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Ductile extrusion, underplating, and out-of-sequence thrusting within the Himalayan metamorphic core,… Ambrose, Tyler Kurtis 2014

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DUCTILE EXTRUSION, UNDERPLATING, AND OUT-OF-SEQUENCE THRUSTING WITHIN THE HIMALAYAN METAMORPHIC CORE, KANCHENJUNGA, NEPALbyTyler Kurtis AmbroseB.Sc. (Honours), The University of Victoria, 2011A THESIS SUBMITTED IN PARTIAL FULFILLMENT OFTHE REQUIREMENTS FOR THE DEGREE OFMASTER OF SCIENCEinTHE COLLEGE OF GRADUATE STUDIES(Environmental Sciences)THE UNIVERSITY OF BRITISH COLUMBIA(Okanagan)September 2014© Tyler  Kurtis Ambrose, 2014AbstractThe Himalayan Metamorphic Core (HMC) is a package of greenschist to granulite grade metamorphic rocks that was buried to midcrustal levels and subsequently exhumed during Himalayan orogenesis. Until recently, most kinematic models for burial and exhumation have focused on the two fault systems that bound the HMC: the South Tibetan detachment system above and the Main Central thrust below. Increasing chronologic and thermobarometric data from across the HMC indicate that a significant amount of horizontal shortening and vertical thickening was accommodated along structures within the HMC. These structures have only a cryptic surface expression; they are often recognized in P-T-t(-D) paths only after fieldwork has been completed. Although such P-T-t(-D) discontinuities have been identified along the length of the Himalaya, little is yet known about how they developed and their overall importance to the evolution of the orogen.The Kanchenjunga region of far north-eastern Nepal exposes a thick section of garnet + biotite to migmatitic, K-feldspar + sillimanite grade paragneisses of the HMC. Pseudosection modelling and in-situ laser ablation split-stream U-Th/Pb monazite petrochronology methods were applied to anatectic paragneisses from this area to identify and elucidate cryptic structures within the HMC. The resulting P-T-t paths confirm previously reported discontinuities and reveal the presence of others previously unidentified. Our data outline a series of thrust sense discontinuities that record an early protracted history of ductile extrusion (ca. 41-21 Ma) and a later history of underplating that drove metamorphism in the footwall material (ca. 31-12 Ma). These structures were repeated by early Miocene (ca. 20-18 Ma) out-of-sequence thrusting coincident with the previously mapped High Himal thrust. The resulting kinematic model for the evolution of the HMC in the Kanchenjunga area demonstrates that the HMC is significantly more complex than a thick package of homoclinal rocks bound between two faults. Understanding the internal structure of the HMC is critical to elucidating the kinematics of the orogen and convergence accommodation processes in general. iiPrefaceThis thesis is my own work. Dr. Kyle Larson and Dr. Carl Guilmette provided scientific direction, thought provoking discussion, and editorial assistance. Dr. John Cottle assisted with processing geochronology data. Heather Buckingham assisted in conducting fieldwork.iiiTable of ContentsAbstract ...................................................................................................................................................... iiPreface ....................................................................................................................................................... iiiList of Abbreviations ................................................................................................................................ ixAcknowledgements ....................................................................................................................................xChapter 1.  Introduction ............................................................................................................................11.1  General Introduction .................................................................................................................11.2  Tectonostratigraphic Framework ..............................................................................................11.3  The Himalayan Metamorphic Core...........................................................................................31.4  Statement of Problem ................................................................................................................51.5  Objective of this Study ..............................................................................................................7Chapter 2.  Geology of the Kanchenjunga Region: Basantapur to Yangma ........................................82.1  Geologic Setting ........................................................................................................................82.2  Divisions of the HMC ...............................................................................................................82.3  Previously Mapped Structures within the HMC .....................................................................112.3.1  MCT .............................................................................................................................112.3.2  High Himal Thrust ........................................................................................................11Chapter 3.  Pressure and Temperature of Metamorphism ..................................................................123.1  Equilibrium Thermodynamics in Metamorphic Petrology .....................................................123.1.1  Software Packages used for Phase Equilibria Modelling .............................................133.2  Methodology  ..........................................................................................................................143.2.1  Sampling Technique .....................................................................................................143.2.2  Mineral Chemistry ........................................................................................................143.2.3  Model System ...............................................................................................................163.2.4  Bulk Composition .........................................................................................................163.3  Petrography .............................................................................................................................163.4  Mineral Chemistry  .................................................................................................................233.5  Phase Equilibria Modelling Results ........................................................................................28ivChapter 4.  Monazite Petrochronology ..................................................................................................374.1  Background .............................................................................................................................374.1.1  P-T-t Paths ....................................................................................................................384.2  Methodology ...........................................................................................................................394.3  Results .....................................................................................................................................414.4  Interpretation of Dates ............................................................................................................63Chapter 5.  Discussion and Conclusions ................................................................................................665.1  P-T-t Paths ...............................................................................................................................665.2  P-T-t Discontinuities  ..............................................................................................................685.3  Tectonic Implications ..............................................................................................................735.4  Conclusions .............................................................................................................................785.5  Future Work ............................................................................................................................78References .................................................................................................................................................80Appendices ................................................................................................................................................90Appendix A: Investigation Locality Information ...........................................................................90Appendix B: Pressure-Temperature Data ......................................................................................96B.1:Temperature-XFe3+ Pseudosections  ................................................................................96B.2: Isopleths ..........................................................................................................................99B.3. EMP Spot Locations and Composition Data ................................................................108Appendix C: Monazite Elemental Maps and BSE Images ..........................................................130vList of TablesTable 3.1    Modal mineral abundances .................................................................................................15Table 3.2    Representative mineral chemistries ....................................................................................24Table 3.3    Bulk composition of specimens used   to for P-T calculations. .........................................30Table 4.1    Monazite geochronology results and Y concentrations .....................................................42Table A.1   Summary of investigation localitites ...................................................................................90Table B.1   Garnet compositions from specimen KA007 ....................................................................109Table B.2   Biotite compositions from specimen KA007 .....................................................................110Table B.3   Plagioclase compositions from specimen KA007 .............................................................111Table B.4   Muscovite compositions from specimen KA007 ...............................................................112Table B.5   Garnet compositions from specimen KA044 ....................................................................114Table B.6   Biotite compositions from specimen KA044 .....................................................................117Table B.7   Plagioclase compositions from specimen KA044 .............................................................118Table B.8   K-feldspar compositions from specimen KA044 ..............................................................119Table B.9   Garnet compositions from specimen KA064A .................................................................121Table B.10 Biotite compositions from specimen KA064A ..................................................................126Table B.11 Plagioclase compositions from specimen KA064A ...........................................................128Table B.12 K-feldspar compositions from specimen KA064A ...........................................................129viList of FiguresFigure 1.1    Overview of Himalayan orogen ...........................................................................................2Figure 1.2    Tectonic models for the Himalaya .......................................................................................4Figure 1.3    Hybrid tectonic model for the HMC involving ductile extrusion and critical taper ......6Figure 2.1    Geologic map of study area ..................................................................................................9Figure 2.2    Geologic cross section of study area ..................................................................................10Figure 3.1    Photographs of specimens used for P-T and petrochronology .......................................17Figure 3.2    Photomicrographs of KA007 .............................................................................................18Figure 3.3    Photomicrographs of KA044 .............................................................................................20Figure 3.4    Photomicrographs of KA064A ...........................................................................................22Figure 3.5    Mineral chemistry of KA007 .............................................................................................26Figure 3.6    Mineral chemistry of KA044 .............................................................................................27Figure 3.7    Mineral chemistry of KA064A ...........................................................................................29Figure 3.8    Pseudosection results for KA007 .......................................................................................32Figure 3.9    Pseudosection results for KA044 .......................................................................................33Figure 3.10  Pseudosection results for KA064A ....................................................................................34Figure 4.1    Relationship between monazite and garnet HREE zoning .............................................40Figure 4.2    Location of analyzed monazite grains in thin section .....................................................56Figure 4.3    Monazite petrochronology diagrams ................................................................................57Figure 4.4    Summary of Y and dates. ...................................................................................................64Figure 5.1    Summary of P-T paths .......................................................................................................69Figure 5.2    Timing of metamorphism in the HMC .............................................................................70Figure 5.3    Geologic map of interpreted faults ....................................................................................71Figure 5.4    Geologic cross-section showing the location of interpretted faults ................................72Figure 5.5    Tectonic evolution model for the HMC .............................................................................75viiFigure B.1   Temperature versus XFe3+ pseudosection for KA007 ....................................................96Figure B.2   Temperature versus XFe3+ pseudosection for KA044 ....................................................97Figure B.3   Temperature versus XFe3+ pseudosection for KA064A ..................................................98Figure B.4   Almandine isopleths for specimen KA007 ........................................................................99Figure B.5   Grossular isopleths for specimen KA007 ........................................................................100Figure B.6   Biotite Mg# isopleths for KA007 ......................................................................................101Figure B.7   Almandine isopleths for specimen KA044 ......................................................................102Figure B.8   Grossular isopleths for specimen KA044 ........................................................................103Figure B.9   Biotite Mg# for specimen KA044 .....................................................................................104Figure B.10 Almandine isopleths for specimen KA064A ....................................................................105Figure B.11 Grossular isopleths for specimen KA064A .....................................................................106Figure B.12 Biotite Mg# isopleths for specimen KA064A ..................................................................107Figure B.13 KA007 EMP mineral spot analysis locations ..................................................................108Figure B.14 KA044 EMP mineral spot analysis locations ..................................................................113Figure B.15 KA064A EMP mineral spot analysis locations ...............................................................120Figure C.1   Monazite element maps and BSE images .......................................................................130viiiList of AbbreviationsAlm*   almandineAls  aluminosilicateBSE  back-scattered electronBt   biotiteChl   chloriteCrd   cordieriteD   deformationEDS  energy dispersive spectroscopyEMP  electron microprobeFsp  feldsparGrs  grossularGrt  garnetHREE  heavy rare earth elementsICP-MS inductively coupled plasma mass spectroscopyIlm  ilmeniteID-TIMS isotope dilution thermal ionization mass spectroscopyKfs  potassium feldsparKy  kyaniteL  liquid (melt)LASS  laser ablation split streamLREE  light rare earth elementsMCT  Main Central thrustMnz  monaziteMs  muscovitePl  plagioclaseP   pressureQz   quartz REE  rare earth elementsRu   rutileSRC   Saskatchewan Research CouncilSil   sillimaniteSps   spessartineSTDS  South Tibetan Detachment SystemT   temperaturet  timeWDS   wavelength dispersive spectroscopy* Mineral abbreviations after Whitney and Evans (2009)ixAcknowledgementsThis thesis represents the combined efforts of many people from across the world. First and foremost, I thank my advisor Dr. Kyle Larson for selecting me for such an amazing project that was brilliantly planned from the start. I have had an absolute blast with this project. I thank my co-advisor Carl Guilmette for sharing his passion and knowledge of metamorphic geology. It is because of both of you that I will be confining myself tFo at least three more years as a graduate student. Thank you. Before I acknowledge anymore people directly involved with this thesis, I would like to thank everyone I had the pleasure of knowing during my undergrad at the University of Victoria. In particular, I thank Dr. Stephen Johnston for igniting my love of not only geology and tectonics, but science in general. Mike Burns, I thank you for turning me on to geology. I thank Graham Lederer and Jake Poletti from the UCSB for an awesome month around Manaslu. I also thank Graham for his help with geochronology and, in particular, driving to the lab in the middle of the night. During the three months I spent in Nepal, I was continuously in awe of the Nepali attitude. I especially thank Pradap Tamang whom I spent nearly 3 months with. By the end he felt like family. I thank Nawang, Tsering, Sartha, Teke and Sunam-Dawa Tamang and all the porters, who not only made this project possible, but were an absolute pleasure to spend time with in the field.I thank everyone in the lab here at UBC (Shah, Asghar, Heather, Mikkel and Sudip) who I have had the pleasure to work with. I have learnt a lot from all of you. Sudip, thank you for converting me to Theriak/Domino. This thesis would not have been the same if I had stuck with THERMOCALC. To everyone at UWaterloo, I thank you for making my three months out there enjoyable. While in Waterloo, Brian Kendall generously donated his time to teach us a geochronology class, which included hours of marking assignments. I am extremely grateful for this course that has proved critical to my thesis. Ben and Sudip, we spent too many hours in that windowless office at UWaterloo. I thank John Cottle (UCSB) for helping processes the petrochronology data, Marc Beauchamp (UWO) for operating the the EMP in London, Steven Creighton (SRC) for EMP data, and David Arkinstall (UBCO) for assistant with the SEM. I thank Doug Tinkham (Laurentian) and Paul Starr (U of C) for their generous assistance and discussion regarding Theriak/Domino. I thank my committee members John Greenough and David Jack for thought provoking questions and for improvements to the text of this thesis.This project was funded by an NSERC CGS, multiple UBCO graduate fellowships, and a Geological Society of America graduate student research award to Tyler Ambrose. I am very grateful to David Barclay and the GEM-MFC for their generous support.I thank my family for their encouragement, even if they didn’t understand why I quit my job to return to school. I know that you understand now. Finally, I thank Courtney Dean, who moved to Kelowna as my girlfriend, and is leaving to England with me as my wife. I could not imagine going through this with anyone else.xChapter 1.  Introduction1.1  General IntroductionThe Himalayan-Tibetan orogen is the result of the ongoing continent-continent collision between the Indian and Eurasian plates, which began approximately 50 million years ago with the closure of the Tethys ocean (Figure 1.1; Najman et al., 2010). Paleozoic to Mesozoic subduction beneath the southern margin of Eurasia leading to the closure of the ocean basin resulted in the sequential accretion of at least four crustal blocks: the Eastern Kunlun-Qaidam terrane, the Lhasa terrane, the Songpan-Ganzi-Hoh Xil terrane, and the Qiangtang terrane. Protracted subduction after the accretion of the southernmost Lhasa terrane produced the Andean-style Trans-Himalayan batholiths (Yin and Harrison, 2000). The development of this volcanic suite ended with the collision of India with Eurasia and resulted in severe thickening of both the northern margin of the Indian craton and the Eurasian continental crust leading to the formation of the Himalaya and the Tibetan Plateau. Prior to collision, a thick southward tapering, supracrustal passive margin succession accumulated on the northern margin of the Indian craton (Yin and Harrison, 2000). These rocks were scraped off of the Indian margin and deformed and metamorphosed as part of a southward propagating orogenic wedge that marks the transition from the Tibetan Plateau to the Indian Shield (Figure 1.1). 1.2  Tectonostratigraphic FrameworkThe Himalaya form a WNW-ESE trending, 2,500 km long arcuate belt between two structural syntaxes: Nanga Parbat to the west and Namche Barwa to the east (Figure 1.1). Bound by the Indian shield to the south and Eurasia to the north, the Himalaya are commonly divided into 4 fault bound tectonostratigraphic units: the Tethyan Sedimentary Sequence (TSS), the Greater Himalayan Sequence (GHS), the Lesser Himalayan Sequence (LHS), and the Sub-Himalayan Sequence (SHS) (Figure 1.1; Yin and Harrison, 2000; Hodges, 2000). The TSS, GHS and LHS represent the Proterozoic to Eocene, proximal to distal stratigraphic succession deposited on the northward facing Indian passive margin (Hodges, 2000; Searle et al., 2008; Chakungal et al., 2010; Long et al., 2011). The TSS, separated from Eurasian rocks to the north by the Indus Tsangpo suture zone, consists of upper Proterozoic to Eocene, generally unmetamorphosed, clastic sedimentary rocks (Vannay and Hodges, 1996; Hodges, 2000). The South Tibetan detachment system (STDS), a north dipping extensional shear zone, juxtaposes the TSS against the subjacent GHS. The GHS is the exhumed metamorphic core of the orogen; it is a package of Neoproterozoic to Ordovician, upper greenschist to granulite-grade metasedimentary rock, Ordovician felsic orthogneiss, and Miocene anatectic leucogranite (Parrish and Hodges, 1996; Hodges, 2000). The contact between the GHS and the underlying LHS has been the root of considerable confusion (see Searle et al., 2008 for a review). Heim and Gansser (1939) and Gansser (1964) originally defined the base of the GHS as the Main Central thrust (MCT), a crustal scale reverse-sense fault that places high-grade metamorphic rocks of the GHS on top of low-grade metamorphic rocks of the LHS. In that definition the contact is strictly tectonostratigraphic. 1Depth (km)Horizontal Distance (km)0 100 200050100North SouthIndian BasementCITSZ = Indus Tsangpo suture zoneSTDS = South Tibetan detachment systemMCT = Main Central thrustMBT = Main Boundart thrustMFT = Main Frontal thrust6 710989245311112DiscontinuityHimalayan Metamorphic Core (Greater Himalaya Sequence)Main Central ThrustLesser Himalaya SequenceMain Boundary ThrustMain Frontal ThrustSub Himalaya SequenceThimphuKathmanduPokhara Tethyan Sedimentary Sequence South Tibetan DetachmentleucogranitesTibetan PlateauIndian ShieldABFigure 2.1500 kmFigure 1.1BNanga ParbatNamche BarwaFigure 1.1   Overview of Himalayan orogenFigure 1.1. Overview of Himalayan orogen. (A) Global relief model of the Himalaya, Indian shield, and Tibetan plateau (Amante and Eakins, 2009) (B) Simplified geologic map of the Himalaya showing the main tectonometamorphic units (modified after McQuarrie et al., 2014). Study area for this thesis is outlined in the black box. Numbers in yellow circles identify discontinuities: 1, Garhwal India (Spencer et al. 2010); 2, NW Nepal (Yakymchuk and Godin, 2012); 3 Mangri Shear Zone, Mugu Karnali  (Montomoli et al., 2013); 4 Toijem Shear Zone, Lower Dolpo (Carosi et al., 2010); 5 Modi Khola, Central Nepal (Martin et al., 2010); 6 Bhanuwa Tvhrust, Sinuwa Thrust (Corrie and Kohn, 2011) 7 Manaslu-Himal Chuli (Larson et al., 2010, 2011) 8 Tama Kosi (Larson et al., 2012; Larson and Cottle 2014);  9 High Himalayan Thrust, Kanchenjunga (Goscombe et al., 2006); 10 Sikkim (Rubatto et al., 2013); 11 Laya-Kakhtang Thrust, Bhutan (Grujic et al., 2002, 2011;Warren et al., 2011); 12 Zimithang Thrust NE India (Warren et al., 2014). (C) Geologic cross section of the Himalaya  through central Nepal (modified from Herman et al., 2010). Legend is the same as for Figure 1.1B.2In central Nepal, the structural contact has been interpreted to coincide with a lithologic contact (e.g. Goscombe et al. 2006). However, in other parts of the orogen, such as the field area of this thesis, the MCT occurs below the lithologic contact observed in central Nepal (Goscombe et al., 2006). Because of the confusion surrounding the structure, the MCT has been been mapped at various structural levels along the length of the orogen based on a variety of criteria including isotopic signature, detrital geochronology, and kyanite isograd (Searle et al., 2008 and references cited therein). It is stressed that for this thesis, the MCT is defined structurally, as a crustal scale, high strain shear zone, commonly found at the base of an inverted metamorphic sequence that places high grade rocks on top of low grade rocks (Heim and Gansser 1939; Gansser, 1964; Searle et al., 2008). The LHS, which occurs in the footwall of the MCT, consists of Palaeo- to Mesoproterozoic, unmetamorphosed to low-grade metasedimentary rock. The LHS is thrust atop the SHS along the north dipping Main Boundary thrust fault. Composed of foreland basin deposits, the SHS, also referred to as the Siwaliks, is the southernmost unit of the Himalaya. It is thrust over the Indian craton along the presently active, north dipping Main Frontal thrust.1.3  The Himalayan Metamorphic CoreAs noted above, much of the former Indian passive margin sedimentary succession has been metamorphosed at greenschist-grade or higher. Those rocks, which were pervasively metamorphosed during the evolution of the Cenozoic collision, comprise the Himalayan Metamorphic Core (HMC). Adhering to the tectonostratigraphy discussed above, GHS and HMC are synonymous; however, to avoid confusion with the different definitions that have been used to define the GHS this thesis will use the more neutral and less implication-laden HMC rather than GHS henceforth. Metamorphism in the HMC was initially thought to record two discrete events, the Eohimalayan (ca. 35 Ma) and the Neohimalayan (ca. 22 Ma; Vannay and Hodges, 1996; Hodges, 2000). More recent work, however, has documented a continuous protracted Late Eocene to middle Miocene metamorphic history characterized by early high-pressure, low-temperature metamorphism related to crustal thickening and later low-pressure, high-temperature conditions related to coeval, opposite sense shear movement and extrusion between the MCT and STDS (e.g. Cottle et al., 2009; Grujic, 2002).Three commonly proposed hypotheses for the evolution of the HMC are channel flow, tectonic wedging and critical wedge taper. The channel flow hypothesis suggests the HMC was extruded from beneath the Tibetan plateau during the Miocene byway of ductile midcrustal flow between the STDS and MCT (Figure 1.2A; e.g. Grujic et al., 1996; Beaumont et al., 2001; Beaumont et. al., 2004; Jamieson et al., 2004). In this model, southward midcrustal flow of melt-weakened rock occurs in response to a lateral pressure gradient created between the over thickened crust of the Tibetan plateau and the normal thickness crust of the Indian craton. The tectonic wedging hypothesis is similar to channel flow in that it suggests that the HMC was inserted between the TSS and LHS (Figure 1.2B; Webb et al., 2007; Webb et al., 2011). In this hypothesis, the indenting wedge results in the same kinematics as the channel flow hypothesis but, in contrast, does not occur in response to a lateral pressure gradient, nor does it require partial melting. In the 3Critical  wedge taperCMCTSTDSLHSTSS HMCSNTectonic WedgingBSTDSMCTLHSTSSHMCAMCTSTDSLHSTSSHMCFigure 1.2: Tectonic models for the Himalayan orogen. (A) Channel flow  after Beaumont et al. (2001). (B) Tectonic wedging after Webb et al. (2007, 2011). Critical wedge taper after Kohn et al. (2008). Figure modified from Kohn (2014).Figure 1.2   Tectonic models for the Himalaya4tectonic wedging hypothesis, rather, the HMC is interpreted as being driven by differential thrusting at the backside of the orogenic wedge. Not all researchers, however, agree that either channel flow or tectonic wedging are recorded in the HMC. Kohn (2008), for example, argues that the metamorphic pressure-temperature data extracted from the HMC in central Nepal, part of the purported channel/tectonic wedge, do not support midcrustal flow/insertion, but are the result of critical taper wedge processes (Figure 1.2C). In critical taper wedge models, the Himalaya can be approximated as a deforming wedge-shaped region bound by a basal decollement (Platt, 1986; Dahlen, 1990). The shape of the wedge, the angle between the basal decollement and the topographic profile, is controlled by the strength of the material that comprises it and the friction along the basal fault. Through lateral growth, by foreland propagation of thrust faults, and vertical growth, by internal deformation and underplating, the wedge maintains a critical, stable angle between the basal and upper surfaces during continuous convergence and the addition of new material. For example, underplating at the base of the wedge, which causes the taper angle to increase and become unstable, is counterbalanced by foreland propagating thrust faults and erosion, which together decreases the angle and brings high-pressure rocks to the surface (Platt, 1986; Dahlen, 1990).1.4  Statement of ProblemLateral extrusion and critical taper models treat the HMC as a thick, homogenous slab that has evolved through a single end-member process. Until recently, most kinematic models for burial and exhumation have focused on the two fault systems that bound the HMC. Evidence of crustal flow, tectonic wedging and critical wedge taper processes from across the Himalaya, however, is incompatible with models that involve a single processes as the sole means of convergence accommodation. This has led some researchers to suggest that the HMC has evolved through a combination of lateral extrusion and critical wedge taper process (Figure 1.3; Beaumont and Jamieson, 2010; Larson et al, 2010; Chambers et al. 2011; Larson et al., 2011; Corrie et al., 2012; Yakymchuk and Godin, 2012; Larson et al. 2013 Larson and Cottle, 2014). An increasing number of chronologic and thermobarometric data from across the Himalaya, furthermore, indicate that a significant amount of horizontal shortening and vertical thickening was accommodated along structures within the HMC, rather than limited to the bounding structures (e.g. Montomoli et al., 2013; Larson and Cottle, 2014). As these structures were active at midcrustal depths their surface expression is cryptic; most structures are identified only through pressure-temperature-time-deformation (P-T-t-D) data and are most often discovered once fieldwork has been completed. Such P-T-t-D discontinuities have been reported from the length of the Himalaya (Figure 1.1A) yet remain poorly understood. This thesis currently represents the most detailed study of P-T-t discontinuities in the Himalaya.5MAINCENTRALTHRUSTTHININDIAT IBETAN  P LATEAUINDIAN  C RATONASIATHINTHINANSMCTSTDSTSST IBETAN  P LATEAUINDIAN  C RATONTHICKBMCTSTDST IBETAN  P LATEAUINDIAN  C RATONTHICKCMCTSTDSTSSFigure 1.3: Model for the tectonic evolution of HMC through time (A-C) that invloves both channel flow and critical taper prossses (modified from Larson et al. 2010, 2013).Figure 1.3   Hybrid tectonic model for the HMC involving ductile extrusion and critical taper61.5  Objective of this StudyThis study aims to identify and elucidate P-T-t-D discontinuities within the HMC and to develop a new kinematic model for the evolution of the HMC through time. Specifically, this thesis asks the following questions:1. What tectonic model best fits with P-T-t-D data recorded by rocks in the field area. 2. Is there a P-T-t-D discontinuity within the HMC in eastern Nepal as mapped by Goscombe et al. (2006)3.  