1.09 100.02AMS027_BG3MT_48a 32.05 - 66.45 1.22 99.71AMS027_PRMT4_002 30.72 0.28 63.16 1.55 95.71AMS027_PRMT4_010 30.91 0.55 63.79 1.77 97.02AMS027_PRMT4_017 33.49 0.06 62.13 1.27 96.96AMS027_PRMT4_022 32.01 0.04 66.23 1.28 99.55AMS027_SmMT4_003 32.09 0.03 65.95 0.90 98.96AMS027_SmMT4_006 31.06 0.07 64.70 1.28 97.11AMS027_SmMT4_009 30.45 0.42 64.27 1.19 96.32AMS027_SmMT4_020 31.17 0.04 65.50 1.12 97.84AMS027_SmMT4_027 31.63 0.01 66.37 1.51 99.53AMS027_SmMT4_029 31.49 - 66.82 1.17 99.48AMS027_SmMT4_032 31.95 - 66.74 1.16 99.86AMS013_BG3MT_2a 32.37 - 67.11 1.26 100.73AMS013_BG3MT_2b 32.44 - 66.79 1.41 100.65AMS013_BG3MT_3 32.34 - 67.16 1.23 100.73AMS013_BG3MT_10b 32.29 - 66.71 1.44 100.44AMS013_BG3MT_10a 32.26 - 66.69 1.28 100.23AMS013_BG3MT_11 31.99 0.04 64.93 1.74 98.69AMS013_BG3MT_12a 32.21 0.01 66.75 1.15 100.11AMS013_BG3MT_12b 32.44 0.01 66.53 1.50 100.48AMS013_BG3MT_13a 32.31 - 67.22 1.19 100.72AMS013_BG3MT_13b 32.75 - 66.72 1.62 101.09AMS013_BG3MT_14 32.17 - 66.88 1.37 100.43AMS013_BG3MT_15 32.27 - 67.24 1.26 100.77AMS013_BG3MT_18a 31.99 0.01 67.45 1.17 100.62AMS013_BG3MT_18b 32.29 - 66.90 1.53 100.71AMS013_BG3MT_21a 32.31 - 67.24 1.04 100.58AMS013_BG3MT_21b 32.73 0.02 67.09 1.48 101.32AMS013_BG3MT_24 32.24 - 67.27 1.09 100.60AMS013_BG3MT_25 32.08 - 65.35 1.52 98.95AMS013_BG3MT_26b 31.93 - 67.14 1.61 100.69Dashed values indicate values below dectection limit; Electron probe micro-analyser spots placed in same CL zone as LA-ICPMS spots119Sample SiO2 CaO2 ZrO2 HfO2 TotalOxide (wt. %) wt. %AMS013_BG3MT_26a 31.92 - 67.30 1.12 100.34AMS013_BG3MT_32 32.07 - 66.82 1.11 100.00AMS013_RouP4_002 32.27 0.05 67.30 1.19 100.81AMS013_RouP4_006 32.11 0.01 66.87 1.22 100.21AMS013_RouP4_020 32.19 0.01 66.40 1.16 99.76AMS013_RouP4_030 32.19 - 65.91 1.07 99.16AMS013_RouP4_032 32.21 0.01 66.53 1.41 100.16AMS013_PRMT4_016 31.94 0.01 66.24 1.59 99.78AMS013_PRMT4_030 32.23 0.01 66.97 1.58 100.78AMS013_PRMT4_037 31.96 - 65.43 1.79 99.18AMS013_PRMT4_040 31.68 - 65.93 1.22 98.84AMS030AA_1 32.20 0.03 65.97 1.63 99.82AMS030AA_12 30.70 1.06 63.49 1.31 96.57AMS030AA_26 32.27 0.01 66.95 1.69 100.92AMS030AA_28 30.64 0.29 63.94 1.56 96.43AMS030AA_37 30.98 0.42 63.61 1.31 96.32AMS030AA_38 30.80 0.40 60.67 4.69 96.55AMS030AA_43 32.29 - 67.57 1.52 101.38AMS030AA_52 32.03 - 66.06 1.96 100.06AMS030AA_55 32.34 - 66.84 1.64 100.82AMS030AA_56 30.99 0.13 65.30 1.70 98.12AMS030AA_59 32.52 - 66.60 1.64 100.76AMS030AA_63 32.09 0.03 66.65 1.24 100.01AMS030AA_68 31.10 0.09 65.53 1.42 98.14AMS030AA_71 32.30 0.01 66.13 1.64 100.09AMS030AA_86 32.14 0.03 65.45 2.35 99.98AMS030AA_88 32.01 0.02 65.92 1.29 99.24AMS030AA_93 32.38 - 66.90 1.65 100.94AMS030AA_97 32.37 0.01 66.89 1.28 100.56AMS030AA_99 32.46 - 66.49 1.15 100.09AMS030AA_102 32.74 0.01 67.00 1.12 100.88AMS030AA_108 32.53 - 67.42 1.07 101.02AMS030B_6 32.63 0.01 66.04 1.75 100.42AMS030B_13 32.22 - 66.51 1.67 100.40AMS030B_17 32.25 - 67.04 1.30 100.59AMS030B_31 31.98 0.04 65.08 1.82 98.92AMS030B_33 32.53 - 67.21 1.11 100.85AMS030B_34 31.53 0.07 64.36 1.10 97.07AMS030B_35 31.20 0.18 63.90 2.25 97.53AMS030B_40 32.23 - 66.69 0.96 99.88AMS030B_41 32.25 - 66.62 1.59 100.45AMS030B_48 32.40 - 66.56 1.51 100.47AMS030B_54 32.16 - 65.89 1.53 99.57AMS030B_58 31.77 0.01 66.31 1.53 99.62Dashed values indicate values below dectection limit; Electron probe micro-analyser spots placed in same CL zone as LA-ICPMS spots120Sample SiO2 CaO2 ZrO2 HfO2 TotalOxide (wt. %) wt. %AMS030B_82 30.52 0.65 62.89 1.61 95.67AMS030B_93 32.61 0.01 67.55 0.94 101.11AMS030C_2 31.70 0.05 64.69 1.49 97.92AMS030C_4 32.09 0.01 66.54 1.38 100.01AMS030C_5 31.21 0.05 64.30 2.98 98.54AMS030C_12 30.47 0.80 61.74 1.38 94.40AMS030C_14 31.88 0.09 65.27 1.65 98.89AMS030C_15 32.08 0.02 66.26 1.69 100.06AMS030C_21 31.15 0.20 65.45 1.29 98.09AMS030C_29 30.55 0.43 63.17 1.42 95.57AMS030C_32 31.19 0.16 64.45 1.46 97.26AMS030C_33 32.02 0.01 66.72 1.52 100.27AMS030C_45 31.87 0.03 66.44 1.73 100.07AMS030C_56 32.32 - 68.09 1.09 101.51AMS030C_69 32.03 0.05 66.25 1.62 99.94AMS030C_76 31.88 0.04 66.32 1.15 99.38AMS030C_80 32.30 0.01 66.53 1.80 100.65AMS030C_81 32.48 0.01 67.06 1.08 100.62AMS030C_90 30.91 0.16 63.88 0.98 95.92AMS030C_91 31.85 - 67.03 1.64 100.52AMS030C_97 32.05 0.02 66.82 1.33 100.23AMS030C_101 31.86 - 66.67 1.51 100.04AMS030C_104 31.80 0.01 66.51 1.79 100.12AMS039_BG3MT_1 32.07 - 66.41 1.17 99.66AMS039_BG3MT_4 32.21 - 67.59 1.42 101.22AMS039_BG3MT_5 32.44 - 67.24 1.29 100.97AMS039_BG3MT_7 31.92 - 67.00 1.06 99.98AMS039_BG3MT_13 31.99 - 65.90 1.55 99.43AMS039_BG3MT_16 31.95 - 66.07 1.00 99.03AMS039_BG3MT_17 30.78 0.30 64.51 0.96 96.55AMS039_BG3MT_21 32.29 0.01 66.88 1.04 100.21AMS039_BG3MT_26 32.03 0.06 65.64 1.36 99.09AMS039_BG3MT_27 32.05 0.01 67.62 1.24 100.92AMS039_BG3MT_29 32.00 0.02 67.06 1.29 100.36AMS039_BG3MT_32 31.70 0.02 67.02 1.05 99.79AMS039_MedPk4_04 32.13 - 67.08 1.12 100.32AMS039_MedPk4_05 32.05 - 66.97 1.15 100.16AMS039_MedPk4_07 32.09 - 66.97 1.27 100.33AMS039_MedPk4_13 32.21 - 67.05 1.15 100.41AMS039_MedPk4_17 31.73 0.03 66.30 0.97 99.02AMS039_MedPk4_25 31.98 - 66.32 1.00 99.30AMS039_MedPk4_30 31.64 0.01 66.55 1.04 99.24AMS008_08 32.31 0.01 66.89 1.12 100.34AMS008_09 32.10 0.01 67.31 1.33 100.75Dashed values indicate values below dectection limit; Electron probe micro-analyser spots placed in same CL