If there is a discontinuity, what does it represent? 4. Do other previously unidentified discontinuities exist?5.  What is the importance of discontinuities to the evolution of the HMC in eastern Nepal?6. If a discontinuity exists, what is its relationship to other previously reported discontinuities from across the orogen?7. What is the importance of discontinuities in the overall evolution of the Himalaya-Tibet orogen?To answer these questions, the following were completed:1. Three weeks of geological mapping and rock specimen collection between Basantapur and Yang-ma in the Kanchenjunga region of northeastern Nepal (Chapter 2).2. Detailed petrographic observation of thin sections made from specimens collected across the HMC (Chapter 2).3. Metamorphic phase equilibria modelling of 3 specimens to generate P-T paths (Chapter 3).4. In situ monazite geochronology and trace element analysis of 8 specimens (Chapter 4).5. Integration of phase equilibria modelling, geochronology and trace element analysis to constrain P-T-t paths and develop a new kinematic model for the HMC (Chapter 5).7Chapter 2.  Geology of the Kanchenjunga Region: Basantapur to Yangma2.1  Geologic SettingThe Kanchenjunga region of northeastern Nepal is underlain by rocks of the HMC and LHS (Figure 1.1, 2.1; Shrestha et al., 1984; Schelling, 1992; Goscombe and Hand 2000; Goscombe et al., 2006). The LHS is exposed in the Tamor Window and comprises Chl + Bt + Ms phyllite and quartzite (Shrestha et al., 1984; Schelling 1992) which have been intruded by Paleoproterozoic granite (now orthogneiss; Upreti et al., 2003; Sakai et al., 2013). The overlying HMC is a dominantly metapelitic assemblage of paragneiss and quartzite with subordinate calc-silicate, metabasite and orthogneiss. Structurally above the Tamor Window, rocks of the HMC form an inverted metamorphic sequence from Ms + Bt + Grt grade at the base to Kfs + Sil grade in the upper portion within the field area. Inverted metamorphic isograds are closely spaced near the base of the HMC and become more widely spaced up structural section (Figure 2.1). The uppermost unit of the HMC reached in this study is marked by the appearance of Ms ± Chl, possibly indicating a decrease in metamorphic grade. The HMC is locally intruded by Tur + Ms + Bt bearing leucogranite dykes and sills. Near the top of the HMC (not reached in this study) leucogranite intrusions are pervasive (Schelling et al., 1992; Goscombe et al 2006). 2.2  Divisions of the HMCIn the studied area, the HMC consists of a thick, generally monotonous package of predominantly gneiss and quartzite. The lack of distinguishing features can lead to confusion regarding the location of contacts. To avoid such confusion, the HMC examined in this study has been divided into 5 geologic units based on new metamorphic and geochronologic data from this thesis (discussed in chapters 4 and 5) in addition to the dominantly lithology (Figure 2.1, 2.2). The structurally lowest unit comprises Grt + Chl + Ms + Bt ± Ky ± St phyllites and schists as well as the mylonitic orthogneiss discussed above. This unit includes what has previously been mapped as the uppermost Seti Formation, the Ulleri and Kushma Formations (Shresta et al., 1984), and the lowermost Junbesi Paragneiss (Schelling, 1992). The base of the structurally overlying units to the southwest and north is marked by the first appearance of migmatite, which contrasts sharply with the underlying rocks that contain low (0-10%) melt volume (Figure 2.1). To the southwest, these rocks comprise locally migmatitic Grt + Bt + Ms ± Ky schist, gneiss and quartzite previously mapped as the Junbesi Paragneiss (Schelling et al., 1992), while to the north they consist of locally migmatitic Kfs + Sil + Grt + Bt + Ms ± Ky gneiss and quartzite previously mapped as the uppermost Junbesi Paragneiss and lowermost Kanchenjunga Migmatites (Schelling, 1992). Metamorphic grade continues to increase to the north through the overlying, dominantly migmatitic unit previously mapped as the Kanchenjunga Paragneiss (Schelling, 1992).This unit has the same assemblage as both the underlying and overlying units but lacks muscovite (Kfs + Sil + Grt + Bt). The base of the structurally highest unit observed in the field area, previously mapped as part of the Kanchenjunga Migmatites (Schelling, 1992) and Yangma Paragneiss (Goscombe et al., 2006), is marked by the return of muscovite (Kfs + Sil + Grt + Bt +Ms). 8geological contact (approximate, inferred)tectonic foliation and mineral lineationtrail, roadvillagestream, rivertopographic contour(in meters)4000petrochronology specimenP-T and petrochronology specimenlocation of cross section (Figure 2.2)N10 kminvestigation locality009thrust faultGeology of the Kanchenjunga Region: Basantapur to YangmaAChl + Ms + Bt phyllite/schist and quartziteGrt + Chl + Ms + Bt ± Ky ± St phyllite/schist and quarzite and calc-silicateMylonitic orthogneissKy + Grt + Bt + Ms gneiss/schist (locally migmatitic) and quartzite Kfs + Sil + Grt + Bt + Ms ± Ky  gneiss (locally migmatitic) and quartzite Kfs + Sil + Grt + Bt ± Ky migmatitic paragneiss, quartzite, minor calc silicateKfs + Sil + Grt + Bt ± Ms ± Chl migmatitic paragneiss, quartzite and metapsammiteLesser HimalayaHimalayan Metamorphic Core80012004000 4400 4800 5200520048005600160016002000200024002400ChaukiDeuraliBasantapurGufa PokhariTaplejungDobhanMitlungChiruwaSekathumRamsyangpatiNupHellokOlangchungolaYangmaTamor Window21091822461812102928290422265747494339555272392950444431 352726685973 564039152120017018019020021022023024025026027028029030032033035036038047046045043042001002003004005006 008010011012013 014015016048049053052051050054056057059060061062063066065041040039KA007KA031BKA034KA037KA044KA055KA058BKA064A27˚ 10' 27˚ 10'87˚ 30'87˚ 30'87˚ 40'87˚ 50'87˚ 50'87˚ 40'27˚ 20'27˚ 30'27˚ 30'27˚ 40'27˚ 50' 27˚ 50'27˚ 40'27˚ 20'ABCFigure 2.1 Geologic map of study areaFigure 2.1. Geologic map of the studied area. The location of this map is shown in Figure 1.1B.9Figure 2.2 Geologic cross section of study areaA CB24602460kmKA007KA031BKA034KA037KA044 KA055 KA05BKA064MCTMCTHHTFigure 2.2. Vertical geologic cross section of the Kanchenjunga Region between Basantapur and Yangma as shown on Figure 2.1. See Figure 2.1 for lithologic legend. The location of specimens used for analyses is shown. Approximate distribution of indicator minerals is shown.  Dotted lines indicate tectonic foliation whereas dashed lines indicate interpretted eroded contacts. Horizontal and vertical scales are the same.102.3  Previously Mapped Structures within the HMC2.3.1  MCTThere is a broad zone of deformation associated with the MCT and as such interpreting where it should be mapped is difficult and varies with the preference of the researcher (see Searle et al., 2008 for a summary of problems associated with mapping the MCT). For this thesis, the MCT is mapped at the approximate location of the first appearance of garnet. This is done for two reasons, both consistent with the definition of the structure by Searle et al. (2008). First, the garnet-in isograd is located near the base of closely spaced, inverted, metamorphic isograds that overlie relatively unmetamorphosed rock. Second, the garnet-in isograd is approximately located between rocks above, that record Himalayan-related metamorphism, and rocks below, that were relatively unaffected; a mylonitic orthogneiss unit, just up structural section from the garnet-in isograd, records Cenozoic cooling ages, whereas Paleoproterozoic granites, near the center of the Tamor Window, record Paleoproterozoic cooling ages (Figure 2.1; Sakai et al., 2013). Previous studies have variably mapped the MCT at the base (Goscombe et al., 2006), top (Schelling, 1992), and just above (Imayama et al., 2010) the mylonitic orthogneiss.2.3.2  High Himal ThrustIn addition to the MCT, as mapped in this thesis, a major ductile shear zone within the HMC has been mapped throughout eastern Nepal (Brunel and Kienast, 1983; Lombardo, 1986; Goscombe and Hand, 2000; Goscombe et al., 2006). To the west of the area examined in this thesis, in the Makalu and Everest regions, Brunel and Kienast (1986) and Lombardo et al. (1993) mapped this structure as the MCT. In the Kanchenjunga region, Goscombe and Hand (2000) also mapped this structure as the MCT, however, more detailed follow-up work by Goscombe et al. (2006) mapped the same structure as the High Himal Thrust (HHT). They interpreted moderate-pressure, high-temperature metamorphism from ca. 24 to 20 Ma in the hanging wall as being consistent with ductile extrusion of the HMC between the STDS and HHT. The footwall, as far south as the MBT, is interpreted to record, relatively high-pressure, moderate-temperature, metamorphism, which they attribute to brittle extrusion, between ca. 18 and 6 Ma (Goscombe et al., 2006). The HHT is interpreted as being equivalent to the MCT in channel flow models (e.g. Beaumont et al., 2004: Jamieson et al., 2004) as well as being laterally equivalent to the MCT in central Nepal. Moreover, it is also equivalent to tectonometamorphic discontinuities identified in central (Larson et al. 2010; 2011) and eastern Nepal (Larson et al. 2013; Larson and Cottle, 2014) that are interpreted to mark the transition between rocks that record deep hinterland deformational processes and those that record shallower foreland processes.11Chapter 3.  Pressure and Temperature of Metamorphism3.1  Equilibrium Thermodynamics in Metamorphic PetrologyMetamorphic reactions proceed in the direction that reduces the total energy of the system. Once the lowest energy state is reached, the system is in thermodynamic equilibrium. In petrologic systems, the most useful type of energy to consider is Gibbs energy (G) as it is a function of the pressure and temperature a rock is at and its composition. The G of phases (minerals, liquids, and fluids) can be calculated using a thermodynamic dataset that contains molar values for Gibbs energy of formation, enthalpy of formation, entropy, volume and heat capacity for each phase of interest. Several software packages are available that can be used to calculate fields of stable phase assemblages (i.e assemblages with the lowest G) with varying pressures and temperatures using an internally consistent thermodynamic dataset and activity-composition models that account for phase end-member mixing. The resulting phase diagrams are referred to in the literature, more or less interchangeably, as pseudosections, equilibrium phase diagrams, multivariable phase diagrams and isochemical phase diagrams. A thorough review of phase equilibria modelling is beyond the scope of this thesis, but can be found in Spear (1995) and many other sources including the excellent “Teaching Phase Equilibria” section of the “Integrating Education and Research” website (serc.carleton.edu/research_education/equilibria/index.html)An equilibrium phase assemblage in a phase equilibria model is defined by P, T and the proportion and composition of phases (Powell and Holland, 2010). The total number of variables required to define the assemblage depends on the number of components in the system. Pseudosections are two dimensional representations of these stable assemblages plotted against two variables, the most common being P and T (Powell and White, 2005), while other variables are held constant. The fields that comprise a pseudosection are defined by variable conditions, for example P-T, where an assemblage is stable. A field is bound by lines which mark the gain or loss of a phase while the overall geometry of fields and lines is referred to as the topology. Fields can be contoured for mineral composition (isopleths) and mineral abundance (isomodes).Pseudosections are typically used to help interpret observed metamorphic textures qualitatively in terms of the P-T evolution (going from one field to another, crossing isomodes) of a specimen and also allow for quantitative thermobarometry defined by intersecting isopleths. If a sample is in equilibrium (texturally and chemically), all of the isomodes and isopleths should intersect at a point corresponding to the pressure and temperature conditions at which the assemblage last equilibrated. Up to approximately middle amphibolite grade metamorphism, this point is typically the maximum temperature reached as intracrystalline diffusion rates (and thus ranges) are at their maximum and intragranular diffusion is enhanced by available dehydration fluids (Spear, 1995). In higher metamorphic grade rocks, however, re-equilibration may continue during cooling if temperatures are sufficient to allow significant diffusion (Spear, 1991; Spear and Florence, 1992; Florence and Spear, 1991). In anatectic rocks, the last equilibrium 12state typically preserved is from the final stages of retrograde melt crystallization; this corresponds to the last point at which there was an intergranular fluid or a liquid available to enhance diffusion rates and ranges (White and Powell 2002; Indares et al., 2008). Moreover, during crystallization the melt will release dissolved fluids which will help re-equilibrate the rocks to the current conditions (e.g. Kohn et al., 1997; Kriegsman, 2001; Sawyer, 2008).In addition to the the final equilibrium state, several previous states (assemblages) may be preserved in a rock. Porphyroblasts (grains that have grown larger than others) may preserve previous assemblages by retaining growth and/or retrograde zoning as well as shielding inclusions from reacting with the smaller matrix grains. Within the matrix, where intragranular and intracrystalline diffusion occurs over a smaller distance, previous textures are more easily overprinted. The P-T conditions of preserved, earlier, equilibrium states may be retrieved using spatially restricted isopleths if compositions are not reset or diffusionally homogenized. Garnet isopleths are commonly used for constraining previous states as garnet: (1) occurs across a range of different rock types, (2) is stable over a wide range of pressures and temperatures and (3) is sensitive to changes in both P and T. In addition to isopleth constraints, metamorphic textures (inclusions, incomplete reactions) preserved in the rock can further constrain the sequence of past equilibria. By linking the P-T points of different equilibrium states a P-T path can be approximated.A number of factors influence whether or not isomodes and isopleths intersect within the modelled field corresponding to the observed assemblage. Foremost, the components analysed must be in or near textural and chemical equilibrium. That being said, in order to estimate previous equilibrium states there must be some degree of disequilibria. Detailed, careful petrography is necessary to correctly identify the equilibrium assemblage, or partial equilibria assemblage of interest. It is also necessary that the bulk composition used to generate the pseudosection is representative of the thin section and hence petrographic observations. The specimen used to estimate the bulk composition must be smaller than, and taken within, the equilibrium volume of the system. For anatectites, however, melt loss can modify the composition of the rock resulting in a composition that is not representative of the protolith. Although phase equilibria modelling of rocks that have undergone melt loss can help elucidate the P-T path prior to melt loss, there is an increase in uncertainty (White et al., 2002; Indares et al., 2008). 3.1.1  Software Packages used for Phase Equilibria ModellingThree software packages are commonly used to calculate pseudosections: THERMOCALC (Holland and Powell, 1998), Perple_X (Connolly, 1990) and Theriak/Domino (de Capitani and Brown, 1987; de Capitani and Petrakakis, 2010). All three are available as free downloads from their related websites and use the same activity-composition models and thermodynamic database (Powell and Holland, 1994). They use different approaches and algorithms to calculate the phase diagrams but the result should be essentially the same. THERMOCALC computes pseudosections by calculating each individual line of each field where, by definition, the change in G between adjacent assemblages is zero. Perple_X and Theriak/13Domino compute phase diagrams by scanning the diagram along a grid and, through different algorithms, determine the mineral assemblage with the lowest total G for each point of the grid. When the scanning is complete the lines between fields are interpolated. In other words, THERMOCALC calculates lines where the change in G of the reaction is zero, whereas Perple_X and Theriak/Domino calculate fields where the change is minimized. As both Perple_X and Theriak/Domino are automated it allows more time for interpreting the result rather than simply constructing the diagram. THERMOCALC has the advantage in that it forces users to have an intimate understanding of each field, point, and line. This project began using THERMOCALC to produce phase equilibria models, but it was found that Theriak/Domino produced the same result and was substantially more efficient than THERMOCALC. Only Theriak/Domino is discussed for the remainder of the thesis.3.2  Methodology 3.2.1  Sampling TechniqueA total of 64 specimens were collected from 66 investigation localities along a ~100 km transect between Basantapur and Yangma in the Kanchenjunga region of northeast Nepal (Figure 2.1). Specimens, oriented where possible, were selected based on suitability for phase equilibria modelling, geochronology, thermochronology and microstructural analyses. A total of 50 polished thin sections were made for investigation with a petrographic microscope and, where necessary, a scanning electron microscope to identify mineral assemblages. Eight quartzo-feldspathic paragneisses were selected for phase equilibria modelling based on mineral assemblage, texture and structural position. Each thin section was mapped for select major and trace elements by a Cameca SX100 electron microprobe (EMP) at the Saskatchewan Research Council to create chemical distribution maps that could be used to determine the modal abundance of phases (Table 3.1). Of these, one kyanite grade (KA007) and two Sil-Kfs grade (KA044 and KA064A) specimens contained the partial-equilibria assemblages required to constrain P-T paths. 3.2.2  Mineral ChemistrySpot analysis of minerals with solid solutions (minerals with a composition that varies between end-members) were performed at the Earth and Planetary Materials Analysis Laboratory at the University of Western Ontario using a JEOL 8530F Hyperprobe electron microprobe (EMP) using a 15 keV accelerating voltage and a 20 nA beam current. Twenty second counting times were used for both peak and background positions. Matrix corrections were performed using the ZAF correction procedures included in the JEOL software. As garnet was the primary mineral used for isopleth calculations, detailed profiles were measured across 2-3 grains to determine chemical zoning. In addition, analyses targeted solid solution minerals in different textural settings comprising inclusions in garnet, rimming garnet and distal to garnet. Oxide weight percent data from the EMP were converted to atoms per formula unit (a.p.f.u.) using spreadsheets provided for download by Andy Tindle (A. Tindle, personal communication, 2014). 14KA007 KA044 KA064AQz 31% 30% 35%Pl 50% 17% 16.5%Kfs 0 21% 14%Grt 2.5% 12% 2.5%Bt 14.0% 7% 25%Ky+Sil 2% 12% 7%Ru+Ilm 0.3% 1% 0.1%Total 100% 100% 100%Table 3.1. Modal mineral abundancesTable 3.1    Modal mineral abundances153.2.3  Model SystemPseudosections were modelled in the system NCKFMASHTO (Na2O-CaO-K2O-FeO-MgO- Al2O3-SiOs-H2O-TiO2-Fe2O3) using Theriak/Domino version 03.01.2012 (de Capitani and Brown, 1987, de Capitani and Petrakakis, 2010) with THERMOCALC dataset 55 (Holland and Powell, 1998; updated 2004). Manganese is the only major element not used as activity composition models for it are not reliable at the pressures and temperatures experienced by these specimens (White et al., 2007; Powell and Holland, 2010). Moreover, manganese is believed to only affect the stability of garnet at lower grades (Spear and Cheney, 1989; White et al., 2007) and the maximum spessartine [(Mn/(Fe+Mg+Ca+Mn)] content of garnet in each specimen is low (1.9-11.0%) such that any potential effect is further reduced. The following activity-composition models were used: cordierite and staurolite (Holland and Powell, 1998), biotite, garnet and melt (White et al., 2007), plagioclase and K-feldspar (Holland and Powell, 2003), ilmenite (White et al., 2000), muscovite (Coggon and Holland, 2002), magnetite and spinel (White et al., 2002), orthopyroxene (White et al. 2002). Water, quartz, kyanite, sillimanite and rutile were entered as pure phases. 3.2.4  Bulk CompositionBulk rock chemistry for all oxides, except for H2O and Fe2O3, was determined by X-ray fluorescence spectrometry at the Saskatchewan Research Council for KA064A and at ACTLabs (Ancaster) for specimens KA007 and KA044. In order to best represent the composition of the thin section, thin section cut offs were used for analysis. Manganese and phosphorous were subtracted from the bulk as they are not included in the model system and all values were normalized to 100%. As phosphorous occurs mainly in apatite [(Ca5(PO4)3(F,Cl,OH)]; a proportionate amount of calcium was also removed. Water content was calculated based on the modal abundance and composition of biotite and muscovite (the only hydrous phases present) as determined by EMP spot analyses (White et al., 2007). To determine the proportion of ferric iron, a T- XFe3+ [XFe3+=(Fe3+/(Fe2++Fe3+)] pseudosection was made for each specimen (Appendix B.1). In each, only the Fe-Ti oxide equilibria are significantly affected by changing XFe3+. XFe3+ was set at 1% for all pseudosections because this resulted in the stability of the oxide assemblage (rutile and ilmenite) observed in thin section. As this value is poorly constrained, the position of rutile and ilmenite equilibria are not used for interpreting P-T conditions. 3.3  PetrographyKA007Specimen KA007 is a Ky + Grt + Bt + Qz + Pl gneissic schist collected near the southern end of the study area ~3,700 m structurally above the MCT (Figures 2.1, 2.2, 3.1). The specimen comprises garnet and kyanite porphyroblasts within a finer grained matrix of quartz, plagioclase and biotite (Figure 3.2A). Accessory phases include rutile, monazite, zircon, apatite and xenotime. At the outcrop scale the rock is 16Figure 3.1 Photographs of specimens used for P-T and petrochronology2 cm2 cm2 cm2 cm2 cm2 cm2 cm2 cmKA007P-TP-TP-TKA031BKA034 KA037KA044KA058B KA064AKA055Figure 3.1. Photographs of specimens used for petrochronology and phase equilibria modelling.17Figure 3.2 Photomicrographs of KA007500 um500 um200 umAC DB200 umQzBtMsMsMsBtQzQzKyGrtPlPlQzPlKyPlBtBtPlPlQzPlFigure 3.2. Textures of specimen KA007. (A) Kyanite porphyroblast containing quartz inclusions and a garnet grain being replaced by biotite. (B) skeletal kyanite intergrown with quartz. (B) and (C) both show remnant muscovite that has otherwise been replaced by biotite.18homogeneous aside from minor, thin, concordant leucogranite segregations which were not sampled. A foliation is defined by weakly aligned biotite grains.Garnet occurs as anhedral porphyroblasts up to 1.7 mm in diameter. Inclusions of rutile and quartz in garnet range in abundance from rare to common (Figure 3.2A). Kyanite occurs as non-aligned porphyroblasts up to 1.8 mm in length. Kyanite grains, which are commonly strongly embayed and skeletal, contain inclusions of, and is typically surrounded by quartz (Figure 3.2 B). The matrix is dominated by plagioclase and quartz while biotite occurs as both weakly aligned fine grained flakes within the matrix and fine grained flakes replacing garnet consistent with melt crystallization through a reaction such as L + Grt + Kfs = Bt + Als + Pl + Qz (Le Breton and Thompson, 1988; Vielzeuf and Holloway, 1988; Figure 3.2A). A few grains of muscovite, present as inclusions within biotite and less commonly plagioclase (Figure 3.2 A, B), are interpreted as relicts of a previous (prograde) assemblage rather than the final equilibrium state (Figure 3.2C, D).KA044Specimen KA044 is a Sil + Grt + Pl + Kfs + Qz + Bt gneiss collected ~3 km north of the village of Sekathum and ~7,050 m structurally above the MCT (Figures 2.1, 2.2, 3.1). The specimen is homogenous at both the outcrop and thin section scale. A well developed foliation is defined by thin bands of alternating dark (melanosome) and light coloured (leucosome) minerals (Figure 3.1). The melanosome comprises biotite, ilmenite and garnet while the leucosome comprises Qz, Kfs, Pl and Sil. Accessory phases include ilmenite, rutile, zircon, monazite, graphite and apatite. A well developed lineation is defined by the alignment of sillimanite, biotite, and quartz. Garnet is the only phase to occur as porphyroblasts, which are typically found within the finer grained matrix that makes up the leucosome and melanosome (Figure 3.3A, B). Garnet is subhedral to anhedral and ranges in diameter from less than 0.5 mm up to 4 mm with a typical size of ~3 mm. Garnet grains contain abundant inclusions of quartz, rutile, and less commonly biotite, ilmenite and kyanite, which define a foliation that is not continuous with the matrix (Figure 3.3B). Some garnet grains contain inclusion free rims along faces that are perpendicular to the foliation (Figure 3.3A, B).Biotite occurs as aligned fine grained flakes within the matrix, as fine grained flakes replacing garnet, as inclusions within sillimanite and intergrown with sillimanite (Figure 3.3C). Biotite is typically absent in garnet strain shadows. K-feldspar occurs as fine grains in the matrix and as coarser aggregates within garnet strain shadows (Figure 3.3 A, B). Indares and Dunning (2001) interpreted similar K-feldspar domains associated with garnet as former melt pods. K-feldspar also occurs with plagioclase as two feldspar aggregates interpreted to be the breakdown product of high temperature ternary feldspar (Figure 3.3D). The inclusion-free garnet rims adjacent to strain shadows, increased abundance of K-feldspar, and lack of biotite indicate that the strain shadows preserve a higher grade assemblage that has been overprinted elsewhere in the thin section. Moreover, this implies that much of the biotite in the matrix 19Figure 3.3 Photomicrographs of KA044KfsKfsPl Pl200 µmQzSilSilBtMzKfs1 mmPlPlGrKyKyBtKfs2mmQzQzKySilSil QzBtGrtGrtKfsA BC DFigure 3.3. Textures of specimen KA044. (A) The alignment of biotite, graphite and sillimanite define the foliation. K-feldspar is best preserved in garnet strain shadows (B) Kyanite occurs both in the matrix and as inclusions in garnet. Inclusion free garnet rims are preserved along some faces perpendicular to the foliation. (C) Sillimanite occurs as aggregates and as individual needles intergrown with biotite. The small dots on this particularly large monazite are laser pits. K-feldspar is characteristically perthitic. (D) Two feldspar aggregate interpetted as the breakdown product ternary feldspar. 20could be the result of retrograde breakdown of K-feldspar through a reaction such as L + Grt + Kfs = Bi + Als + Pl + Qz (Le Breton and Thompson, 1988; Vielzeuf and Holloway, 1988). Sillimanite occurs as aggregates of prismatic crystals that are associated with, and commonly replacing, biotite (Figure 3.3C) and as individual needles within quartz. Kyanite occurs as inclusions within garnet and as small anhedral grains within the matrix (Figure 3.3A, B). Kyanite is not observed to be directly breaking down to sillimanite which could be explained by two simultaneously occurring reactions such as 3 Ky + 3 Qz → 2 Ms and 2 Ms → 3 Sil + 3 Qz (Carmichael, 1969). Such a reaction series is consistent with the presence of sillimanite needles in quartz.KA064ASpecimen KA064A is a Ky + Grt + Sil + Kfs + Pl + Bt + Qz gneiss collected above the village of Yangma, ~9,600 m structurally above the previous specimen (Figures 2.1, 2.2). Monazite, zircon, rutile and ilmenite occur as accessory phases. At the outcrop scale, in addition to the sampled lithology, there are intercalated quartzites and large (1 m thick by 2 m long), concordant, coarse grained, Tur + Ms + Fsp leucogranite lenses. Within the gneiss, the alignment of biotite and sillimanite, as well as thin, alternating bands of leucosome and melanosome (Figure 3.1) define a foliation that generally dips moderately to the northeast. Melanosome consists of mainly of biotite while the leucosome consists mainly of quartz, plagioclase and K-feldspar. Garnet porphyroblasts occur within a matrix of quartz, biotite, plagioclase, K-feldspar and sillimanite (Figure 3.4A). Garnet grains are sub- to anhedral and range in diameter from less than 0.5 mm to over 3 mm with a typical size around 2 mm. They contain inclusions that are dominantly quartz and less commonly biotite and rutile. The density of inclusions in different garnet grains is variable but rims are typically inclusion free. Some grains preserve an inclusion free core, poikiloblastic mantle and inclusion free rim.Biotite occurs as well aligned, large flakes and aggregates within the matrix (Figures 3.4A, B, C), replaces garnet along margins parallel to the foliation (strain caps; Figure 3.4A), is found as inclusions in garnet (Figure 3.4A), and is symplectically intergrown with quartz (Figure 3.4 A, B, C). Sillimanite occurs as fibrolytic pods and prismatic crystals that are typically interlayered with and replacing biotite and as needles within quartz (Figures 3.4A, B). Kyanite occurs as skeletal grains and is not seen directly breaking down to sillimanite which, like in specimen KA044, may indicate a set of intermediate reactions (Figure 3.4C). The occurrence of these intermediate reactions are again consistent with the presence of sillimanite needles within quartz (Figure 3.4B). Plagioclase occurs throughout the matrix and as thin films that appear to be replacing garnet (Figure 3.4A). K-feldspar is typically perthitic and occurs throughout the matrix associated with quartz and plagioclase. K-felspar is also located in garnet strain shadows but it is not found in strain caps.Textural evidence indicates that a significant amount of the biotite present crystallized during retrograde 21Figure 3.4 Photomicrographs of KA064A50 um250 um500 um250 um250 umA BC DEQz lmKyBtSilBtQzKfsSilBtQzKfsBtQzQzSilQz + SilBtBtPlSilKfsQzBtBtPlKfsSil Pl GrtQzQzBtFigure 3.4. Textures of specimen KA064A. (A) Garnet porphyroblast is replaced along the rims by biotite and plagioclase. (B) Sillimanite occurs fibrolitic mats and as needles within biotite and quartz. (C) Kyanite occurs as ragged blades within the matrix. (D) Thin films of quartz surrounding some biotite flakes are interpreted as former melt. (E) Intergrowths of quartz and biotite are interpreted to have replaced K-feldspar.22reactions. The preservation of K-feldspar in strain shadows and the replacement of garnet by biotite and plagioclase is indicative of retrograde melt crystallization through a reaction such as L + Grt + Kfs = Qz + Ky/Sil + Bt + Pl (Vielzeuf and Holloway, 1988). The intricate association of biotite and sillimanite is consistent with melt crystallization in the sillimanite field (Figure 3.4B). Moreover, Waters (2001) interpreted symplectic intergrowths of biotite and quartz to be the result of sub-solidus, retrograde replacement of K-feldspar by biotite and quartz (Figure 3.4E; Waters, 2001). There is evidence, however, that prograde biotite remains in this specimen. Thin films of quartz between K-feldspar and corroded biotite are interpreted as residual melt (Sawyer, 2008) that formed through the incomplete melting of biotite through a simplified reaction such as Bt + Qz + Ky/Sil = Kfs + L + Grt (Figure 3.4D).3.4  Mineral Chemistry Representative spot analyses for each specimen are shown in Table 3.2. Complete mineral analyses for each specimen as well as the location of each spot are shown in appendix B-3. Note that in this section spessartine = Mn/(Fe+Mg+Ca+Mn), grossular = Ca/(Fe+Mg+Ca+Mn), Fe# = Fe/(Fe+Mg) and Mg# = Mg(/Fe+Mg). KA007Profiles from two garnet grains were measured in specimen KA007. The larger garnet grain (Figure 3.5) preserves chemical zoning, while in the smaller grain spessartine (7%), grossular (3.5%), and Fe# (84%) are fairly homogenous. In the larger grain: Fe# increases gradually from the core (83%), to just before the rim (85%), and sharply at the outermost rim (87%); spessartine increases from the core (6%) to the rim (9.5%); and grossular decreases from the core (4.5%) to the rim (2.5%). These patterns are typical of diffusional homogenization at high temperature which has altered prograde growth zoning and resulted in profiles reflecting retrograde diffusion (Spear, 1991; Caddick et al. 2010). Additionally, increasing spessartine towards the rim is characteristic of garnet resorption, as Mn is not easily exchanged with other phases; as garnet volume decreases Mn typically becomes more concentrated (Woodsworth, 1977).The Ti concentration of biotite increases with decreasing Mg# from Mg#=0.41 and Ti=0.35 a.p.f.u to Mg#=0.34 and Ti=0.48 a.p.f.u. (Figure 3.5C). Matrix biotite typically has higher Ti and a lower Mg# than biotite that is replacing garnet. As Ti concentration and temperature typically exhibit a positive relationship (Henry and Guidotti, 2002; Tajcmanova et al., 2009), this indicates that matrix biotite grew at higher temperatures than the biotite surrounding garnet, consistent with garnet replacement during melt crystallization. The composition of plagioclase is homogenous throughout (Ab76-80). KA044 Profiles from three garnet grains were measured in specimen KA044. The largest garnet (Figure 3.6A) best preserves Fe-Mg zoning, with Fe# decreasing slightly from the core (78%) through the mantle (77%) 23Table 3.2    Representative mineral chemistriesTable 3.2. Representative mineral analysesGrt Grt Bt Ms Pl Grt Grt Grt Bt Bt Pl Kfscore rim matrix matrix matrix core mantle rim matrix garnet8 14 1 2 19 35 39 42 7 4 15 1SiO2 37.90 37.59 35.51 48.76 67.21 39.10 39.43 39.26 36.67 36.39 59.68 65.27TiO2 0.03 0.00 4.27 1.75 0.01 0.05 0.04 0.05 4.67 0.86 0.01 0.03Al2O3 21.93 21.58 19.90 34.46 23.68 22.42 22.63 22.07 18.53 21.78 26.74 19.70FeO 32.88 33.35 20.51 1.30 0.14 30.68 29.48 34.09 18.88 15.71 0.00 0.04MnO 2.61 4.25 - - 0.00 0.56 0.44 0.85 0.04 0.01 0.00 0.00MgO 3.80 2.92 6.58 0.99 - 4.89 5.27 3.70 10.04 13.60 0.01 0.00CaO 1.60 0.94 0.05 0.08 3.14 3.94 3.61 1.82 0.02 0.07 7.34 0.00Na2O - - 0.11 0.35 6.77 0.00 0.00 0.02 0.09 0.48 6.87 1.41K2O - - 8.50 8.35 0.32 - - - 9.88 8.49 0.25 14.40Total 100.74 100.63 95.43 96.04 101.27 101.64 100.89 101.86 98.81 97.38 100.91 100.84CationsSi 2.99 2.99 5.33 6.33 2.88 3.00 3.01 3.03 2.68 2.63 2.63 2.96Ti 0.00 0.00 0.48 0.17 0.00 0.00 0.00 0.00 0.26 0.05 0.00 0.00Al 2.04 2.03 3.52 5.28 1.20 2.04 2.06 2.02 1.60 1.86 1.39 1.05Fe 2+ 2.21 2.26 2.58 0.14 0.01 2.03 1.98 2.28 1.15 0.95 0.00 0.00Mn 0.17 0.29 - - 0.00 0.04 0.03 0.06 0.00 0.00 - -Mg 0.45 0.35 1.47 0.19 - 0.56 0.60 0.43 1.09 1.47 - -Ca 0.14 0.08 0.01 0.01 0.14 0.32 0.30 0.15 0.00 0.01 0.3 0.1Na - - 0.03 0.09 0.56 - - - 0.01 0.07 0.59 0.83K - - 1.63 1.38 0.02 - - - 0.92 0.78 0.01 0.01Total 8.00 8.00 15.06 13.59 4.81 7.99 7.98 7.97 7.72 7.81 4.97 4.99Oxygen 12 12 22 22 8 12 12 12 11 11 8 8alm 74.54 75.98 - - - 68.77 68.18 78.30 - - - -gr 4.56 2.71 - - - 11.00 10.13 5.10 - - - -prp 15.03 11.65 - - - 18.99 20.66 14.61 - - - -sps 5.87 9.66 - - - 1.24 0.98 1.91 - - - -Mg# 0.17 0.13 0.36 0.58 - 0.22 0.23 0.16 0.49 0.61 - -An - - - - 0.20 - - - - - 0.37 0.00Ab - - - - 0.78 - - - - - 0.62 0.13Or - - - - 0.02 - - - - - 0.01 0.87KA007 KA044wt.%24Table 3.2 (continued)Grt Grt Bt Bt Pl Kfscore rim matrix grt matrix matrix28 35 3 2 10 4SiO2 38.61 38.22 35.44 35.66 62.95 65.80TiO2 0.00 0.01 3.60 0.66 0.01 0.01Al2O3 22.42 22.17 20.43 22.76 25.37 20.43FeO 33.84 33.75 22.17 23.06 0.01 0.02MnO 2.15 4.58 - - 0.00 0.00MgO 3.89 2.27 6.476 7.42 - -CaO 1.19 1.05 0.00 0.04 5.17 0.07Na2O - - 0.22 0.24 7.60 2.04K2O - - 8.68 9.21 0.35 12.30Total 102.11 102.05 97.02 99.05 101.47 100.68CationsSi 2.99 2.99 5.33 5.26 2.74 2.96Ti 0.00 0.00 0.41 0.07 0.00 0.00Al 2.06 2.06 3.62 3.96 1.30 1.08Fe 2+ 2.26 2.28 2.79 2.85 0.00 0.00Mn 0.14 0.30 - - 0.00 0.00Mg 0.45 0.27 1.45 1.63 - -Ca 0.10 0.09 0.00 0.01 0.24 0.00Na - - 0.06 0.07 0.6 0.2K - - 1.66 1.73 0.02 0.71Total 8.00 7.99 15.32 15.58 4.94 4.93Oxygen 12 12 22 22 8 8alm 76.62 77.66 - - - -gr 3.27 2.90 - - - -prp 15.23 9.01 - - - -sps 4.79 10.33 - - - -Mg# 0.17 0.10 0.34 0.36 - -An - - - - 0.27 0.00Ab - - - - 0.71 0.20Or - - - - 0.02 0.80wt.%KA064A25Figure 3.5 Mineral chemistry of KA007500 µm Ca500 µm Fe500 µm Mn8590051 2 3 4 5 6 710Fe#SpsGrsEnd Member %950 µm0.30.320.340.360.380.40.420.440.460.480.50.34 0.35 0.36 0.37 0.38 0.39 0.4 0.41Ti (a.p.f.u.)Mg #Bt replacing GrtMatrix BtHighLowA)B)C)Relative ConcentrationFigure 3.5 Mineral chemistry for specimen KA007.  (A) Compositional maps for garnet porphyroblast showing profile location. (B) Compositional profile across garnet. (C) Biotite spot analyses indicating textural setting.26Figure 3.6 Mineral chemistry of KA044Fe500 µm 500 µm Ca500 µm Mn7476788082840246810122 4 6 8 10 12 141 3 5 7 9 11 134 mmFe#SpsGrsEnd Member %00.050.10.150.20.250.30.45 0.5 0.55 0.6 0.65 0.7Ti (a.p.f.u.)Mg#Bt rimming GrtMatrix BtBt included in GrtA) B)C)HighLowRelative ConcentrationFigure 3.6. Mineral chemistry for specimen KA044. (A) Compositional maps for garnet porphyroblast showing profile location. (B) Compositional profile across garnet. (C) Biotite spot analyses indicating textural setting.27and increasing sharply at the rim (84%; Figure 3.6B). In the same garnet, grossular is homogenous in the core (11%) and decreases moderately through the mantle and sharply at the rim (5%). In the other two grains, grossular increases slightly from the core (5%) to the mantle (6-9%) before decreasing at the rim (5%). Spessartine from each profile appears fairly homogenous (1-2%) aside from a minor increase at the rim (Figure 3.6B). As with the previous specimen, the chemical composition has likely been modified by diffusion at high temperature. However, unlike the previous specimen, while the mantle and rim profiles are typical of retrograde diffusion, the profile of the core appears to preserve prograde growth zoning. Biotite grains included in garnet have relatively low Ti (0.0-0.25 a.p.f.u.) and high Mg# (0.51-0.67.; Figure 3.6). Biotite in contact with and replacing garnet has intermediate Ti (0.17-0.25 a.p.f.u.) and Mg# (46-56%) values. Matrix biotite has the highest Ti content (0.25-0.29 a.p.f.u.) and lowest Mg# (47-49%). Although the absolute compositions have likely been modified by retrograde diffusion, the Ti concentrations indicate that matrix biotite crystallized at higher temperatures than biotite which is replacing garnet, while biotite included in garnet grew at the lowest temperatures. The compositions of plagioclase ranges between Ab58 and Ab64 whereas K-feldspar ranges between Or77 and Or89.KA064AProfiles measured from four garnet grains in specimen KA064A show similar trends but different absolute concentrations. Profiles from each garnet are available in Appendix B-3, but only the largest grain, which is pervasively replaced by biotite along one face, is described here (Figure 3.7). In this grain, the Fe# increases slightly (84%) from the core through the mantle (85%), and sharply at the outermost rim (88-90%) while spessartine is homogenous in the core (5%), increases slightly through the mantle (6%) and sharply at the rim (8%). Grossular is homogenous through the core and mantle (2-4%) but appears to decrease slightly at the rim. As with the previous specimens, these profiles are indicative of homogenization at high temperature and destruction of original prograde growth zoning. The trends through the mantle and rim are the result of retrograde diffusion.Unlike the previous specimens, there is no clear relationship between Ti and Mg# in biotite (Figure 3.7C). Different textural settings do, however, show a relationship with Ti. Biotite located in the matrix typically has the highest Ti content (0.38-0.44 a.p.f.u) and Mg# values between 34-35%. Biotite included in and rimming garnet have a similar, relatively large range in Ti (0.01-0.4 a.p.f.u.) and Mg# (33-39%). The Ti content indicates that biotite in the matrix equilibrated at higher temperatures than biotite included in and rimming Grt. The composition of plagioclase in contact with garnet (Ab26-32) overlaps with but is generally less albitic than plagioclase in the matrix (Ab22-31). The composition of K-feldspar located in the matrix ranges from Or72 to Or84. 3.5  Phase Equilibria Modelling ResultsThe bulk compositions used to construct the pseudosections for each specimen are shown in Table 3.3. 28Figure 3.7 Mineral chemistry of KA064A500 µm Ca500 µm Fe500 µm Mn246810121 3 5 7 9 118385878991Fe#SpsGrs1.6 mmEnd Member %0.0000.0500.1000.1500.2000.2500.3000.3500.4000.4500.5000.32 0.33 0.34 0.35 0.36 0.37 0.38 0.39Ti (a.p.f.u.)Mg#Bt rimming GrtMatrix BtBt included in GrtA)B)C)HighLowRelative ConcentrationFigure 3.7 Mineral chemistry for specimen KA064A. (A) Compositional maps for garnet porphyroblast showing profile location. (B) Compositional profile across garnet. (C) Biotite spot analyses indicating textural setting.29KA007 KA044 KA064A KA007 KA044 KA064AMnO 0.15 0.10 0.13 - - - -Na2O 5.35 1.18 1.42 Na 9.43 2.23 2.56CaO 1.98 1.78 0.80 Ca 1.88 1.73 0.76K2O 1.78 2.39 4.50 K 2.07 2.97 5.34FeO - - 0.00 Fe2+ 3.65 8.08 5.61MgO 0.9 1.87 1.38 Mg 1.22 2.72 1.91Al2O3 17.2 21.49 17.20 Al 18.44 24.70 18.86SiO2 66 56.76 63.50 Si 60.02 55.35 59.08H2O - - - H 2.68 1.32 5.13TiO2 0.84 1.11 0.97 Ti 0.57 0.81 0.68Fe2O3 5.39 11.13 8.10 Fe3+0.04 0.08 0.06P2O5 0.08 0.19 0.05 - - - -Theriak/Domino Input (mol %)Tabel 3.3. Whole-rock compositionsRaw Data (wt %)Table 3.3    Bulk composition of specimens used   to for P-T calculations.30The calculated pseudosections all have a similar general topology, which reflects the similarities in the rock types (Figures 3.8-3.10). The kyanite-sillimanite transition splits each diagram into an upper half, where kyanite is the stable aluminosilicate, and a lower half, where sillimanite is stable. The solidus, which ranges between 730 and 830 oC amongst the specimens, has a steeply negative slope in muscovite absent fields and a steeply positive slope in muscovite bearing fields. At lower pressures the biotite-out lines parallel the solidi. Muscovite bearing fields typically occur at high pressure and low temperature. The rutile-in and ilmenite-out lines are shown in gray as they are dependent on the proportion of Fe3+ which, as discussed above, is not well constrained in the specimens. In each diagram the appearance of cordierite at low pressures is shown by a gray box which contains no details of other phases. Overlain on the topology are isopleths of grossular (Ca/(Ca+Mg+Fe)), almandine (Fe/(Fe+Mg+Ca)), Mg# (Mg/(Mg+Fe)) of biotite, and isomodes of garnet. Note that Mn is not used to calculate isopleths as it is not a component in the system used. The length of isopleths shown is restricted to fields corresponding to core and rim intersections. Additional isopleths are compiled in Appendix B-2.Melting and melt crystallisation textures have been observed both at the macro (e.g. segregated leucosomes, leucogranite lenses) and micro scale (e.g. evidence of muscovite and biotite dehydration melting in addition to evidence that garnet was breaking down during melt crystallization ). As such it is assumed that the rocks underwent peak metamorphism above their solidi, which is located at a minimum T of 730 ˚C in these specimens. At such temperatures, diffusion and reaction rates are expected to have been high enough to significantly modify original growth zoning and composition of garnet from the thermal peak (Spear, 1991; Spear and Florence, 1992; Caddick et al., 2010). Additionally, it is likely the composition of garnet exteriors was further modified by diffusion during initial cooling (Spear, 1991). As such, temperatures approximated from garnet isopleths for peak conditions are minimum estimates. As discussed previously, although diffusion has modified the absolute values in garnet, it is anticipated that the general trends are preserved (Caddick et al., 2010).Mineral assemblages, melt textures, and mineral compositions are consistent with peak metamorphism at granulite grade conditions. White et al. (2002) demonstrated that, depending on the bulk rock composition, number of melt loss episodes and the P-T conditions at which such episodes occur, some degree of melt loss is required to preserve granulite peak assemblages. As such, it is possible that the bulk compositions used to generate the pseudosections do not represent the systems prior to the last melt loss episode (if there was melt loss), which would have likely occurred during prograde heating. Indares et al. (2008) and Guilmette et al. (2010), however, have shown that reintegrating melt in pelitic compositions does not significantly change the position of garnet isopleths at temperatures above the solidus, which allows some restrained modeling of pre-peak and peak conditions from the observed restitic bulk.KA007The observed equilibrium assemblage for KA007 is shown with red text in Figure 3.8A. Garnet core isopleths intersect in a muscovite bearing, kyanite free field at ~765 oC and ~11.5 kbar (point C). This is 31Figure 3.8 Pseudosection results for KA007AlmandineGrossularBiotite Mg#Garnet modes650 700 750 800 850Temperature [C]600070008000900010000110001200013000Pressure [Bar](all elds + Qz + Grt)Bt Ky PlIlm LiqBt SilIlm Liq Kfs Pl-PlBt SilIlm Liq Kfs Bt  Ky  Ilm Pl  Bt Ky  Ilm Kfs PlBt Ky  Ilm Ms Pl  Bt  ky  ilm kfs Ms Pl Liq Ms Pl Bt  Ky  IlmLiq Ms Pl Bt Ky Ilm Ru Bt  Ilm Ms Pl Ru Bt  Ilm Ms Pl Ru KyKfs Bt IlmPl Ms RuKfs Bt Ilm KyPl Ms RuKfs Bt  MsPl Ru Liq Ilm Pl RuMs Bt Bt Ilm Ms Ru Liq Ll KfsIlm Ky Ru Liq Kfs PlIlm Ky Ru Liq Kfs Bt PlIlm Sil Ru Liq Kfs Pl Ilm Sil Liq Kfs Pl  Pl  Bt   Sil  Ilm  Liq Pl   Bt   Sil  Ilm Pl  +Crd?CRA2345768895872346?CRC31-25 Ma24-19 MaCR?.78.79.80.055.05.045.84 .83.85.03.025.035.33.34.32BFigure 3.8. Phase equilibria results and petrochronology interpretation for specimen KA007. All diagrams are the same size to allow for comparison. (A) Labelled topology with the observed field in red. (B) Contoured garnet and biotite isopleths used to constrain the core and rim P-T points. (C) Garnet isomodes and timing constrains from monazite petrochronology. The trajectory of the prograde path is not constained in this specimen but petrochronolgy has constrained the timing of prograde metamorphism. Cordierite bearing fields are grayed out.32Figure 3.9 Pseudosection results for KA044700 750 800 850 900Temperature [C]6000800010000120001400016000Pressure [Bar] CRPl Ilm Liq Sil RuPl Bt Ilm Liq Sil RuPl  Bt Ilm Liq  Ky RuPl Ilm Liq Ky RuPl  Liq Ky RuPl Liq Ms Ky RuPl Ilm Liq SilPl  IlmLiq Sil BtPl Ilm Sil BtPl  IlmSil Bt RuPl IlmKy Bt RuPl  Ilm Ky Bt Ru MuPl Ilm ky Bt Ru Liq MsPl  Ilm Ky Ru MsPl Ky Bt Ru MsPl Ky Ru MsPl  Ilm Ky Bt+CrdA (all elds + Qz + Grt + Kfs) .05.045.04CR.115.11.105.71.70.69.75.74.73BCR1820222426C17-16 Ma31-19 MaAlmandineGrossularGarnet modesFigure 3.9. Phase equilibria results and petrochronology interpretation for specimen KA044. All diagrams are the same size to allow for comparison. (A) Labelled topology with the observed field in red. (B) Contoured garnet isopleths used to constrain the core and rim P-T points.  (C) Garnet isomodes. Cordierite bearing fields are grayed out.33Figure 3.10 Pseudosection results for KA064A700 750 800 850 900Temperature [C]4000600080001000012000Pressure [Bar]Pl Liq Bt Sil Ilm +Crd Pl Liq Bt Ky Ilm Pl Bt Sil Ilm Pl Bt Ky Ilm Pl Bt Ky Ilm MsPl Bt KyIlm Ms Liq Pl Bt Ky Ilm Ru MsPl Bt Ky Ilm Ru Ms LiqPl Liq Sil Ilm Pl Liq Sil Ilm RuPl Liq Sil Ilm Ru BtPl Liq Ilm Ru BtPl Liq Ky Ilm Ru Liq Ky Ilm RuBt Liq Ky Ilm RuLiq Ky Ilm Ru?RC(all elds + Qz + Grt + Kfs)A?RC141210862416C24-20 Ma35-26 Ma?RC.79.80.78.87.02.025.03.035.04.045.85.86BAlmandineGrossularBiotite Mg#Garnet modesFigure 3.10. Phase equilibria results and petrochronology interpretation for specimen KA064A. All diagrams are the same size to allow for comparison. Multiple P-T paths refelct the uncertainty regarding the trajectory from core to rim constraints. (A) Labelled topology with the observed field in red. (B)  Contoured garnet and biotite isopleths used to constrain the core and rim P-T points.  (C) Garnet isomodes. Cordierite bearing fields are grayed out.34consistent with the presence of muscovite relics identified in the matrix. Garnet rim isopleths intersect near the center of the observed assemblage field at ~740 oC and ~9.2 kbar (point R). This is in close agreement with matrix biotite Mg# isopleths that estimate temperatures of ~745-755 oC for the same pressure. The interpreted P-T path is a clockwise, decompressional path, with minor cooling, in the kyanite field beginning at point C (Figure 3.8). Textural evidence that kyanite grew in the presence of melt requires that the kyanite-in line was crossed in a melt liquid bearing field. If the path entered a K-feldspar bearing field at slightly higher T no evidence remains. The specimen then followed a decompressional cooling path through point R before crossing the solidus in the kyanite field (Figure 3.8). The entire length of the path crosses decreasing garnet isomodes which is consistent with textural evidence of garnet replacement by biotite during melt crystallization as well as spessartine zoning that indicates garnet resorption.KA044 The observed assemblage for KA044, split in two by the rutile-in line, is shown with red text in Figure 3.9A. Garnet core isopleths intersect in a kyanite and muscovite bearing subsolidus field (point C) at ~715 oC and ~12 kbar. Although no muscovite is preserved, the intersection location is consistent with the presence of kyanite inclusions within garnet. Garnet rim isopleths do not intersect on the diagram which may be reflective of a number of possibilities. First, the measured bulk composition may not be representative of the system. This issue was minimized, however, by measuring the bulk composition from offcuts from the thin section used for EMP analyses. Second, the composition of garnet rims may have been altered by retrograde diffusion. Spear (1991) showed that, depending on diameter, cooling rate, and ratio of garnet to biotite, diffusion can impact garnet rim compositions to temperatures as low at 550 oC. As the diffusion of Ca in garnet is orders of magnitude slower than Fe and Mg (Vielzeuf et al., 2007), and reaction rates are considerably slower below the solidus (White and Powell, 2002), the intersection of the grossular isopleths with the solidus (point C) is taken as the P-T conditions at which the rim last equilibrated.The interpreted prograde P-T path is a heating path with minor burial in the kyanite field (Figure 3.9). Such a trajectory across decreasing almandine and grossular isopleths is consistent with garnet profiles (Figure 3.6). The P-T path crosses into a biotite free field before crystallization of retrograde biotite, consistent with observed biotite textures. The path crosses the kyanite-sillimanite transition in the presence of biotite as biotite occurs as inclusions in sillimanite and sillimanite is observed to terminate along biotite faces. This indicates decompression with minor cooling to at which point the solidus is intersected. A retrograde trajectory across decreasing garnet isomodes is consistent with textural evidence of garnet replacement by biotite.KA064A The observed assemblage for KA064A, split in two by the rutile-in line, is shown with red text in Figure 3.10A. Garnet core isopleths intersect in the observed assemblage at ~8.5 kbar and ~780 oC (point C). 35Garnet rim isopleths intersect in the same field, near the solidus, at ~6.5 kbar and ~760 oC (point R). This is similar to temperatures of ~775 oC estimated by biotite Mg# isopleths for the same pressure.The interpreted P-T path begins in the kyanite field, consistent with kyanite located in the matrix and as inclusions in garnet. Weak chemical zonation of garnet, consistent with homogenization at high temperatures, which make deciphering the prograde path difficult. The maximum grossular content measured in all garnet analyses (4.2%), however, indicates that the maximum pressure reached by this specimen was only ~8 kbar. This is consistent with a near isobaric heating path from the kyanite field to the intersection of core isopleths (point C). The P-T path from core to rim isopleths is also poorly constrained as it occurs in the same large field, resulting in limited textural evidence. The temperatures calculated from garnet cores, as discussed above, are minimum estimates. As such, the thermal peak of this specimen is likely higher than determined by almandine isopleths. Textural evidence of some prograde biotite, however, indicates it was stable at the thermal peak and hence that the P-T path did not cross the biotite-out line (~820 oC). The resulting portion of the interpreted P-T path allows for various combinations of heating, cooling, and decompression in an otherwise overall clockwise path (Figure 3.10). Decreasing garnet isomodes during cooling is consistent, furthermore, with textural evidence of biotite replacing garnet during melt crystallization.36Chapter 4.  