zone as LA-ICPMS spots121Sample SiO2 CaO2 ZrO2 HfO2 TotalOxide (wt. %) wt. %AMS008_22 31.95 0.09 66.41 1.10 99.54AMS008_26 32.03 0.02 65.80 1.66 99.52AMS008_27 31.53 0.11 64.95 1.29 97.88AMS008_34 31.23 0.35 63.16 1.43 96.18AMS008_37 31.65 0.54 65.08 1.33 98.60AMS008_44 31.96 0.02 65.57 1.23 98.79AMS008_47 31.58 0.04 64.47 1.55 97.64AMS008_62 31.79 0.03 65.70 1.45 98.97AMS008_79 32.13 0.01 65.90 1.47 99.50AMS008_85 31.82 0.03 65.85 1.12 98.82AMS031A4_PrBG2MT_02 31.47 - 65.83 0.82 98.12AMS031A4_PrBG2MT_06 32.56 0.01 67.22 1.39 101.17AMS031A4_PrBG2MT_09 31.59 - 66.31 1.01 98.90AMS031A4_PrBG2MT_10 32.34 0.01 66.63 1.40 100.37AMS031A4_PrBG2MT_24 31.60 0.01 66.16 0.98 98.75AMS031A8_RouBG1MT_02 32.09 0.01 64.79 1.21 98.10AMS031A8_RouBG1MT_07 32.57 - 65.60 1.29 99.46AMS031A8_RouBG1MT_08 32.04 0.01 66.24 1.32 99.60AMS031A8_RouBG1MT_13 31.83 - 66.88 1.48 100.19AMS031A8_RouBG1MT_14 32.06 0.01 66.64 1.48 100.19AMS031A8_RouBG1MT_23 32.08 - 67.05 1.19 100.32AMS031A8_RouBG1MT_30 32.11 - 66.16 1.01 99.28AMS031A8_PrBG1MT_03 32.00 0.01 66.88 1.26 100.14AMS031A8_PrBG1MT_05 31.67 0.04 65.97 0.90 98.58AMS031A8_PrBG1MT_06 31.63 - 66.34 0.84 98.80AMS031A8_PrBG1MT_08 31.91 - 66.92 0.99 99.82AMS031A8_PrBG1MT_21 31.78 0.02 66.58 1.18 99.56AMS031A8_PrBG1MT_30 31.62 0.02 66.73 0.97 99.34AMS031A8_MedPk5_01 32.10 - 66.28 1.04 99.42AMS031A8_MedPk5_08 31.63 0.02 66.74 0.94 99.33AMS031A8_MedPk5_20 31.90 - 67.30 0.86 100.06AMS001_MedPk5_06 30.54 0.21 63.84 1.45 96.04AMS001_RouPk5_17 31.61 0.02 65.80 1.46 98.89AMS001_RouPk5_28 30.03 1.09 60.96 1.49 93.57AMS001_RouPk5_33 30.59 0.23 63.49 1.40 95.71AMS001_BG2_03 31.83 0.01 65.61 1.60 99.05AMS001_BG2_12 30.87 0.28 64.08 1.49 96.71AMS001_BG2_30 32.56 - 66.21 1.64 100.42AMS001_BG2_31 30.09 0.68 61.51 1.12 93.40Dashed values indicate values below dectection limit; Electron probe micro-analyser spots placed in same CL zone as LA-ICPMS spots122Table D 2  Major and minor element oxides in zircon from the Kvanefjord BlockSample SiO2 CaO2 ZrO2 HfO2 TotalOxide (wt. %) wt. %GLZ1_518006_01 31.31 0.02 64.98 1.64 97.95GLZ2_518006_01 32.16 0.01 66.04 1.71 99.92GLZ2_518006_02 31.93 0.01 66.21 1.72 99.86GLZ2_518006_09 31.92 0.01 64.26 1.91 98.10GLZ2_518006_13 31.81 0.03 65.57 1.56 98.96GLZ2_468623_01 32.15 - 65.79 1.53 99.47GLZ2_468623_02 32.03 0.01 66.16 1.51 99.70GLZ2_468623_03 32.31 - 66.31 1.49 100.11GLZ2_468623_04 31.99 - 66.15 1.52 99.66GLZ1_508281_01 31.98 - 66.92 1.24 100.15GLZ1_508281_05 32.08 - 66.34 1.44 99.86GLZ2_508281_02 31.29 - 67.37 1.52 100.18GLZ2_508281_05 32.24 - 65.92 1.68 99.85GLZ2_508281_08 32.01 - 64.80 1.17 97.98GLZ2_508281_09 32.35 - 66.16 1.40 99.92GLZ2_508281_11 32.02 - 66.22 1.26 99.50GLZ2_508281_13 32.13 - 65.38 1.39 98.90GLZ2_508281_14 32.16 0.02 66.28 1.43 99.90GLZ2_518001_02 31.17 0.22 65.61 1.06 98.06GLZ2_518001_03_1 32.19 - 66.03 1.19 99.40GLZ2_518001_03_2 31.90 - 66.48 1.39 99.77GLZ2_518001_09 32.12 - 65.74 1.89 99.75GLZ2_518001_07 31.70 - 66.77 1.20 99.68GLZ2_518001_06 31.36 - 66.40 1.01 98.77GLZ2_518001_04 31.50 0.02 66.20 0.96 98.68GLZ2_518001_10 32.22 0.01 66.62 1.44 100.29Dashed values indicate values below dectection limit; Electron probe micro-analyser spots placed in same CL zone as LA-ICPMS spots123Appendix E  Complete trace element analyses of zircon from the Acasta Gneiss Complex, Northwest Territories, Canada, determined by LA-ICPMSTable E 1  Trace element concentrations of zircon from the Acasta Gneiss Complex measured by LA-ICPMSSample Ti 2σ La 2σ Ce 2σ Pr 2σ Nd 2σ Sm 2σ Eu 2σ Gd 2σ Tb 2σAMS027 BG3MT 005 11.9 0.7 15.5 1.2 180 13 41 3 40 3 151 8 9.05 0.47 358 17 64.7 2.5AMS027 BG3MT 006 30 1 125 6 1820 80 662 32 665 42 1046 62 36.5 1.7 2620 130 123 8AMS027 BG3MT 013 5.4 0.2 3.96 0.23 47 2 13.5 0.7 17 1 68 4 2.87 0.13 111 5 15.8 0.6AMS027 BG3MT 018a 15.8 1.2 163 25 830 140 354 67 409 69 1010 210 48.9 8.9 1830 330 119 26AMS027 BG3MT 026 5.9 0.4 70.4 4.9 1050 70 313 20 318 15 288 13 9.89 0.63 1210 51 71.6 3.2AMS027 BG3MT 045 18 1 195 11 1920 420 990 69 1318 91 3780 290 147 11 5180 370 394 26AMS027 BG3MT 048 30 3 57.6 7.4 900 120 296 37 358 43 1030 100 44 5 1310 110 109 5AMS027 PRMT4 010 9.0 0.5 32.8 2.2 347 24 77 4 83 5 257 17 16.11 0.81 413 24 47 3AMS027 SMMT4 009 17 1 36.9 3.3 199 11 57 2 59 3 233 11 40 2 361 17 48 3AMS027 SMMT4 012 10.9 0.8 7.34 0.96 107 16 24 4 28 4 124 18 19.9 3 184 25 31 4AMS027 SMMT4 027 14.5 1.3 5.9 1.2 98 15 16 3 20 3 80 13 12.7 2.2 140 23 28 4AMS013 BG3MT 013b 6.3 0.6 1.91 0.18 9.48 0.75 0.94 0.12 6.09 0.71 4.16 0.42 1.78 0.19 8.05 0.69 4.05 0.29AMS013 BG3MT 014 9.8 0.5 0.0198 0.0054 21.1 0.7 0.193 0.014 4 0.19 8.17 0.21 1.4 0.1 20.9 0.3 9.82 0.18AMS013 BG3MT 015 10.3 0.5 0.054 0.031 18.9 0.9 0.14 0.02 2.86 0.27 5.57 0.41 0.975 0.081 15.9 1.2 8.05 0.58AMS013 BG3MT 018a 6.3 0.4 0.138 0.073 7.7 0.4 0.147 0.046 2.26 0.31 3.47 0.21 0.758 0.048 8.56 0.25 4.19 0.14AMS013 BG3MT 018b 9.8 0.5 2.91 0.21 13.8 0.87 1.29 0.1 7.99 0.63 5.39 0.45 1.5 0.1 8.71 0.65 4.0 0.3AMS013 BG3MT 021a 11.4 0.8 0.55 0.11 18.6 0.4 0.406 0.039 5.06 0.37 6.86 0.41 1.6 0.1 16.48 0.76 7.35 0.3AMS013 BG3MT 021b 8.0 0.5 3.96 0.47 15.8 1.5 2.12 0.2 13 1.2 7.69 0.61 2.3 0.2 11.69 0.81 4.43 0.27AMS013 BG3MT 024 14.1 0.6 0.034 0.011 13.8 0.2 0.12 0.01 2.01 0.10 3.47 0.11 1.00 0.04 9.12 0.21 4.39 0.12AMS013 BG3MT 025 6.3 0.5 42.7 9.3 70 12 6.4 1.2 31 5 9.34 