Monazite Petrochronology4.1  BackgroundPressure-temperature (P-T) paths can provide valuable insight into geologic processes occurring within the lithosphere (e.g. Thompson and England, 1984; England and Thompson 1984). Advancements in metamorphic petrology, specifically phase equilibria modelling as discussed in the previous chapter, have greatly improved our ability to generate well-constrained P-T paths. These paths in isolation, however, do not allow us to robustly test models of tectonometamorphic processes such as burial, metamorphism, melting, crystallization and exhumation where timescales are important (Gervais and Brown, 2011). Accessory phases such as monazite, zircon, rutile and titanite are chronometers that can be analysed to provide timing constraints. Moreover, the chemistry of these accessory phases in metamorphic rocks can be used to help inform the growth and/or consumption of major phases thereby allowing chronology to be tied directly to metamorphic processes (e.g. Kylander-Clark et al., 2013). The interpretation of ages based on isotopic and trace element data is known as petrochronology (Fraser et al., 1997). When integrated with phase equilibria modelling, petrochronology can help provide robust timing constraints on P-T paths (e.g. Kylander-Clark et al., 2013). In particular, monazite heavy rare earth element (HREE) petrochonology has been valuable for constraining garnet growth and consumption (e.g. Gibson et al., 2004; Larson et al. 2011). In this thesis, monazite petrochronology from 8 specimens collected across the HMC is used to constrain the timing of metamorphism at various structural levels.Monazite [(LREE)PO4] is an accessory mineral found commonly in igneous, sedimentary and metamorphic rocks (Overstreet, 1967; Chang et al. 1996 ). It can crystallize in hydrothermal, igneous and metamorphic environments so understanding which process(es) was(were) responsible is critical in its interpretation. Monazite is more reactive and less refractory than zircon resulting in (re-)crystallization and persistence through a wider range of pressure and temperature conditions (Foster et al., 2002; Foster et al., 2004; Kylander-Clark et al., 2013). As such, monazite is commonly present in a variety of rock types over a large P-T range. In metamorphic rocks specifically, the growth of monazite is complex and possible through many different reactions (see Table 1 in Catlos et al. (2002) for a summary). Monazite in a metamorphic rock may be a relict detrital grain from a sedimentary protolith that persisted through diagenesis (Overstreet, 1967). Monazite is commonly produced through the breakdown of allanite, apatite, and REE and Th oxides during prograde metamorphism (Catlos et al., 2002; Corrie and Kohn, 2008; Spear 2010). It is typically stable at greenschist facies and higher depending on the composition of the protolith (Spear and Pyle, 2002). In anatectites, however, the solubility of REE and phosphate in melt can result in the dissolution of monazite (Spear and Pyle, 2002; Kelsey et al., 2008). The degree of dissolution (as well as growth during cooling) is dependent on P-T conditions, composition of the melt, amount of melt, and LREE content of the rocks (Kelsey et al., 2008, Yakymchuk and Brown, 2014)The LREE site of monazite accepts Th and to a lesser extent U substitutions, but is highly incompatible 37with Pb (Overstreet, 1967; Foster et al., 2002). The incorporation of both Th and U in monazite allows isotopic age determination through three independent decay chains: 232Th → 208Pb,235U → 207Pb and 238U → 206Pb. As with zircon geochronology, Wetherill concordia diagrams (206Pb/238U-207Pb/235U) are useful for old monazite. However, with young monazite, low levels of radiogenic 207Pb (from low initial levels of total U and low natural abundance of 235U) can result in imprecise 207Pb/235U dates. As Th levels are typically orders of magnitude higher than U (Chang et al 1998) and the natural abundance of 232Th is nearly 100%, U-Th-Pb concordia diagrams (206Pb/238U-208Pb/232U) are better suited for young monazite. Unsupported 206Pb from the decay of 230Th, an intermediate decay product of 238U, can result in reversely discordant, age plots (Scharer, 1984). Therefore, although U-Th-Pb concordia plots are useful for visualizing data, the most robust ages for young monazite are typically considered to be those calculated from 232Th/208Pb ratios.Despite being more reactive than zircon, the monazite U-Th-Pb system is equally robust; both Pb and U can be essentially immobile up to granulite grades (Parish, 1990; Cherniak et al. 2004). In an experimental diffusion study of both natural and synthetic monazite, Cherniak et al. (2004) reported that for 10 μm grains the closure temperature for Pb is over 900 oC for a cooling rate of 10 oC/Ma in fluid absent conditions. They also suggest that monazite is more resistant to lattice and radiation damage than zircon, resulting in more commonly concordant ages. The Cherniak et al. (2004) study does not, however, investigate the effects of fluid induced recrystallization and alteration. Williams et al. (2011) studied the effect of alteration by subjecting monazite to fluid-present, greenschist facies conditions (4.5 kbar, 450 oC) for 16 days. The results show, that at temperatures well below the closure temperature for Pb, there was a near complete removal of not only Pb, but also U from altered zones along the rim and fractures.4.1.1  P-T-t PathsThe potential of monazite petrochronology is best realized when used in conjunction with in situ dating methods that preserve textural relationships. As monazite is quite reactive, it is common for it to retain a complex growth history manifested as different zones within a grain. These different growth zones commonly have chemical characteristics distinct to the time at which that portion of the monazite was growing. Previous studies have documented the correlation of changes in Th, U and Y (a proxy for HREE) with different ages (e.g. Foster et al., 2000, 2004, Gibson et al. 2004; Larson et al. 2011). Advances in laser sampling methods have made it possible to sample these individual growth domains in monazite; effective spot size can be as small as 7 μm. Moreover, recent analytical improvements have made it possible not only to extract isotopic data from the ablated volume, but also to analyse for trace element data at the same time (Kylander-Clark et al., 2013). During metamorphism, monazite composition and modal abundance is typically coupled to garnet (Pyle and Spear, 1999; Foster et al. 2002, 2004; Gibson et al., 2004; Spear, 2010). In the absence of other REE phases such as xenotime [Y,HREE(PO4)], which commonly leave the system early in the metamorphic history (Spear and Pyle, 2002), the HREE+Y composition and modal abundance of monazite is controlled by the growth and resorption of garnet which, due to its larger volume and stronger partition 38coefficient, controls the overall budget in the rock (Spear and Pyle, 1999; Gibson et al., 2004). In the presence of and/or during garnet growth, HREE and Y are sequestered, resulting in relatively low levels of HREE and Y in monazite. In the absence of and/or during the resorption of garnet, HREE and Y are available for incorporation into monazite resulting in increased abundance in any growth during that time. Monazite growth at the onset of and during initial garnet growth along a typical clockwise P-T path for a metamorphosed pelitic rock is expected to have relatively high HREE and Y as there are free components available (Kohn et al., 2005; Stage 1, Figure 4.1). Garnet growth during increasing P-T, however, progressively sequesters HREE and Y resulting in relatively low levels available for monazite grown at that time (Stage 2, Figure 4.1). Garnet resorption, which can occur along an isobaric or slightly decompressional heating path, would increase the availability of HREE and Y for monazite (Stage 3, Figure 4.1). During anatexis, monazite typically resorbs with increasing melt volume (Kelsey et al., 2008) releasing HREE and Y into the melt and can lead to garnet growth with relatively high concentrations (Stage 4, Figure 4.1). Depending on the degree of resorption, previous HREE and Y signatures, and growth zones within the monazite could be partially destroyed or completely erased. Garnet resorption and melt crystallization during cooling provide HREE and Y which can lead to monazite growth with relatively high concentrations (Stage 5, Figure 4.1). Subsolidus retrograde resorption of garnet can continue to release HREE and Y which can lead to monazite growth with relatively high concentrations (Stage 6, Figure 4.1). In addition to these processes, monazite HREE and Y patterns can be further complicated by inherited and detrital components as well as late fluid-related alteration and recrystallization. 4.2  MethodologyTo constrain the timing of metamorphism in the HMC, monazite grains in 8 specimens were analyzed in situ by laser ablation split stream (LASS) inductively couple plasma mass spectroscopy (ICP-MS). A Cameca SX100 electron microprobe (EMP) housed at the Saskatchewan Research Council (SRC) was used to generate full thin section maps for major elements as well as Ce for each specimen in order to help locate monazite grains and determine their textural relationships. These element maps were made using a 30 μm step-size, 20 kV accelerating voltage and a 60 nA beam current utilizing both energy dispersive (EDS) and wavelength dispersive X-ray spectroscopy (WDS). Each monazite was also mapped for U, Th, Pb and Y at the SRC to identify compositional zoning, help guide laser spot placement and help elucidate relationships between age and composition. Backscattered electron images of each grain selected for dating were captured using a Tescan Mira3 XMU Field Emission Scanning Electron Microscope at the University of British Columbia SEMLab in order to locate grains during LASS-ICP-MS analyses. A complete set of elemental maps and BSE images can be found in Appendix C.Monazite isotopic age and trace element analyses were carried out at the University of California, Santa Barbara (UCSB) LASS Facility. A 7.2 µm spot size with a pit depth of ~3-4 µm was ablated using a Photon Machines 193 nm ArF excimer. The aerosol was then split between an Agilent 7700X quadrupole ICP-MS for trace element analyses and a Nu Instruments Plasma high resolution multi-collector ICP-39Figure 4.1 Relationship between monazite and garnet HREE zoning?HREE+YPressureTemperature+Melt123456Figure 4.1 Idealized P-T path demonstrating the potential effects of garnet growth/resorption (hexagons outside the path) on the HREE+Y composition of monazite. Not all processes will necessarily occur or be preserved. See text for explanation40MS to for isotopic analyses (U-Th-Pb). Each analysis was preceded by two preablation (cleaning) shots followed by a 15 second gap to allow the lines to flush. Laser rep rate was 4 Hz and run over 25 seconds for a total of 100 shots at energy of 3 mJ. 1-12 spot analyses were collected on each grain with ~ 10 grains analyzed in each specimen. A primary, secondary and tertiary standard were analyzed approximately every 6 shots. The primary standard, monazite “44069”, which has an age of 424 Ma as determined by isotope dilution-thermal ionization mass spectrometry (ID-TIMS; Aleinikoff et al., 2006), was used to correct for mass bias as well as Pb/U and Pb/Th fractionation. The primary standard was also used to normalize trace element data. A secondary standard “Stern” (512.1 ± 1.9 Ma, ID-TIMS 238U-206Pb age; Palin et al 2013) and tertiary standard “Manangotry” (559 ± 1 Ma, ID-TIMS 238U-206Pb age; Palin et al., 2013) were treated as unknowns and used to monitor data accuracy. Data reduction was carried out using Igor Pro version 6.24 with Iolite Software version 2.5 as per the methods of Paton et al. (2010). All concordia plots were generated using Isoplot version 2.4 (Ludwig, 2000) as an add-in for Excel version 2003 with the decay constants of Steiger and Jäger (1977). All uncertainties are 2 standard deviation. As there is no error correlation between 206Pb/238U and 208Pb/232Th,, dates are plotted as crosses rather than ellipses.4.3  ResultsThe results from all analyses are shown in Table 4.1 and a photograph of each specimen is presented in Figure 3.1. The 8 specimens analyzed are discussed below in order from south to north (Figure 2.1). With the exception of KA007, for which the structural position is uncertain, the order discussed also corresponds to increasing structural level (Figure 2.2). For the reasons discussed previously, all quoted dates are calculated from 238Th/208Pb ratios. KA007Specimen KA007 is a Ky + Grt + Bt + Qz + Pl gneissic schist collected near the southern end of the study area (Figure 2.1, 2.2, 3.1). It is the only metamorphic specimen analyzed for monazite petrochronology south of the Tamor window. Monazite grains in this specimen occurs solely within the matrix, are 30-60 µm across in thin section, anhedral to subhedral and equant to elongate in shape, and are commonly spatially associated with quartz, plagioclase and biotite (Figure 4.2). Element maps show irregular zoning of U and minor to no zoning of Th. Y maps typically show low Y cores and high Y rims (Figure 4.3). 44 analyses on 10 monazite grains yielded dates ranging from 30.7 ± 0.7 to 18.6 ± 0.4 Ma (Table 4.1). Four analyses in total were omitted (Table 4.1). There is a negative relationship between date and Y concentration in this specimen (Figure 4.3). From ca. 31 to 24 Ma, concentrations range between 13,600 and 64,000 ppm and show no discernable trend. From ca. 24 to 19 Ma, concentrations range between ~34,600 and 170,000 ppm and increase sharply with decreasing date.41AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA007 1 1.1 131 13200 78100 34000 5.97 0.0796 3.42 0.00383 2.86 0.00122 2.76 24.6 0.7KA007 2 1.2 95 7370 50200 54400 6.93 0.1257 6.26 0.00404 3.06 0.00135 3.31 27.3 0.9KA007 3 1.3 79 4190 57400 94300 13.75 0.1002 3.60 0.00331 2.43 0.00099 2.33 20.0 0.5KA007 4 1.4 75 4060 54300 94500 13.49 0.1287 4.05 0.00350 2.61 0.00099 2.59 20.0 0.5KA007 5 1.5 113 6710 57300 28100 8.59 0.0837 3.28 0.00462 2.26 0.00140 2.29 28.3 0.6KA007 6 1.6 109 8110 54000 25000 6.71 0.0719 3.20 0.00456 2.38 0.00143 2.32 28.9 0.7KA007 7 2.1 62 6230 46900 121000 7.45 0.0693 3.70 0.00288 2.34 0.00093 2.32 18.7 0.4KA007 8 2.2 60 6630 46900 122000 7.11 0.0699 3.61 0.00284 2.31 0.00092 2.26 18.6 0.4KA007 9 2.3 98 7410 49500 27200 6.68 0.0685 3.29 0.00432 2.30 0.00140 2.34 28.2 0.7KA007 10 2.4 94 8220 47900 32800 5.80 0.0687 3.33 0.00423 2.31 0.00140 2.47 28.3 0.7KA007 11 2.5 80 9200 41300 31500 4.49 0.0681 3.34 0.00395 2.29 0.00136 2.32 27.5 0.6KA007 12 2.6 69 8050 47300 89000 6.35 0.0785 3.70 0.00329 2.36 0.00104 2.29 21.0 0.5KA007 13 3.1 75 5200 46200 80000 9.34 0.0831 4.16 0.00357 3.14 0.00112 3.18 22.6 0.7KA007 14 3.2 82 8120 42800 43500 5.33 0.0668 3.30 0.00393 2.28 0.00137 2.36 27.7 0.7KA007 15 3.3 73 15600 49700 62000 3.25 0.0685 3.32 0.00295 2.40 0.00103 2.68 20.9 0.6KA007 16 3.4m 19 2790 13300 189000 4.78 0.2144 5.51 0.00264 3.62 0.00103 3.97 20.7 0.8KA007 17 3.5 85 24400 52300 46000 2.15 0.0626 3.16 0.00318 2.25 0.00117 2.35 23.6 0.6KA007 18 3.6m 5 215 670 119000 2.77 0.4940 6.77 0.00960 8.22 0.00652 13.17 131.0 17.2KA007 19 4.1 92 10500 52800 37400 4.98 0.0695 3.61 0.00379 2.31 0.00127 2.81 25.7 0.7KA007 20 4.2 105 8540 50100 20900 5.56 0.0681 3.33 0.00428 2.36 0.00149 2.32 30.2 0.7KA007 21 4.3 113 12900 61800 40000 4.77 0.0668 3.35 0.00397 2.61 0.00133 2.80 26.9 0.8KA007 22 4.4 130 8700 61700 18760 7.06 0.0881 3.45 0.00455 2.31 0.00151 2.28 30.5 0.7KA007 23 4.5 110 10960 58700 26600 5.31 0.0660 3.27 0.00408 2.34 0.00132 2.30 26.7 0.6KA007 24 4.6 127 8210 62100 18200 7.42 0.0973 3.37 0.00451 2.36 0.00146 2.38 29.5 0.7KA007 25 5.1 98 7225 61300 66200 7.96 0.0703 3.85 0.00388 2.41 0.00112 2.45 22.7 0.6KA007 26 5.2 114 17660 69900 46400 3.86 0.0646 3.31 0.00355 2.43 0.00115 2.37 23.3 0.6KA007 27 5.3 139 12680 71900 32700 5.50 0.0638 3.25 0.00439 2.33 0.00136 2.41 27.5 0.7KA007 28 5.4 124 11610 70200 62000 5.83 0.0633 3.31 0.00404 2.62 0.00124 2.68 25.1 0.7KA007 29 6.1 119 9840 56900 13600 5.60 0.0644 3.29 0.00473 2.54 0.00150 2.54 30.3 0.8KA007 30 6.2 121 14670 73900 34600 4.90 0.0668 3.35 0.00378 2.37 0.00117 2.46 23.7 0.6KA007 31 7.1 95 12950 55900 36200 4.49 0.0934 3.45 0.00370 2.37 0.00122 2.47 24.7 0.6KA007 32 7.2 96 20580 60000 44000 2.95 0.0808 3.66 0.00344 2.35 0.00114 2.43 23.1 0.6KA007 33 7.3 62 8700 32900 63900 3.73 0.1396 4.20 0.00363 2.46 0.00136 2.82 27.4 0.8KA007 34 7.4 81 5930 60600 76200 10.38 0.0811 3.81 0.00311 2.35 0.00096 2.42 19.4 0.5Measured Isotopic Ratios Ages (Ma)Concentration (ppm)*Table 4.1. Monazite geochronology and geochemistryTable 4.1    Monazite geochronology results and Y concentrations42AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA007 35 7.5 73 6250 53200 71200 8.55 0.1249 4.00 0.00315 2.42 0.00098 2.54 19.7 0.5KA007 36 7.6 70 4920 51500 68900 10.57 0.1074 5.08 0.00323 2.59 0.00099 2.52 20.0 0.5KA007 37 8.1m 35 3560 22300 179000 6.17 0.2904 3.57 0.00351 2.75 0.00113 2.89 22.7 0.7KA007 38 8.2x 249 6730 52200 23800 7.67 0.0639 3.46 0.00950 3.19 0.00357 3.31 72.0 2.4KA007 39 8.3 67 4170 46500 77900 11.12 0.0811 3.88 0.00347 2.50 0.00103 2.48 20.7 0.5KA007 40 9.1 68 10610 43300 49200 4.33 0.0691 3.54 0.00345 2.39 0.00110 2.53 22.3 0.6KA007 41 9.2 76 7110 41500 22700 5.80 0.0683 3.55 0.00404 2.68 0.00129 2.68 26.0 0.7KA007 42 9.3 78 13730 50300 46600 3.64 0.0653 3.20 0.00345 2.29 0.00111 2.40 22.4 0.5KA007 43 10.1 98 8180 70800 59000 8.36 0.0717 5.04 0.00343 3.40 0.00105 3.32 21.3 0.7KA007 44 10.2 113 6770 53200 19300 7.78 0.0655 3.44 0.00477 2.32 0.00152 2.39 30.7 0.7KA007 45 10.3 99 6480 61800 94000 9.44 0.0878 4.63 0.00359 3.55 0.00109 3.54 22.1 0.8KA007 46 10.4 86 8010 64900 163000 7.97 0.0639 3.81 0.00301 2.34 0.00094 2.31 18.9 0.4KA007 47 10.5 94 8750 71300 174000 8.08 0.0634 3.47 0.00294 2.22 0.00093 2.25 18.9 0.4KA007 48 10.6 109 9880 78000 148000 7.84 0.0675 3.41 0.00322 2.52 0.00099 2.60 19.9 0.5KA31B 1 1.1 61 7660 44500 4170 9.38 0.1888 3.35 0.00338 2.05 0.00098 2.17 19.7 0.4KA31B 2 1.2 72 10150 47400 980 7.90 0.1666 3.21 0.00356 2.09 0.00108 2.11 21.8 0.5KA31B 3 1.3 69 9570 45000 715 8.18 0.1729 3.18 0.00362 2.01 0.00110 2.06 22.3 0.5KA31B 4 1.4 61 10420 38700 562 6.53 0.1356 3.31 0.00341 2.02 0.00111 2.10 22.5 0.5KA31B 5 1.5 62 9070 41500 2090 7.98 0.1579 3.19 0.00340 2.07 0.00104 2.18 20.9 0.5KA31B 6 1.6 46 7380 41800 21300 9.74 0.1408 3.64 0.00259 2.06 0.00078 2.09 15.9 0.3KA31B 7 2.1 80 9020 53900 1180 8.25 0.1886 3.24 0.00349 2.03 0.00105 2.08 21.1 0.4KA31B 8 2.2 81 9090 53600 1010 7.78 0.1827 3.21 0.00353 2.08 0.00107 2.11 21.7 0.5KA31B 9 2.3 91 9690 59400 834 7.53 0.1820 3.18 0.00353 2.10 0.00109 2.16 21.9 0.5KA31B 10 2.4 99 9800 63200 570 7.50 0.1811 3.20 0.00362 2.06 0.00111 2.10 22.5 0.5KA31B 11 2.5 105 10300 66900 508 7.16 0.1788 3.18 0.00362 2.06 0.00111 2.14 22.4 0.5KA31B 12 2.6 86 8400 57900 1010 7.28 0.1889 3.22 0.00347 2.08 0.00106 2.22 21.4 0.5KA31B 13 3.1e 1 27 149 40 5.46 0.8600 68.67 0.00420 66.69 0.00224 41.11 45.0 18.5KA31B 14 3.2 67 5850 63000 16500 9.79 0.1534 3.69 0.00259 2.23 0.00076 2.10 15.4 0.3KA31B 15 3.3 106 9960 71000 1600 6.63 0.1741 3.23 0.00350 2.03 0.00105 2.12 21.3 0.5KA31B 16 3.4 105 9700 68500 1120 6.65 0.1810 3.16 0.00358 2.08 0.00109 2.15 22.0 0.5KA31B 17 3.5 100 9510 66300 1090 6.69 0.1768 3.19 0.00354 2.11 0.00108 2.16 21.8 0.5KA31B 18 3.6 100 10870 68500 1230 6.15 0.1756 3.19 0.00340 2.13 0.00104 2.13 21.0 0.4KA31B 19 4.1Grt 101 11400 61900 307 5.51 0.1593 3.30 0.00376 2.34 0.00119 2.19 24.1 0.5Measured Isotopic Ratios Ages (Ma)Table 4.1. (continued)Concentration (ppm)*43AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA31B 20 4.2Grt 86 8270 67900 7100 8.38 0.1240 3.71 0.00297 2.91 0.00091 2.87 18.4 0.5KA31B 21 5.1 63 4930 66200 14900 13.56 0.1143 4.16 0.00230 2.25 0.00068 2.15 13.7 0.3KA31B 22 5.2 94 5290 59200 375 11.14 0.1346 3.38 0.00378 2.14 0.00114 2.17 23.0 0.5KA31B 23 5.3 111 11440 72600 583 6.26 0.1668 3.13 0.00356 2.03 0.00109 2.15 22.1 0.5KA31B 24 5.4 102 9970 69900 1110 6.91 0.1819 3.18 0.00345 2.14 0.00105 2.18 21.1 0.5KA31B 25 6.1 73 7250 61000 7400 9.05 0.1827 3.32 0.00294 2.16 0.00086 2.10 17.3 0.4KA31B 26 6.2 113 9040 77100 518 9.51 0.1594 3.23 0.00361 2.07 0.00106 2.12 21.3 0.5KA31B 27 6.3 114 9490 75900 334 9.25 0.1514 3.23 0.00357 2.11 0.00107 2.17 21.5 0.5KA31B 28 6.4 105 8790 74200 1680 9.97 0.1868 3.28 0.00345 2.14 0.00100 2.20 20.3 0.4KA31B 29 6.5 86 5880 61000 1480 12.57 0.2023 3.26 0.00360 2.15 0.00100 2.20 20.3 0.4KA31B 30 6.6 94 9250 66400 1470 8.94 0.1780 3.22 0.00339 2.22 0.00102 2.19 20.5 0.5KA31B 31 7.1 84 7750 63000 3610 9.60 0.1790 3.26 0.00315 2.18 0.00093 2.19 18.8 0.4KA31B 32 7.2 55 6160 57000 18800 10.51 0.0751 4.01 0.00215 2.25 0.00068 2.25 13.8 0.3KA31B 33 7.3 64 6400 59000 11500 10.04 0.1299 3.56 0.00262 2.24 0.00077 2.34 15.6 0.4KA31B 34 7.4 87 8260 72100 5900 9.31 0.1876 3.50 0.00293 2.34 0.00088 2.67 17.8 0.5KA31B 35 7.5 66 7540 58000 13400 7.70 0.1525 3.39 0.00266 2.25 0.00081 2.29 16.5 0.4KA31B 36 7.6 65 7260 58200 16900 7.78 0.1483 3.38 0.00256 2.28 0.00079 2.24 16.0 0.4KA31B 37 8.1Grt 104 5850 70300 659 11.88 0.1465 3.42 0.00362 2.22 0.00105 2.23 21.2 0.5KA31B 38 8.2Grt 79 6610 49700 600 7.93 0.1194 3.32 0.00355 2.15 0.00111 2.19 22.5 0.5KA31B 39 9.1Grt 107 4730 66900 467 16.09 0.1772 3.56 0.00406 2.33 0.00113 2.28 22.7 0.5KA31B 40 9.2Grt 100 5880 63400 516 13.28 0.1519 3.30 0.00387 2.31 0.00111 2.35 22.4 0.5KA31B 41 10.1 92 10940 59000 688 8.59 0.1682 3.13 0.00352 2.31 0.00110 2.35 22.2 0.5KA31B 42 10.2 90 10200 56900 494 9.19 0.1688 3.15 0.00363 2.19 0.00112 2.23 22.6 0.5KA31B 43 10.3 52 5950 45700 8880 12.94 0.2131 4.88 0.00295 3.03 0.00082 2.86 16.7 0.5KA31B 44 10.4 88 9720 59100 1820 10.31 0.1829 3.14 0.00349 2.23 0.00106 2.27 21.5 0.5KA31B 45 10.5 85 9430 56900 2840 10.25 0.1641 3.22 0.00341 2.20 0.00105 2.23 21.2 0.5KA31B 46 10.6 100 10650 61600 342 9.50 0.1563 3.19 0.00363 2.15 0.00114 2.27 23.1 0.5KA034 1 1.1 45 3950 33600 1450 8.66 0.0740 4.52 0.00296 2.71 0.00095 2.80 19.2 0.5KA034 2 1.2 27 2310 21700 2380 9.31 0.1324 5.88 0.00279 2.72 0.00088 2.59 17.8 0.5KA034 3 1.3 68 7690 53300 2960 6.96 0.0828 3.50 0.00280 2.32 0.00091 2.28 18.3 0.4KA034 4 1.4 64 7700 50400 3320 6.58 0.0653 3.69 0.00275 2.32 0.00090 2.42 18.2 0.4KA034 5 1.5 78 8350 63700 3280 7.56 0.0650 3.61 0.00273 2.44 0.00088 2.37 17.7 0.4KA034 6 1.6 70 8140 57300 3130 6.89 0.0714 3.66 0.00269 2.46 0.00088 2.44 17.9 0.4Measured Isotopic Ratios Ages (Ma)Table 4.1. (continued)Concentration (ppm)*44AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA034 7 2.1 59 4800 44600 2140 9.11 0.1329 3.67 0.00289 2.69 0.00094 2.74 18.9 0.5KA034 8 2.2 56 4680 48500 4380 10.08 0.0709 4.32 0.00252 2.56 0.00082 2.44 16.6 0.4KA034 9 2.3 64 5410 51400 3260 9.34 0.0731 4.25 0.00269 2.61 0.00088 2.59 17.9 0.5KA034 10 2.4 44 4140 39000 4360 9.29 0.0937 4.55 0.00245 2.57 0.00081 2.62 16.4 0.4KA034 11 2.5 67 5380 54700 4190 10.06 0.0705 3.85 0.00264 2.48 0.00086 2.54 17.4 0.4KA034 12 2.6fx 34 2960 26500 2200 8.70 0.0725 5.68 0.00264 2.76 0.00092 2.61 18.7 0.5KA034 13 3.1 85 6690 68800 2420 10.34 0.0696 3.96 0.00271 2.52 0.00088 2.44 17.8 0.4KA034 14 3.2 93 7560 75200 2540 9.96 0.0685 3.99 0.00271 2.48 0.00088 2.59 17.8 0.5KA034 15 3.3 97 7530 75900 2500 10.22 0.0699 3.77 0.00276 2.38 0.00091 2.34 18.4 0.4KA034 16 3.4 88 6600 71100 2330 10.95 0.0702 3.86 0.00271 2.43 0.00088 2.44 17.7 0.4KA034 17 3.5 92 6760 73500 2370 11.06 0.0705 4.03 0.00276 2.55 0.00088 2.51 17.8 0.4KA034 18 3.6 118 9840 96600 2580 10.09 0.0685 3.63 0.00269 2.29 0.00086 2.32 17.4 0.4KA034 19 4.1 74 6337 71900 10700 11.59 0.0949 5.43 0.00240 2.54 0.00072 2.59 14.5 0.4KA034 20 4.2 91 12210 79000 2890 6.69 0.0626 3.94 0.00256 2.33 0.00082 2.36 16.5 0.4KA034 21 4.3 63 7300 53600 3010 7.56 0.0757 5.73 0.00260 2.55 0.00085 2.40 17.2 0.4KA034 22 4.4 87 11530 73900 3510 6.69 0.0590 3.82 0.00260 2.27 0.00083 2.28 16.7 0.4KA034 23 4.5 70 8560 59300 3090 7.22 0.0613 4.09 0.00262 2.36 0.00084 2.41 16.9 0.4KA034 24 4.6 29 2979 28850 6340 10.04 0.1303 5.69 0.00229 2.76 0.00074 3.06 14.9 0.5KA034 25 5.1 45 5910 51700 14900 9.20 0.0640 6.10 0.00198 3.35 0.00063 3.13 12.8 0.4KA034 26 5.2 42 4220 43900 11770 10.36 0.0678 6.75 0.00216 3.20 0.00068 2.88 13.7 0.4KA034 27 5.3 65 8780 55500 3470 6.61 0.0696 4.25 0.00259 2.61 0.00084 2.65 17.0 0.5KA034 28 5.4 49 5390 45600 11000 8.88 0.1032 8.13 0.00247 4.32 0.00078 4.04 15.7 0.6KA034 29 5.5m 2 193 2100 220 10.99 0.3600 30.70 0.00470 21.35 0.00081 11.33 16.5 1.9KA034 30 5.6 54 6740 59700 21700 9.10 0.0593 4.64 0.00203 2.56 0.00064 2.41 12.9 0.3KA034 31 6.1 69 5960 56400 3630 9.42 0.0698 4.05 0.00278 2.42 0.00088 2.52 17.7 0.4KA034 32 6.2 62 5160 51100 2860 9.84 0.0704 4.33 0.00274 2.56 0.00086 2.63 17.3 0.5KA034 33 6.3 60 5100 52700 3400 10.11 0.0690 4.17 0.00266 2.30 0.00083 2.43 16.7 0.4KA034 34 6.4 47 4700 47500 17400 9.79 0.0646 4.78 0.00223 2.39 0.00071 2.32 14.4 0.3KA034 35 7.1 49 7610 46200 12300 5.83 0.0564 4.13 0.00233 2.40 0.00076 2.52 15.3 0.4KA034 36 7.2 58 6610 49600 4010 7.15 0.0658 3.96 0.00270 2.35 0.00084 2.41 17.0 0.4KA034 37 7.3 53 7190 44000 4350 5.80 0.0602 3.90 0.00259 2.30 0.00087 2.38 17.5 0.4KA034 38 8.1x, ell 33 4258 20440 867 4.48 0.0608 4.21 0.00284 2.91 0.00115 3.35 23.2 0.8KA034 39 8.2x, ell 27 3393 16380 800 4.48 0.0612 4.81 0.00283 3.20 0.00118 3.64 23.8 0.9KA034 40 8.3x, ell 30 3486 18480 1060 4.97 0.0663 4.94 0.00284 3.43 0.00114 3.73 23.1 0.9Measured Isotopic Ratios Ages (Ma)Table 4.1. (continued)Concentration (ppm)*45AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA034 41 8.4x, ell 37 4090 24240 1090 5.54 0.0609 4.33 0.00284 3.00 0.00109 3.32 21.9 0.7KA034 42 8.5x, ell 30 3404 17900 1000 4.97 0.0680 4.75 0.00286 3.53 0.00118 4.08 23.9 1.0KA034 43 8.6x, ell 21 2234 16550 3480 6.98 0.0577 6.00 0.00239 2.79 0.00088 3.01 17.8 0.5KA034 44 8.7x, ell 22 2293 12890 694 5.46 0.0641 5.30 0.00284 3.34 0.00119 3.83 24.1 0.9KA034 45 8.8x, ell 25 2641 15620 820 5.75 0.0601 5.13 0.00284 3.38 0.00114 3.58 23.1 0.8KA034 46 8.9x, ell 20 2145 15000 2940 6.89 0.0561 7.25 0.00254 3.39 0.00092 3.74 18.7 0.7KA034 47 9.1 36 3410 40800 13000 11.66 0.0711 4.31 0.00211 2.68 0.00064 2.63 13.0 0.3KA034 48 9.2 47 5350 44000 5450 8.01 0.0589 4.16 0.00244 2.46 0.00077 2.33 15.6 0.4KA034 49 9.3 49 5170 44600 5690 8.43 0.0588 4.17 0.00246 2.48 0.00078 2.49 15.7 0.4KA034 50 9.4 50 3920 47600 5720 11.61 0.0612 4.68 0.00243 2.33 0.00076 2.35 15.3 0.4KA034 51 10.1 39 3760 33100 3860 8.73 0.0653 4.07 0.00264 2.28 0.00084 2.34 16.9 0.4KA034 52 10.2 43 4100 34200 2890 8.32 0.0673 4.02 0.00279 2.39 0.00089 2.43 17.9 0.4KA034 53 10.3 43 4690 35000 2720 7.48 0.0683 3.90 0.00279 2.37 0.00089 2.36 17.9 0.4KA034 54 10.4 43 4590 34800 3250 7.61 0.0682 4.09 0.00280 2.34 0.00089 2.36 18.0 0.4KA034 55 10.5 38 4240 35300 4680 8.36 0.0598 4.37 0.00242 2.50 0.00077 2.51 15.5 0.4KA034 56 10.6 39 4280 35600 4410 8.38 0.0610 4.44 0.00243 2.41 0.00078 2.58 15.7 0.4KA037 22 3.1 81 6790 59100 1170 8.73 0.0843 3.61 0.00315 2.20 0.00096 2.17 19.5 0.4KA037 13 3.1 76 6250 56400 1060 9.19 0.0856 3.42 0.00314 2.19 0.00096 2.24 19.3 0.4KA037 23 3.11 34 1098 25000 5400 21.37 0.2240 6.53 0.00344 3.42 0.00097 3.00 19.6 0.6KA037 24 3.12 64 5000 49000 2970 10.08 0.0688 3.80 0.00297 2.27 0.00091 2.27 18.4 0.4KA037 14 3.2 78 6640 57900 1010 8.83 0.0846 3.48 0.00316 2.24 0.00096 2.23 19.4 0.4KA037 15 3.3 90 7480 66600 800 8.99 0.0930 3.36 0.00312 2.19 0.00096 2.18 19.4 0.4KA037 16 3.4 73 6870 53800 810 7.90 0.1086 3.43 0.00320 2.25 0.00097 2.22 19.7 0.4KA037 17 3.5 83 7230 61200 777 8.54 0.0946 3.39 0.00313 2.23 0.00096 2.23 19.5 0.4KA037 18 3.6 66 6530 52600 5050 8.11 0.0853 3.42 0.00289 2.21 0.00089 2.29 18.0 0.4KA037 19 3.7 75 6470 55100 1020 8.48 0.0862 3.47 0.00319 2.21 0.00097 2.23 19.6 0.4KA037 20 3.8 102 8840 75400 980 8.55 0.0909 3.28 0.00311 2.25 0.00096 2.23 19.5 0.4KA037 21 3.9 64 5610 47900 1290 8.57 0.0766 3.66 0.00307 2.20 0.00095 2.24 19.1 0.4KA037 1 4.1 67 3440 52400 2450 16.08 0.0845 4.05 0.00302 2.40 0.00091 2.34 18.4 0.4KA037 2 4.2 66 2781 50500 2680 17.64 0.0893 4.34 0.00305 2.43 0.00094 2.37 19.1 0.5KA037 3 4.3 76 2378 58400 2920 24.88 0.0934 4.55 0.00317 2.54 0.00094 2.38 19.0 0.5KA037 4 4.4 83 4050 63900 890 16.53 0.0955 3.98 0.00307 2.43 0.00095 2.37 19.1 0.5Table 4.1. (continued)Concentration (ppm)* Measured Isotopic Ratios Ages (Ma)46AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA037 5 4.5 86 4070 64100 569 16.15 0.0951 3.92 0.00313 2.34 0.00096 2.23 19.5 0.4KA037 6 4.6 68 1685 54500 4700 33.21 0.0778 5.95 0.00300 2.48 0.00090 2.34 18.3 0.4KA037 7 5.1 81 6280 62100 860 10.19 0.0914 3.59 0.00306 2.32 0.00093 2.38 18.9 0.4KA037 8 5.2 57 4670 43900 790 9.62 0.0892 3.81 0.00302 2.34 0.00094 2.51 19.0 0.5KA037 9 5.3 49 3020 38600 2040 13.03 0.0919 4.28 0.00293 2.43 0.00091 2.27 18.4 0.4KA037 10 5.4 57 4330 43800 1440 10.32 0.0790 3.93 0.00306 2.39 0.00094 2.31 19.1 0.4KA037 11 5.5 86 8510 63400 760 7.57 0.0837 3.43 0.00306 2.26 0.00097 2.34 19.6 0.5KA037 12 5.6 79 7240 58000 790 8.11 0.0855 3.42 0.00312 2.27 0.00097 2.28 19.6 0.4KA037 34 6.1 78 7540 55200 850 7.17 0.0894 3.38 0.00318 2.29 0.00100 2.32 20.2 0.5KA037 25 6.1 50 4760 43700 10800 9.14 0.1069 6.45 0.00256 3.24 0.00081 3.10 16.3 0.5KA037 35 6.11 76 6940 54700 860 7.72 0.0860 3.66 0.00312 2.27 0.00099 2.27 20.0 0.5KA037 36 6.12 75 6920 54500 840 7.67 0.0839 3.49 0.00318 2.29 0.00099 2.39 20.1 0.5KA037 26 6.2 61 5220 43300 780 8.23 0.0902 3.60 0.00321 2.32 0.00100 2.38 20.2 0.5KA037 27 6.3 90 7910 65600 820 8.24 0.0889 3.50 0.00316 2.40 0.00097 2.35 19.5 0.5KA037 28 6.4 60 5170 42600 730 8.18 0.0870 3.64 0.00319 2.53 0.00099 2.59 20.0 0.5KA037 29 6.5fx 102 7060 60900 850 8.59 0.2653 3.25 0.00420 2.50 0.00120 2.60 24.3 0.6KA037 30 6.6 58 2540 44200 3180 17.53 0.0828 4.34 0.00321 2.62 0.00092 2.39 18.7 0.4KA037 31 6.7 53 4670 37800 760 8.01 0.0846 3.82 0.00315 2.40 0.00100 2.38 20.2 0.5KA037 32 6.8 58 4880 42200 910 8.50 0.0861 3.72 0.00321 2.24 0.00098 2.22 19.9 0.4KA037 33 6.9 67 5870 48400 820 8.06 0.0875 3.57 0.00316 2.30 0.00098 2.40 19.8 0.5KA037 37 7.1 64 5900 47000 1190 7.78 0.0808 3.66 0.00317 2.39 0.00100 2.45 20.1 0.5KA037 38 7.2 71 5840 52200 724 8.60 0.0910 3.53 0.00319 2.37 0.00100 2.45 20.1 0.5KA037 39 7.3 83 6380 59600 800 9.06 0.0955 3.44 0.00315 2.22 0.00100 2.32 20.2 0.5KA037 40 7.4 73 7410 53300 900 7.03 0.0867 3.65 0.00313 2.39 0.00101 2.37 20.4 0.5KA037 41 7.5 84 7730 64600 2530 8.07 0.0915 3.84 0.00309 2.38 0.00095 2.37 19.1 0.5KA037 42 7.6 37 4520 33800 12100 7.05 0.1326 3.76 0.00251 2.60 0.00079 2.48 15.9 0.4KA037 43 8.1 54 5210 43300 2290 8.00 0.0836 3.91 0.00293 2.55 0.00090 2.49 18.2 0.5KA037 44 8.2 56 5310 45700 2940 8.35 0.0864 4.09 0.00286 