0.84 3.38 0.37 18.5 1.1 8.7 0.28AMS013 BG3MT 026a 13 1 4.8 1.1 47 4 3.35 0.83 23.8 5.3 23.3 3.5 5.6 1.3 41.8 3.4 17.3 1.1AMS013 BG3MT 026b 5.1 0.3 0.228 0.036 6.73 0.19 0.101 0.013 0.861 0.056 1.46 0.07 0.23 0.01 6.25 0.2 4.2 0.1AMS013 BG3MT 032 13.1 0.6 0.094 0.02 19.1 0.4 0.60 0.03 9.5 0.6 12.2 0.8 2.67 0.13 25.9 1.0 11.0 0.3Raw data was reduced with the Iolite v3 software, using Hf wt% measured by EPMA as an internal standard124Table E 1  (continued) Trace element concentrations of zircon from the Acasta Gneiss Complex measured by LA-ICPMSSample Dy 2σ Ho 2σ Er 2σ Tm 2σ Yb 2σ Lu 2σ Pb 2σ Th 2σ U 2σ Hf 2σAMS027 BG3MT 005 712 26 251 9 1072 44 231 10 2080 110 334 10 1180 90 564 33 1010 80 1308 88AMS027 BG3MT 006 220 9 64.1 4.4 388 19 55 3 528 21 89.2 4.7 1140 140 216 13 511 32 991 85AMS027 BG3MT 013 122 4 36.0 0.8 152 4 33 1 284 7 55.1 1.2 127 5 34.8 3.2 41.2 1.8 1253 86AMS027 BG3MT 018a 393 78 88 16 381 69 59 9 503 79 87 13 190 29 100 24 423 49 1277 87AMS027 BG3MT 026 303 11 101 4 502 17 95 4 829 37 149 4 963 69 261 13 411 26 1253 86AMS027 BG3MT 045 1370 80 315 10 1340 56 219 7 1740 190 319 13 2290 200 777 37 879 47 1253 86AMS027 BG3MT 048 472 21 126 6 548 26 95 5 772 25 129 5 409 24 109 9 304 21 1033 84AMS027 PRMT4 010 314 33 88.2 9.8 376 43 78 9 720 67 134 13 361 32 120 15 951 60 1499 89AMS027 SMMT4 009 317 14 82.1 2.7 313 11 59 2 519 17 98.3 3.5 338 22 217 10 545 66 1007 84AMS027 SMMT4 012 246 31 72 8.6 291 31 62 7 561 57 102 9 415 42 205 24 328 39 1010 90AMS027 SMMT4 027 256 34 83 10 357 42 78 8 734 64 135 12 552 47 296 32 424 30 1284 87AMS013 BG3MT 013b 48 2 18.1 0.6 87.8 2.5 21.4 0.4 214 5 40.1 1.2 12.2 0.3 48 2 194 4 1374 85AMS013 BG3MT 014 113 2 38.6 0.4 163 2 37.8 0.6 392 11 45.9 0.6 54 2 135 2 123 6 1163 85AMS013 BG3MT 015 100 7 36.2 2.6 161 11 39 3 428 22 52.7 3.7 49.1 3.9 124 12 147 8 1067 84AMS013 BG3MT 018a 52 1 18.6 0.3 84 1 21.0 0.4 231 6 29.2 0.3 24.7 1.0 66 1 115 5 993 88AMS013 BG3MT 018b 47 2 16.6 0.7 74.5 2.8 18.3 0.5 201 4 27.0 0.6 22.7 0.9 55 3 189 5 1296 84AMS013 BG3MT 021a 86.1 3.1 29 1 130 4 30.3 0.9 331 12 40.3 0.9 39.9 1.7 99 4 97 4 881 87AMS013 BG3MT 021b 43.8 1.6 13.3 0.3 57.7 0.5 14.3 0.2 167 4 23.4 0.2 11.9 0.5 27 2 157 6 1252 84AMS013 BG3MT 024 54.1 1.1 19.1 0.4 86.6 1.6 20.9 0.4 237 4 29.3 0.6 21 1 50 1 69 2 923 87AMS013 BG3MT 025 117 3 44.1 1.2 215 6 55.1 1.2 644 13 87.3 2.1 47.2 1.3 119 4 991 25 1288 87AMS013 BG3MT 026a 185 8 56.7 1.4 238 5 53.3 1.2 554 9 68.3 1.9 109 3 265 9 269 7 948 88AMS013 BG3MT 026b 61 1 23.4 0.4 113 2 29.4 0.6 343 10 45.5 0.7 32.9 0.7 88 1 312 9 1367 84AMS013 BG3MT 032 126 3 40.9 0.9 174 4 39.5 0.9 416 9 48.8 0.9 62.7 1.7 148 3 135 5 937 84Raw data was reduced with the Iolite v3 software, using Hf wt% measured by EPMA as an internal standard125Appendix F  Cathodoluminescence images of zircon grains from the Acasta Gneiss ComplexSample: AMS027Rock Type: GranodioriteNotes:Yellow circles indicate locations of 25 μm spots for U-Pb LA-ICPMS analyses. Green spots indicate locations of 35-50 μm spots for trace element LA-ICPMS analyses. Sample numbers are found in the bottom left of each image and correspond to analyses in Table A.1, Appendix A.1b1a3a3b3c13a13b18a18b126Sample: AMS027Rock Type: Granodiorite25a 25b26a26b36a36b21a21b127Sample: AMS027Rock Type: Granodiorite46b 46a38a38b39a39b128Sample: AMS027Rock Type: Granodiorite129Sample: AMS027Rock Type: Granodiorite3a3b4a4b5a5b6a6b6c8a8b1a1b130Sample: AMS013Rock Type: Granodiorite1a1b2a 2b5a5b5c10a 10b12a12b13a13b17a17b17c131Sample: AMS013Rock Type: Granodiorite18b18a20b20a21b21a23b23a26b26a28b28a29b29a 30b30a31b31a132Sample: AMS013Rock Type: Granodiorite35b35a37b37a4b4a5b5a7b7a133Sample: AMS013Rock Type: Granodiorite134Sample: AMS013Rock Type: Granodiorite001a001b001b001a_Pk7 _Pk8001c135Sample: AMS013Rock Type: Granodiorite006b006a_Pk8136Sample: AMS030A-ARock Type: Tonalitic layer of layered gneiss26a26b 28a28b30a30b137Sample: AMS030A-ARock Type: Tonalitic layer of layered gneiss138Sample: AMS030A-ARock Type: Tonalitic layer of layered gneiss55a 55b139Sample: AMS030A-ARock Type: Tonalitic layer of layered gneiss20a20b20c81a81b003a003b003c001b001a002a002c002b003a003b004a004b140Sample: AMS030BRock Type: Tonalitic layer of layered gneiss141Sample: AMS030BRock Type: Tonalitic layer of layered gneiss142Sample: AMS030BRock Type: Tonalitic layer of layered gneiss143Sample: AMS030BRock Type: Tonalitic layer of layered gneiss144Sample: AMS030CRock Type: Tonalitic layer of layered gneiss145Sample: AMS030CRock Type: Tonalitic layer of layered gneiss38a38b146Sample: AMS030CRock Type: Tonalitic layer of layered gneiss147Sample: AMS030CRock Type: Tonalitic layer of layered gneiss97a97b065b065a148Sample: AMS001Rock Type: Meta-tonaliteAMS001Big_BG2_001 AMS001Big_BG2_002 AMS001Big_BG2_003AMS001Big_BG2_004 AMS001Big_BG2_005 AMS001Big_BG2_006AMS001Big_BG2_008 AMS001Big_BG2_009 AMS001Big_BG2_012AMS001Big_BG2_013 AMS001Big_BG2_014 AMS001Big_BG2_015AMS001Big_BG2_016 AMS001Big_BG2_020 AMS001Big_BG2_021149Sample: AMS001Rock Type: Meta-tonaliteAMS001Big_BG2_023 AMS001Big_BG2_024 AMS001Big_BG2_025AMS001Big_BG2_029 AMS001Big_BG2_030 AMS001Big_BG2_031AMS001Big_BG2_032 AMS001Big_BG2_033 AMS001Big_BG2_034AMS001Big_BG2_036 AMS001Big_BG2_037 AMS001Big_BG2_038AMS001Big_BG2_039 AMS001Big_BG2_040 AMS001Big_BG2_042150Sample: AMS001Rock Type: Meta-tonaliteMed MedMed Med Med151Sample: AMS001Rock Type: Meta-tonalite005a005b009a009b009c 010a010b010c010c011a011b011c012a012b012c012d013b013a013c013d015c015a015b015a015b152Sample: AMS008Rock Type: Meta-tonalite153Sample: AMS008Rock Type: Meta-tonalite154Sample: AMS008Rock Type: Meta-tonalite155Sample: AMS008Rock Type: Meta-tonalite156Sample: AMS039Rock Type: Meta-tonalite014a014b157Sample: AMS039Rock Type: Meta-tonalite006a006b158Sample: AMS039Rock Type: Meta-tonalite159Sample: AMS039Rock Type: Meta-tonalite160Sample: AMS031ARock Type: Dioritic layer of layered gneissAMS031A4Pr_BG2_001 AMS031A4Pr_BG2_002 AMS031A4Pr_BG2_004AMS031A4Pr_BG2_005 AMS031A4Pr_BG2_006 AMS031A4Pr_BG2_007AMS031A4Pr_BG2_009 AMS031A4Pr_BG2_010 AMS031A4Pr_BG2_012AMS031A4Pr_BG2_015 AMS031A4Pr_BG2_017 AMS031A4Pr_BG2_018AMS031A4Pr_BG2_019 AMS031A4Pr_BG2_024 AMS031A4Pr_BG2_026161Sample: AMS031ARock Type: Dioritic layer of layered gneiss005a005b010a010bAMS031A4Pr_BG2_027 AMS031A4Pr_BG2_028 AMS031A4Pr_BG2_029AMS031A4Pr_BG2_031 AMS031A4Pr_BG2_032 AMS031A4Pr_BG2_033AMS031A4Pr_BG2_036 AMS031A4Pr_BG2_037 AMS031A4Brou_BG2_003AMS031A4Brou_BG2_004 AMS031A4Brou_BG2_005 AMS031A4Brou_BG2_010AMS031A4Brou_BG2_011 AMS031A4Brou_BG2_012 AMS031A4Brou_BG2_015162Sample: AMS031ARock Type: Dioritic layer of layered gneissAMS031A4Brou_BG2_016 AMS031A4Brou_BG2_020 AMS031A4Brou_BG2_021AMS031A4Brou_BG2_023 AMS031A4Brou_BG2_034 AMS031A4Brou_BG2_035AMS031A4Brou_BG2_039 AMS031A4Brou_BG2_040 AMS031A4Brou_BG2_045AMS031A8Brou_BG1_002 AMS031A8Brou_BG1_003 AMS031A8Brou_BG1_007AMS031A8Brou_BG1_008 AMS031A8Brou_BG1_009 AMS031A8Brou_BG1_013163Sample: AMS031ARock Type: Dioritic layer of layered gneiss026b026aAMS031A8Brou_BG1_014 AMS031A8Brou_BG1_017 AMS031A8Brou_BG1_022AMS031A8Brou_BG1_023 AMS031A8Brou_BG1_026 AMS031A8Brou_BG1_027AMS031A8Brou_BG1_028 AMS031A8Brou_BG1_030 AMS031A8Brou_BG1_032AMS031A8Brou_BG1_033 AMS031A8Pr_BG1_001 AMS031A8Pr_BG1_003AMS031A8Pr_BG1_005 AMS031A8Pr_BG1_006 AMS031A8Pr_BG1_007164Sample: AMS031ARock Type: Dioritic layer of layered gneissAMS031A8Pr_BG1_008 AMS031A8Pr_BG1_010 AMS031A8Pr_BG1_011AMS031A8Pr_BG1_014 AMS031A8Pr_BG1_015 AMS031A8Pr_BG1_019AMS031A8Pr_BG1_020 AMS031A8Pr_BG1_021 AMS031A8Pr_BG1_022AMS031A8Pr_BG1_026 AMS031A8Pr_BG1_027 AMS031A8Pr_BG1_029AMS031A8Pr_BG1_030 AMS031A8Med_Pk5_001 AMS031A8Med_Pk5_002165Sample: AMS031ARock Type: Dioritic layer of layered gneissAMS031A8Med_Pk5_004 AMS031A8Med_Pk5_006 AMS031A8Med_Pk5_008AMS031A8Med_Pk5_014 AMS031A8Med_Pk5_020 AMS031A8Med_Pk5_021AMS031A8bte_BG1_025025b025a166Appendix G  Thin section scans of samples from the Kvanefjord blockSample: 518001Latitude: 61°49.065 Longitude: - 49°16.487Rock Type: tonalite gneissMain minerals: plagioclase, quartz, K-feldspar, biotite, hornblendeAccessory mineral phases: zircon, apatiteNotes: TS = Transmitted light; XPL = Cross-polarised light; Scale bars are 0.5 cmTS XPL167Sample: 518006Latitude: 61°49.223 Longitude: - 49°15.919Rock Type: tonalite gneissMain minerals: plagioclase, quartz, K-feldspar, biotite, muscoviteAccessory mineral phases: zircon, apatiteNotes: TS = Transmitted light; XPL = Cross-polarised light; Scale bars are 0.5 cmXPLTS168Sample: 508281Latitude: 62°8.415 Longitude: -49°31.765Rock Type: tonalite gneissMain minerals: plagioclase, quartz, K-feldspar, biotite, epidoteAccessory mineral phases: zircon, apatiteNotes: TS = Transmitted light; XPL = Cross-polarised light; Scale bars are 0.5 cmTS XPL169Sample: 468623Latitude: 64°11.081 Longitude: - 50°16.376Rock Type: tonalite gneissMain minerals: plagioclase, quartz, K-feldspar, biotite, garnetAccessory mineral phases: zircon, apatiteNotes: TS = Transmitted light; XPL = Cross-polarised light; Scale bars are 0.5 cmXPLTS170Appendix H  Complete U-Pb analyses of zircon from the Kvanefjord block, GreenlandTable H 1  Zircon LA-ICPMS U-Pb data for the Kvanefjord block samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gGLZ1-518001_01 1117 11.7 0.6 0.433 0.014 2.31 0.07 0.1955 0.0082 0.60 2320 62 2.7 2579 49 1.9 2789 69 2.5 16.8 13243 no 0.08GLZ1-518001_02 378 13.0 0.8 0.467 0.019 2.14 0.08 0.2018 0.0090 0.67 2472 81 3.3 2680 56 2.1 2841 72 2.5 13.0 13302 no 0.04GLZ1-518001_03 531 11.6 0.6 0.425 0.013 2.35 0.07 0.1975 0.0082 0.61 2282 61 2.7 2570 49 1.9 2806 68 2.4 18.7 129068 no 0.00GLZ2-518001_01 502 16.1 1.2 0.554 0.032 1.81 0.11 0.2113 0.0107 0.75 2841 134 4.7 2885 74 2.6 2915 82 2.8 2.5 64926 no 0.01GLZ2-518001_02 274 14.1 1.1 0.479 0.028 2.09 0.12 0.2136 0.0107 0.77 2523 124 4.9 2757 74 2.7 2933 81 2.8 14.0 yesGLZ2-518001_03-1 193 15.4 1.2 0.547 0.030 1.83 0.10 0.2038 0.0105 0.73 2813 124 4.4 2839 72 2.5 2857 84 2.9 1.5 8467 no 0.06GLZ2-518001_03-2 340 11.9 0.9 0.402 0.023 2.48 0.14 0.2140 0.0102 0.77 2180 107 4.9 2595 70 2.7 2936 77 2.6 25.7 yesGLZ2-518001_04 403 13.7 1.0 0.478 0.027 2.09 0.12 0.2083 0.0097 0.77 2519 117 4.6 2731 69 2.5 2893 75 2.6 12.9 54747 no 0.01GLZ2-518001_06 182 13.5 1.0 0.473 0.031 2.11 0.14 0.2064 0.0055 0.93 2497 136 5.5 2712 67 2.5 2878 43 1.5 13.2 908887 no 0.00GLZ2-518001_07 251 18.2 1.2 0.604 0.037 1.66 0.10 0.2185 0.0054 0.93 3044 148 4.8 3000 63 2.1 2970 40 1.3 -2.5 45696 no 0.01GLZ2-518001_08 181 13.8 1.0 0.483 0.032 2.07 0.14 0.2071 0.0057 0.92 2538 139 5.5 2735 68 2.5 2883 45 1.6 11.9 yesGLZ2-518001_09 401 16.9 1.2 