2.66 0.00089 2.67 17.9 0.5KA037 45 8.3 67 4910 50130 1030 9.98 0.1037 3.73 0.00325 2.58 0.00097 2.70 19.5 0.5KA037 46 8.4 46 4350 33380 1090 7.65 0.0930 3.96 0.00318 2.50 0.00099 2.59 20.0 0.5KA037 47 8.5 42 4540 30570 1240 6.70 0.0848 3.97 0.00314 2.79 0.00098 2.76 19.8 0.5KA037 48 8.6 44 3597 32600 1940 8.95 0.0872 4.48 0.00314 2.60 0.00097 2.62 19.6 0.5KA037 49 9.1 56 2981 44700 3810 14.73 0.0716 4.71 0.00302 2.56 0.00088 2.44 17.7 0.4KA037 50 9.2 66 2660 55400 3410 21.12 0.0736 4.95 0.00303 2.63 0.00087 2.53 17.5 0.4KA037 51 9.3 76 7330 56500 4320 7.86 0.0922 3.64 0.00314 2.49 0.00097 2.48 19.5 0.5Table 4.1. (continued)Concentration (ppm)* Measured Isotopic Ratios Ages (Ma)47AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA037 52 9.4 60 4340 47200 3180 10.78 0.0750 4.69 0.00300 2.64 0.00091 2.55 18.4 0.5KA037 53 9.5 68 5770 53800 3280 9.55 0.0923 3.90 0.00300 2.82 0.00092 2.70 18.5 0.5KA037 54 9.6m 4 443 2770 400 6.44 0.1510 15.52 0.00266 5.21 0.00101 4.84 20.3 1.0KA044 1 1.1 43 3600 15930 2010 4.42 0.0635 3.72 0.00565 2.22 0.00194 2.29 39.1 0.9KA044 2 1.2 55 4140 21610 2350 5.25 0.0599 3.80 0.00566 2.23 0.00180 2.38 36.4 0.9KA044 3 1.3 107 2775 53600 640 19.23 0.1040 3.51 0.00467 2.28 0.00141 2.25 28.4 0.6KA044 4 1.4 61 3452 23430 2000 6.61 0.0691 3.54 0.00565 2.12 0.00186 2.26 37.5 0.8KA044 5 1.5 59 5410 22220 2320 3.99 0.0679 3.28 0.00578 2.19 0.00188 2.25 37.9 0.9KA044 6 1.6 123 3160 48000 1300 14.47 0.0739 3.78 0.00575 2.19 0.00179 2.25 36.2 0.8KA044 7 1.7 55 4850 21450 2160 4.24 0.0587 3.54 0.00563 2.22 0.00182 2.27 36.7 0.8KA044 8 1.8 60 5110 23730 2170 4.48 0.0583 3.84 0.00561 2.14 0.00179 2.16 36.2 0.8KA044 9 1.9 51 4340 19610 1990 4.37 0.0592 3.62 0.00568 2.16 0.00184 2.30 37.2 0.9KA044 10 1.10 127 3630 61400 651 16.51 0.0967 3.64 0.00482 2.31 0.00145 2.19 29.2 0.6KA044 11 1.11 110 2617 64400 737 24.15 0.1358 4.00 0.00417 2.53 0.00121 2.32 24.4 0.6KA044 12 1.12 143 3540 69900 790 19.68 0.0980 3.57 0.00510 2.23 0.00145 2.27 29.3 0.7KA044 13 2.1 72 840 54000 900 63.90 0.1233 6.42 0.00376 2.87 0.00095 2.44 19.1 0.5KA044 14 2.2 106 861 68200 1600 79.05 0.1345 5.88 0.00415 2.87 0.00113 2.23 22.7 0.5KA044 15 2.3 79 2540 44900 488 17.33 0.1384 4.59 0.00440 2.62 0.00124 2.51 25.1 0.6KA044 16 2.4 123 4030 63000 682 15.23 0.0999 3.55 0.00466 2.32 0.00141 2.37 28.6 0.7KA044 17 2.5 116 3660 60300 880 16.00 0.1213 3.94 0.00466 2.50 0.00135 2.52 27.2 0.7KA044 18 2.6 112 3400 51300 537 14.56 0.1352 4.11 0.00509 2.47 0.00152 2.35 30.8 0.7KA044 19 2.7 123 3517 57600 497 15.57 0.1897 4.67 0.00560 2.94 0.00153 2.47 30.8 0.8KA044 20 2.8 125 4120 62600 680 14.54 0.1046 3.41 0.00476 2.20 0.00144 2.27 29.1 0.7KA044 21 2.9 106 3240 57400 940 17.45 0.1212 3.69 0.00451 2.42 0.00129 2.37 26.0 0.6KA044 22 2.1 128 4157 66300 656 15.66 0.1119 3.40 0.00469 2.21 0.00137 2.19 27.8 0.6KA044 23 2.11 99 3490 51400 652 14.59 0.1045 3.66 0.00461 2.44 0.00137 2.50 27.7 0.7KA044 24 2.12m 12 821 8090 1260 9.89 0.2780 8.13 0.00320 4.73 0.00106 3.88 21.4 0.8KA044 25 3.1 89 1287 66300 816 53.91 0.1013 5.86 0.00388 2.32 0.00096 2.30 19.3 0.4KA044 26 3.2 93 2010 56500 1320 30.40 0.0958 4.57 0.00417 2.49 0.00117 2.41 23.6 0.6KA044 27 3.3 144 5210 64200 2400 12.80 0.0740 3.41 0.00549 2.24 0.00163 2.37 32.8 0.8KA044 28 3.4 142 5590 60100 1970 11.28 0.0716 3.51 0.00557 2.31 0.00170 2.36 34.3 0.8KA044 29 3.5 152 5300 60100 2350 11.66 0.0735 3.55 0.00582 2.35 0.00181 2.41 36.6 0.9KA044 30 3.6 140 5140 58300 2590 11.64 0.0727 3.64 0.00562 2.40 0.00172 2.39 34.8 0.8Table 4.1. (continued)Concentration (ppm)* Measured Isotopic Ratios Ages (Ma)48AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA044 31 4.1fx 65 2182 21280 361 9.67 0.0946 3.93 0.00630 2.62 0.00219 2.63 44.3 1.2KA044 40 4.1 88 3310 32500 539 10.37 0.0755 3.83 0.00577 2.62 0.00191 2.61 38.5 1.0KA044 41 4.11 64 2517 25800 558 10.91 0.0822 3.94 0.00539 2.86 0.00173 3.05 34.9 1.1KA044 42 4.12 75 2466 34100 397 14.68 0.1012 4.01 0.00484 2.43 0.00154 2.46 31.1 0.8KA044 32 4.2 61 1736 31300 343 17.81 0.1285 4.27 0.00446 2.70 0.00140 2.62 28.3 0.7KA044 33 4.3 88 3006 33400 440 11.01 0.0747 3.93 0.00574 2.46 0.00189 2.62 38.2 1.0KA044 34 4.4 84 3124 31430 501 9.98 0.0735 3.96 0.00579 2.48 0.00195 2.69 39.3 1.1KA044 35 4.5 32 1837 28000 3230 15.03 0.0714 7.62 0.00238 2.80 0.00080 2.55 16.1 0.4KA044 36 4.6 90 2141 41300 355 19.32 0.1115 4.09 0.00493 2.49 0.00154 2.60 31.1 0.8KA044 37 4.7 84 3190 31600 535 10.01 0.0752 3.76 0.00578 2.50 0.00191 2.64 38.5 1.0KA044 38 4.8 77 2946 29000 538 10.01 0.0780 3.95 0.00565 2.65 0.00189 2.85 38.1 1.1KA044 39 4.9 99 3750 37100 488 10.27 0.0732 3.79 0.00576 2.75 0.00191 2.87 38.6 1.1KA044 43 6.1 79 1287 56000 860 45.70 0.2480 5.35 0.00447 4.01 0.00105 3.89 21.2 0.8KA044 44 6.2 64 3050 52400 2280 17.76 0.0761 5.06 0.00300 2.52 0.00086 2.62 17.4 0.5KA044 45 6.3 74 1046 45000 930 44.50 0.1483 5.88 0.00409 3.04 0.00115 2.60 23.3 0.6KA044 46 6.4 81 1698 61000 1210 36.78 0.0868 6.60 0.00359 2.40 0.00094 2.51 19.1 0.5KA044 47 6.5 92 1429 59300 1210 41.77 0.0989 5.71 0.00377 3.05 0.00111 2.52 22.4 0.6KA044 48 6.6 58 5170 50200 6800 9.47 0.0629 4.85 0.00249 2.50 0.00084 2.65 17.0 0.5KA044 49 8.1Grt 175 3040 107000 182 32.43 0.1522 3.70 0.00468 2.70 0.00118 2.74 23.9 0.7KA044 50 9.1f 80 1390 50000 123 32.79 0.1537 6.06 0.00468 7.69 0.00116 7.07 23.4 1.7KA044 51 9.2f 18 400 14300 - 32.36 0.1560 8.86 0.00430 13.84 0.00108 13.09 21.9 2.9KA044 52 9.3f 27 479 4750 43 9.27 0.1000 10.34 0.00716 4.56 0.00406 5.49 81.8 4.5KA044 53 9.4f 32 777 5510 119 6.76 0.0847 7.80 0.00712 4.45 0.00419 5.34 84.4 4.5KA044 54 9.5f 18 554 3570 23 6.39 0.1010 13.22 0.00615 7.85 0.00368 8.89 74.2 6.6KA044 55 9.6f 9 215 1600 - 7.82 0.1410 13.11 0.00734 9.30 0.00381 10.92 76.8 8.4KA044 56 9.7f 11 267 1970 - 7.58 0.1460 16.71 0.00765 9.84 0.00388 11.74 78.2 9.2KA044 57 9.8f 35 1093 8020 69 7.81 0.1130 5.13 0.00572 3.63 0.00311 5.17 62.8 3.2KA044 58 10.1x, fx 112 606 68600 1250 115.07 0.3290 6.24 0.00622 4.40 0.00115 2.37 23.3 0.6KA044 59 10.2 111 831 70000 691 89.13 0.1663 6.29 0.00489 2.88 0.00112 2.45 22.5 0.6KA044 60 10.3 76 1440 43300 355 31.67 0.1451 4.83 0.00448 2.65 0.00123 2.57 24.8 0.6KA044 61 10.4 91 3900 45500 569 11.96 0.1226 3.98 0.00472 2.49 0.00143 2.40 29.0 0.7KA044 62 10.5 106 3034 66100 890 21.51 0.1229 3.77 0.00421 2.60 0.00115 2.60 23.3 0.6Table 4.1. (continued)Concentration (ppm)* Measured Isotopic Ratios Ages (Ma)49AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA044 66 11.2 127 4900 72900 751 14.93 0.1176 3.73 0.00439 2.47 0.00123 2.57 24.9 0.6KA044 67 11.3 129 4380 62700 910 14.25 0.1687 3.43 0.00517 2.34 0.00146 2.39 29.4 0.7KA044 68 11.4 129 4460 69000 684 15.33 0.1101 3.55 0.00466 2.33 0.00133 2.43 26.9 0.7KA044 69 11.5 146 4740 74300 703 15.56 0.1152 3.56 0.00481 2.29 0.00140 2.29 28.3 0.6KA044 70 11.6m 9 370 5900 - 15.57 0.1050 16.47 0.00360 30.61 0.00106 31.19 21.4 6.7KA055 1 1.1 74 13340 60600 13200 4.67 0.0517 3.91 0.00265 2.28 0.00086 2.38 17.5 0.4KA055 2 1.2 76 12270 60200 9600 4.99 0.0521 3.90 0.00272 2.23 0.00089 2.29 18.0 0.4KA055 3 1.3 82 10370 62600 8600 6.20 0.0526 3.77 0.00283 2.22 0.00093 2.32 18.7 0.4KA055 4 1.4 75 9280 57900 7700 6.45 0.0551 3.93 0.00285 2.30 0.00092 2.46 18.7 0.5KA055 5 1.5 75 9630 60100 7890 6.36 0.0512 4.19 0.00277 2.31 0.00089 2.42 18.1 0.4KA055 6 2.1x, e 3 159 483 38 2.84 0.1240 46.07 0.00633 8.56 0.00439 14.02 89.0 12.5KA055 7 2.2x, e 9 658 2030 109 2.91 0.0728 12.99 0.00437 4.29 0.00338 5.36 68.2 3.7KA055 8 2.3x, e 4 326 1023 80 3.00 0.0820 28.21 0.00415 6.98 0.00300 7.24 60.6 4.4KA055 9 2.4x, e 9 672 2020 127 2.74 0.0610 16.67 0.00437 4.50 0.00317 5.08 64.1 3.3KA055 10 2.5x, e 9 602 1910 130 2.87 0.0690 19.08 0.00529 8.14 0.00333 8.32 67.2 5.6KA055 11 2.6x, e 9 675 1910 74 2.56 0.0734 12.62 0.00415 4.92 0.00324 5.56 65.3 3.6KA055 12 2.7x, e 10 678 2180 134 2.86 0.0591 12.88 0.00447 5.03 0.00326 5.53 65.7 3.6KA055 13 3.1 211 14420 143400 3300 9.17 0.0550 3.33 0.00351 2.23 0.00109 2.30 22.1 0.5KA055 14 3.2 138 10920 87200 2930 7.59 0.0560 3.59 0.00354 2.42 0.00117 2.47 23.6 0.6KA055 15 3.3 114 11540 74600 2980 6.34 0.0570 3.40 0.00350 2.43 0.00113 2.39 22.7 0.5KA055 16 3.4 118 10410 78100 3270 7.59 0.0589 3.45 0.00349 2.32 0.00112 2.34 22.6 0.5KA055 17 3.5 134 11060 88500 3590 8.32 0.0543 3.46 0.00352 2.31 0.00111 2.40 22.4 0.5KA055 18 3.6 82 8940 68000 8700 8.10 0.0540 3.63 0.00280 2.44 0.00088 2.37 17.8 0.4KA055 19 3.7 106 9060 71000 4060 8.89 0.0624 3.56 0.00342 2.43 0.00108 2.43 21.7 0.5KA055 20 3.8 89 9980 72800 12200 8.27 0.0555 3.60 0.00274 2.27 0.00087 2.38 17.6 0.4KA055 21 4.1 80 10250 65800 12000 7.24 0.0530 3.88 0.00282 2.43 0.00087 2.46 17.5 0.4KA055 22 4.2 77 7960 58500 5430 8.10 0.0557 3.50 0.00306 2.33 0.00094 2.44 19.1 0.5KA055 23 4.3m 6 672 3350 960 5.31 0.2140 12.97 0.00325 7.00 0.00131 10.09 26.5 2.7KA055 24 4.4 109 9650 69700 3220 7.73 0.0556 3.59 0.00357 2.26 0.00112 2.29 22.6 0.5KA055 25 4.5 97 11010 72000 6910 6.64 0.0539 3.53 0.00306 2.30 0.00093 2.25 18.9 0.4KA055 26 4.6 81 12200 68300 12000 5.65 0.0536 3.50 0.00267 2.29 0.00083 2.43 16.7 0.4KA055 27 5.1 124 11610 85100 5800 7.39 0.0537 3.46 0.00333 2.32 0.00101 2.37 20.5 0.5Table 4.1. (continued)Concentration (ppm)* Measured Isotopic Ratios Ages (Ma)50AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA055 28 5.2 85 11990 71900 27400 6.20 0.0531 3.76 0.00249 2.49 0.00080 2.55 16.2 0.4KA055 29 5.3 127 10080 80900 4510 8.28 0.0534 3.64 0.00349 2.36 0.00106 2.33 21.4 0.5KA055 30 5.4m 16 2370 12100 8100 5.17 0.1070 14.34 0.00276 4.37 0.00091 4.47 18.4 0.8KA055 31 5.5 129 9970 83000 4260 8.65 0.0529 3.76 0.00348 2.22 0.00104 2.28 21.1 0.5KA055 32 5.6 132 12260 81600 3800 7.00 0.0531 3.48 0.00341 2.30 0.00107 2.38 21.6 0.5KA055 33 6.1 118 13690 72200 3080 5.58 0.0544 3.48 0.00339 2.39 0.00110 2.41 22.2 0.5KA055 34 6.2 124 14200 79800 4380 5.92 0.0542 3.52 0.00332 2.39 0.00106 2.39 21.4 0.5KA055 35 6.3 162 14420 103400 3420 7.44 0.0550 3.27 0.00342 2.26 0.00109 2.31 21.9 0.5KA055 36 6.4 82 16190 72000 16100 4.55 0.0525 3.66 0.00250 2.19 0.00080 2.39 16.1 0.4KA055 37 6.5 146 16540 99980 4800 6.07 0.0535 3.37 0.00322 2.28 0.00103 2.30 20.8 0.5KA055 38 6.6 103 14960 77400 10600 5.15 0.0531 3.45 0.00286 2.42 0.00094 2.44 19.1 0.5KA055 39 7.1 92 7800 59600 2700 7.20 0.0664 3.94 0.00359 2.38 0.00115 2.42 23.3 0.6KA055 40 7.2m, x 21 2810 13200 1760 4.19 0.1056 5.69 0.00312 2.88 0.00125 3.37 25.1 0.8KA055 41 7.3m, x 4 390 750 - 1.83 0.1620 23.04 0.00327 11.46 0.00306 18.39 62.0 11.4KA055 42 7.4m, x 7 169 260 - 1.39 0.1790 27.54 0.00400 32.55 0.00409 14.54 83.0 12.1KA055 43 7.5 111 10150 73700 2770 7.10 0.0600 3.91 0.00355 2.30 0.00113 2.33 22.9 0.5KA055 44 7.6x 15 340 2100 3 7.69 0.0490 100.04 0.00160 100.02 0.00060 100.02 12.0 12.0KA055 45 8.1 68 10120 52000 18400 5.20 0.0686 4.29 0.00280 2.74 0.00093 2.75 18.8 0.5KA055 46 8.2 45 6630 37900 7460 5.89 0.0925 4.34 0.00263 2.76 0.00085 2.81 17.2 0.5KA055 47 8.3 95 15070 80700 5860 5.54 0.0537 3.63 0.00266 2.47 0.00084 2.49 17.0 0.4KA055 48 8.4 81 11800 67200 11050 6.04 0.0588 4.05 0.00264 2.56 0.00083 2.67 16.8 0.4KA055 49 8.5 97 13870 75900 8700 5.78 0.0571 3.77 0.00273 2.27 0.00088 2.30 17.8 0.4KA055 50 8.6 62 8040 43900 9060 5.76 0.0594 4.26 0.00286 2.79 0.00098 2.83 19.8 0.6KA055 51 9.1 117 15660 84100 11400 5.79 0.0575 3.76 0.00279 2.47 0.00092 2.54 18.5 0.5KA055 52 9.2 123 18330 97600 16300 5.71 0.0663 4.25 0.00261 2.42 0.00083 2.50 16.8 0.4KA055 53 9.3 36 4350 23800 3500 5.94 0.0685 5.80 0.00295 3.12 0.00100 3.36 20.2 0.7KA055 54 9.4 142 11990 81300 3640 7.28 0.0577 3.65 0.00359 2.42 0.00115 2.42 23.2 0.6KA055 55 9.5x 23 1350 11900 560 9.79 0.0728 11.13 0.00539 11.83 0.00130 7.62 26.2 2.0KA055 56 9.6 59 9490 45100 9300 5.03 0.0748 5.90 0.00278 3.55 0.00087 4.21 17.6 0.7KA055 57 9.7 116 14830 87300 9600 5.92 0.0561 3.58 0.00285 2.40 0.00091 2.62 18.5 0.5KA055 58 10.1 130 13740 102200 9700 7.41 0.0572 3.46 0.00286 2.32 0.00089 2.43 18.0 0.4KA055 59 10.2 209 21210 135300 4690 6.34 0.0545 3.42 0.00342 2.28 0.00108 2.21 21.7 0.5KA055 60 10.3 213 21920 137900 4660 6.22 0.0538 3.37 0.00341 2.20 0.00109 2.31 21.9 0.5Table 4.1. (continued)Concentration (ppm)* Measured Isotopic Ratios Ages (Ma)51AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA055 61 10.4 187 19210 127300 4350 6.42 0.0547 3.42 0.00336 2.41 0.00105 2.52 21.2 0.5KA055 62 10.5 175 16290 114200 4730 6.81 0.0533 3.46 0.00350 2.35 0.00111 2.40 22.5 0.5KA058B 1 1.1e 33 4060 23700 - 5.53 0.1250 26.57 0.00357 8.32 0.00125 8.99 25.3 2.3KA058B 2 1.2m 19 2590 13500 1860 4.86 0.1225 4.93 0.00310 2.84 0.00112 2.97 22.6 0.7KA058B 3 1.3 70 11620 46100 2820 3.83 0.0554 3.81 0.00343 2.32 0.00117 2.46 23.7 0.6KA058B 4 1.4 110 18910 70500 3800 3.67 0.0516 3.42 0.00353 2.22 0.00118 2.45 23.9 0.6KA058B 5 1.5 89 14580 62600 3630 4.27 0.0543 3.62 0.00330 2.19 0.00107 2.50 21.7 0.5KA058B 6 1.6m 1 659 272 66 0.21 0.0920 17.65 0.00342 4.47 0.00109 85.34 22.0 18.8KA058B 7 2.1 149 21970 97800 4480 4.37 0.0552 3.60 0.00349 2.09 0.00115 2.42 23.3 0.6KA058B 8 2.2 68 11320 52800 6560 4.48 0.0782 3.78 0.00294 2.52 0.00094 2.67 19.0 0.5KA058B 9 3.1Grt 209 24080 108300 5610 4.27 0.0529 3.23 0.00460 3.72 0.00145 2.98 29.3 0.9KA058B 10 3.2Grt 240 26350 115500 5410 4.12 0.1409 4.92 0.00463 3.71 0.00173 3.33 34.9 1.2KA058B 11 3.3Grt 168 24360 112100 4810 4.23 0.0512 3.33 0.00351 2.13 0.00110 2.19 22.3 0.5KA058B 12 3.4Grt 166 25570 112300 5360 3.99 0.0522 3.37 0.00347 2.12 0.00108 2.16 21.8 0.5KA058B 13 4.1i 796 17210 133400 8060 7.23 0.0604 3.39 0.01093 3.83 0.00496 5.56 100.1 5.6KA058B 14 4.2 199 8120 73100 3540 8.55 0.1070 3.86 0.00633 2.50 0.00203 3.52 41.0 1.4KA058B 15 4.3i 667 15240 109800 7200 7.04 0.0595 3.39 0.01220 2.61 0.00482 2.75 97.1 2.7KA058B 16 4.4i 636 12530 109600 8910 8.69 0.0588 3.16 0.01380 8.88 0.00416 8.85 84.7 7.5KA058B 17 5.1m, e 15 2283 7070 1140 3.09 0.1134 4.97 0.00313 3.95 0.00155 5.30 31.3 1.7KA058B 18 5.2i 462 4010 13450 3240 3.49 0.0575 3.18 0.05570 4.02 0.02380 5.37 476.0 25.6KA058B 19 5.3i 1264 4860 29810 7700 6.54 0.0589 3.06 0.08010 2.60 0.02991 3.31 596.0 19.7KA058B 20 5.4i 1245 6660 35000 9700 5.51 0.0602 3.05 0.06670 2.44 0.02521 2.92 503.0 14.7KA058B 21 5.5i 832 8220 42500 6300 5.38 0.0583 3.09 0.03640 3.76 0.01378 3.50 276.6 9.7KA058B 22 5.6i 1281 2870 29200 9100 10.60 0.0647 3.08 0.08380 2.54 0.03114 2.96 620.0 18.4KA058B 23 5.7i 772 1557 15560 6460 10.40 0.0627 3.33 0.08670 2.93 0.03460 3.41 687.0 23.4KA058B 24 5.8i 999 2312 18120 5400 7.98 0.0601 3.13 0.08780 2.90 0.04030 3.72 797.0 29.6KA058B 25 6.1 283 28940 110900 5380 3.95 0.0537 3.22 0.00541 2.57 0.00181 2.97 36.5 1.1KA058B 26 6.2 83 14280 58200 3740 4.21 0.0991 4.33 0.00314 2.42 0.00101 2.50 20.4 0.5KA058B 27 6.3i 1140 22010 110400 12000 5.20 0.0565 3.05 0.02040 7.09 0.00714 7.51 144.0 10.8Table 4.1. (continued)Concentration (ppm)* Measured Isotopic Ratios Ages (Ma)52AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA058B 28 6.4i 929 31470 128200 9500 4.22 0.0562 3.17 0.01332 3.44 0.00536 3.35 108.0 3.6KA058B 29 6.5m 11 1193 4070 230 3.42 0.2190 7.48 0.00411 4.51 0.00200 5.80 40.4 2.3KA058B 30 6.6 61 10850 44600 3660 4.25 0.0998 4.32 0.00288 2.36 0.00097 2.48 19.5 0.5KA058B 31 7.1Grt 3070 21030 100000 16000 4.79 0.0580 3.04 0.06940 2.60 0.02345 2.73 468.5 12.8KA058B 32 8.1x 958 15820 147400 7200 9.46 0.1422 5.82 0.02670 3.06 0.00499 2.88 100.6 2.9KA058B 33 8.2i 3310 27950 103600 28900 3.67 0.0595 3.01 0.07340 2.26 0.02264 2.44 452.6 11.0KA058B 34 8.3i 1678 6200 56900 13200 9.00 0.0613 3.19 0.07580 2.77 0.01979 2.89 396.0 11.5KA058B 35 8.4 165 18940 100100 6400 5.10 0.0717 3.58 0.00410 2.86 0.00112 2.77 22.6 0.6KA058B 36 8.5m, x 255 3690 83400 4470 20.58 0.1561 5.03 0.02670 6.26 0.00217 4.49 43.9 2.0KA058B 37 9.1i 3233 31520 128300 15300 4.19 0.0579 3.05 0.06200 3.15 0.02017 4.11 404.0 16.6KA058B 38 9.2 271 23500 124900 4210 5.83 0.0535 3.28 0.00427 2.92 0.00146 5.14 29.5 1.5KA058B 39 9.3 164 27060 107200 5220 4.33 0.0566 3.57 0.00340 2.18 0.00108 2.43 21.8 0.5KA058B 40 9.4 91 15310 56900 8090 4.11 0.1588 4.00 0.00331 2.49 0.00115 2.54 23.1 0.6KA058B 41 10.1 285 26630 129300 4000 5.54 0.0537 3.24 0.00540 4.97 0.00151 5.23 30.5 1.6KA058B 42 10.2i 1931 35560 129500 13300 4.13 0.0567 3.06 0.03600 4.29 0.01128 4.08 226.6 9.2KA058B 43 10.3i 736 26520 126900 8400 5.65 0.0571 3.11 0.01050 6.26 0.00424 6.86 85.5 5.9KA058B 44 10.4 84 11550 48600 1860 4.90 0.0937 4.47 0.00364 3.52 0.00136 2.94 27.4 0.8KA058B 45 10.5 78 17380 60900 3480 3.95 0.0639 3.62 0.00291 2.37 0.00095 2.51 19.1 0.5KA058B 46 10.6 114 21760 82300 3660 4.25 0.0524 3.43 0.00317 2.29 0.00102 2.49 20.5 0.5KA058B 47 10.7 102 16800 80200 7700 5.18 0.0948 7.68 0.00296 2.36 0.00092 2.54 18.6 0.5KA064A 7 1.1 98 3210 69900 27500 11.25 0.0672 4.44 0.00330 2.19 0.00101 2.15 20.5 0.4KA064A 8 1.2 86 3070 62000 29400 10.69 0.0661 4.83 0.00333 2.12 0.00102 2.14 20.6 0.4KA064A 9 1.3 93 3318 67200 29900 11.05 0.0650 4.41 0.00331 2.22 0.00102 2.14 20.7 0.4KA064A 10 1.4 99 3090 70300 28400 12.97 0.0671 4.90 0.00337 2.19 0.00103 2.24 20.9 0.5KA064A 11 1.5 102 3290 72900 30000 13.17 0.0638 4.57 0.00330 2.17 0.00103 2.19 20.7 0.5KA064A 12 1.6 95 3104 67700 26300 13.62 0.0609 4.82 0.00328 2.21 0.00103 2.29 20.8 0.5KA064A 1 2.1 106 6100 38700 13100 4.59 0.0611 3.36 0.00627 2.08 0.00197 2.11 39.7 0.8KA064A 2 2.2 115 7490 42900 14600 3.81 0.0585 3.26 0.00614 2.00 0.00192 2.10 38.7 0.8KA064A 3 2.3 122 7850 44200 16500 3.54 0.0580 3.29 0.00626 2.15 0.00198 2.27 40.1 0.9KA064A 4 2.4 111 6770 41500 17400 3.59 0.0562 3.79 0.00607 2.44 0.00191 2.33 38.6 0.9KA064A 5 2.5m 15 415 6150 10340 8.47 0.3660 6.72 0.00621 3.55 0.00183 3.30 36.9 1.2Table 4.1. (continued)Concentration (ppm)* Measured Isotopic Ratios Ages (Ma)53AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA064A 6 2.6m 138 9620 46000 16800 2.62 0.0572 3.47 0.00617 2.18 0.00222 2.40 44.9 1.1KA064A 13 3.1Grt 61 2293 35400 13900 12.17 0.0822 4.36 0.00362 2.22 0.00124 2.25 25.1 0.6KA064A 14 3.1Grt 295 5280 113500 8310 17.82 0.0697 3.61 0.00628 2.25 0.00191 2.27 38.5 0.9KA064A 15 3.1Grt 124 2433 49300 4260 17.73 0.0716 5.98 0.00573 2.90 0.00185 3.28 37.3 1.2KA064A 16 3.1Grt 52 1569 24660 7930 14.64 0.0704 10.39 0.00411 3.64 0.00154 3.24 31.1 1.0KA064A 17 3.1Grt, i 646 3770 86100 10200 22.43 0.0591 3.23 0.02790 4.01 0.00524 4.07 105.6 4.3KA064A 18 3.1Grt, i 347 6960 9980 24300 1.43 0.0580 3.03 0.07585 2.09 0.02489 2.14 496.8 10.7KA064A 19 4.1i 2215 6360 119900 22040 19.32 0.0587 3.10 0.03961 2.56 0.01338 2.43 268.6 6.5KA064A 20 4.2 182 5566 82600 20600 17.70 0.0658 3.68 0.00488 4.10 0.00153 3.82 30.8 1.2KA064A 21 4.3 221 4460 80700 6220 22.15 0.0665 3.66 0.00646 2.09 0.00194 2.12 39.1 0.8KA064A 22 4.4 227 4750 86000 6460 22.34 0.0650 3.44 0.00634 2.06 0.00190 2.13 38.3 0.8KA064A 23 4.5 226 4610 84100 6930 22.83 0.0659 3.59 0.00647 2.15 0.00193 2.12 38.9 0.8KA064A 24 4.6 237 4830 87700 6570 22.72 0.0649 3.70 0.00646 2.20 0.00194 2.20 39.2 0.9KA064A 25 4.7 202 4900 78000 11700 20.05 0.0644 3.70 0.00618 2.16 0.00185 2.26 37.4 0.8KA064A 26 4.8 133 6820 73700 27800 13.68 0.0640 3.71 0.00428 2.16 0.00130 2.27 26.2 0.6KA064A 27 4.9 95 2973 69000 23500 29.55 0.0591 5.61 0.00335 2.14 0.00098 2.16 19.9 0.4KA064A 28 4.10 105 5860 64900 29500 13.99 0.0630 3.73 0.00390 2.27 0.00117 2.25 23.7 0.5KA064A 29 4.11 129 6950 70600 26500 12.73 0.0620 3.57 0.00429 2.11 0.00131 2.18 26.5 0.6KA064A 30 4.12 181 4660 67400 8400 18.12 0.0616 3.58 0.00642 2.22 0.00192 2.20 38.9 0.9KA064A 31 5.1 89 2962 65200 20700 27.55 0.0567 5.63 0.00335 2.32 0.00098 2.34 19.8 0.5KA064A 32 5.2 53 1573 33560 8400 26.38 0.2251 5.07 0.00477 3.27 0.00113 2.89 22.7 0.7KA064A 33 5.3 116 6550 56200 23100 10.55 0.0631 3.47 0.00464 2.28 0.00145 2.35 29.4 0.7KA064A 34 5.4 138 4280 51200 5500 14.64 0.0648 4.42 0.00639 2.72 0.00197 2.71 39.8 1.1KA064A 35 5.5 146 4330 54100 5960 15.36 0.0664 3.43 0.00630 2.25 0.00191 2.21 38.6 0.9KA064A 36 5.6 127 6950 60000 13400 10.65 0.0642 5.17 0.00473 2.94 0.00149 2.99 30.1 0.9KA064A 37 6.1 98 6300 50500 24200 9.64 0.0606 3.42 0.00435 2.27 0.00137 2.36 27.6 0.7KA064A 38 6.2 85 3480 59100 30500 18.48 0.0661 4.48 0.00335 2.26 0.00102 2.25 20.5 0.5KA064A 39 6.3 85 3690 59100 32300 16.20 0.0641 4.33 0.00334 2.34 0.00103 2.24 20.7 0.5KA064A 40 6.4 81 3640 56900 31600 15.07 0.0649 4.30 0.00334 2.16 0.00102 2.19 20.7 0.5KA064A 41 6.5 76 3740 54000 32200 13.27 0.0624 4.27 0.00332 2.29 0.00102 2.25 20.5 0.5KA064A 42 6.6 85 3570 64000 18800 15.78 0.0629 6.60 0.00321 3.03 0.00097 2.85 19.5 0.6KA064A 43 7.1 65 3177 42400 27100 11.30 0.0648 4.77 0.00346 2.33 0.00109 2.30 22.1 0.5KA064A 44 7.2 50 2692 31100 17100 9.15 0.1066 3.81 0.00434 2.40 0.00118 2.51 23.9 0.6Table 4.1. (continued)Concentration (ppm)* Measured Isotopic Ratios Ages (Ma)54AnalysisSample Number Grain.Spot Pb (ppm) U (ppm) Th (ppm) Y ppm Th/U Pb207/Pb206 2s% Pb206/U238 2s% Pb208/Th232 2s% Pb208/Th232 2s absKA064A 45 7.3 99 6280 48600 22000 6.23 0.0611 3.36 0.00498 2.41 0.00150 2.44 30.4 0.7KA064A 46 7.4 120 6240 49900 15700 6.61 0.0611 3.42 0.00559 2.36 0.00177 2.47 35.7 0.9KA064A 47 7.5 113 6230 44000 16000 5.90 0.0615 3.49 0.00578 2.48 0.00189 2.44 38.2 0.9KA064A 48 7.6 107 5730 41500 12900 6.08 0.0624 3.48 0.00597 2.83 0.00193 2.67 38.9 1.0KA064A 49 8.1 105 4780 38100 9070 6.70 0.0606 3.51 0.00646 2.20 0.00205 2.27 41.5 0.9KA064A 50 8.2 67 2747 48700 14800 13.27 0.0684 5.31 0.00328 2.42 0.00103 2.36 20.7 0.5KA064A 51 8.3 93 7330 45900 23900 4.55 0.0605 3.43 0.00466 2.42 0.00151 2.48 30.5 0.8KA064A 52 8.4 100 7690 48300 27100 4.49 0.0606 3.31 0.00467 2.28 0.00154 2.38 31.0 0.7KA064A 53 8.5 94 7490 47400 28000 4.45 0.0588 3.45 0.00454 2.30 0.00148 2.33 29.9 0.7KA064A 54 8.6 86 7530 46900 26000 4.44 0.0603 3.51 0.00424 2.33 0.00138 2.35 27.9 0.7KA064A 55 8.7 82 7030 45000 24400 4.68 0.0598 3.70 0.00424 2.23 0.00138 2.27 27.8 0.6KA064A 56 8.8 104 7360 53000 24300 6.97 0.0611 3.59 0.00454 2.31 0.00146 2.34 29.5 0.7KA064A 57 8.9 119 6950 55500 22500 8.33 0.0603 3.43 0.00487 2.41 0.00158 2.39 32.0 0.8KA064A 58 8.1 138 6590 58100 23900 9.96 0.0593 3.39 0.00532 2.37 0.00173 2.46 34.9 0.9KA064A 59 8.11 142 4320 51800 8980 14.14 0.0622 3.75 0.00618 2.41 0.00200 2.45 40.3 1.0KA064A 60 8.12 146 6650 61600 24900 11.31 0.0591 3.44 0.00518 2.26 0.00170 2.33 34.3 0.8KA064A 61 9.1 174 5960 68700 17900 14.33 0.0620 3.41 0.00552 2.39 0.00180 2.49 36.4 0.9KA064A 62 9.2 170 6870 73500 23600 12.99 0.0623 3.48 0.00516 2.41 0.00164 2.48 33.0 0.8KA064A 63 9.3 119 2875 78900 25500 31.35 0.0904 9.13 0.00357 2.54 0.00106 2.33 21.5 0.5KA064A 64 9.4 167 7790 81200 27500 11.46 0.0608 3.50 0.00462 2.48 0.00146 2.52 29.5 0.7KA064A 65 9.5 202 6830 83600 20400 13.09 0.0601 3.42 0.00535 2.49 0.00170 2.52 34.3 0.9KA064A 66 9.6 138 5520 83400 27900 15.56 0.0687 3.63 0.00372 2.29 0.00116 2.42 23.4 0.6KA064A 67 10.1 133 3160 92100 18300 29.03 0.0660 4.60 0.00338 2.47 0.00101 2.44 20.3 0.5KA064A 68 10.2 125 3350 85000 23700 22.46 0.0656 4.97 0.00339 2.50 0.00104 2.47 20.9 0.5KA064A 69 10.3 132 3480 91200 25800 22.85 0.0660 4.95 0.00337 2.47 0.00102 2.42 20.7 0.5KA064A 70 10.4 131 3480 90700 26700 22.71 0.0640 4.45 0.00339 2.46 0.00103 2.55 20.8 0.5KA064A 71 10.5 242 5380 89600 10800 14.44 0.0628 3.47 0.00620 2.39 0.00193 2.48 39.0 1.0KA064A 72 11.1Grt, m 186 7120 83100 24000 10.04 0.0599 3.52 0.00516 2.41 0.00160 2.55 32.3 0.8ell elliptical spotTable 4.1. (continued)Concentration (ppm)* Measured Isotopic Ratios Ages (Ma)m missed grainx high error/ strongly discordantfx fracturee instrument errorI inherited ageGrt grain included in garnet* concentrations normalized to the primary standard55Figure 4.2 Location of analyzed monazite grains in thin section12345678910115 mmKA064A123456789105 mmKA058B123 456789105 mmKA055KA04412345678910115 mmKA044125436789105 mmKA03712345 678910 5 mmKA034123456789105 mmKA031B123457689105 mmKA007Figure 4.2. Location of monazite grains analyzed for petrochronology. Numbers corresponds to grains listed in Table 4.1.56Figure 4.3 Monazite petrochronology diagrams050001000015000200002500012 13 14 15 16 17 18 19 2012141618200.00160.00200.00240.00280.00320.0005 0.0006 0.0007 0.0008 0.0009 0.0010 0.0011206 Pb/238 U208Pb/ 232Th14.5±0.416.5±0.417.2±0.416.7±0.416.9±0.414.9±0.512 3456Grain 4208Pb/ 232Th Age (Ma)Y (ppm)050001000015000200002500013 15 17 19 21 23 25141822260.00160.00200.00240.00280.00320.00360.00400.00440.0005 0.0007 0.0009 0.0011 0.0013206 Pb/238 U208Pb/ 232Th13.7±0.3 23.0±0.5 22.1±0.521.1±0.51234Grain 5208Pb/ 232Th Age (Ma)Y (ppm)02000040000600008000010000012000014000016000018000020000017 19 21 23 25 27 29 31208Pb/ 232Th Age (Ma)Y (ppm)18222630340.0020.0030.0040.0050.0007 0.0009 0.0011 0.0013 0.0015 0.0017206 Pb/238 U208Pb/ 232Th12345621.3±0.730.7±0.722.1±0.819.9±0.518.9±0.418.9±0.4Grain 10KA007KA031BKA034571416182022240.00200.00240.00280.00320.00360.00400.00065 0.00075 0.00085 0.00095 0.00105 0.00115 0.00125206 Pb/238 U208Pb/ 232Th05000100001500020000250003000015 16 17 18 19 20 21 22 23 24208Pb/ 232Th Age (Ma)Y (ppm)12345678 22.1±0.523.6±0.622.7±0.522.6±0.522.4±0.517.8±0.421.7±0.517.6±0.41216202428323640440.00150.00250.00350.00450.00550.00650.0004 0.0008 0.0012 0.0016 0.0020 0.0024206 Pb/238 U208Pb/ 232Th01000200030004000500060007000800014 19 24 29 34 39208Pb/ 232Th Age (Ma)Y (ppm)1 23 45621.2±0.817.4±0.523.3±0.619.1±0.522.4±0.617.0±0.5Grain 6Grain 3161820220.00220.00260.00300.00340.00380.0007 0.0008 0.0009 0.0010 0.0011206 Pb/238 U208Pb/ 232Th0200040006000800010000120001400015 16 17 18 19 20208Pb/ 232Th Age (Ma)Y (ppm)12345620.1±0.520.1±0.520.2±0.520.4±0.519.1±0.515.9±0.4Grain 7KA044KA037KA0555816202428323640440.0020.0030.0040.0050.0060.0070.0006 0.0010 0.0014 0.0018 0.0022206 Pb/238 U208Pb/ 232Th0500010000150002000025000300003500018 23 28 33 38 4301002003004005000.000.020.040.060.080.0 0.2 0.4 0.6206 Pb/238 U207 Pb/ 235 UIntercepts at -19 ± 16 & 562 ± 82 MaMSW D= 25208Pb/ 232Th Age (Ma)Y (ppm)12345678910111241.5±0.920.7±0.530.5±0.831.0±0.727.9±0.729.9±0.727.8±0.629.5±0.732.0±0.834.9±0.940.3±1.034.3±0.8Grain 8010002000300040005000600070008000900016 21 26 31 36 41208Pb/ 232Th Age (Ma)Y (ppm)16202428323640440.0020.0030.0040.0050.0060.0070.0006 0.0010 0.0014 0.0018 0.0022206 Pb/238 U208Pb/ 232Th01002003004005006000.000.020.040.060.080.100.0 0.2 0.4 0.6 0.8206 Pb/238 U207 Pb/ 235 UIntercepts at -13± 25 & 624 ± 41 MaMSW D = 115404.0±16.6 29.5.0±1.521.8±0.523.1±0.61 234Grain 6KA058BKA064A59KA031BSpecimen KA031B, a Sil + Ky + Grt + Bt + Qz + Pl + Ms gneiss, is the structurally lowest specimen north of the Tamor Window (Figure 2.1, 3.1). It is located ~1,550 m structurally above the MCT (2.2). Monazite in this specimen occurs both in the matrix and as inclusions in garnet (Figure 4.2). Grains that occur in the matrix are anhedral to subhedral and equant to elongate in shape, 30 to 120 µm in size and commonly spatially associated with muscovite. The three grains analyzed that occur as inclusions within garnet are anhedral and range from 25 to 50 µm in size. Element maps for all grains show irregular zoning in Th, U and Y. Y maps generally show lower concentrations in the core and higher concentrations towards the rim (Figure 4.3). 46 analyses were performed on 10 grains (Table 4.1). Analysis of matrix grains yielded dates spanning from 23.1 ± 0.5 Ma to 13.7 ± 0.3 Ma. Analyses on grains included within garnet yielded dates ranging from 24.1 ± 0.5 Ma to 18.4 ± 0.5 Ma. There is a negative relationship between dates and Y concentration in this specimen for grains that occur in the matrix as well as inclusions in garnet (Figure 4.3). From ca. 24 to 20 Ma, Y concentrations range between ~330 and 2,800 ppm and show a slight increase with decreasing date. From ca. 20 and 14 Ma, concentrations are higher (~3,600 -21,000 ppm) and increase sharply with decreasing date.KA034Specimen KA034 is a Bt + Grt + Fsp + Qz gneiss located approximately 2,400 m structurally above the previous specimen (Figure 2.1, 2.2, 3.1). Monazite grains in this specimen occur solely within the matrix, are anhedral to subhedral and equant to elongate in shape, 50-120 µm in size and are typically associated with quartz and less commonly biotite and plagioclase (Figure 4.2). Element maps demonstrate weak irregular zoning of Th and U. Y maps generally show a thin rim with high concentrations and lower concentrations in the core (Figure, 4.3). 56 spot analyses were performed on 10 grains (Table 4.1). All analyses from grain 8 were omitted as the laser pits are highly elliptical and the dates are strongly discordant. Pits that are elliptical in shape are typically the result of an out of focus beam and/or an ablated material with different optical properties than what the beam is calibrated for. Both cases can lead to an increase in error, therefore, such analyses are excluded. Spot 6 on grain 2 was omitted because the pit is on a large fracture and spot 5 on grain 5 was omitted because the analysis missed the intended grain. The remaining 45 analyses yielded dates ranging from 19.2 ± 0.5 to 12.8 ± 0.4 Ma (Figure 4.3). There is a negative relationship between dates and Y concentration in this specimen (Figure 4.3). From ca. 19 Ma to 16 Ma concentrations range between ~1,500 and 4,400 and show a slight increase with decreasing date. From ca. 16 to 13 Ma concentrations range between ~4,400 and ~22,000 and increase sharply with decreasing date.KA037Specimen KA037 is a Grt + Ms + Bi + Fsp + Qz gneiss located approximately 1,750m structurally above the previous specimen (Figure, 2.1, 2.2, 3.1). Monazite grains in this specimen occur solely within the 60matrix, range from 80 - 400 µm in size, are anhedral to subhedral and equant to elongate in shape, and are commonly associated with biotite, quartz, muscovite, and plagioclase (Figure 4.2). Elemental maps show irregular zoning in Th, U and Y. Y maps typically show relatively low concentrations in the core and higher values towards to the rim (Figure 4.3). 