0.580 0.035 1.72 0.10 0.2114 0.0069 0.88 2949 144 4.9 2930 66 2.3 2916 53 1.8 -1.1 61687 no 0.02GLZ2-518001_10 436 14.0 1.0 0.482 0.031 2.08 0.13 0.2102 0.0055 0.92 2534 133 5.2 2747 65 2.4 2907 42 1.5 12.8 9973 no 0.06GLZ2-518001_11 321 12.7 0.9 0.453 0.030 2.21 0.14 0.2043 0.0043 0.95 2407 131 5.5 2661 65 2.4 2861 35 1.2 15.9 13019 no 0.04GLZ1-518006_01 729 13.3 0.6 0.468 0.017 2.14 0.08 0.2063 0.0047 0.85 2474 77 3.1 2701 41 1.5 2876 37 1.3 14.0 27527 no 0.03GLZ1-518006_02 569 12.3 0.5 0.447 0.018 2.24 0.09 0.1990 0.0040 0.89 2380 78 3.3 2624 41 1.6 2818 33 1.2 15.5 6508 no 0.17GLZ1-518006_04 566 13.5 0.7 0.474 0.017 2.11 0.07 0.2059 0.0084 0.65 2501 73 2.9 2712 51 1.9 2874 67 2.3 13.0 9124 no 0.10GLZ1-518006_05 717 12.4 0.8 0.431 0.018 2.32 0.10 0.2084 0.0106 0.64 2311 83 3.6 2634 63 2.4 2893 83 2.9 20.1 12219 no 0.07GLZ1-518006_06a 761 11.8 0.6 0.439 0.014 2.28 0.07 0.1944 0.0080 0.61 2345 62 2.7 2586 48 1.9 2780 67 2.4 15.6 20930 no 0.04GLZ2-518006_01 250 12.7 1.0 0.461 0.031 2.17 0.15 0.1991 0.0071 0.88 2446 137 5.6 2655 72 2.7 2819 58 2.1 13.2 yesGLZ2-518006_02 296 11.1 1.0 0.387 0.028 2.58 0.19 0.2074 0.0096 0.84 2111 130 6.2 2530 80 3.2 2885 75 2.6 26.8 7599 no 0.09GLZ2-518006_03 242 13.6 1.1 0.494 0.034 2.02 0.14 0.1991 0.0074 0.88 2589 147 5.7 2720 74 2.7 2819 61 2.2 8.2 yesGLZ2-518006_04 788 11.7 1.6 0.398 0.041 2.51 0.26 0.2128 0.0202 0.74 2159 191 8.9 2579 133 5.1 2927 154 5.3 26.3 yesGLZ2-518006_06 1172 12.2 1.2 0.432 0.035 2.31 0.19 0.2043 0.0122 0.81 2316 159 6.9 2619 95 3.6 2861 97 3.4 19.0 yesGLZ2-518006_07 530 8.0 0.8 0.297 0.027 3.36 0.30 0.1948 0.0108 0.85 1677 132 7.9 2229 95 4.3 2783 91 3.3 39.7 42432 no 0.02GLZ2-518006_09 465 10.7 1.0 0.392 0.033 2.55 0.22 0.1986 0.0095 0.87 2131 155 7.3 2500 91 3.6 2815 78 2.8 24.3 31580 no 0.03GLZ2-518006_10 476 14.7 1.4 0.513 0.040 1.95 0.15 0.2077 0.0102 0.85 2668 172 6.5 2795 88 3.2 2888 80 2.8 7.6 61358 no 0.01GLZ2-518006_11 385 13.7 1.3 0.492 0.039 2.03 0.16 0.2023 0.0100 0.85 2580 168 6.5 2731 88 3.2 2845 80 2.8 9.3 11060 no 0.08GLZ2-518006_13 254 14.4 1.5 0.489 0.042 2.04 0.17 0.2131 0.0130 0.81 2567 180 7.0 2775 100 3.6 2930 99 3.4 12.4 15860 no 0.06GLZ2-518006_14 533 13.0 1.3 0.460 0.039 2.17 0.18 0.2042 0.0104 0.85 2440 171 7.0 2676 93 3.5 2860 83 2.9 14.7 yesGLZ1-508281_01 204 14.8 0.8 0.531 0.023 1.88 0.08 0.2027 0.0052 0.86 2744 98 3.6 2804 48 1.7 2848 42 1.5 3.7 25242 no 0.04GLZ1-508281_02 76 15.0 0.8 0.517 0.023 1.94 0.08 0.2110 0.0066 0.81 2684 96 3.6 2817 51 1.8 2913 51 1.7 7.9 yesGLZ1-508281_03 260 13.6 0.6 0.495 0.020 2.02 0.08 0.1993 0.0044 0.88 2590 86 3.3 2722 43 1.6 2821 36 1.3 8.2 yesGLZ1-508281_04 316 14.9 0.7 0.514 0.022 1.95 0.08 0.2098 0.0049 0.87 2673 92 3.5 2807 46 1.6 2904 38 1.3 8.0 77059 no 0.01Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))x100; f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)171Table H 1  (continued) Zircon LA-ICPMS U-Pb data for the Kvanefjord block samplesRatios b Dates (Ma)d Common PbSample Name U (ppm)a 207Pb/235Uc ±2σ 206Pb/238U ±2σ 238U/206Pb ±2σ 207Pb/206Pb ±2σ rho 206Pb/238U ±2σ ±2σ% 207Pb/235U ±2σ ±2σ% 207Pb/206Pb ±2σ ±2σ% disc. (%)e 206Pb/204Pb 204Pb <DL?f ƒ206%gGLZ1-508281_05 659 15.1 0.6 0.541 0.019 1.85 0.06 0.2029 0.0049 0.82 2788 78 2.8 2824 40 1.4 2849 39 1.4 2.2 yesGLZ1-508281_08 407 15.8 0.7 0.555 0.021 1.80 0.07 0.2060 0.0050 0.84 2847 87 3.0 2863 43 1.5 2874 39 1.4 0.9 14997 no 0.05GLZ2-508281_02 365 15.2 1.3 0.513 0.035 1.95 0.13 0.2144 0.0103 0.82 2669 149 5.6 2826 80 2.8 2939 78 2.6 9.2 58922 no 0.02GLZ2-508281_03 624 13.0 1.2 0.445 0.034 2.25 0.17 0.2119 0.0107 0.84 2371 152 6.4 2679 87 3.2 2920 81 2.8 18.8 10120 no 0.10GLZ2-508281_04 272 17.7 1.4 0.586 0.036 1.71 0.10 0.2196 0.0108 0.78 2974 146 4.9 2976 76 2.5 2978 80 2.7 0.1 yesGLZ2-508281_05 229 13.5 1.1 0.452 0.031 2.21 0.15 0.2163 0.0102 0.83 2403 139 5.8 2713 79 2.9 2953 76 2.6 18.6 4527 no 0.20GLZ2-508281_06-1 262 15.2 1.2 0.513 0.032 1.95 0.12 0.2149 0.0104 0.80 2669 138 5.2 2828 76 2.7 2943 78 2.7 9.3 yesGLZ2-508281_06-2 287 14.7 1.2 0.514 0.032 1.95 0.12 0.2078 0.0103 0.78 2672 137 5.1 2797 76 2.7 2889 81 2.8 7.5 18422 no 0.02GLZ2-508281_07 1008 16.3 1.9 0.533 0.047 1.88 0.17 0.2215 0.0166 0.76 2754 199 7.2 2893 112 3.9 2991 121 4.0 7.9 17388 no 0.06GLZ2-508281_08 773 15.6 1.4 0.537 0.032 1.86 0.11 0.2100 0.0142 0.67 2773 136 4.9 2850 87 3.0 2906 110 3.8 4.6 34640 no 0.03GLZ2-508281_09 214 15.4 1.4 0.538 0.032 1.86 0.11 0.2070 0.0135 0.68 2777 135 4.9 2838 85 3.0 2882 106 3.7 3.7 4060 no 0.18GLZ2-508281_11 228 15.4 1.4 0.537 0.032 1.86 0.11 0.2084 0.0140 0.67 2771 136 4.9 2843 86 3.0 2893 109 3.8 4.2 11935 no 0.05GLZ2-508281_12 237 15.8 1.5 0.564 0.037 1.77 0.11 0.2026 0.0136 0.69 2883 150 5.2 2862 89 3.1 2847 110 3.9 -1.3 yesGLZ2-508281_13 169 14.9 1.4 0.525 0.034 1.90 0.12 0.2062 0.0146 0.67 2720 143 5.3 2810 92 3.3 2876 116 4.0 5.4 70815 no 0.01GLZ2-508281_14 177 11.1 0.9 0.385 0.026 2.60 0.18 0.2091 0.0108 0.80 2099 122 5.8 2531 80 3.1 2899 83 2.9 27.6 yesGLZ1-468623_01 724 14.6 0.8 0.499 0.018 2.01 0.07 0.2125 0.0092 0.65 2608 79 3.0 2790 54 1.9 2925 70 2.4 10.8 18268 no 0.05GLZ1-468623_02 759 8.46 0.48 0.291 0.011 3.43 0.13 0.2105 0.0090 0.66 1649 55 3.3 2281 52 2.3 2910 69 2.4 43.3 435 no 2.54GLZ1-468623_03 270 15.4 1.0 0.543 0.018 1.84 0.06 0.2050 0.0112 0.52 2798 