54 analyses were performed on 7 grains (Table 4.1). 2 analyses were omitted: Spot 6 on grain 9 missed the intended grain and spot 5 on grain 6 hit a large fracture. The remaining 52 analysis yielded dates range from 20.4 ± 0.5 to 15.9 ± 0.4 Ma. There is a relationship between dates and Y concentration in this specimen (Figure 4.3). From ca. 20 and 19 Ma, concentrations range between ~570 and 5400 ppm and show no discernable trend. From ca. 19 to 16 Ma concentrations range between ~2,000 and 12,000 ppm and increase sharply with decreasing dates.KA044Specimen KA044 is a Sil + Grt + Bt + Fsp + Qz gneiss located approximately 1,350 m structurally above the previous specimen (Figure 2.1, 2.2, 3.1). With one exception, monazite grains occur within the matrix, are anhedral to subhedral and equant to elongate in shape, 50 - 550 µm in size and spatially associated with quartz, plagioclase, K-feldspar, and sillimanite (Figure 4.2). A single 20 µm subhedral monazite, grain 8 (Table 4.1), occurs as an inclusion in garnet. Elemental maps for all grains typically show weak to moderate irregular zoning in Th, U and Y. Y maps show weak zonation with rims typically showing higher concentrations (Figure 4.3). 70 spot analyses were performed on 11 grains. All analyses from grain 9 (8 spots) were omitted as the ablation was weak and the resulting pits are very elliptical. Four other spots were omitted for either being on fractures or missing the grain (Table 4.1). The remaining 62 analyses yielded dates ranging from 39.3 ± 1.1 Ma to 16.1 ± 0.4 Ma (Table 4.1, Figure 4.3). The only analysis from the grain included in garnet (grain 8) yielded a date of 23.9 ± 0.7 Ma. The relationship between dates and Y concentrations is more complicated in this specimen than in those previously discussed at structurally lower levels and help to identify three different populations (Figure 4.3). From ca. 39 to 33 Ma Y concentrations range between ~400 and ~2,500 ppm with no obvious trend. Between ca. 31 Ma and 21 Ma Y concentrations range between ~100 and ~1,600 ppm and show no obvious trend. The youngest dates from this specimen (ca. 19 to 16 Ma) correspond to a sharp increase in Y with concentrations between ~2,300 and ~6,800 ppmKA055Specimen KA055 is a Grt + Bt + Fsp + Qz gneiss located approximately 3,800 m structurally above the previous specimen (Figure 2.1, 2.2, 3.1). Monazite grains occur solely as part of the matrix, are generally anhedral and equant to elongate in shape, 60-120 µm in size, and typically associated with biotite, quartz, and plagioclase (Figure 4.2). Elemental maps show weak, patchy to no zoning in Th and U. Y maps, however, show moderate irregular internal zoning with thin, high concentration rims (Figure 4.3). 62 spots were analyzed on 10 grains (Table, 4.1). All 7 spots from grain 2 were omitted as the pits are highly elliptical and the dates are strongly discordant (Table 4.1). 7 other points were omitted for either falling on 61fractures, missing the intended grain or having a significantly higher error than other analyses (Table 4.1). The remaining 48 analyses range from 23.6 ± 0.6 Ma to 16.1 ± 0.4 Ma. Y concentrations help identify an older and younger population of dates (Figure 4.3). From ca. 24 to 20 Ma, Y concentrations range between ~2,700 and 5,000 and increase slightly with decreasing date. From ca. 20 and 16 Ma, Y concentrations range between 5,400 and 27,000 and show no obvious trend with date.KA058BSpecimen KA058B is a Grt + Bt + Sil + Qz + Fsp gneiss located approximately 4,250 m structurally above the previous specimen (Figure 2.1, 2.2, 4.1). Monazite grains analyzed occur both within the matrix and as inclusions in garnet (Figure 4.2). Grains located in the matrix are anhedral and typically elongate in shape, range from 30 to 100 µm in size, and are commonly associated with feldspar, biotite and quartz (Figure 4.2). Two grains that occur as inclusions in garnet, are anhedral and oblate to elongate in shape, and 25-40 µm is size. 47 spots were analyzed on 10 grains (Table 4.1). 8 spots were excluded for being considerably distant from concordia, missing the intended grain, burning through the grain, or falling on fractures. Dates from the remaining 39 spots define two populations (Figure 4.3). Dates from the older population span from 797.0 ± 29.6 to 84.7 ± 7.5 Ma while the younger population ranges between 41.0 ± 1.0 and 18.6 ± 0.5 Ma (Figure 4.3). In the older population Y concentrations vary between ~3,200 and ~29,000 ppm and show no obvious trend. In the younger population there appear to be 3 different growth events (Figure 4.3). The 2 oldest dates (ca. 41 and 37 Ma) have Y concentrations of ~3,500 and ~5,400 ppm and define the first growth event. Three analyses with dates between ca. 31 and 27 Ma define the second population and range in Y concentration from ~1,900 to ~4,200 ppm. A third growth event from ca. 24 to 19 Ma has Y concentrations that range ~2,800 and ~8,100 and show no obvious trend.KA064ASpecimen KA064A is a Grt + Sil + Bt + Fsp + Qz gneiss from the highest structural level examined during this study (Figure 3.1). It is located approximately 1,550 m structurally above the previous specimen and approximately 17 km structurally above the MCT (Figure 2.1, 2.2). Monazite grains analysed occur both within the matrix and as inclusions in garnet (Figure 4.2). Matrix monazite grains are anhedral and oblate to elongate in shape, 50 to 150 µm in size, and commonly associated with biotite, K-feldspar, quartz, and/or sillimanite. Two grains that occur as inclusions in garnet are anhedral in shape and 17-50 µm in size. Elemental maps for all grains show weak to moderate patchy and irregular zoning of Th, U and Y. Y maps typically show lower concentrations in cores and higher concentrations towards the rim (Figure 4.3). 72 spots were analyzed on 11 grains (Table 4.1). Three spots were excluded for falling off the intended grain including the only spot on one of the grains included in garnet (Table 4.1). The remaining 69 spots on 10 grains define two populations (Figure 4.3). An older population (n=3), of which two analyses are from grains included in garnet, spans between 496.8 ± 10.7 and 105.6 ± 4.3 Ma. A younger population (n=66) ranges between 41.5 ± 0.9 Ma to 19.5 ± 0.6 Ma. In the younger population there appears to be three growth 62events that show a relationship between date and Y concentration (Figure 4.3). From ca. 42 Ma to 36 Ma Y ranges between ~5,000 to ~18,000 ppm and shows no obvious trend. From ca. 35 to 26 Ma, however, Y is generally higher and increases with decreasing date; with the exception of one analysis (ca. 30 Ma, 13,000 ppm) Y ranges between ~20,000 and 28,000 ppm. From ca. 24 to 20 Ma Y ranges between 8,400 and 32,000 ppm and shows no discernable trend.4.4  Interpretation of DatesThe composition and modal abundance of monazite is coupled to garnet and other accessory phases that incorporate REE and Y (e.g. Spear and Pyle, 1999; Foster et al., 2000; Gibson et al., 2004). Xenotime, an accessory phase that can exert a strong control on the REE and Y budget of a rock (Spear and Pyle, 1999), was not identified in any specimen. Other accessory phases that can incorporate significant REE and Y, such as apatite and zircon, were either not identified or rare. As such, it is a reasonable assumption that garnet, which is present in each analyzed specimen, exerted a primary control on the HREE and Y budget. Furthermore, it is reasonable to assume that the HREE and Y concentrations of monazite, the dominant HREE phase in each specimen, reflects changes in the modal abundance of garnet, which acts as a sink for HREE and Y due to its larger volume. Monazite that grew during increasing and/or a high modal abundance of garnet is expected to have relatively low concentrations of HREE and Y (Figure 4.1). Likewise, monazite that grew during decreasing and/or low modal abundance of garnet is expected to have relatively high concentrations of HREE and Y as they are more freely available (Figure 4.1). The following section is an interpretation of metamorphic monazite ages based on HREE and Y concentrations. Dates older than 42 Ma are interpreted as being inherited and/or detrital and hence are not discussed for the remainder of this thesis.KA044, KA058B, KA064AMonazite from KA044, KA058B and KA064A are discussed together as they record similar, relatively old dates. Monazite from KA044 records 3 chemically distinct growth events during the: (1) Middle Eocene to Early Oligocene, (2) Early Oligocene to Early Miocene and (3) Early to Middle Miocene (Figure 4.3, 4.4). Low concentrations of HREE and Y in monazite with dates from the first and second growth event indicate that garnet was growing. A slight decrease in HREE and Y concentrations from the first to second growth event is consistent with progressive garnet growth during this time. Finally, an increase in HREE and Y in monazite with dates from the final growth event indicates that garnet was breaking down during this time.Similar to KA044, monazite from KA064A and KA058B, record three chemically distinct growth events during the: (1) Middle to Late Eocene, (2) Late Eocene/Early Oligocene to Late Oligocene and (3) Late Oligocene to Early Miocene (Figure 4.3, 4.4). The concentration of HREE and Y in monazite from KA058B is low and shows little variation which suggests limited availability of HREE and Y. However, the modal abundance of garnet is low (~0.5%) in this specimen and xenotime was not identified which is consistent with an overall lack of available HREE and Y. The general lack of HREE and Y variation 63Figure 4.4 Summary of Y and dates.0500010000150002000025000300003500011.0 16.0 21.0 26.0 31.0 36.0 41.0020000400006000080000100000120000140000160000180000200000KA044KA058BKA064AKA007KA055KA031BKA037KA034Y (ppm)Y (ppm) for KA007208Pb/ 232Th DatesFigure 4.4: Compiled Y concentration versus date plots  for all specimens.  Low concentrations of Y are consistent with garnet growth, while high concentrations are consistent with garnet breakdown.64and low abundances limits this specimen’s usefulness for petrogenesis interpretations. Although KA064A records similar ages, total HREE and Y levels are higher than KA058B and show considerable variation. Relatively low HREE and Y concentrations in monazite dates from the first growth event in this specimen indicate that garnet had already grown or was growing during this time. Relatively high HREE and Y concentrations in monazite with dates from the second growth event, in addition to a general increase with decreasing date, indicate that garnet was breaking down during this time. HREE and Y concentrations in monazite with dates from the final growth event range from relatively low to the highest recorded in this specimen. These high values are consistent with garnet breakdown but the large range indicates that HREE and Y were not homogenous throughout the specimen.KA007Unlike the previously discussed specimens, monazite from KA007 does not record a protracted, episodic history (Figure 4.3, 4.4).There are two explanations for why an earlier history is not recorded in this specimen. First, it is possible that higher degrees of partial melting resulted in the complete resorption of earlier monazite in this specimen. Textures indicate, however, that there was a similar, or less amount of melt, as specimens which preserve an earlier history (Figure 3.1). This is consistent with monazite growth in this specimen not occurring in this specimen until ca. 31 Ma. Relatively low HREE and Y concentrations in monazite with dates between ca. 31 and 24 Ma indicate that garnet was growing during this time or had already grown. This period broadly coincides with the second monazite growth event recorded in KA044, KA058B and KA064A (Figure 4.4). Increasing HREE and Y concentrations in monazite with from ca. 24 and 19 Ma are consistent with garnet breakdown down during this time. These younger dates broadly coincide with the final episode of monazite growth in KA044, KA058B and KA064A and the onset of monazite growth in KA031B, KA034, KA037 and KA055. This is consistent with contemporaneous garnet breakdown in KA007, KA044, KA058B and KA064A, and garnet growth in KA031B, KA034, KA037 and KA055 (discussed below).KA031B, KA034, KA037, KA055Monazite from KA031B, KA034, KA037 and KA055 are generally younger than, but record similar HREE and Y trends, as KA007 (Figure 4.4). Rather, these specimens record a relatively short history that begins in the Late Oligocene or Early Miocene, broadly coincidental with the final growth events of KA044, KA058B and KA064A. As with KA007, these specimens have similar amounts of melt as specimens that record an early protracted history (Figure 3.1). As such, it is reasonable to assume that an early history was not destroyed through resorption. 65Chapter 5.  Discussion and Conclusions5.1  P-T-t PathsThe integration of pseudosections and petrochronology can be used to constrain P-T-t paths and unravel geologic histories. In this thesis, P-T-t paths generated for three specimens from different, strategic structural levels were used to elucidate the geologic history and, in particular, the internal structure of the HMC. These specimens are discussed below from lower to higher structural level.KA007The chemistry of monazite grains in KA007 is consistent with garnet growth to between ca. 31 and 24 Ma and garnet breakdown to between ca. 24 and 19 Ma (Figure 4.3). It was not possible to determine the full prograde P-T path from this specimen, however, garnet growth from ca. 31 to 24 is consistent with prograde metamorphism. The decompressional cooling path outlined in the pseudosection for this specimen crosses closely spaced, decreasing garnet isomodes during melt crystallization (Figure 3.8C). Below the solidus, a decompressional cooling path would continue to cross decreasing isomodes, but they are more widely spaced. As such, it is interpreted that the majority of garnet breakdown, and resulting release of HREE and Y available for incorporation into monazite, likely occurred during melt crystallization from ca. 24 to 19 Ma (Figure 3.8C).KA044Monazite grains in KA044 record three growth events (Figure 4.3). The first two events are interpreted to reflect simultaneous garnet growth while the final event is interpreted to record garnet breakdown. Low HREE and Y concentrations in monazite domains associated with the first event from ca. 39 to 33 Ma, consistent with initial prograde garnet growth, were followed by even lower concentrations for the second event from ca. 31 to 19 Ma, consistent with further garnet growth and HREE and Y sequestration. The P-T path for this specimen interpreted from the pseudosection only reveals the high metamorphic grade history. As garnet is stable at lower pressures and temperatures than what is recorded, it is likely that initial growth occurred at lower metamorphic grades than those estimated by the P-T path. The second monazite growth event, however, may correlate with the near isothermal heating path interpreted on the pseudosection (Figure 3.9C). As monazite typically resorbs with increasing melting fraction (Kelsey et al., 2008; Spear, 2010), this implies that the second event is the result of subsolidus growth consistent with subsolidus garnet growth between ca. 31 and 19 Ma. The subsequent hiatus in monazite growth from ca. 19 to 17 Ma is consistent with increasing melt fraction, and hence continued heating, during this time (Figures 3.9). In addition to helping add timing constraints, the HREE and Y concentrations measured in monazite can help constrain the trajectory of the prograde path in this specimen. Based on isomodes, garnet would be expected to breakdown along a heating path with minor decompression thereby releasing HREE and Y. 66As HREE and Y do not increase in monazite domains yielding dating from ca. 31 to 19 Ma this requires either a near isobaric or burial path during this time. The youngest monazite growth in the specimen records a sudden increase in HREE and Y, consistent with garnet breakdown along the retrograde path. As with the previous specimen, garnet isomodes are closely spaced above the solidus and widely spaced below implying that the majority of garnet breakdown is likely to have taken place above the solidus. This is consistent with garnet breakdown during melt crystallization from ca. 17 to 16 Ma.KA064AMonazite grains in KA064A record three growth events. Low HREE and Y associated with the first growth event are consistent with garnet growth between ca. 42 and 36 Ma (Figure 4.3). The interpreted P-T path for KA064A crosses increasing garnet isomodes below and above the solidus during heating (Figure 3.10); monazite, however, likely resorbed with increasing melt fraction above the solidus (Kelsey et al., 2008; Spear et al., 2010). Monazite growth between ca. 42 and 36 Ma, is therefore interpreted to coincide with subsolidus garnet growth. As with the previous specimen, initial garnet growth likely began at lower pressures and temperatures than estimated by pseudosections built with the observed restitic bulk. Dates from the oldest monazite domains may correspond to initial prograde garnet growth. In contrast to early monazite growth, the later two growth events are both interpreted to record garnet breakdown. HREE and Y concentrations increase significantly from the first monazite growth event to the second, indicating that garnet was breaking down between ca. 36 and 26 Ma. This could occur along a decompressional heating path that crosses decreasing garnet isomodes (Figure 3.10). The subsolidus heating path shown in Figure 3.10C, however, crosses widely spaced, increasing garnet isomodes. There are two possibilities that may explain garnet breakdown along a similar path. First, prior to melt loss the muscovite-in line would have occurred at lower pressures and temperatures (e.g. Guilmette et al., 2010; Groppo et al. 2012), resulting in closely spaced, near horizontal garnet isomodes at the pressures and temperatures of the estimated P-T path. An isobaric or decompressional heating path through a muscovite bearing field would result in significant subsolidus garnet breakdown. Such a path, however, would also cross decreasing grossular isopleths. This is not consistent with measured garnet core and mantle compositions in this specimen which record constant grossular content. A second explanation is that pressures are underestimated. If the P-T path shown in Figure 3.10 was 1 kbar higher (9 kbar), it would result in subsolidus decompressional heating that would cause garnet breakdown. Again, this explanation is not supported by measured garnet compositions. It is possible, however, that substantial residence time at high temperatures has destroyed prograde garnet zoning (Caddick et al., 2010). This would imply that either explanation, or a combination of both, could explain the breakdown of garnet during between ca. 35 and 26 Ma. High HREE and Y concentrations during the final monazite growth event are consistent with garnet breakdown. As with specimens discussed previously, isomodes are more widely spaced below the solidus, consistent with the majority of garnet breakdown occurring during melt crystallization between ca. 24 and 20 Ma.675.2  P-T-t Discontinuities P-T-t paths and petrochronology reveal distinct metamorphic histories for specimens collected at different structural levels across the HMC (Figure 5.1). Whereas specimens KA044, KA058B and KA064A record protracted, middle Eocene to early Miocene monazite growth and metamorphic histories, specimens KA031B, KA034, KA037, and KA055, in contrast, record relatively short, late Oligocene to middle Miocene, monazite growth/metamorphic histories (Figure 5.2). Similar to KA031B, KA034 and KA037, specimen KA007 also records a relatively short metamorphic history (Figure 5.2). Unlike those other specimens, however, it records an early Oligocene to early Miocene history. The present spatial distribution of these specimens with unique geologic histories is not only consistent with the position of a previously mapped tectonometamorphic discontinuity but also reveals the presence of additional ones. Five total discontinuities were identified in this study and are discussed below from higher to lower structural levels, which roughly corresponds to decreasing age.Ms-in isograd Whereas specimens KA058B and KA064A record middle Eocene to early Miocene prograde metamorphism followed by late Oligocene to early Miocene retrograde metamorphism (Figures 5.1, 5.2), the structurally lower specimen KA055, records late Oligocene to early Miocene prograde metamorphism followed by early Miocene retrograde metamorphism. Although no structure was identified in the field to precisely constrain the location of such a discontinuity, the specimens fall on either side of the muscovite-in isograd. The isograd is, therefore, interpreted to result from a structural contact (Figures 5.3, 5.4 )High Himal Thrust (KA55 over KA44)Specimens KA044 and KA055 consist of similar, high metamorphic grade, muscovite-free assemblages. As discussed previously, KA055 records late Oligocene to early Miocene prograde metamorphism followed by early Miocene retrograde metamorphism (Figure 5.2). The structurally lower KA044, in contrast, records protracted middle Eocene to early Miocene prograde metamorphism followed by early Miocene retrograde metamorphism. The break between these specimens coincides with the HHT of Goscombe et al. (2006; Figures 5.3, 5.4). Ms-out isograd (KA44 over KA37, 34, 31)Whereas specimen KA044 records protracted middle Eocene to early Miocene prograde metamorphism, the structurally lower specimens KA037, KA034 and KA031B, in contrast, record late Oligocene/early Miocene prograde metamorphism followed by early to middle Miocene retrograde metamorphism (Figure 5.2). Although no structure was identified in the field to precisely constrain the location of such a discontinuity, the specimens fall on either side of the muscovite-out isograd (Figures 5.3, 5.4). The isograd is, therefore, interpreted to result from a structural contact.68Figure 5.1 Summary of P-T paths?650 700 750 800 850Temperature [C]500070009000110001300015000Pressure [Bar]KySil31-19 Ma17-16 Ma35-26 Ma24-20 Ma24-19 MaKA064AKA044KA00731-25 MaFigure 5.1: Summary of P-T-t paths for specimens from the HMC. Lines representing the prograde portions of the P-T-t paths are thinner to indicate increased uncertainty as discussed in the text. Prograde portion of the P-T path for KA007 is in gray to indicate it is not constrained.  Only the middle retrograde path is presented for KA044.69Figure 5.2 Timing of metamorphism in the HMCKA007KA031BKA034KA037KA044KA055KA058BKA064ATime (Ma)Specimen22 20 1828 2426 16 121436 34 3242 3840 30Eocene Oligocene MioceneMelting?Melting?Melting?Figure 5.2: Timing of metamorphism in the HMC for all specimens analysed in this thesis. Red lines correspond to periods of heating, while blue lines correspond to melt crystallization and cooling70Figure 5.3 Geologic map of interpreted faultsgeological contact (approximate, inferred)tectonic foliation and mineral lineationtrail, roadvillagestream, rivertopographic contour(in meters)4000petrochronology specimenP-T and petrochronology specimenlocation of cross section (Figure 2.2)N10 kminvestigation locality009thrust faultGeology of the Kanchenjunga Region showing the location of interpreted faultsAChl + Ms + Bt phyllite/schist and quartziteGrt + Chl + Ms + Bt ± Ky ± St phyllite/schist and quarzite and calc-silicateMylonitic orthogneissKy + Grt + Bt + Ms gneiss/schist (locally migmatitic) and quartzite Kfs + Sil + Grt + Bt + Ms ± Ky  gneiss (locally migmatitic) and quartzite Kfs + Sil + Grt + Bt ± Ky migmatitic paragneiss, quartzite, minor calc silicateKfs + Sil + Grt + Bt ± Ms ± Chl migmatitic paragneiss, quartzite and metapsammiteLesser HimalayaHimalayan Metamorphic Core80012004000 4400 4800 5200520048005600160016002000200024002400ChaukiDeuraliBasantapurGufa PokhariTaplejungDobhanMitlungChiruwaSekathumRamsyangpatiNupHellokOlangchungolaYangmaHHTMs-inMs-outBase of migmatites MCTBase of migmatites017018019020021022023024025026027028029030032033035036038047046045043042001002003004005006 008010011012013 014015016048049053052051050054056057059060061062063066065041040039KA007KA031BKA034KA037KA044KA055KA058BKA064A27˚ 10' 27˚ 10'87˚ 30'87˚ 30'87˚ 40'87˚ 50'87˚ 50'87˚ 40'27˚ 20'27˚ 30'27˚ 30'27˚ 40'27˚ 50' 27˚ 50'27˚ 40'27˚ 20'ABCFigure 5.3. Geologic map showing the location of interpreted faults.71A CB24602460kmKA007KA031B KA034KA037KA044 KA055KA05BKA064HHTMs-inMs-outBase of migmatitesBase ofmigmatitesMCTMCTFigure 5.4 Vertical geologic cross section showing the location of interpretted faults. See Figure 5.3 for lithologic legend. Horizontal and vertical scales are the same.Figure 5.4 Geologic cross-section showing the location of interpretted faults72Base of Migmatites North of the Tamor Window, KA031B is the structurally lowest specimen for which there is detailed metamorphic and geochronologic data (Figure 2.1, 2.2). To the north of the Tamor Window, locality KA029 marks the approximate location of the structurally lowest migmatites observed, while specimen KA031B, located ~2,000 m to the northeast, and ~350 m up structural section, marks the first definitive appearance of sillimanite (Figure 2.1, 2.2). It is possible that sillimanite occurs closer to, or at the location of KA029, however, it was not identified in outcrop and no specimens were collected for more detailed petrography. Immediately below the location KA029 are considerably lower metamorphic grade schists and phyllites that do not contain sillimanite, and have significantly lower anatexite volumes. The location of KA029, furthermore, roughly coincides with a sharp up structural section drop in metamorphic pressures and a change in garnet mineral chemistry (Imayama et al., 2010). Below KA029, rocks record pressures of ~11 kbar and garnet grains preserve prograde growth zoning (Imayama et al., 2010). Rocks up structural section, in contrast, record pressures of ~5 kbar and garnet grains exhibit chemical profiles typical of retrograde zoning (Imayama et al., 2010). Consistent with metamorphic and lithologic data, the juxtaposition of the structurally lowest migmatites and the underlying rock is interpreted as a resulting from structural contact (Figures 5.3, 5.4). KA031B over KA007Similar to KA029 north of the Tamor Window, the location of KA011 marks the structurally lowest occurrence of migmatites observed south of the Tamor Window (Figure 2.1). Although these migmatites have been previously mapped as belonging to the same continuous unit (Shrestha et al 1984; Schelling, 1992; Goscombe and Hand, 2001, Goscombe et al., 2006), this study suggests that they record distinct geochronologic and metamorphic histories. Specimens KA031B, KA034 and KA037, north of the Tamor Window (Figure 2.1, 2.2), record late Oligocene/early Miocene prograde metamorphism followed by early to middle Miocene retrograde metamorphism, whereas specimen KA007, located southwest of the Tamor Window, records early to late Oligocene prograde metamorphism followed by late Oligocene to early Miocene retrograde metamorphism (Figure 5.2). In addition to different timing, the migmatites also record different metamorphic grades; rocks to the north of the Tamor Window were metamorphosed at sillimanite grade conditions, whereas those to the southwest only reached kyanite grade. These data are consistent with a discontinuity separating the locally migmatitic rocks to the southwest of the Tamor Window from the locally migmatitic rocks to the north. Such a discontinuity is interpreted as being completely eroded in the study area, but may have been exposed prior to the formation of Tamor Window.5.3  Tectonic ImplicationsP-T-t paths and petrochronology from this study indicate that the evolution and internal structure of the HMC is considerably more complex than previously thought. During the collision between the Indian and Eurasian plates, specimens KA064, KA058B and KA044 were buried to depths sufficient for garnet 73growth by the middle Eocene. A thickened continental crust during this time is consistent with: 1) U-Pb zircon ages of ca. 44 Ma from granites in southeast Tibet that are interpreted to postdate the majority of crustal thickening in the TSS (Aikman et al., 2008); 2) Lu-Hf garnet ages as old as ca. 54 Ma and 51 Ma from the Majba and Kangmar gneiss domes, respectively (Smit et al., 2014) and, 3) illite 40Ar/39Ar ages of ca. 42 Ma interpreted to record initial crustal thickening in the northwest Himalaya of India (Wiesmayr and Grasemann, 2002).By the latest Eocene or earliest Oligocene these rocks, by that time forming part of the HMC, were being laterally extruded towards the Himalayan foreland, possibly due to the development of a lateral pressure gradient between the thickened Tibetan plateau and thin Indian shield (Beaumont, 2001; Figure 5.5A). As this early extrusion occurred prior to melting (Figure 4.4), this is inconsistent with channel flow models that require a melt weakened midcrust (e.g. Beaumont et al., 2004; Jamieson et. al. 2004). Extrusion during this period is, however, consistent with the tectonic wedging models of Webb et al. (2007, 2011) that do not require melting.As the HMC was extruded towards the foreland, possibly along a ramp, continued convergence buried specimen KA007 to garnet grade depths by ca. 31 Ma (Figure 5.5B). Continued burial of KA007 during the late Oligocene was contemporaneous with the onset of melting in portions of the HMC. Whereas KA064A began melting atat ca. 26 Ma, the structurally lower specimen KA044, did not begin to melt until ca. 5 myr later. This can be explained by the P-T path from KA064A (Figure 3.10) that crosses the solidus at ~750 oC, whereas the P-T path for KA044 does not cross the solidus until ~800 oC (Figure 3.9). This is consistent with an isothermal depth profile across this structural level (Imayama et al. 2010); although KA044 was deeper, it was also at approximately the same temperature. The higher temperatures required to cross the solidus can be explained by a combination of a different bulk composition and higher pressures.Decompression of specimen KA007 at ca. 24 Ma coincides with melt crystallization in specimens KA064A and KA058B (Figure 4.4, 5.2). This is consistent with a rock package containing specimen KA007 being accreted to and, causing further exhumation/cooling of, the extruding HMC (Figure 5.5C). The onset of metamorphism recorded by specimens KA055 and KA031B at about the same time is consistent with underthrusting below, and/or overriding of, the HMC during this time (Figure 5.5C). From ca. 24 until 20 Ma specimens KA055 and KA031B continued to be underthrust/overrode while specimens KA007, KA044 and KA064A were exhumed together (Figures 5.5D, E). Between ca. 20 and 18 Ma, specimen KA055 was exhumed while the record of metamorphism in KA058B and KA64A ceased (Figure 5.2). Meanwhile, specimens KA034 and KA037 record initial metamorphism, and KA044 reached peak metamorphic conditions and partial melting (Figure 5.2). The contemporaneous burial of specimens KA034, KA037, and KA044, and exhumation of specimens KA055, KA058B and KA064A is consistent with the development of an out-of-sequence thrust between ca. 20 and 18 Ma (Figures 5.5G-H), coincident with the previously mapped HHT, which Goscombe et al. (2006) interpreted 74??KA058B, KA064AKA031B, KA034, KA037 KA044KA007 KA055> 31 Maca. 31-24 MaBAca. 