75 2.7 2838 61 2.1 2866 89 3.1 2.4 53799 no 0.01GLZ1-468623_04 785 7.11 0.55 0.255 0.013 3.91 0.20 0.2018 0.0117 0.67 1466 68 4.7 2125 69 3.3 2841 94 3.3 48.4 1354 no 0.82GLZ1-468623_06 252 14.6 0.9 0.517 0.015 1.93 0.06 0.2056 0.0111 0.47 2686 64 2.4 2793 58 2.1 2871 88 3.0 6.4 yesGLZ1-468623_07 503 12.6 0.8 0.445 0.014 2.25 0.07 0.2045 0.0110 0.51 2373 63 2.7 2647 59 2.2 2863 88 3.1 17.1 29008 no 0.03GLZ1-468623_08 359 11.3 0.7 0.403 0.014 2.48 0.08 0.2025 0.0111 0.52 2185 62 2.8 2545 60 2.4 2847 89 3.1 23.2 5888 no 0.19GLZ1-468623_09b 613 11.9 0.8 0.428 0.015 2.34 0.08 0.2013 0.0113 0.53 2296 67 2.9 2595 62 2.4 2837 92 3.2 19.0 3275 no 0.34GLZ1-468623_13 459 14.6 0.9 0.522 0.031 1.91 0.11 0.2026 0.0049 0.92 2710 130 4.8 2789 61 2.2 2848 39 1.4 4.8 62771 no 0.02GLZ1-468623_14 259 14.4 1.0 0.501 0.030 2.00 0.12 0.2086 0.0061 0.90 2619 130 4.9 2777 64 2.3 2895 47 1.6 9.5 yesGLZ1-468623_15 313 10.3 0.7 0.387 0.024 2.58 0.16 0.1931 0.0057 0.91 2109 113 5.4 2463 65 2.6 2769 49 1.8 23.8 9865 no 0.11GLZ1-468623_16 616 13.2 0.9 0.481 0.030 2.08 0.13 0.1993 0.0056 0.91 2531 128 5.1 2695 64 2.4 2820 46 1.6 10.3 yesGLZ2-468623_01 239 10.4 1.0 0.369 0.031 2.71 0.23 0.2041 0.0109 0.85 2023 148 7.3 2469 94 3.8 2859 87 3.0 29.2 yesGLZ2-468623_02 343 14.9 1.4 0.531 0.043 1.88 0.15 0.2039 0.0104 0.85 2746 182 6.6 2811 92 3.3 2858 83 2.9 3.9 20407 no 0.02GLZ2-468623_03 480 12.7 1.0 0.449 0.026 2.23 0.13 0.2052 0.0099 0.77 2389 117 4.9 2657 71 2.7 2868 78 2.7 16.7 14345 no 0.08GLZ2-468623_04 610 10.8 0.9 0.386 0.025 2.59 0.17 0.2039 0.0088 0.83 2102 118 5.6 2509 73 2.9 2858 71 2.5 26.4 6468 no 0.08Raw data reduced using an EXCEL macro (Kooijman et al., 2012); b.d. = below detection limit; a concentration uncertainty c. 10 %; b data corrected for common-Pb if 206Pb/204Pb <500, initial Pb estimated using preliminary sample age and two-stage Pb evolution model (Stacey and Kramers, 1975); c 238U/235U = 137.88 (Steiger and Jäger, 1977); d λ238U = 1.55125 x 10-10 yr-1, λ235U = 9.8485 x 10-10 yr-1 (Steiger and Jäger, 1977); e discordance calculated as (1-(206Pb/238U age)/(207Pb/206Pb age))x100; f D.L. = detection limit; g ƒ206% = (common 206Pb/total 206Pb) x 100)172Appendix I  Complete trace element analyses of zircon from the Kvanefjord block, determined by LA-ICPMSTable I 1  Trace element concentrations of zircon from the Kvanefjord block measured by LA-ICPMSSample Ti 2σ La 2σ Ce 2σ Pr 2σ Nd 2σ Sm 2σ Eu 2σ Gd 2σ Tb 2σ Dy 2σGLZ2_518001_02 53.8 7.7 34.2 4.7 267 19 24.6 2.3 188 30 66.7 5.6 17.5 0.8 120 10 22 2 210 23GLZ2_518001_03 14.5 3.4 2.1 0.2 59 6 2.6 0.3 25.1 2.4 18 2 5.5 0.4 40.7 4.4 8.9 0.5 87.5 6.8GLZ2_518001_04 22.1 4.9 10.5 2.2 114 9 6.4 1.2 55.2 7.3 28.2 3.2 8.2 1.0 62.9 7.5 13.2 0.9 123 5GLZ2_518001_05 30.4 4.1 11.7 1.7 321 12 15 1 162 9 111 7 35.7 1.6 239 13 49.3 1.5 450 18GLZ2_518001_06 18 4 20.5 2.9 151 11 11.7 1.5 92.8 9.4 37 2 10.3 0.5 69.6 4.1 14.3 0.7 134 6GLZ2_518001_07 6.2 1.8 0.3 0.1 13 2 0.4 0.1 3.4 0.8 3.0 0.7 1.1 0.2 10.6 1.4 2.5 0.3 28.1 2.5GLZ2_518001_09 25.6 4.6 28 4 520 140 12 2 76 12 47.5 6.5 12.8 1.6 110 13 24 2 232 14GLZ2_518001_10 34.8 4.9 27.5 2.3 213 15 15 1 112 11 49.9 5.9 16.1 1.7 105 13 22.1 2.3 203 21GLZ1_518006_01 27.5 6.8 9 1 60 9 6.9 0.8 41.4 6.7 26.9 3.8 6.6 0.8 61.3 7.3 12.9 1.5 140 22GLZ1_518006_02 19 2 9.1 0.7 46.8 3.9 6.5 0.5 45.5 3.9 18.1 1.5 6.6 0.5 28.3 2.2 4.5 0.3 45.3 2.5GLZ1_518006_04 18.1 3.6 7 1 31.5 4.6 3.3 0.3 26.3 2.4 13.9 1.4 3.4 0.4 28.9 2.7 6.3 1.0 52.6 6.2GLZ2_518006_01 24.4 9.7 7.9 1.2 71.4 7.1 6.5 0.9 76 15 32 5 12.5 1.8 76.6 7.8 16.3 1.5 158 6GLZ2_518006_02 13.6 1.7 2.4 0.2 19.3 1.1 1.8 0.2 17.7 1.7 8.6 0.7 1.6 0.1 24.4 1.6 5.1 0.2 44.1 1.6GLZ2_518006_03 18 1 3.3 0.5 19.8 1.5 2.4 0.2 22.8 1.9 9.1 0.9 2.0 0.2 26.1 2.1 6.0 0.4 68.2 4.2GLZ2_518006_09 20.8 2.7 25.9 1.4 143 6 14.8 0.9 121 4 38.8 2.8 10.2 0.5 112 9 28.5 1.6 312 11GLZ2_518006_10 6.8 1.6 2.3 0.4 24.2 1.4 1.1 0.1 10.8 1.1 9.1 0.7 2.8 0.2 43.3 2.5 10.2 0.5 107 5GLZ2_518006_11 8 2 2.4 0.3 17.1 2.1 2.0 0.3 15.1 1.4 7.0 0.5 1.7 0.3 18.2 1.1 3.9 0.2 40.5 2.1GLZ2_518006_13 45 6 13.8 1.1 85.1 5.5 7.2 0.6 64 5 28 2 5.9 0.5 95.2 8.8 22.6 1.8 237 16GLZ2_518006_14 5.7 1.1 3.7 0.6 20.3 1.2 1.9 0.3 12.7 1.5 7.1 0.6 1.8 0.2 23.4 3.3 5.7 0.8 63.5 8Raw data was reduced with the Iolite v3 software, using Hf wt% measured by EPMA as an internal standard173Table I 1  (continued) Trace element concentrations of zircon from the Kvanefjord block measured by LA-ICPMSSample Ho 2σ Er 2σ Tm 2σ Yb 2σ Lu 2σ Pb 2σ Th 2σ U 2σ Hf 2σGLZ2_518001_02 56.7 3.9 233 17 59.3 3.7 658 36 77.3 4.8 137 10 607 46 653 17 10607 837GLZ2_518001_03 27.2 2.2 122 7 31.4 1.8 385 16 52.7 2.9 49.9 2.8 234 16 352 28 11899 858GLZ2_518001_04 41 2 187 11 44 2 484 21 67 2.9 81.3 5.8 390 23 447 35 13866 874GLZ2_518001_05 135 5 544 17 125 3 1380 45 168 5 258 10 1191 35 645 25 9589 852GLZ2_518001_06 44.2 2.1 188 10 47.6 1.7 531 24 70.1 3.1 72.1 4.4 342 18 383 34 10073 844GLZ2_518001_07 10.4 0.7 52 3 14.1 0.7 177 10 25.3 0.92 13.5 1.5 49.6 7.4 185 7 12045 855GLZ2_518001_09 74.9 4.6 327 20 79.9 6.2 850 53 112 5 165 22 851 68 926 76 18904 906GLZ2_518001_10 68.9 7.1 300 31 74.3 6.5 823 59 111 10 134 16 604 78 655 37 14425 873GLZ1_518006_01 44.3 4.5 168 16 44.1 5.1 464 33 54.6 5.2 38.8 5 154 21 678 71 16392 889GLZ1_518006_02 14.6 0.7 62.6 1.9 16.9 0.7 180 9 24 1 15.4 3.8 52.8 9.3 370 53 17072 890GLZ1_518006_04 13.4 1.3 59.8 3.5 12.0 0.8 130 10 14.1 1.5 24.2 6.4 89 22 448 44 17072 890GLZ2_518006_01 48 4 260 21 46.2 1.9 504 54 60.3 3.1 74 10 348 21 602 87 17050 890GLZ2_518006_02 10.6 0.4 48.1 1.6 7.7 0.4 71 4 9 1 17 1 88.8 2.7 672 37 17151 890GLZ2_518006_03 21.2 1.3 121 8 22.9 1.4 251 12 30.1 2 15.9 0.5 91.4 3.4 590 21 17072 890GLZ2_518006_09 94.5 2.6 474 22 79.6 3.1 746 29 86.3 3.8 332 11 1470 130 2335 72 19139 912GLZ2_518006_10 33.3 1.5 173 6 30.4 1.1 305 10 39 1.5 42.6 3.4 223 14 391 20 17072 885GLZ2_518006_11 12.2 0.5 64.4 2.1 12.8 0.5 135 6 18 0 13.6 0.8 73.3 3.6 445 23 17072 885GLZ2_518006_13 69.6 4.9 310 21 54.5 3.4 484 28 59.9 2.6 344 26 1498 88 1422 93 15628 885GLZ2_518006_14 21 2 99.5 8.9 21.4 1.5 220 11 27.7 1.7 17.2 2.7 96 16 581 30 17072 885Raw data was reduced with the Iolite v3 software, using Hf wt% measured by EPMA as an internal standard174Table I 1  (continued) Trace element concentrations of zircon from the Kvanefjord block measured by LA-ICPMSSample Ti 2σ La 2σ Ce 2σ Pr 2σ Nd 2σ Sm 2σ Eu 2σ Gd 2σ Tb 2σ Dy 2σGLZ2_468623_01 12.8 3.2 6.5 2.3 47.7 8.8 3.2 1.0 25 7 21 3.2 2.2 0.4 86.4 5.3 19.9 2.2 244 27GLZ2_468623_02 12 4 6.2 1.5 32.5 4.5 2.6 0.5 17.8 3.6 12.6 2.9 0.9 0.2 44 3 10.6 1.4 119 10GLZ2_468623_03 12 4 12.6 2.6 63.1 8.3 6 1 40.5 6.2 31.8 2.8 2.3 0.2 124 3 30.3 1.0 335 14GLZ2_468623_04 6.3 3.1 0.6 0.3 16 1 0.3 0.1 3.5 1.2 5.7 0.7 0.4 0.1 64.8 2.8 18.0 0.8 238 7GLZ1_508281_02 10.7 2.2 3.0 0.3 25.7 2.3 1.3 0.1 6.2 0.6 4.4 0.5 1.5 0.2 17.2 2.6 4.2 0.6 49 6GLZ1_508281_05 29.8 3.2 9.6 0.7 44.5 5.8 2.4 0.2 11.2 0.8 5.9 0.9 1.6 0.2 19.6 1.9 4.8 0.5 65.5 5.1GLZ2_508281_02 41.9 7.3 9.5 2.3 114 14 2.4 0.6 16.5 1.6 16.1 2.4 5.2 0.8 84 14 20.7 3.6 233 35GLZ2_508281_04 18.2 6.5 2.8 0.3 93.8 7.1 1.5 0.2 14.1 1.4 17.6 1.8 6.0 0.6 78.5 7.6 20.3 1.5 204 17GLZ2_508281_05 32.8 5.8 42.2 5.1 116 9 8 1 41.5 5.3 21.8 1.9 4.9 0.4 110 8 31.9 1.8 393 22GLZ2_508281_06 36 12 2.1 0.8 190 6 2.4 0.4 35.5 2.7 57.2 3.8 12.5 0.8 193 15 47.6 1.8 447 18GLZ2_508281_08 12.1 3.1 1.7 0.2 30.3 2.9 0.9 0.1 7.2 1.1 8.9 1.2 2.5 0.3 34 4 8.5 0.9 99.7 7.8GLZ2_508281_09 23.9 2.4 4.9 0.4 69 5 2.0 0.2 11.1 1.0 10.6 0.9 2.8 0.2 47 3 12.0 0.4 143 4GLZ2_508281_11 21.2 4.5 2.3 0.5 74.3 5.4 1.3 0.2 11.5 1.3 18.2 1.7 4.6 0.4 80 7 18.8 1.9 203 16GLZ2_508281_12 25.1 3.5 8.6 0.6 65.7 4.7 5.7 0.4 35.7 2.7 11.4 1.0 3.3 0.2 40.3 3.2 9.2 0.6 114 8GLZ2_508281_13 60.8 4.1 15.4 0.8 55.6 2.4 3.5 0.4 16.0 0.8 8.4 1.5 2.5 0.3 32.6 4.8 8 1 93 8.3GLZ2_508281_14 71.8 9.2 11.6 1.3 80.7 7 4.5 0.4 24.4 2.4 14.4 1.5 3.8 0.3 50 4 12 1 133 10Raw data was reduced with the Iolite v3 software, using Hf wt% measured by EPMA as an internal standard175Table I 1  (continued) Trace element concentrations of zircon from the Kvanefjord block measured by LA-ICPMSSample Ho 2σ Er 2σ Tm 2σ Yb 2σ Lu 2σ Pb 2σ Th 2σ U 2σ Hf 2σGLZ2_468623_01 92.2 7.8 431 33 103 7 1119 81 153 12 75.5 6.9 425 47 548 59 15260 887GLZ2_468623_02 48.6 3.5 216 11 55 3 602 28 76.7 3 38.3 3.3 189 19 398 32 15137 886GLZ2_468623_03 123 4 540 20 117 4 1166 35 153.5 6.8 90.2 3.3 494 16 596 24 14895 883GLZ2_468623_04 99.1 3.4 471 16 114 4 1132 37 156.9 4.5 120 6 588 26 987 55 15245 878GLZ1_508281_02 16.7 1.7 66.9 6 20.8 1.6 272 17 33.1 1.3 17.7 2.2 52 8 507 41 12364 858GLZ1_508281_05 24.3 1.9 103 6 31 2 349 26 49 1.7 23.7 4.3 114 13 338 40 14419 870GLZ2_508281_02 81 10 353 42 83.1 8.3 942 87 107 11 141 19 620 110 1022 92 15166 864GLZ2_508281_04 69.5 4.7 300 16 74.8 3.8 789 51 98.8 6.3 93.2 7.3 398 23 478 48 13931 890GLZ2_508281_05 144 9 622 36 146 9 1420 76 183 10 96.7 3.6 494 18 1203 73 16834 864GLZ2_508281_06 122 7 433 21 93.5 3.4 936 44 99.7 5 331 24 1340 210 944 60 13931 873GLZ2_508281_08 30.8 2.1 135 9 35 2 402 22 50.4 2.9 34.6 3.4 166 13 485 35 11699 859GLZ2_508281_09 46.7 1.1 206 5 50.5 1.3 544 14 67.5 1.5 63.4 4.1 376 26 508 31 14035 874GLZ2_508281_11 57.2 3.8 217 13 51.7 3.3 558 38 61.7 3.2 93 13 414 53 383 36 12611 867GLZ2_508281_12 38.1 2.7 178 13 43.7 2.3 483 37 63.7 3.1 36.6 2.9 166 11 323 43 13931 863GLZ2_508281_13 28.2 2.7 132 13 31.7 2.7 385 29 49.4 4.7 26.6 2.8 115 14 240 12 13910 862GLZ2_508281_14 40.8 2.8 178 11 42.7 2.4 443 23 56.4 2.2 41.9 3 201 16 270 18 14341 861Raw data was reduced with the Iolite v3 software, using Hf wt% measured by EPMA as an internal standard176Appendix J  Cathodoluminescence images of zircon from the Kvanefjord block analysed by LA-ICPMSSample: 468623Rock Type: Tonalite gneissNotes:Yellow circles indicate locations of 25 μm spots for U-Pb LA-ICPMS analyses. Green spots indicate locations of 35 μm spots for trace element LA-ICPMS analyses. Sample numbers are found in the bottom left of each image and correspond to analyses in Table A.1, Appendix A.177Sample: 468623Rock Type: Tonalite gneissGLZ2GLZ2 GLZ2 GLZ2GLZ2178Sample: 518001Rock Type: Tonalite gneiss179Sample: 518006Rock Type: Tonalite gneiss180Sample: 508281Rock Type: Tonalite gneiss181Sample: 508281Rock Type: Tonalite gneiss182Appendix K  Optical microscopy images for Kvanefjord Block and Bastar Craton apatite grains analysed by LA-MC-ICPMSSample: 518001 Sample: 518001Sample: 468623Notes:Scale bars are 200 μm. Laser ablation spot sizes are 50 or 90 μm.183Sample: 508281Sample: AMA04Sample: AMA01A  Notes:Scale bars are 200 μm. Laser