24 MaCFigure 5.5 Tectonic evolution model for the HMCFigure 5.5. Interpretted tectonic evolution of the Himalayan midcrust through time. See text for explanation. Thick  black line indicates active structure. Solid gray line indicates previously active structures. Dashed gray line indicates location future structures. Dashed black line indicates the Moho. A question mark inside a circle indicates uncertain geometry or kinematics.75KA058B, KA064AKA031B, KA034, KA037 KA044KA007 KA055ca. 24-20 MaDca. 24-20 MaEca. 20-18 MaFFigure 5.5. continued76MFTMBTMCTHHTHHTKA058B, KA064AKA031B, KA034, KA037 KA044KA007 KA055ca. 12-2 MaIca. 20-18 MaHca. 20-18 MaGFigure 5.5. continued77as the primary structure that controlled the evolution of the HMC. They interpreted metamorphism and deformation within the hanging wall as being consistent with ductile extrusion, and, although not explicitly, they interpret deformation and metamorphism within the footwall as being consistent with underplating. They proposed that in eastern Nepal, and possibly through Bhutan, the HHT is equivalent to the MCT in the channel flow models of Beaumont et al. (2004) and Jamieson et al. (2004). The data from this study, however, indicate that the HHT was relatively short lived. Our data are inline with Brunel and Kienast (1986) and Brunel (1986), who interpreted displacement along the HHT (which they mapped as the MCT) in the Everest and Makalu regions as postdating metamorphism. Out-of-sequence thrusting is also consistent with interpretations of the Laya-Kakthang thrust in Bhutan (Warren et al., 2011; Grujic et al., 2002, 2011) and northeast India (Warren et al., 2014). Following out-of-sequence thrusting during this interval, deformation migrated back towards the foreland resulting in the crystallization/cooling/exhumation of the remaining specimens by ca. 12 Ma. The continuation of these processes and continued underplating of progressively lower metamorphic grade rock may have led to the formation of the Lesser Himalayan duplex and exhumation of the HMC (Figure 5.5I; e.g. Bollinger et al. 2006;Webb, 2013).5.4  ConclusionsThis thesis demonstrates that the HMC is more complex that a slab of rock bound by two faults. The results of this thesis have shown that:1. Metamorphism of the HMC:a. varied temporally and spatiallyb. was protractedc. was not Barrovian2. P-T-t discontinuities identified in the study area reflect the juxtaposition of distinct of rock pack-ages 3. The HMC evolved through a combination of lateral extrusion, out-of-sequence thrusting and underplating.4. The HHT is an out-of-sequence thrust that was active at ca. 20 Ma 5. The protoliths of the rocks forming the HMC were buried to garnet grade depths by at least the middle Eocene, consistent with the presence of a thickened continental crust by this time.6. The inverted metamorphic sequence at the base of the HMC can be explained by the underplat-ing of progressively younger and lower grade rock.5.5  Future WorkThis thesis represents the most detailed investigation of structures within the HMC to date. It is possible, and rather likely, however, that additional complexities exists beyond the resolution of these data. The following are some recommendations for work that would help elucidate the internal structure of the HMC.78Ground Checking StructuresMost of the structures identified in this study were not identified in the field. Now that the location of such structures is clearer, it may be possible to locate them in the field.Additional PetrochronologyThe data presented in this thesis indicate the presence of a structure between nearly every specimen; out of 8 specimens, 5 discontinuities were identified. P-T-t paths from more tightly spaced specimens may reveal additional discontinuities and allow for the refinement of the tectonic model presented herein. For example, the model predicts the burial of KA037 followed by KA034 and finally by KA031B and subsequent exhumation in the reverse order (Figure 5.5). The ages for burial and exhumation, however, do not support this prediction. Additional timing constraints from structural levels between specimens KA031B and KA037 could help refine the model for this portion of the HMC. As monazite was not identified in rocks structurally down section from KA031B, the timing of metamorphism in the structurally lowest rocks of the HMC remains unknown. In these rocks, however, there may be other datable mineral such as xenotime and allanite. Dating these minerals would test the prediction that the structurally lowest portion of the HMC was metamorphosed later than structurally higher levels.Garnet HREE Zoning and DatingIn this thesis, it was assumed that the HREE composition of monazite was only coupled to garnet. If garnet and monazite are the only phases controlling the HREE budget of rocks, then trace element profiles across garnet may reflect the growth and consumption of accessory phases such as monazite (Buick et al., 2006). 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Investigation locality coordinates and structural measurements  Appendices90Locality Latitude Longitude Elevation (m) Rock type(s) Feature Measurement220/23210/11Lmica 22/033ST 245/29Lmica 06/045ST 334/04L 00/189ST 184/25L mica 04/017Scren 115/80ST 115/05C' 118/19KA016 27.3151 87.5542 2541 orthogneiss ST 139/29ST 266/34Lcren 13/289Lqrods/qblebs  ST 235/20ST 199/28ST 269/36ST 270/33FAxial plane 274/40ST 249/26Lmin 23/340Lcren 05/281Lfold axis 20/303ST 261/43Lcren 27/298Lcren 26/286ST 245/28ST 210/34L Min 20/000L Min 22/349C' 221/32ST 220/23ST 250/29Lmin 04/179ST 250/31L Min 14/006Lcren 295/25S fabric 268/65ST 251/48ST/S0 241/22L M (chl) 26/356Lcren 09/010ST 268/25L M 24/021C 285/28S 284/41C' 300/00157027.3115 87.5497 261227.2942 87.5265 294327.3690 87.6238 64768587.619227.364827.344227.3410 87.6103 111827.3389 87.6031KA015 Ms schistKA017 Grt phylliteKA014 phyllitic schistmetapelite phyllite/quarztiteKA020 metapelite phyllite/quarztiteKA018 sandstone/phyllite98387.6121KA021KA019 phylliteKA022 metapelite phyllite/quartzite1272ST27.3369 87.590891Locality Latitude Longitude Elevation (m) Rock type(s) Feature MeasurementST/S0 289/57Lcren 52/350C 289/57S 289/66C' 291/45ST 195/39ST 220/36ST 315/45ST 275/47L Min 49/008ST 275/22ST 273/33ST 274/31L Min Align 19/011C 276/54S 289/75C' 283/40ST/S0 296/43L Min (elongate mica) 39/349ST 234/56ST 221/55L Min Shape 52/345KA029 27.4820 87.7405 1282 migmatitic gneiss ST/AP 253/39KA030 27.4890 87.7471 1277 gneissic schist ST 217/72ST 259/43ST 265/47ST 270/61ST 340/39L Mica 29/030Sclv 187/65ST 314/24ST 350/71ST 343/50ST 330/63ST 340/34ST 325/25ST 334/48ST 246/64ST 255/54ST 255/53ST 320/30L mineral shape 25/03281027.4925 87.7620 131427.4735 87.7387 128727.4389 87.7024 974gneissic schistKA031KA025 orthogneissKA024 schistose phylliteKA023 schistose phyllite87.696627.4195 21227.4036 87.6808 79727.3949 87.6703KA028 gneissic schistKA027 schistKA026 augeniferous orthogneiss27.4296 87.7005 984KA034 gneissKA033 gneissKA032 schist/quartzite27.5245 87.8005 157127.5202 87.7965 159527.4990 87.7858 1392KA035 gneiss27.5407 87.7980 161492Locality Latitude Longitude Elevation (m) Rock type(s) Feature MeasurementST 336/44L Mica 44/061ST 339/39ST 304/36KA038 27.5713 87.7965 1886 gneissST 335/31L mineral shape 35/076ST 355/31ST 296/25ST 273/11ST 320/15L M 12/044ST 011/16KA041 27.5875 87.7981 1851 gneiss ST 339/43ST 330/41ST 341/41L mineral alignment/stretch 40/065SDyke 212/87ST 316/50Lmineral stretching 50/046ST 334/47ST 300/36LSil alignment 32/042ST 338/32L M (mica/qtz) 32/046ST 303/27L mineral shape/alignment 26/052KA046 27.6066 87.8021 2163 gneiss ST 285/52ST 298/68L min 59/003ST 296/73L mica alignment/stretch 56/060ST 319/20L Min 34/066ST 300/40Fault 222/36Fault 251/41Slickenlines 4/034215827.6479 87.7997 257827.6172 87.8046 250427.5892 87.8000 214427.5806 87.7969 203727.5789 87.7956 190427.5554KA037 gneiss,graniteKA047 gneissKA048KA045gneiss, quartziteKA036 quartzite, graniteL mineral shape Qz-rods, Ms 36/04827.5684 87.7974 182087.7947 1733gneissgneissKA042 gneissKA043 gneiss, meltKA049 leucograniteKA039KA044 gneissKA040 gneiss, quartzite27.6588 87.7987 258627.5976 87.8004 208927.5930 87.7999 207927.6038 87.800493Locality Latitude Longitude Elevation (m) Rock type(s) Feature MeasurementST 281/30Lmica and Qz stretch 18/052ST 284/23L min 22/047KA052 27.6705 87.8037 2830 paragneissST 314/26L mica alignment 25/043ST 346/90ST 318/90KA055 27.6950 87.8251 3126 gneissST 310/50ST 262/37ST 319/39ST 310/59ST 309/30ST 315/43ST 311/49L min mica 46/040ST 275/10Lcren 06/290ST 233/15L min mica align/stretch 07/044ST 236/26L M 07/040ST 234/12ST 244/43Lcren 30/360Lfold axis 38/320Upper Limb 029/41Lower Limb 337/64ST 278/6027.7812 87.8592 412027.6677 87.8008 286027.6695 87.8020 290027.7572 87.8533 395727.6805 87.8141 298927.6716 290787.805427.8082 87.8603 421927.7898 87.8616 411027.8021 87.8623 419027.8130 87.8598 4284KA058 gneiss, graniteKA057KA050KA051KA054KA053 paragneissKA061 gneiss, melt, psammiteKA060 quarztiteKA056 gneissKA059 quartzite, gneisscalc silicategneissgneissgneiss94Locality Latitude Longitude Elevation (m) Rock type(s) Feature MeasurementST 338/19ST 342/22ST 353/21ST 348/21LM bio/qmin stretch 12/020ST 000/22L 06/359L 40/326ST 011/21ST 005/30ST 306/49ST 020/25LM 24/134Dyke 335/08ST 307/26ST 308/20LM (mica/qtz) 20/053ST 329/21ST 342/33ST 342/2027.8250 87.8708 438627.8216 87.8676 435227.8489 87.8519 502327.8491 87.8509 497627.8268 87.8740 4356KA062 quarztiteKA066 quarztite, metapelite, leucograniteKA063 gneissKA064 gneiss, felsiteKA065 quarztite + melt blebs95Appendix B: Pressure-Temperature DataB.1:Temperature-XFe3+ Pseudosections T h e r i a k  -  D  o m i n o0.000 0.025 0.050 0.075 0.100650675700725750775800Temperature [C] Bulk(1)= NA(9.43)CA(1.88)K(2.07)FE(3.69)MG(1.22)AL(18.44)SI(60.02)TI(0.57)H(2.68)F3(0)O(?)Bulk(2)= NA(9.43)CA(1.88)K(2.07)FE(0)MG(1.22)AL(18.44)SI(60.02)TI(0.57)H(2.68)F3(3.69)O(?)PLC1GT07W2BI07ILM0MTSP02qsill23 4 1113X Fe3++ LiqPl + Grt + Bt + Ilm+ Qz + Sil+ Kfs+ LiqFigure B.1. Temperature versus XFe3+ pseudosection at 6 kbar for specimen KA007  +MtFigure B.1 Temperature versus XFe3+ pseudosection for KA00796Kfs + Pl + Grt + Bt + Ilm + Q + Als+Ru+Ru-IlmT h e r i a k  -  D  o m i n o0.000 0.025 0.050 0.075 0.100700750800850900Temperature [C]Bulk(1)= NA(2.23)CA(1.73)K(2.97)FE(8.16)MG(2.72)AL(24.68)SI(55.30)TI(0.81)H(1.32)F3(0)O(?)Bulk(2)= NA(2.23)CA(1.73)K(2.97)FE(0)MG(2.72)AL(24.68)SI(55.30)TI(0.81)H(1.32)F3(8.16)O(?)X Fe3+KySill+ Liq- BtFigure B.2. Temperature versus XFe3+ pseudosection at 9 kbar for specimen KA044Figure B.2 Temperature versus XFe3+ pseudosection for KA044 970.000 0.025 0.050 0.075 0.100X Fe3+700750800850900Temperature [C]Bulk(1)= NA(2.56)CA(.76)K(5.34)FE(5.67)MG(1.91)AL(18.86)SI(59.08)TI(0.68)H(5.13)F3(0)O(?)Bulk(2)= NA(2.56)CA(.76)K(5.34)FE(0)MG(1.91)AL(18.86)SI(59.08)TI(0.68)H(5.13)F3(5.67)O(?)23456117122136149150+Liq+MtBt-outKfs + Grt + Bt + Ilm + SilFigure B.3. Temperature versus XFe3+ pseudosection at 7 kbar for specimen KA064AFigure B.3 Temperature versus XFe3+ pseudosection for KA064A 98650 700 750 800 850Temperature [C]600070008000900010000110001200013000Pressure [Bar]Bulk(1)= NA(9.43)CA(1.88)K(2.07)FE(3.6531)MG(1.22)AL(18.44)SI(60.02)TI(0.57)H(2.68)F3(0.0369)O(?)0.860.850.840.830.820.810.80.710.860.80.850.840.710.830.830.820.810.720.81 0.80.790.77 0.760.750.740.730.790.80.80.770.780.790.790.780.770.720.720.730.740.750.760.770.780.760.740.720.750.710.850.840.820.850.840.830.820.810.80.820.76 0.77CR?Figure B.4. Almandine isopleths for specimen  KA007B.2: IsoplethsFigure B.4 Almandine isopleths for specimen KA00799650 700 750 800 850Temperature [C]600070008000900010000110001200013000Pressure [Bar]Bulk(1)= NA(9.43)CA(1.88)K(2.07)FE(3.6531)MG(1.22)AL(18.44)SI(60.02)TI(0.57)H(2.68)F3(0.0369)O(?)0.020.0150.0250.0150.030.020.0150.045 0.040.035 0.0250.05 0.0350.030.0250.020.060.0550.050.0450.040.0350.030.0650.060.055 0.0450.040.0250.060.050.0350.030.0450.040.020.040.050.01CR?Figure B.5. Grossular isopleths for specimen  KA007Figure B.5 Grossular isopleths for specimen KA007100650 700 750 800 850Temperature [C]600070008000900010000110001200013000Pressure [Bar]Bulk(1)= NA(9.43)CA(1.88)K(2.07)FE(3.6531)MG(1.22)AL(18.44)SI(60.02)TI(0.57)H(2.68)F3(0.0369)O(?)0.320.330.34 0.350.320.330.340.420.410.40.440.430.410.40.410.420.460.45 0.420.490.480.470.440.430.430.44CR?Figure B.6. Biotite Mg# isopleths for KA007Figure B.6 Biotite Mg# isopleths for KA007101700 750 800 850 900Temperature [C]6000800010000120001400016000Pressure [Bar]Bulk(1)= NA(2.23)CA(1.73)K(2.97)FE(8.08)MG(2.72)AL(24.68)SI(55.30)TI(0.81)H(1.32)F3(0.08)O(?)0.750.710.70.70.740.730.730.71 0.70.70.690.690.680.660.670.660.660.720.710.70.690.680.670.750.720.670.670.70.71CRFigure B.7. Almandine isopleths for specimen   KA044Figure B.7 Almandine isopleths for specimen KA044102700 750 800 850 900Temperature [C]6000800010000120001400016000Pressure [Bar]Bulk(1)= NA(2.23)CA(1.73)K(2.97)FE(8.08)MG(2.72)AL(24.68)SI(55.30)TI(0.81)H(1.32)F3(0.08)O(?)0.030.0350.0250.05 0.0450.040.035 0.030.0650.060.055 0.05 0.040.0850.080.0750.07 0.055 0.050.0450.1 0.0950.090.0750.070.0650.060.0550.110.1050.10.0950.090.080.0750.070.09 0.0850.110.1050.10.10.095 0.090.115 0.1050.120.110.0550.1050.050.050.060.0650.080.0250.030.0350.095CRFigure B.8. Grossular isopleths for specimen  KA044Figure B.8 Grossular isopleths for specimen KA044103700 750 800 850 900Temperature [C]6000800010000120001400016000Pressure [Bar]Bulk(1)= NA(2.23)CA(1.73)K(2.97)FE(8.08)MG(2.72)AL(24.68)SI(55.30)TI(0.81)H(1.32)F3(0.08)O(?)0.51 0.5 0.490.480.520.520.510.530.50.490.60.590.610.620.49CRFigure B.9. Biotite Mg# isopleths for specimen  KA044Figure B.9 Biotite Mg# for specimen KA044104700 750 800 850 900Temperature [C]4000600080001000012000Pressure [Bar]Bulk(1)= NA(2.56)CA(.76)K(5.34)FE(5.61)MG(1.91)AL(18.86)SI(59.08)TI(0.68)H(5.13)F3(.06)O(?)0.860.70.830.70.770.760.750.740.730.720.70.70.740.870.850.820.80.790.780.770.760.750.730.720.870.810.840.86 0.850.860.8424-20 Ma?RCFigure B.10. Almandine isopleths for specimen  KA064AFigure B.10 Almandine isopleths for specimen KA064A105700 750 800 850 900Temperature [C]4000600080001000012000Pressure [Bar]Bulk(1)= NA(2.56)CA(.76)K(5.34)FE(5.61)MG(1.91)AL(18.86)SI(59.08)TI(0.68)H(5.13)F3(.06)O(?)0.020.020.020.020.030.0250.035 0.03 0.0250.0450.040.0350.030.0550.050.050.0350.060.0550.0550.050.0450.0650.0650.060.0550.050.0650.060.070.0250.040.020.045 0.040.020.0524-20 Ma?RCFigure B.11. Grossular isopleths for specimen  KA064AFigure B.11 Grossular isopleths for specimen KA064A106700 750 800 850 900Temperature [C]4000600080001000012000Pressure [Bar]Bulk(1)= NA(2.56)CA(.76)K(5.34)FE(5.61)MG(1.91)AL(18.86)SI(59.08)TI(0.68)H(5.13)F3(.06)O(?)0.30.350.40.450.50.30.35 0.50.40.450.50.550.30.450.50.550.3B.12. Biotite Mg# isopleths for specimen  KA064AFigure B.12 Biotite Mg# isopleths for specimen KA064A107121 21122337881476655533444KfsPlMsBtGrt5mmB.3. EMP Spot Locations and Composition DataFigure B.13. KA007 EMP mineral spot analysis locations shown on an iron EMP map.. Figure B.13 KA007 EMP mineral spot analysis locations108wt % 1 2 3 4 5 6 7 8 9 10 11 12 13 14SiO2 37.84 37.67 37.71 37.86 37.87 37.92 37.92 37.90 38.01 37.98 37.81 38.01 37.72 37.59TiO2 0.24 0.01 0.04 0.02 0.01 0.01 0.02 0.03 0.04 0.03 0.00 0.00 0.02 0.00Al2O3 21.69 21.58 21.81 21.63 21.78 21.93 21.84 21.93 21.98 21.76 21.79 21.78 21.77 21.58FeO 33.31 32.98 33.30 32.94 33.18 33.18 33.15 32.88 33.32 33.27 33.75 33.24 32.90 33.35MnO 4.36 4.28 2.98 3.01 2.97 3.26 2.61 2.71 2.86 3.09 3.17 3.54 4.25MgO 2.97 2.98 3.66 3.57 3.57 3.59 3.57 3.80 3.74 3.66 3.63 3.51 3.41 2.92CaO 1.01 1.23 1.25 1.31 1.25 1.29 1.21 1.60 1.47 1.50 1.21 1.22 1.21 0.94Cr2O3 0.03 0.00 0.02 0.03 0.03 0.00 0.00 0.00 0.00 0.01 0.00 0.03 0.03 0.00Total 101.46 100.72 100.76 100.38 100.66 97.91 100.96 100.75 101.28 101.07 101.29 100.96 100.59 100.63ionsSi 2.99 3.00 2.98 3.00 2.99 2.99 2.99 2.99 2.99 2.99 2.99 3.00 2.99 2.99Ti 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Al 2.03 2.03 2.04 2.03 2.04 2.04 2.04 2.04 2.04 2.03 2.03 2.03 2.04 2.03Fe 2.24 2.23 2.24 2.23 2.24 2.23 2.23 2.21 2.23 2.23 2.25 2.24 2.22 2.26Mn 0.29 0.29 0.20 0.20 0.20 0.20 0.22 0.17 0.18 0.19 0.21 0.21 0.24 0.29Mg 0.35 0.35 0.43 0.42 0.42 0.42 0.42 0.45 0.44 0.43 0.43 0.41 0.40 0.35Ca 0.09 0.10 0.11 0.11 0.11 0.11 0.10 0.14 0.12 0.13 0.10 0.10 0.10 0.08Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Total 7.99 8.00 8.00 7.99 8.00 8.00 8.00 8.00 8.00 8.00 8.00 7.99 8.00 8.00O 12 12 12 12 12 12 12 12 12 12 12 12 12 12Alm 75.49 74.90 75.25 75.16 75.55 75.24 75.08 74.54 75.00 74.85 75.34 75.43 74.96 75.98Grs 2.80 3.52 3.49 3.65 3.46 3.67 3.45 4.56 4.17 4.24 3.43 3.40 3.37 2.71Prp 11.79 11.90 14.51 14.26 14.18 14.22 14.13 15.03 14.75 14.46 14.31 13.93 13.56 11.65Sps 9.83 9.69 6.70 6.82 6.70 6.87 7.34 5.87 6.07 6.42 6.91 7.15 8.01 9.66Total 99.91 100.00 99.94 99.89 99.90 100.00 100.00 99.99 100.00 99.97 100.00 99.91 99.90 100.00Alm (-Mn) 0.84 0.83 0.81 0.81 0.81 0.81 0.81 0.79 0.80 0.80 0.81 0.81 0.82 0.84Grs (-Mn) 0.03 0.04 0.04 0.04 0.04 0.04 0.04 0.05 0.04 0.05 0.04 0.04 0.04 0.03Fe# 0.86 0.86 0.84 0.84 0.84 0.84 0.84 0.83 0.84 0.84 0.84 0.84 0.85 0.87Table. B.1. Garnet compositions from specimen KA007. Corresponding locations are shown in B.13. Table B.1   Garnet compositions from specimen KA007109wt % 1 2 3 4 5 6 7 8SiO2 35.51 36.73 37.13 35.54 37.05 35.42 32.55 36.43TiO2 4.27 4.00 3.30 3.21 3.32 3.49 3.96 3.87Al2O3 19.90 20.30 21.97 20.01 20.65 20.41 18.22 19.78FeO 20.51 21.02 20.08 20.92 21.21 20.61 20.96 20.14MgO 6.58 7.37 7.74 7.40 7.84 7.43 6.18 7.13CaO 0.05 0.05 0.20 0.14 0.02 0.01 0.13 0.15Na2O 0.11 0.13 0.34 0.27 0.12 0.09 0.19 0.31K2O 8.50 9.31 9.04 9.23 8.50 9.18 9.29 9.16F 0.043 0.449 0.414 0.15 0.4 0.226 0.149 0.26Cl 0.006 0.006 0.026 0.03 0.008 0.002 0.019 0.031Total 95.48 99.36 100.23 96.90 99.12 96.86 91.64 97.26ionsSi 5.33 5.31 5.27 5.30 5.34 5.28 5.26 5.37Ti 0.48 0.44 0.35 0.36 0.36 0.39 0.48 0.43Al 3.52 3.46 3.68 3.52 3.51 3.58 3.47 3.44Fe 2.58 2.54 2.38 2.61 2.55 2.57 2.83 2.48Mg 1.47 1.59 1.64 1.65 1.68 1.65 1.49 1.57Ca 0.01 0.01 0.03 0.02 0.00 0.00 0.02 0.02Na 0.03 0.04 0.09 0.08 0.03 0.03 0.06 0.09K 1.63 1.72 1.64 1.76 1.56 1.74 1.91 1.72Fe 0.02 0.21 0.19 0.07 0.18 0.11 0.08 0.12Cl 0.00 0.00 0.01 0.01 0.00 0.00 0.01 0.01Total 15.06 15.11 15.09 15.30 15.04 15.24 15.52 15.12O 22 22 22 22 22 22 22 22Mg# 0.36 0.38 0.41 0.39 0.40 0.39 0.34 0.39Table. B.2. Biotite compositions from specimen KA007. Corresponding locations are shown in B.13. Table B.2   Biotite compositions from specimen KA007110wt % 1 2 3 4 5 6SiO2 67.21 66.22 66.07 66.01 67.37 66.20Al2O3 23.68 23.26 23.14 23.13 23.57 22.96CaO 3.14 3.16 3.11 3.33 3.07 3.03Na2O 6.77 7.53 7.27 7.32 6.22 7.60K2O 0.32 0.38 0.37 0.36 0.35 0.38Total 101.12 100.56 99.96 100.14 100.57 100.17ionsSi 2.88 2.87 2.88 2.87 2.90 2.88Al 1.20 1.19 1.19 1.19 1.20 1.18Ca 0.14 0.15 0.15 0.16 0.14 0.14Na 0.56 0.63 0.61 0.62 0.52 0.64K 0.02 0.02 0.02 0.02 0.02 0.02Total 4.80 4.86 4.85 4.85 4.77 4.86O 8 8 8 8 8 8An 0.20 0.18 0.19 0.20 0.21 0.18Ab 0.78 0.79 0.79 0.78 0.76 0.80Or 0.02 0.03 0.03 0.03 0.03 0.03Table. B.3. Plagioclase compositions from specimen KA007. Corresponding locations are shown in B.13. Table B.3   Plagioclase compositions from specimen KA007111wt % 1 2 3 4 5SiO2 51.10 48.76 47.33 42.81 50.43TiO2 2.55 1.75 1.74 1.74 2.06Al2O3 35.78 34.46 35.75 27.86 36.90FeO 1.27 1.30 1.41 1.32 1.26MgO 0.94 0.99 0.96 0.72 0.90Na2O 0.25 0.35 0.26 0.19 0.46K2O 7.59 8.35 7.98 7.15 7.80F 0.15 0.15 0.26 0.10 0.39Cl 0.00 0.01 0.02 0.01 0.02Total 99.63 96.11 95.70 81.90 100.21ionsSi 6.36 6.33 6.18 6.52 6.26Ti 0.24 0.17 0.17 0.20 0.19Fe 0.13 0.14 0.15 0.17 0.13Mg 0.17 0.19 0.19 0.16 0.17Na 0.06 0.09 0.07 0.06 0.11K 1.20 1.38 1.33 1.39 1.24F 0.06 0.06 0.11 0.05 0.15Cl 0.00 0.00 0.01 0.00 0.00Al total 5.25 5.28 5.50 5.00 5.40Fe# 0.43 0.42 0.45 0.51 0.44Table B.4. Muscovite compositions from specimen KA007. Corresponding locations are shown in B.13. Table B.4   Muscovite compositions from specimen KA007112111697151091819111213205761234512345643121415 161211117282442121316101715141098657KfsPlMsBtGrtFigure B.14 KA044 EMP mineral spot analysis locations shown on an iron EMP map.Figure B.14 KA044 EMP mineral spot analysis locations 113wt % 1 2 3 4 5 6 7 8 9 10 11 12 13 14SiO2 39.22 39.23 39.35 39.43 39.31 39.24 39.32 39.22 39.36 39.12 39.16 39.25 39.55 38.93TiO2 0.02 0.03 0.06 0.01 0.04 0.02 0.02 0.04 0.05 0.04 0.14 0.03 0.03 0.00Al2O3 22.24 22.60 22.62 22.73 22.52 22.69 22.73 22.80 22.64 22.63 22.76 22.88 22.51 22.58FeO 32.36 31.67 30.82 30.04 30.76 31.07 30.84 31.08 31.24 31.15 31.38 30.85 31.19 33.37MnO 0.63 0.58 0.42 0.41 0.46 0.46 0.46 0.45 0.45 0.45 0.43 0.41 0.45 0.63MgO 5.06 5.22 5.54 5.66 5.71 5.78 5.68 5.74 5.80 5.79 5.76 5.65 5.52 4.48CaO 1.88 2.59 3.22 3.11 2.82 2.19 2.63 2.18 2.06 2.09 2.10 2.38 2.51 1.60Cr2O3 0.03 0.01 0.02 0.05 0.02 -0.01 0.02 -0.01 0.01 0.06 0.01 0.07 0.06 0.04Total 101.45 101.93 102.06 101.44 101.64 101.46 101.70 101.50 101.60 101.33 101.75 101.50 101.83 101.63ionsSi 3.02 3.00 3.00 3.00 3.00 3.00 3.00 2.99 3.00 3.00 2.99 2.99 3.02 3.00Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00Al 2.03 2.05 2.04 2.06 2.04 2.06 2.06 2.07 2.05 2.06 2.06 2.07 2.04 2.07Fe 2.15 2.09 2.03 2.00 2.03 2.06 2.04 2.07 2.07 2.07 2.08 2.06 2.06 2.24Mn 0.04 0.04 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.03 0.04Mg 0.58 0.60 0.63 0.64 0.65 0.66 0.65 0.65 0.66 0.66 0.66 0.64 0.63 0.51Ca 0.16 0.21 0.26 0.25 0.23 0.18 0.22 0.18 0.17 0.17 0.17 0.19 0.20 0.13Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Total 7.98 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.98 7.99O 12 12 12 12 12 12 12 12 12 12 12 12 12 12Alm 73.48 71.24 68.78 68.39 69.01 70.39 69.64 70.59 70.73 70.63 70.85 70.47 70.54 76.51Grs 5.20 7.20 8.84 8.56 7.82 6.14 7.27 6.12 5.72 5.65 5.83 6.42 6.80 4.38Prp 19.83 20.26 21.39 22.01 22.12 22.46 22.02 22.31 22.54 22.54 22.34 21.97 21.46 17.58Sps 1.39 1.28 0.92 0.91 1.00 1.02 1.01 0.99 0.98 0.99 0.95 0.91 1.00 1.40Total 99.90 99.98 99.93 99.86 99.95 100.02 99.93 100.02 99.98 99.80 99.98 99.78 99.81 99.87Alm(-Mn) 74.59 72.18 69.47 69.11 69.75 71.10 70.39 71.29 71.45 71.48 71.55 71.28 71.40 77.70Grs(-Mn) 5.37 7.31 9.00 8.78 7.94 6.19 7.41 6.16 5.80 5.90 5.91 6.70 7.07 4.58Fe# 0.79 0.78 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.76 0.77 0.81Table B.5. Garnet compositions from specimen KA044. Corresponding locations are shown in B.14. Table B.5   Garnet compositions from specimen KA04411415 16 17 18 19 20 21 22 23 24 25 26 27 2839.05 39.34 38.87 38.92 39.26 39.12 39.34 39.30 39.29 39.46 39.43 39.27 39.15 39.180.02 0.02 0.01 0.01 0.05 0.04 0.03 0.03 0.02 0.03 0.05 0.01 0.03 0.0222.63 22.59 22.38 22.50 22.60 22.65 22.69 22.75 22.82 22.77 22.51 22.71 22.56 22.4632.34 32.19 33.34 32.24 31.20 31.68 30.93 32.07 31.85 31.75 31.48 32.02 32.07 33.280.67 0.61 0.66 0.59 0.52 0.47 0.51 0.51 0.53 0.56 0.57 0.51 0.62 0.665.06 5.25 4.51 5.04 5.40 5.57 5.70 5.72 5.60 5.52 5.51 5.48 5.26 4.751.67 2.04 1.70 1.93 2.26 2.27 2.01 1.83 1.89 2.30 2.18 1.86 1.92 1.750.01 0.00 0.05 0.06 0.00 0.01 0.00 0.02 0.05 0.04 0.00 0.00 0.07 0.02101.44 102.05 101.52 101.28 101.29 101.80 101.21 102.24 102.04 102.42 101.73 101.86 101.68 102.113.00 3.01 3.00 3.00 3.01 2.99 3.01 2.99 2.99 3.00 3.01 3.00 3.00 3.010.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002.06 2.05 2.05 2.06 2.05 2.05 2.06 2.05 2.06 2.05 2.04 2.06 2.05 2.042.16 2.13 2.23 2.16 2.08 2.09 2.07 2.11 2.11 2.09 2.09 2.12 2.13 2.210.04 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.03 0.04 0.04 0.03 0.04 0.040.58 0.60 0.52 0.58 0.62 0.63 0.65 0.65 0.64 0.63 0.63 0.62 0.60 0.540.14 0.17 0.14 0.16 0.19 0.19 0.16 0.15 0.15 0.19 0.18 0.15 0.16 0.140.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.007.99 7.99 7.99 7.99 7.98 7.99 7.98 7.99 7.99 7.99 7.98 7.99 7.99 7.9912 12 12 12 12 12 12 12 12 12 12 12 12 1274.00 72.58 76.02 73.52 71.37 71.10 70.94 71.72 71.88 71.12 71.21 72.41 72.75 75.134.65 5.70 4.64 5.25 6.36 6.29 5.64 5.03 5.13 6.24 6.10 5.19 5.16 4.8419.81 20.37 17.71 19.73 21.12 21.56 22.28 22.08 21.70 21.29 21.43 21.26 20.50 18.521.49 1.35 1.48 1.32 1.16 1.04 1.14 1.12 1.15 1.22 1.27 1.13 1.36 1.4699.96 100.00 99.84 99.81 100.00 99.98 100.00 99.95 99.86 99.88 100.00 99.99 99.78 99.9575.15 73.57 77.28 74.64 72.20 71.85 71.76 72.57 72.82 72.09 72.12 73.24 73.92 76.284.77 5.77 4.87 5.51 6.43 6.37 5.71 5.14 5.33 6.44 6.17 5.25 5.46 4.970.79 0.78 0.81 0.79 0.77 0.77 0.76 0.76 0.77 0.77 0.77 0.77 0.78 0.80Table B.5. continued 11529 30 31 32 33 34 35 36 37 38 39 40 41 4238.59 39.31 39.36 39.47 39.24 39.11 39.10 38.94 39.40 39.33 39.43 39.38 39.46 39.260.04 0.03 0.05 0.05 0.04 0.03 0.05 0.05 0.05 0.05 0.04 0.02 0.04 0.0522.33 22.52 22.53 22.61 22.41 22.59 22.42 22.55 22.50 22.48 22.63 22.68 22.52 22.0733.18 30.03 29.97 29.31 30.14 30.05 30.68 30.21 30.30 30.30 29.48 30.05 31.58 34.090.79 0.56 0.50 0.61 0.58 0.55 0.56 0.57 0.54 0.53 0.44 0.50 0.67 0.854.01 5.27 5.26 5.07 4.98 4.98 4.89 5.04 5.12 5.20 5.27 5.25 4.86 3.701.73 2.95 3.43 3.82 3.93 3.90 3.94 3.73 3.83 3.75 3.61 3.50 3.11 1.820.00 0.00 0.04 0.03 0.05 0.04 0.00 0.00 0.00 0.00 0.02 0.02 0.04 0.02100.66 100.68 101.12 100.98 101.38 101.24 101.64 101.09 101.74 101.63 100.90 101.39 102.28 101.863.00 3.02 3.01 3.02 3.01 3.00 3.00 3.00 3.01 3.01 3.01 3.01 3.01 3.030.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002.06 2.05 2.05 2.05 2.04 2.06 2.04 2.06 2.04 2.04 2.06 2.06 2.04 2.022.25 2.02 2.00 1.97 2.00 2.01 2.03 2.02 2.00 2.00 1.98 2.00 2.08 2.280.05 0.04 0.03 0.04 0.04 0.04 0.04 0.04 0.03 0.03 0.03 0.03 0.04 0.060.47 0.60 0.60 0.58 0.57 0.57 0.56 0.58 0.58 0.59 0.60 0.60 0.55 0.430.14 0.24 0.28 0.31 0.32 0.32 0.32 0.31 0.31 0.31 0.30 0.29 0.25 0.150.