ablation spot sizes are 50 or .90 μm.184Appendix L  Apatite Sr isotope data of samples from the Kvanefjord block, Greenland, and the Baster Craton, India, determined by LA-MC-ICPMSTable L 1  LA-MC-ICPMS Sr isotope data for Kvanefjord block apatiteSample name Spot Number Sampling time (sec)87Sr/86Sr 2 S.D. 84Sr/86Sr 2 S.E. 87Rb/86Sr1 2 S.E. 174Yb(2+)/ 86Sr22 S.E. Total Sr-Beam (V)Initial 87Sr/86Sr3468623 468623-9 36.0 0.7227 0.0010 0.0559 0.0014 0.00334 0.00030 0.0582 0.0033 0.42 0.7226468623 468623-12 35.5 0.7254 0.0013 0.057 0.001 0.00872 0.00076 0.0894 0.0042 0.42 0.7250468623 468623-13 35.0 0.72271 0.00084 0.0548 0.0014 0.00321 0.00016 0.0605 0.0011 0.41 0.72258468623 468623-14 35.0 0.72646 0.00094 0.0565 0.0014 0.00271 0.00015 0.05290 0.00078 0.41 0.72636518001 518001-15 34.5 0.70332 0.00022 0.05634 0.00032 0.000131 0.000025 0.00099 0.00010 2.19 0.70331518001 518001-16 30.8 0.70385 0.00026 0.05680 0.00031 0.000115 0.000036 0.00067 0.00012 1.95 0.70385518001 518001-17 34.0 0.70393 0.00022 0.05662 0.00031 0.000127 0.000034 0.00118 0.00011 2.01 0.70393518001 518001-18 34.0 0.70312 0.00026 0.05649 0.00026 0.000088 0.000026 0.00108 0.00011 2.10 0.70311518001 518001-19 20.5 0.70389 0.00041 0.05643 0.00035 0.000190 0.000034 0.00115 0.00014 2.03 0.70389518001 518001-21 34.0 0.70331 0.00030 0.05654 0.00029 0.000274 0.000057 0.00097 0.00011 2.01 0.70330518001 518001-23 33.5 0.70428 0.00027 0.05652 0.00034 0.000053 0.000029 0.000512 0.000095 1.87 0.70428518001 518001-87 38.5 0.70563 0.00056 0.05674 0.00025 0.000144 0.000022 0.001172 0.000085 2.58 0.70562518001 518001-88 35.7 0.70373 0.00018 0.05631 0.00021 0.00044 0.00010 0.001340 0.000079 2.54 0.70371518001 518001-89 33.9 0.70380 0.00019 0.05686 0.00028 0.000119 0.000030 0.001223 0.000094 2.55 0.70379518001 518001-20 26.5 0.70411 0.00054 0.0564 0.0010 0.00077 0.00013 0.00176 0.00030 0.72 0.70408518001 518001-22 26.0 0.70406 0.00069 0.05624 0.00091 0.00006 0.00009 0.00096 0.00034 0.74 0.70406518001 518001-85 33.5 0.70389 0.00064 0.05641 0.00088 0.00026 0.00011 0.00085 0.00037 0.70 0.70388518006 518006-52 34.5 0.70881 0.00040 0.05602 0.00068 0.000645 0.000061 0.01067 0.00031 0.98 0.70879518006 518006-53 34.0 0.70856 0.00048 0.05608 0.00052 0.000719 0.000063 0.01349 0.00025 0.94 0.70853518006 518006-54 26.7 0.70855 0.00048 0.05611 0.00064 0.000922 0.000071 0.01454 0.00024 1.12 0.70851518006 518006-57 30.5 0.70964 0.00048 0.05534 0.00070 0.000796 0.000070 0.01198 0.00031 1.00 0.70961518006 518006-55 27.9 0.7077 0.0014 0.0562 0.0031 0.00074 0.00026 0.0145 0.0012 0.27 0.7077518006 518006-56 32.9 0.7080 0.0012 0.0564 0.0020 0.00082 0.00021 0.0115 0.0008 0.27 0.7080508281 508281-81 28.8 0.70615 0.00043 0.05673 0.00025 0.000324 0.000084 0.00127 0.00014 2.73 0.70613508281 508281-83 34.0 0.70294 0.00021 0.0564 0.0002 0.000119 0.000027 0.001347 0.000091 2.94 0.70293508281 508281-84 34.5 0.70438 0.00027 0.05649 0.00023 0.000098 0.000023 0.001381 0.000071 2.84 0.70437508281 508281-90 33.5 0.71123 0.00019 0.05644 0.00024 0.000113 0.000026 0.001094 0.000070 2.38 0.71122508281 508281-91 31.7 0.70844 0.00027 0.05659 0.00023 0.000185 0.000025 0.001832 0.000086 2.76 0.708431 87Rb was calculated from 85Rb (Rb-factor = 0.3861); 2 From 173Yb(2+) measured on m/z = 86.5; 3 87Rb decay constant = 1.393x10-11 yr-1 (Nebel et al., 2011)185Table L 2  LA-MC-ICPMS Sr isotope data for Bastar Craton apatiteSample name Spot Number Sampling time (sec)87Sr/86Sr 2 S.D. 84Sr/86Sr 2 S.E. 87Rb/86Sr1 2 S.E. 174Yb(2+)/ 86Sr22 S.E. Total Sr-Beam (V)Initial 87Sr/86Sr3AMA01A AMA01A-45 33.6 0.70317 0.00029 0.05638 0.00036 0.00209 0.00012 0.00383 0.00015 1.73 0.70307AMA01A AMA01A-48 18.0 0.70134 0.00057 0.05614 0.00053 0.00170 0.00043 0.00662 0.00035 1.81 0.70126AMA01A AMA01A-46 34.8 0.70890 0.00069 0.0560 0.0013 0.00021 0.00012 0.00271 0.00041 0.45 0.70889AMA01A AMA01A-50 28.9 0.70242 0.00069 0.0550 0.0016 0.00147 0.00020 0.00700 0.00052 0.51 0.70234AMA01A AMA01A-51 33.5 0.70140 0.00092 0.0556 0.0012 0.00124 0.00024 0.00548 0.00055 0.48 0.70134AMA04 AMA04-58 34.5 0.70319 0.00037 0.05623 0.00028 0.000452 0.000033 0.00588 0.00036 1.95 0.70317AMA04 AMA04-59 33.5 0.70324 0.00030 0.05639 0.00034 0.000365 0.000034 0.00475 0.00013 1.85 0.70323AMA04 AMA04-60 31.9 0.70174 0.00033 0.05631 0.00032 0.0120 0.0022 0.00292 0.00019 2.06 0.70112AMA04 AMA04-61 34.0 0.70160 0.00026 0.05640 0.00032 0.000256 0.000037 0.00288 0.00011 2.07 0.70158AMA04 AMA04-67 32.2 0.70485 0.00029 0.05645 0.00035 0.001138 0.000052 0.00194 0.00013 1.80 0.70480AMA04 AMA04-68 31.2 0.70303 0.00030 0.05652 0.00034 0.000626 0.000052 0.00477 0.00022 1.86 0.70300AMA04 AMA04-69 33.0 0.70168 0.00038 0.05658 0.00036 0.000299 0.000032 0.00425 0.00026 1.97 0.70167AMA04 AMA04-62 33.4 0.70365 0.00069 0.0568 0.0011 0.00043 0.00012 0.00256 0.00045 0.53 0.70363AMA04 AMA04-63 34.0 0.70418 0.00051 0.05674 0.00091 0.00044 0.00012 0.00328 0.00041 0.56 0.70416AMA04 AMA04-65 33.5 0.70138 0.00064 0.0561 0.0011 0.00022 0.00012 0.00263 0.00038 0.54 0.70137AMA04 AMA04-66 33.5 0.70254 0.00062 0.0565 0.0012 0.00014 0.00012 0.00444 0.00041 0.51 0.702531 87Rb was calculated from 85Rb (Rb-factor = 0.3861); 2 From 173Yb(2+) measured on m/z = 86.5; 3 87Rb decay constant = 1.393x10-11 yr-1 (Nebel et al., 2011)

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