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.007.99 7.98 7.98 7.98 7.99 7.99 7.99 7.99 7.99 7.99 7.98 7.99 7.99 7.9712 12 12 12 12 12 12 12 12 12 12 12 12 1277.32 69.63 68.68 67.96 68.29 68.43 68.77 68.59 68.26 68.17 68.18 68.63 71.02 78.304.95 8.36 9.52 10.68 10.85 10.81 11.00 10.47 10.69 10.46 10.13 9.74 8.55 5.1015.95 20.75 20.58 19.90 19.40 19.42 18.99 19.68 19.87 20.19 20.66 20.47 18.84 14.611.78 1.26 1.10 1.36 1.29 1.23 1.24 1.25 1.18 1.17 0.98 1.11 1.46 1.91100.00 100.00 99.88 99.91 99.83 99.89 100.00 100.00 100.00 100.00 99.95 99.95 99.87 99.9278.72 70.52 69.53 68.96 69.30 69.36 69.63 69.46 69.08 68.98 68.89 69.43 72.17 79.895.04 8.46 9.75 10.92 11.17 11.06 11.14 10.61 10.82 10.59 10.28 9.90 8.80 5.270.83 0.77 0.77 0.77 0.78 0.78 0.78 0.78 0.77 0.77 0.77 0.77 0.79 0.84Table B.5. continued116wt % 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21SiO2 38.16 35.67 38.43 36.39 36.27 35.97 36.67 34.84 34.18 36.39 33.71 35.34 34.74 35.63 35.97 35.76 35.63 35.47 36.29 35.07 36.88TiO2 0.13 3.69 0.69 0.86 4.43 4.51 4.67 5.13 1.43 0.04 3.04 4.18 4.11 4.94 4.92 4.03 4.07 4.61 3.06 4.48 4.51Al2O3 20.83 19.58 23.61 21.78 18.78 19.01 18.53 17.99 20.09 24.41 19.65 17.68 17.63 18.81 18.73 18.62 18.30 17.87 19.60 18.66 19.99FeO 13.39 17.55 17.72 15.71 18.62 18.55 18.88 19.27 17.79 14.68 16.17 18.51 17.90 18.26 18.87 18.17 18.00 18.90 16.21 17.65 17.81MgO 15.55 10.62 11.58 13.60 10.07 10.10 10.04 9.55 11.57 13.17 11.53 10.03 9.64 9.66 9.62 10.30 9.86 9.43 11.36 9.48 10.23CaO 0.05 0.01 0.13 0.07 0.00 0.00 0.02 0.01 0.10 0.11 0.03 0.05 0.04 0.01 0.01 0.04 0.05 0.02 0.03 0.04 0.03Na2O 0.23 0.11 0.10 0.48 0.11 0.14 0.09 0.11 0.21 0.21 0.30 0.14 0.11 0.13 0.12 0.10 0.14 0.09 0.13 0.16 0.12K2O 8.72 9.85 7.92 8.49 9.84 9.88 9.88 9.85 8.57 8.49 9.38 9.56 9.45 9.75 9.86 9.65 9.62 9.74 9.84 9.83 9.71F 0.99 0.44 0.46 0.09 0.56 0.55 0.41 0.40 0.08 0.26 0.83 0.51 0.40 0.82 0.44 0.65 0.64 0.56 0.79 0.45 0.56Cl 0.02 0.00 0.02 0.02 0.00 0.00 0.00 0.00 0.03 0.01 0.01 0.02 0.01 0.00 0.01 0.02 0.03 0.01 0.01 0.01 0.01Total 98.14 97.61 100.66 97.51 98.81 98.88 99.26 97.27 94.07 97.80 94.73 96.08 94.09 98.17 98.62 97.45 96.45 96.91 97.41 96.01 99.97ionsSi 5.46 5.28 5.38 5.27 5.34 5.29 5.37 5.25 5.22 5.21 5.16 5.36 5.37 5.29 5.31 5.33 5.37 5.35 5.36 5.31 5.32Ti 0.01 0.41 0.07 0.09 0.49 0.50 0.51 0.58 0.16 0.00 0.35 0.48 0.48 0.55 0.55 0.45 0.46 0.52 0.34 0.51 0.49Al 3.52 3.42 3.90 3.72 3.26 3.30 3.20 3.19 3.62 4.12 3.54 3.16 3.21 3.29 3.26 3.27 3.25 3.18 3.41 3.33 3.40Fe 1.60 2.17 2.08 1.90 2.29 2.28 2.31 2.43 2.27 1.76 2.07 2.35 2.31 2.27 2.33 2.27 2.27 2.38 2.00 2.23 2.15Mg 3.32 2.35 2.42 2.93 2.21 2.21 2.19 2.14 2.64 2.81 2.63 2.27 2.22 2.14 2.12 2.29 2.22 2.12 2.50 2.14 2.20Ca 0.01 0.00 0.02 0.01 0.00 0.00 0.00 0.00 0.02 0.02 0.00 0.01 0.01 0.00 0.00 0.01 0.01 0.00 0.01 0.01 0.01Na 0.06 0.03 0.03 0.14 0.03 0.04 0.03 0.03 0.06 0.06 0.09 0.04 0.03 0.04 0.04 0.03 0.04 0.03 0.04 0.05 0.03K 1.59 1.86 1.42 1.57 1.85 1.85 1.84 1.89 1.67 1.55 1.83 1.85 1.86 1.85 1.86 1.84 1.85 1.87 1.85 1.90 1.79F 0.45 0.21 0.20 0.04 0.26 0.26 0.19 0.19 0.04 0.12 0.40 0.25 0.19 0.38 0.21 0.31 0.31 0.26 0.37 0.21 0.26Cl 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.01 0.00 0.00 0.00 0.00Total 16.03 15.74 15.52 15.68 15.72 15.74 15.64 15.71 15.71 15.64 16.07 15.76 15.69 15.81 15.66 15.80 15.78 15.72 15.89 15.68 15.64O 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22 22Mg# 0.67 0.52 0.54 0.61 0.49 0.49 0.49 0.47 0.54 0.62 0.56 0.49 0.49 0.49 0.48 0.50 0.49 0.47 0.56 0.49 0.51Table B.6. Biotite compositions from specimen KA044. Corresponding locations are shown in B.14. Table B.6   Biotite compositions from specimen KA044117wt % 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16SiO2 60.38 59.72 60.30 59.82 59.72 60.18 59.43 58.83 60.98 59.33 60.05 60.33 60.41 58.44 59.68 60.04Al2O3 27.20 26.91 26.33 27.00 27.19 26.32 27.09 26.94 26.94 26.80 26.44 26.05 27.15 27.27 26.74 26.23CaO 7.50 7.37 6.95 7.37 7.62 6.88 7.62 7.70 7.16 7.33 7.30 6.74 7.47 7.98 7.34 7.00Na2O 6.72 7.15 7.02 7.12 6.41 7.29 6.81 6.72 5.72 6.41 6.68 6.84 6.10 6.63 6.87 7.12K2O 0.25 0.16 0.30 0.23 0.29 0.27 0.27 0.25 0.26 0.20 0.18 0.15 0.26 0.22 0.25 0.28Total 102.05 101.31 100.90 101.53 101.22 100.93 101.22 100.44 101.06 100.07 100.64 100.10 101.38 100.54 100.89 100.67ionsSi 2.63 2.62 2.66 2.62 2.62 2.65 2.62 2.61 2.67 2.63 2.65 2.67 2.64 2.59 2.63 2.65Al 1.40 1.39 1.37 1.40 1.41 1.37 1.40 1.41 1.39 1.40 1.37 1.36 1.40 1.43 1.39 1.37Ca 0.35 0.35 0.33 0.35 0.36 0.32 0.36 0.37 0.34 0.35 0.34 0.32 0.35 0.38 0.35 0.33Na 0.57 0.61 0.60 0.61 0.55 0.62 0.58 0.58 0.49 0.55 0.57 0.59 0.52 0.57 0.59 0.61K 0.01 0.01 0.02 0.01 0.02 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02Total 4.96 4.98 4.97 4.98 4.95 4.98 4.98 4.98 4.89 4.94 4.94 4.94 4.92 4.98 4.97 4.97O 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8An 0.38 0.36 0.35 0.36 0.39 0.34 0.38 0.38 0.40 0.38 0.37 0.35 0.40 0.39 0.37 0.35Ab 0.61 0.63 0.63 0.63 0.59 0.65 0.61 0.60 0.58 0.61 0.62 0.64 0.59 0.59 0.62 0.64Or 0.01 0.01 0.02 0.01 0.02 0.02 0.02 0.01 0.02 0.01 0.01 0.01 0.02 0.01 0.01 0.02Table B.7. Plagioclase compositions from specimen KA044. Corresponding locations are shown in B.14. Table B.7   Plagioclase compositions from specimen KA044118wt % 1 2 3 4 5 6 7 8 9 10 11SiO2 65.27 65.47 66.42 65.63 64.50 66.73 64.49 64.52 65.07 67.42 65.83Al2O3 19.70 19.92 20.29 19.74 19.63 20.10 19.60 19.59 19.63 20.13 20.10CaO 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Na2O 1.41 1.49 1.44 1.25 1.36 1.43 1.27 1.23 1.13 1.33 2.34K2O 14.40 13.37 12.95 14.11 13.37 12.33 13.86 14.09 14.09 12.01 12.11BaO 0.39 0.42 0.41 0.39 0.44 0.45 0.49 0.38 0.38 0.33 0.23Total 101.23 100.70 101.58 101.15 99.32 101.09 99.79 99.86 100.33 101.28 100.63ionsSi 2.96 2.97 2.98 2.97 2.97 2.99 2.97 2.97 2.97 3.00 2.97Al 1.05 1.07 1.07 1.05 1.07 1.06 1.06 1.06 1.06 1.06 1.07Ca 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Na 0.12 0.13 0.12 0.11 0.12 0.12 0.11 0.11 0.10 0.12 0.20K 0.83 0.77 0.74 0.82 0.78 0.70 0.81 0.83 0.82 0.68 0.70Ba 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.00Total 4.99 4.95 4.92 4.96 4.95 4.89 4.97 4.97 4.96 4.87 4.95O 8 8 8 8 8 8 8 8 8 8 8An 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Ab 0.13 0.14 0.14 0.12 0.13 0.15 0.12 0.12 0.11 0.14 0.23Or 0.87 0.86 0.86 0.88 0.87 0.85 0.88 0.88 0.89 0.86 0.77Table B.8. K-feldspar compositions from specimen KA044. Corresponding locations are shown in B.14. Table B.8   K-feldspar compositions from specimen KA04411911611b1b1122346771281134101712131323121924b35b20 26911587610121517141316141516192324252622212018965785234KfsPlMsBtGrtFigure B.15. KA064A EMP mineral spot analysis locations shown on an iron EMP map. Figure B.15 KA064A EMP mineral spot analysis locations 120wt% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17SiO2 37.66 37.56 37.64 37.61 37.70 37.16 37.70 37.97 37.95 37.67 37.50 37.76 37.98 37.82 37.74 37.69 38.07TiO2 0.00 0.02 0.00 0.01 0.00 0.01 0.02 0.01 0.00 0.01 0.00 0.01 0.00 0.02 0.02 0.00 0.03Al2O3 22.33 21.85 22.06 22.06 21.78 21.75 22.11 21.95 21.90 21.80 21.80 21.74 21.90 22.05 21.96 22.03 21.81FeO 34.13 33.63 34.48 33.88 33.79 33.39 34.20 34.59 33.70 33.85 34.61 34.01 34.06 33.39 33.46 34.15 33.64MnO 3.26 3.73 4.25 4.36 4.73 4.73 2.20 2.29 2.50 3.18 3.48 4.12 1.99 2.04 1.96 2.14 2.25MgO 3.16 2.96 2.72 2.69 2.67 2.63 3.60 3.57 3.51 3.25 3.19 2.83 4.06 4.09 3.98 3.81 3.68CaO 1.00 0.90 0.77 0.87 0.84 0.78 1.41 1.40 1.12 1.21 0.77 1.26 1.17 1.27 1.34 1.36 1.30Cr2O3 0.00 0.02 0.02 0.02 0.00 0.04 0.00 0.00 0.00 0.00 0.01 0.00 0.03 0.01 0.03 0.01 0.01Total 101.54 100.68 101.94 101.50 101.51 100.47 101.23 101.79 100.68 100.98 101.35 101.72 101.19 100.67 100.48 101.20 100.79ionsSi 2.96 2.98 2.97 2.97 2.99 2.97 2.97 2.98 2.99 2.98 2.97 2.99 2.99 2.98 2.98 2.97 3.00Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Al 2.08 2.05 2.06 2.06 2.04 2.06 2.06 2.04 2.05 2.04 2.04 2.03 2.04 2.05 2.05 2.05 2.03Fe 2.30 2.28 2.31 2.29 2.27 2.28 2.29 2.30 2.28 2.28 2.32 2.27 2.27 2.25 2.26 2.28 2.27Mn 0.22 0.25 0.28 0.29 0.32 0.32 0.15 0.15 0.17 0.21 0.23 0.28 0.13 0.14 0.13 0.14 0.15Mg 0.37 0.35 0.32 0.32 0.32 0.31 0.42 0.42 0.41 0.38 0.38 0.33 0.48 0.48 0.47 0.45 0.43Ca 0.08 0.08 0.06 0.07 0.07 0.07 0.12 0.12 0.09 0.10 0.07 0.11 0.10 0.11 0.11 0.11 0.11Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Total 8.01 8.00 8.01 8.01 8.00 8.01 8.01 8.01 8.00 8.00 8.01 8.00 8.00 8.00 8.00 8.01 7.99O 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12Alm 77.30 77.10 77.50 77.05 76.35 76.46 76.84 76.90 77.16 76.49 77.27 76.03 76.26 75.65 75.97 76.25 76.61Grs 2.83 2.52 2.12 2.40 2.39 2.12 3.98 3.96 3.20 3.45 2.18 3.57 3.21 3.57 3.74 3.83 3.67Prp 12.52 11.84 10.75 10.65 10.59 10.53 14.22 14.03 13.99 12.90 12.66 11.16 15.99 16.16 15.78 15.07 14.62Sps 7.34 8.47 9.57 9.83 10.66 10.77 4.95 5.11 5.66 7.16 7.86 9.24 4.44 4.58 4.42 4.81 5.08Total 99.99 99.93 99.94 99.93 100.00 99.88 99.99 100.00 100.01 99.99 99.98 100.00 99.90 99.96 99.91 99.96 99.97Alm (-Mn) 83.43 84.30 85.76 85.52 85.47 85.81 80.85 81.04 81.78 82.40 83.88 83.77 79.89 79.32 79.56 80.14 80.73Grs (-Mn) 3.06 2.76 2.34 2.66 2.67 2.38 4.19 4.17 3.39 3.71 2.37 3.94 3.36 3.75 3.91 4.02 3.87Fe# 0.86 0.87 0.88 0.88 0.88 0.88 0.84 0.85 0.85 0.86 0.86 0.87 0.83 0.82 0.83 0.84 0.84Table B.9. Garnet compositions from specimen KA064A. Corresponding locations are shown in B.15. Table B.9   Garnet compositions from specimen KA064A121wt% 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17SiO2 37.66 37.56 37.64 37.61 37.70 37.16 37.70 37.97 37.95 37.67 37.50 37.76 37.98 37.82 37.74 37.69 38.07TiO2 0.00 0.02 0.00 0.01 0.00 0.01 0.02 0.01 0.00 0.01 0.00 0.01 0.00 0.02 0.02 0.00 0.03Al2O3 22.33 21.85 22.06 22.06 21.78 21.75 22.11 21.95 21.90 21.80 21.80 21.74 21.90 22.05 21.96 22.03 21.81FeO 34.13 33.63 34.48 33.88 33.79 33.39 34.20 34.59 33.70 33.85 34.61 34.01 34.06 33.39 33.46 34.15 33.64MnO 3.26 3.73 4.25 4.36 4.73 4.73 2.20 2.29 2.50 3.18 3.48 4.12 1.99 2.04 1.96 2.14 2.25MgO 3.16 2.96 2.72 2.69 2.67 2.63 3.60 3.57 3.51 3.25 3.19 2.83 4.06 4.09 3.98 3.81 3.68CaO 1.00 0.90 0.77 0.87 0.84 0.78 1.41 1.40 1.12 1.21 0.77 1.26 1.17 1.27 1.34 1.36 1.30Cr2O3 0.00 0.02 0.02 0.02 0.00 0.04 0.00 0.00 0.00 0.00 0.01 0.00 0.03 0.01 0.03 0.01 0.01Total 101.54 100.68 101.94 101.50 101.51 100.47 101.23 101.79 100.68 100.98 101.35 101.72 101.19 100.67 100.48 101.20 100.79ionsSi 2.96 2.98 2.97 2.97 2.99 2.97 2.97 2.98 2.99 2.98 2.97 2.99 2.99 2.98 2.98 2.97 3.00Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Al 2.08 2.05 2.06 2.06 2.04 2.06 2.06 2.04 2.05 2.04 2.04 2.03 2.04 2.05 2.05 2.05 2.03Fe 2.30 2.28 2.31 2.29 2.27 2.28 2.29 2.30 2.28 2.28 2.32 2.27 2.27 2.25 2.26 2.28 2.27Mn 0.22 0.25 0.28 0.29 0.32 0.32 0.15 0.15 0.17 0.21 0.23 0.28 0.13 0.14 0.13 0.14 0.15Mg 0.37 0.35 0.32 0.32 0.32 0.31 0.42 0.42 0.41 0.38 0.38 0.33 0.48 0.48 0.47 0.45 0.43Ca 0.08 0.08 0.06 0.07 0.07 0.07 0.12 0.12 0.09 0.10 0.07 0.11 0.10 0.11 0.11 0.11 0.11Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Total 8.01 8.00 8.01 8.01 8.00 8.01 8.01 8.01 8.00 8.00 8.01 8.00 8.00 8.00 8.00 8.01 7.99O 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12Alm 77.30 77.10 77.50 77.05 76.35 76.46 76.84 76.90 77.16 76.49 77.27 76.03 76.26 75.65 75.97 76.25 76.61Grs 2.83 2.52 2.12 2.40 2.39 2.12 3.98 3.96 3.20 3.45 2.18 3.57 3.21 3.57 3.74 3.83 3.67Prp 12.52 11.84 10.75 10.65 10.59 10.53 14.22 14.03 13.99 12.90 12.66 11.16 15.99 16.16 15.78 15.07 14.62Sps 7.34 8.47 9.57 9.83 10.66 10.77 4.95 5.11 5.66 7.16 7.86 9.24 4.44 4.58 4.42 4.81 5.08Total 99.99 99.93 99.94 99.93 100.00 99.88 99.99 100.00 100.01 99.99 99.98 100.00 99.90 99.96 99.91 99.96 99.97Alm (-Mn) 83.43 84.30 85.76 85.52 85.47 85.81 80.85 81.04 81.78 82.40 83.88 83.77 79.89 79.32 79.56 80.14 80.73Grs (-Mn) 3.06 2.76 2.34 2.66 2.67 2.38 4.19 4.17 3.39 3.71 2.37 3.94 3.36 3.75 3.91 4.02 3.87Fe# 0.86 0.87 0.88 0.88 0.88 0.88 0.84 0.85 0.85 0.86 0.86 0.87 0.83 0.82 0.83 0.84 0.84Table B.9. continued122wt% 18 19 20 21 22 23 24 25 26 1b 2b 3b 4b 5b 6b 7b 8bSiO2 37.79 37.43 37.72 37.98 37.83 37.79 37.97 37.95 37.51 38.64 38.24 38.68 38.11 38.58 38.17 38.27 38.26TiO2 0.01 0.02 0.00 0.02 0.00 0.01 0.02 0.00 0.01 0.02 0.02 0.01 0.03 0.00 0.00 -0.01 0.01Al2O3 21.73 21.55 21.83 21.88 22.02 21.88 21.98 21.97 21.61 22.18 22.18 22.37 22.28 22.13 22.11 22.25 22.26FeO 33.36 33.79 34.23 33.41 33.43 33.62 33.84 34.28 33.39 32.87 33.66 33.87 34.06 33.77 33.67 33.85 33.97MnO 2.59 4.30 2.34 2.07 1.99 2.06 2.30 2.96 4.44 4.75 4.60 4.18 3.52 3.52 3.74 3.40 3.41MgO 3.53 2.42 3.72 3.71 3.79 3.76 3.64 3.43 2.68 2.65 2.77 2.89 3.04 3.14 2.99 3.13 3.07CaO 1.26 0.97 1.23 1.19 1.39 1.28 1.36 0.77 1.05 1.14 0.88 0.91 1.00 1.02 1.08 1.16 0.97Cr2O3 0.01 0.00 0.00 0.02 0.00 0.03 0.00 0.01 0.04 0.04 0.01 -0.01 0.03 0.03 -0.01 -0.02 0.00Total 100.28 100.47 101.08 100.27 100.46 100.43 101.10 101.38 100.73 102.29 102.36 102.89 102.07 102.18 101.74 102.03 101.94ionsSi 3.00 2.99 2.98 3.00 2.98 2.99 2.99 2.99 2.99 3.01 2.99 3.00 2.98 3.00 2.99 2.99 2.99Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Al 2.04 2.04 2.04 2.05 2.06 2.05 2.05 2.05 2.04 2.05 2.05 2.05 2.06 2.04 2.05 2.06 2.06Fe 2.26 2.30 2.29 2.27 2.26 2.27 2.27 2.30 2.26 2.21 2.26 2.26 2.29 2.26 2.27 2.27 2.28Mn 0.17 0.29 0.16 0.14 0.13 0.14 0.15 0.20 0.30 0.31 0.30 0.27 0.23 0.23 0.25 0.22 0.23Mg 0.42 0.29 0.44 0.44 0.45 0.44 0.43 0.40 0.32 0.31 0.32 0.33 0.35 0.36 0.35 0.36 0.36Ca 0.11 0.08 0.10 0.10 0.12 0.11 0.11 0.07 0.09 0.09 0.07 0.08 0.08 0.08 0.09 0.10 0.08Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Total 8.00 8.00 8.01 7.99 8.00 8.00 8.00 8.00 8.00 7.99 8.00 7.99 8.00 7.99 8.00 8.00 8.00O 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12Alm 76.39 77.67 76.54 77.06 76.45 76.70 76.58 77.58 76.18 75.57 76.30 76.79 77.31 76.86 76.70 76.78 77.48Grs 3.60 2.79 3.50 3.36 3.98 3.57 3.85 2.17 2.88 3.12 2.45 2.61 2.74 2.80 3.12 3.36 2.76Prp 14.11 9.72 14.70 14.82 15.07 14.97 14.40 13.58 10.73 10.51 10.91 11.34 11.98 12.38 11.82 12.33 12.12Sps 5.87 9.82 5.26 4.69 4.50 4.66 5.16 6.66 10.09 10.68 10.30 9.31 7.89 7.89 8.40 7.61 7.65Total 99.97 100.00 100.00 99.94 100.00 99.91 99.99 99.98 99.88 99.88 99.96 100.04 99.92 99.92 100.04 100.08 100.01Alm (-Mn) 81.18 86.13 80.80 80.91 80.06 80.53 80.76 83.13 84.84 84.72 85.10 84.63 84.00 83.51 83.70 83.04 83.89Grs (-Mn) 3.83 3.10 3.69 3.53 4.16 3.75 4.06 2.32 3.21 3.50 2.73 2.87 2.98 3.04 3.40 3.63 2.99Fe# 0.84 0.89 0.84 0.84 0.84 0.84 0.84 0.85 0.88 0.88 0.87 0.87 0.87 0.86 0.87 0.86 0.86Table B.9. continued123wt% 9b 10b 11b 12b 13b 14b 15b 16b 17b 18b 19b 20b 21b 22b 23b 24b 25bSiO2 38.30 38.10 38.25 38.41 38.88 38.62 38.83 38.69 38.90 38.63 38.78 38.59 38.68 38.50 38.70 38.28 38.48TiO2 0.02 -0.01 0.03 0.00 0.00 0.04 -0.02 -0.01 -0.02 0.01 0.02 0.02 -0.02 0.00 0.00 0.02 0.01Al2O3 22.08 22.09 22.02 22.26 22.26 22.35 22.37 22.48 22.27 22.28 22.23 22.35 22.29 22.24 22.28 22.09 22.24FeO 33.55 33.56 33.54 33.13 33.62 33.23 33.11 33.13 33.78 33.36 33.80 33.43 33.27 33.90 33.28 33.61 33.46MnO 3.63 4.12 4.33 2.96 2.15 2.07 2.07 2.03 2.04 2.05 2.04 2.04 2.47 2.74 3.50 4.91 3.40MgO 3.01 2.75 2.69 3.50 3.79 3.88 3.93 4.07 4.12 4.00 3.80 3.74 3.49 3.27 3.06 2.66 3.35CaO 1.05 0.88 1.04 1.13 1.19 1.36 1.31 1.09 1.08 1.32 1.35 1.38 1.38 1.29 1.29 0.93 0.87Cr2O3 -0.02 -0.01 0.06 0.01 0.05 0.01 0.00 -0.04 -0.02 0.01 0.01 -0.01 0.00 0.02 -0.01 -0.01 0.06Total 101.62 101.48 101.96 101.39 101.95 101.55 101.62 101.44 102.15 101.66 102.02 101.54 101.57 101.95 102.10 102.50 101.87ionsSi 3.00 2.99 3.00 3.00 3.01 3.00 3.01 3.00 3.01 3.00 3.01 3.00 3.01 3.00 3.01 2.99 3.00Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Al 2.05 2.06 2.04 2.06 2.04 2.06 2.06 2.07 2.04 2.05 2.04 2.06 2.06 2.05 2.05 2.04 2.05Fe 2.26 2.27 2.26 2.24 2.25 2.23 2.23 2.23 2.25 2.23 2.26 2.25 2.24 2.27 2.24 2.25 2.25Mn 0.24 0.27 0.29 0.20 0.14 0.14 0.14 0.13 0.13 0.13 0.13 0.13 0.16 0.18 0.23 0.33 0.22Mg 0.35 0.32 0.31 0.41 0.44 0.45 0.45 0.47 0.47 0.46 0.44 0.43 0.40 0.38 0.35 0.31 0.39Ca 0.09 0.07 0.09 0.09 0.10 0.11 0.11 0.09 0.09 0.11 0.11 0.11 0.12 0.11 0.11 0.08 0.07Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Total 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 7.99 8.00 7.99O 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12 12Alm 76.87 77.24 76.64 76.25 76.87 76.19 76.11 76.30 76.28 75.93 76.72 76.74 76.68 77.31 76.37 75.88 76.65Grs 3.08 2.53 2.77 3.19 3.24 3.84 3.72 3.22 3.11 3.72 3.76 3.94 3.94 3.59 3.70 2.67 2.31Prp 11.94 10.94 10.64 13.88 14.93 15.31 15.52 16.05 16.13 15.74 14.92 14.77 13.82 12.91 12.11 10.49 13.25Sps 8.19 9.31 9.75 6.66 4.81 4.63 4.65 4.56 4.54 4.59 4.56 4.58 5.56 6.13 7.86 10.99 7.62Total 100.08 100.03 99.81 99.98 99.86 99.98 99.99 100.13 100.06 99.98 99.96 100.02 100.00 99.94 100.03 100.03 99.83Alm (-Mn) 83.66 85.15 85.10 81.71 80.88 79.91 79.82 79.84 79.86 79.60 80.42 80.40 81.19 82.42 82.85 85.22 83.13Grs (-Mn) 3.35 2.79 3.08 3.41 3.41 4.03 3.90 3.37 3.26 3.90 3.94 4.13 4.17 3.82 4.01 3.00 2.50Fe# 0.87 0.88 0.88 0.85 0.84 0.83 0.83 0.83 0.83 0.83 0.84 0.84 0.85 0.86 0.86 0.88 0.85Table B.9. continued124wt% 26b 27b 28b 29b 30b 31b 32b 33b 34b 34bSiO2 38.65 38.72 38.61 39.01 38.72 38.60 38.65 38.86 38.75 38.22TiO2 0.01 0.02 0.00 0.01 0.00 0.00 0.00 0.01 0.018 0.005Al2O3 22.41 22.36 22.42 22.24 22.28 22.41 22.33 22.10 22.43 22.17FeO 33.51 33.75 33.84 33.74 33.71 33.69 34.19 33.64 34 33.75MnO 2.46 2.12 2.15 2.09 2.37 2.23 2.33 2.49 2.819 4.578MgO 3.65 3.77 3.89 3.84 3.63 3.80 3.71 3.55 3.402 2.27CaO 1.36 1.21 1.19 1.30 1.28 1.19 1.20 1.30 1.304 1.051Cr2O3 -0.01 -0.02 0.03 0.01 0.00 0.03 -0.01 0.02 0.029 0.033Total 102.04 101.90 102.14 102.24 102.00 101.93 102.40 101.97 102.74 102.08ionsSi 2.99 3.00 2.99 3.01 3.00 2.99 2.99 3.02 2.993 2.993Ti 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.001 3E‐04Al 2.06 2.06 2.06 2.04 2.05 2.06 2.05 2.03 2.053 2.059Fe 2.24 2.26 2.26 2.25 2.26 2.26 2.27 2.25 2.262 2.283Mn 0.16 0.14 0.14 0.14 0.16 0.15 0.15 0.16 0.184 0.304Mg 0.42 0.44 0.45 0.44 0.42 0.44 0.43 0.41 0.392 0.265Ca 0.11 0.10 0.10 0.11 0.11 0.10 0.10 0.11 0.108 0.088Cr 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.002 0.002Total 7.99 7.99 8.00 7.98 7.99 7.99 8.00 7.98 7.995 7.994O 12 12 12 12 12 12 12 12 12 12Alm 76.33 77.02 76.62 76.59 76.76 76.76 76.95 76.72 76.77 77.66Grs 3.87 3.48 3.27 3.63 3.64 3.25 3.39 3.63 3.57 2.90Prp 14.34 14.82 15.23 15.08 14.30 14.92 14.51 14.01 13.30 9.01Sps 5.50 4.75 4.79 4.67 5.31 4.97 5.18 5.57 6.26 10.33Total 100.03 100.08 99.91 99.97 100.01 99.90 100.03 99.93 99.91 99.90Alm (-Mn) 80.74 80.80 80.55 80.37 81.06 80.86 81.12 81.31 81.98 86.70Grs (-Mn) 4.09 3.66 3.44 3.81 3.84 3.42 3.58 3.85 3.82 3.23Fe# 0.84 0.84 0.83 0.84 0.84 0.84 0.84 0.85 0.85 0.90Table B.9. continued125wt % 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18SiO2 34.23 35.66 35.44 33.57 36.48 36.04 25.77 33.92 36.43 35.47 35.31 35.89 35.07 35.84 33.71 35.32 35.49 35.93TiO2 0.11 0.66 3.60 3.71 3.43 4.20 0.03 1.92 1.91 3.96 3.83 4.20 1.92 0.88 1.58 3.69 3.42 3.62Al2O3 22.99 22.76 20.43 19.76 21.13 20.59 21.29 19.53 22.12 20.05 20.08 20.45 20.27 23.95 20.40 20.35 20.19 20.35FeO 25.04 23.06 22.17 21.20 22.22 18.74 38.37 22.23 22.97 23.20 22.70 18.52 24.01 23.50 23.05 22.66 23.50 22.65MgO 7.12 7.42 6.48 6.38 7.08 8.05 6.66 6.24 7.38 6.94 6.98 8.49 8.56 7.13 6.34 6.86 6.80 7.25CaO 0.02 0.04 -0.01 0.04 0.02 0.01 0.06 0.01 0.01 -0.01 -0.01 0.08 0.10 0.02 0.07 0.00 0.00 0.02Na2O 0.20 0.24 0.22 0.29 0.22 0.36 0.06 0.17 0.23 0.22 0.24 0.33 0.26 0.21 0.23 0.20 0.20 0.36K2O 8.21 9.21 8.68 9.25 8.92 8.02 0.01 7.68 7.87 8.70 9.12 8.72 8.02 8.21 8.88 8.58 8.29 8.88F 0.15 0.19 0.20 0.05 0.35 0.13 0.03 0.20 0.21 0.32 0.00 0.10 0.32 0.12 0.10 0.21 0.30 0.37Cl 0.04 0.04 0.04 0.05 0.04 0.03 0.01 0.05 0.06 0.05 0.04 0.03 0.03 0.05 0.04 0.04 0.05 0.04Total 98.09 99.28 97.24 94.30 99.88 96.17 92.28 91.94 99.18 98.88 98.29 96.80 98.57 99.91 94.39 97.91 98.25 99.45ionsSi 5.15 5.26 5.33 5.23 5.33 5.36 4.32 5.40 5.33 5.28 5.27 5.32 5.24 5.22 5.28 5.29 5.31 5.30Ti 0.01 0.07 0.41 0.43 0.38 0.47 0.00 0.23 0.21 0.44 0.43 0.47 0.22 0.10 0.19 0.42 0.39 0.40Al 4.08 3.96 3.62 3.63 3.64 3.61 4.20 3.66 3.82 3.52 3.54 3.57 3.57 4.11 3.76 3.59 3.56 3.54Fe 3.15 2.85 2.79 2.76 2.72 2.33 5.37 2.96 2.81 2.89 2.84 2.30 3.00 2.86 3.02 2.84 2.94 2.80Mg 1.60 1.63 1.45 1.48 1.54 1.78 1.66 1.48 1.61 1.54 1.55 1.88 1.91 1.55 1.48 1.53 1.52 1.59Ca 0.00 0.01 0.00 0.01 0.00 0.00 0.01 0.00 0.00 0.00 0.00 0.01 0.02 0.00 0.01 0.00 0.00 0.00Na 0.06 0.07 0.06 0.09 0.06 0.10 0.02 0.05 0.06 0.06 0.07 0.10 0.08 0.06 0.07 0.06 0.06 0.10K 1.58 1.73 1.66 1.84 1.66 1.52 0.00 1.56 1.47 1.65 1.74 1.65 1.53 1.52 1.77 1.64 1.58 1.67F 0.07 0.09 0.09 0.02 0.16 0.06 0.02 0.10 0.10 0.15 0.00 0.05 0.15 0.05 0.05 0.10 0.14 0.17Cl 0.01 0.01 0.01 0.01 0.01 0.01 0.00 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.01Total 19.62 19.59 19.32 19.48 19.33 19.18 19.59 19.34 19.32 19.38 19.43 19.29 19.56 19.42 19.58 19.35 19.35 19.41O 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00Mg # 0.34 0.36 0.34 0.35 0.36 0.43 0.24 0.33 0.36 0.35 0.35 0.45 0.39 0.35 0.33 0.35 0.34 0.36Table B.10. Biotite compositions from specimen KA064A. Corresponding locations are shown in B.15. Table B.10 Biotite compositions from specimen KA064A126wt % 19 20 21 22 23 24 25 26SiO2 35.91 35.69 35.71 35.17 45.41 34.91 35.88 35.30TiO2 2.70 2.56 3.35 1.54 0.44 3.33 3.48 3.56Al2O3 20.61 19.96 20.50 22.16 28.08 19.94 20.41 20.24FeO 22.87 24.20 23.63 21.43 7.47 23.03 23.61 22.86MgO 6.88 6.77 6.44 7.32 3.14 6.68 6.73 6.82CaO 0.03 0.02 0.00 0.05 0.12 -0.01 -0.01 0.00Na2O 0.28 0.22 0.17 0.24 0.04 0.20 0.20 0.20K2O 8.99 8.84 8.12 8.90 5.63 9.04 8.39 8.90F 0.21 0.21 0.29 0.23 0.63 0.08 0.09 0.10Cl 0.05 0.04 0.07 0.04 0.01 0.04 0.04 0.04Total 98.52 98.53 98.27 97.08 90.95 97.25 98.82 98.02ionsSi 5.35 5.35 5.33 5.28 6.41 5.29 5.32 5.29Ti 0.30 0.29 0.38 0.17 0.05 0.38 0.39 0.40Al 3.62 3.53 3.61 3.92 4.67 3.56 3.57 3.57Fe 2.85 3.03 2.95 2.69 0.88 2.92 2.93 2.86Mg 1.53 1.51 1.43 1.64 0.66 1.51 1.49 1.52Ca 0.01 0.00 0.00 0.01 0.02 0.00 0.00 0.00Na 0.08 0.06 0.05 0.07 0.01 0.06 0.06 0.06K 1.71 1.69 1.55 1.70 1.01 1.75 1.59 1.70F 0.10 0.10 0.14 0.11 0.28 0.04 0.04 0.05Cl 0.01 0.01 0.02 0.01 0.00 0.01 0.01 0.01Total 19.44 19.47 19.29 19.48 17.72 19.46 19.33 19.40O 22.00 22.00 22.00 22.00 22.00 22.00 22.00 22.00Mg # 0.35 0.33 0.33 0.38 0.43 0.34 0.34 0.35Table B.10. Biotite compositions from specimen KA064A. Corresponding locations are shown in B.15. 127wt % 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17SiO2 63.02 62.31 64.08 63.40 62.34 62.24 63.96 62.85 63.13 62.95 63.96 63.63 62.50 62.66 63.66 62.54 63.23Al2O3 25.83 25.76 25.29 25.00 25.56 25.14 24.82 24.93 25.28 25.37 25.56 25.08 25.80 24.81 25.62 25.58 25.39CaO 5.36 5.52 4.95 4.59 5.45 5.19 4.21 4.83 5.17 5.17 4.91 4.63 5.29 4.85 5.23 5.30 4.95Na2O 6.40 7.63 6.38 7.81 7.69 7.88 7.95 7.59 7.23 7.60 5.86 7.60 7.35 7.76 6.11 7.16 7.25K2O 0.29 0.24 0.43 0.34 0.24 0.26 0.42 0.32 0.24 0.35 0.33 0.34 0.33 0.43 0.19 0.25 0.31Total 100.91 101.45 101.13 101.14 101.27 100.70 101.36 100.52 101.05 101.45 100.61 101.28 101.26 100.51 100.81 100.84 101.13ionsSi 2.74 2.71 2.78 2.76 2.72 2.73 2.78 2.75 2.75 2.74 2.78 2.76 2.72 2.75 2.76 2.73 2.75Al 1.32 1.32 1.29 1.28 1.31 1.30 1.27 1.29 1.30 1.30 1.31 1.28 1.32 1.28 1.31 1.32 1.30Ca 0.25 0.26 0.23 0.21 0.25 0.24 0.20 0.23 0.24 0.24 0.23 0.22 0.25 0.23 0.24 0.25 0.23Na 0.54 0.64 0.54 0.66 0.65 0.67 0.67 0.64 0.61 0.64 0.49 0.64 0.62 0.66 0.51 0.61 0.61K 0.02 0.01 0.02 0.02 0.01 0.01 0.02 0.02 0.01 0.02 0.02 0.02 0.02 0.02 0.01 0.01 0.02Total 4.87 4.95 4.86 4.94 4.95 4.96 4.94 4.93 4.91 4.94 4.82 4.92 4.93 4.95 4.85 4.92 4.91O 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8 8An 0.31 0.28 0.29 0.24 0.28 0.26 0.22 0.25 0.28 0.27 0.31 0.25 0.28 0.25 0.32 0.29 0.27Ab 0.67 0.70 0.68 0.74 0.71 0.72 0.75 0.72 0.71 0.71 0.67 0.73 0.70 0.72 0.67 0.70 0.71Or 0.02 0.01 0.03 0.02 0.01 0.02 0.03 0.02 0.02 0.02 0.02 0.02 0.02 0.03 0.01 0.02 0.02Table B.11. Plagioclase compositions from specimen KA064A. Corresponding locations are shown in B.15. Table B.11 Plagioclase compositions from specimen KA064A128wt% 1 2 3 4 5 6 7 8SiO2 66.75 65.88 67.38 65.80 65.38 65.90 66.01 66.35Al2O3 20.58 20.45 21.03 20.43 19.88 20.15 20.27 20.29CaO 0.10 0.07 0.08 0.07 0.05 0.06 0.09 0.05Na2O 2.64 2.36 2.02 2.04 1.86 2.27 2.12 1.43K2O 10.96 11.88 10.46 12.30 13.63 12.53 10.82 11.96BaO 0.73 0.66 0.79 0.84 0.81 0.72 0.76 0.91Total 101.75 101.31 101.75 101.48 101.61 101.62 100.07 100.99ionsSi 2.97 2.96 2.98 2.96 2.96 2.96 2.98 2.98Al 1.08 1.08 1.10 1.08 1.06 1.07 1.08 1.07Ca 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00Na 0.23 0.21 0.17 0.18 0.16 0.20 0.19 0.12K 0.62 0.68 0.59 0.71 0.79 0.72 0.62 0.69Ba 0.01 0.01 0.01 0.01 0.01 0.01 0.01 0.02Total 4.92 4.94 4.85 4.94 4.99 4.96 4.89 4.89O 8 8 8 8 8 8 8 8An 0.01 0.00 0.01 0.00 0.00 0.00 0.01 0.00Ab 0.27 0.23 0.23 0.20 0.17 0.21 0.23 0.15Or 0.73 0.77 0.77 0.80 0.83 0.78 0.77 0.84Table B.12. K-feldspar compositions from specimen KA064A. Corresponding locations are shown in B.15. Table B.12 K-feldspar compositions from specimen KA064A129Appendix C: Monazite Elemental Maps and BSE ImagesThorium Uranium Yttrium BSEKA007_ds1_Th Ma_it2KA007_ds2_Th Ma_it2KA007_ds3_Th Ma_it2KA007_ds4_Th Ma_it2KA007_ds5_Th Ma_it2KA007_ds1_U  Ma_it3KA007_ds2_U  Ma_it3KA007_ds3_U  Ma_it3KA007_ds4_U  Ma_it3KA007_ds5_U  Ma_it3KA007_ds1_Y  La_it4KA007_ds2_Y  La_it4KA007_ds3_Y  La_it4KA007_ds4_Y  La_it4KA007_ds5_Y  La_it4KA007_ds1KA007_ds2KA007_ds3KA007_ds4KA007_ds5Figure C.1. Monazite Th, U and Y element maps, and BSE images. Figure C.1 Monazite element maps and BSE images 130Thorium Uranium Yttrium BSEKA007_ds6_Th Ma_it2KA007_ds7_Th Ma_it2KA007_ds8_Th Ma_it2KA007_ds9_Th Ma_it2KA007_ds10_Th Ma_it2KA007_ds6_U  Ma_it3KA007_ds7_U  Ma_it3KA007_ds8_U  Ma_it3KA007_ds9_U  Ma_it3KA007_ds10_U  Ma_it3KA007_ds6_Y  La_it4KA007_ds7_Y  La_it4KA007_ds8_Y  La_it4KA007_ds9_Y  La_it4KA007_ds10_Y  La_it4KA007_ds6KA007_ds7KA007_ds8KA007_ds9KA007_ds10131Thorium Uranium Yttrium BSEKA031B_ds1_Th Ma_it2KA031B_ds2_Th Ma_it2KA031B_ds3_Th Ma_it2KA031B_ds4_Th Ma_it2KA031B_ds5_Th Ma_it2KA031B_ds1_U  Ma_it3KA031B_ds2_U  Ma_it3KA031B_ds3_U  Ma_it3KA031B_ds4_U  Ma_it3KA031B_ds5_U  Ma_it3KA031B_ds1_Y  La_it4KA031B_ds2_Y  La_it4KA031B_ds3_Y  La_it4KA031B_ds4_Y  La_it4KA031B_ds5_Y  La_it4KA031B_ds1KA031B_ds2KA031b_ds3KA031B_ds4KA031B_ds5132Thorium Uranium Yttrium BSEKA031B_ds6_Th Ma_it2KA031B_ds7_Th Ma_it2KA031B_ds8_Th Ma_it2KA031B_ds9_Th Ma_it2KA031B_ds10_Th Ma_it2KA031B_ds6_U  Ma_it3KA031B_ds7_U  Ma_it3KA031B_ds8_U  Ma_it3KA031B_ds9_U  Ma_it3KA031B_ds10_U  Ma_it3KA031B_ds6_Y  La_it4KA031B_ds7_Y  La_it4KA031B_ds8_Y  La_it4KA031B_ds9_Y  La_it4KA031B_ds10_Y  La_it4KA031B_ds6KA031b_ds7KA031b_ds8KA031b_ds9KA031B_ds10133Thorium Uranium Yttrium BSEKA034_ds1_Th Ma_it2KA034_ds2_Th Ma_it2KA034_ds3_Th Ma_it2KA034_ds4_Th Ma_it2KA034_ds5_Th Ma_it2KA034_ds1_U  Ma_it3KA034_ds2_U  Ma_it3KA034_ds3_U  Ma_it3KA034_ds4_U  Ma_it3KA034_ds5_U  Ma_it3KA034_ds1_Y  La_it4KA034_ds2_Y  La_it4KA034_ds3_Y  La_it4KA034_ds4_Y  La_it4KA034_ds5_Y  La_it4KA034_ds1KA034_ds2KA034_ds3KA034_ds4KA034_ds5134Thorium Uranium Yttrium BSEKA034_ds6_Th Ma_it2KA034_ds7_Th Ma_it2KA034_ds8_Th Ma_it2KA034_ds9_Th Ma_it2KA034_ds10_Th Ma_it2KA034_ds6_U  Ma_it3KA034_ds7_U  Ma_it3KA034_ds8_U  Ma_it3KA034_ds9_U  Ma_it3KA034_ds10_U  Ma_it3KA034_ds6_Y  La_it4KA034_ds7_Y  La_it4KA034_ds8_Y  La_it4KA034_ds9_Y  La_it4KA034_ds10_Y  La_it4KA034_ds6KA034_ds7KA034_ds8KA034_ds9KA034_ds10135Thorium Uranium Yttrium BSEKA037_ds1_placeholderKA037_ds2_placeholderKA037_ds3_Th Ma_it2KA037_ds4_Th Ma_it2KA037_ds5_Th Ma_it2KA037_ds1_Th Ma_it2KA037_ds2_Th Ma_it2KA037_ds3_U  Ma_it3KA037_ds4_U  Ma_it3KA037_ds5_U  Ma_it3KA037_ds1_U  Ma_it3KA037_ds2_U  Ma_it3KA037_ds3_Y  La_it4KA037_ds4_Y  La_it4KA037_ds5_Y  La_it4KA037_ds1_Y  La_it4KA037_ds2_Y  La_it4KA037_ds3KA037_ds4KA037_ds5136Thorium Uranium Yttrium BSEKA037_ds6_Th Ma_it2KA037_ds7_Th Ma_it2KA037_ds8_Th Ma_it2KA037_ds9_Th Ma_it2KA044_ds1_Th Ma_it2KA037_ds6_U  Ma_it3KA037_ds7_U  Ma_it3KA037_ds8_U  Ma_it3KA037_ds9_U  Ma_it3KA044_ds1_U  Ma_it3KA037_ds6_Y  La_it4KA037_ds7_Y  La_it4KA037_ds8_Y  La_it4KA037_ds9_Y  La_it4KA044_ds1_Y  La_it4KA037_ds6KA037_ds7KA037_ds8KA037_ds9KA044_ds1137Thorium Uranium Yttrium BSEKA044_ds2_Th Ma_it2KA044_ds3_Th Ma_it2KA044_ds4_Th Ma_it2KA044_ds5_placeholderKA044_ds6_Th Ma_it2KA044_ds2_U  Ma_it3KA044_ds3_U  Ma_it3KA044_ds4_U  Ma_it3KA044_ds5_Th Ma_it2KA044_ds6_U  Ma_it3KA044_ds2_Y  La_it4KA044_ds3_Y  La_it4KA044_ds4_Y  La_it4KA044_ds5_U  Ma_it3KA044_ds6_Y  La_it4KA044_ds2KA044_ds3KA044_ds4KA044_ds5_Y  La_it4KA044_ds6138Thorium Uranium Yttrium BSEKA044_ds7_placeholderKA044_ds8_Th Ma_it2KA044_ds9_Th Ma_it2KA044_ds10_Th Ma_it2KA044_ds11_Th Ma_it2KA044_ds7_Th Ma_it2KA044_ds8_U  Ma_it3KA044_ds9_U  Ma_it3KA044_ds10_U  Ma_it3KA044_ds11_U  Ma_it3KA044_ds7_U  Ma_it3KA044_ds8_Y  La_it4KA044_ds9_Y  La_it4KA044_ds10_Y  La_it4KA044_ds11_Y  La_it4KA044_ds7_Y  La_it4KA044_ds8KA044_ds9KA044_ds10KA044_ds11139Thorium Uranium Yttrium BSEKA055_ds1_Th Ma_it2KA055_ds2_Th Ma_it2KA055_ds3_Th Ma_it2KA055_ds4_Th Ma_it2KA055_ds5_Th Ma_it2KA055_ds1_U  Ma_it3KA055_ds2_U  Ma_it3KA055_ds3_U  Ma_it3KA055_ds4_U  Ma_it3KA055_ds5_U  Ma_it3KA055_ds1_Y  La_it4KA055_ds2_Y  La_it4KA055_ds3_Y  La_it4KA055_ds4_Y  La_it4KA055_ds5_Y  La_it4KA055_ds1KA055_ds2KA055_ds3KA055_ds4KA055_ds5140Thorium Uranium Yttrium BSEKA055_ds6_Th Ma_it2KA055_ds7_Th Ma_it2KA055_ds8_Th Ma_it2KA055_ds9_Th Ma_it2KA055_ds10_Th Ma_it2KA055_ds6_U  Ma_it3KA055_ds7_U  Ma_it3KA055_ds8_U  Ma_it3KA055_ds9_U  Ma_it3KA055_ds10_U  Ma_it3KA055_ds6_Y  La_it4KA055_ds7_Y  La_it4KA055_ds8_Y  La_it4KA055_ds9_Y  La_it4KA055_ds10_Y  La_it4KA055_ds6KA055_ds7KA055_ds8KA055_ds9KA055_ds10141Thorium Uranium Yttrium BSEKA058B_ds1_Th Ma_it2KA058B_ds2_Th Ma_it2KA058B_ds3_Th Ma_it2KA058B_ds4_Th Ma_it2KA058B_ds5_Th Ma_it2KA058B_ds1_U  Ma_it3KA058B_ds2_U  Ma_it3KA058B_ds3_U  Ma_it3KA058B_ds4_U  Ma_it3KA058B_ds5_U  Ma_it3KA058B_ds1_Y  La_it4KA058B_ds2_Y  La_it4KA058B_ds3_Y  La_it4KA058B_ds4_Y  La_it4KA058B_ds5_Y  La_it4KA058B_ds1KA058B_ds2KA058B_ds3KA058B_ds4KA058B_ds5142Thorium Uranium Yttrium BSEKA058B_ds6_Th Ma_it2KA058B_ds7_Th Ma_it2KA058B_ds8_Th Ma_it2KA058B_ds9_Th Ma_it2KA058B_ds10_Th Ma_it2KA058B_ds6_U  Ma_it3KA058B_ds7_U  Ma_it3KA058B_ds8_U  Ma_it3KA058B_ds9_U  Ma_it3KA058B_ds10_U  Ma_it3KA058B_ds6_Y  La_it4KA058B_ds7_Y  La_it4KA058B_ds8_Y  La_it4KA058B_ds9_Y  La_it4KA058B_ds10_Y  La_it4KA058B_ds6KA058B_ds7KA058B_ds8KA058B_ds9KA058B_ds10143Thorium Uranium Yttrium BSEKA064A_ds1_Th Ma_it2KA064A_ds2_Th Ma_it2KA064A_ds3_Th Ma_it2KA064A_ds4_Th Ma_it2KA064A_ds5_Th Ma_it2KA064A_ds1_U  Ma_it3KA064A_ds2_U  Ma_it3KA064A_ds3_U  Ma_it3KA064A_ds4_U  Ma_it3KA064A_ds5_U  Ma_it3KA064A_ds1_Y  La_it4KA064A_ds2_Y  La_it4KA064A_ds3_Y  La_it4KA064A_ds4_Y  La_it4KA064A_ds5_Y  La_it4KA064A_ds1KA064A_ds2KA064A_ds3KA064A_ds4KA064A_ds5144Thorium Uranium Yttrium BSEKA064A_ds6_Th Ma_it2KA064A_ds7_Th Ma_it2KA064A_ds8_Th Ma_it2KA064A_ds9_Th Ma_it2KA064A_ds10_Th Ma_it2KA064A_ds6_U  Ma_it3KA064A_ds7_U  Ma_it3KA064A_ds8_U  Ma_it3KA064A_ds9_U  Ma_it3KA064A_ds10_U  Ma_it3KA064A_ds6_Y  La_it4KA064A_ds7_Y  La_it4KA064A_ds8_Y  La_it4KA064A_ds9_Y  La_it4KA064A_ds10_Y  La_it4KA064A_ds6KA064A_ds7KA064A_ds8KA064A_ds9KA064A_ds10145Thorium Uranium Yttrium BSEKA064A_ds11_Th Ma_it2 KA064A_ds11_U  Ma_it3 KA064A_ds11_Y  La_it4 KA064A_ds11146

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