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Consolidation and mantle evolution of the Sinokorean Craton in Early Precambrian time Sun, Min 1991

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CONSOLIDATION AND MANTLE EVOLUTION OF THE SINOKOREANCRATON IN EARLY PRECAMBRIAN TIMEByMIN SUNB.Sc., Peking University,1982M.Sc., The University of British Columbia, 1985A THESIS SUBMITTED IN PARTIAL FULFILMENT OFTHE REQUIREMENTS FOR THE DEGREE OFDOCTOR OF PHILOSOPHYinTHE FACULTY OF GRADUATE STUDIES(Department of Geological Sciences)We accept this thesis as conformingto the required standardTHE UNIVERSITY OF BRITISH COLUMBIANovember 1991©Min Sun, 1991In presenting this thesis in partial fulfilment of the requirements for an advanceddegree at the University of British Columbia, I agree that the Library shall make itfreely available for reference and study. I further agree that permission for extensivecopying of this thesis for scholarly purposes may be granted by the head of mydepartment or by his or her representatives. It is understood that copying orpublication of this thesis for financial gain shall not be allowed without my writtenpermission.Department of________________The University of British ColumbiaVancouver, CanadaDateDE-6 (2/88)ABSTRACTThe oldest nuclei of the Sinokorean Craton are the 3.5 Gaamphibolites and grey gneisses of the Qianxi Complex and the3.O Ga Qingyuan Complex that may extend to the Anshan area toinclude the 3.O Ga Tiejiashan and Lishan granites. Other high-grade metamorphic complexes of the Sinokorean Craton are mostlybetween 2.7 and 2.8 Ga in age - the Anshan, Longgang, Jianping,Taishan, Jiaodong, and Taihua complexes. The high-grade FupingComplex formed about 2.6 Ga ago in an environment like a modernisland arc: it is not one of the earliest nuclei. The medium—grade Wutai Complex formed by 2.5 Ga ago, mostly in a tectonicsetting similar to that of Fuping Complex, with the exceptionthat one volcanic cycle formed in an environment like a modernMOR and one unit formed in an environment transitional betweenmodern within-plate and plate margin settings. There is noevidence for continental crust older than 2.6 Ga in theWutaishan and Taihangshan regions. The Sm-Nd systems formetabasaltic rocks in the Wutaishan and Taihangshan region, areall significantly disturbed, in contrast with the undisturbedSm-Nd system reported for rocks older than 2.6 Ga in theSinokorean Craton.High-grade rocks of the Sanggan and Dengfeng complexes,and some granulites in the Qianxi Complex are 2.5 Ga in age.Available Nd isotopic data show that rocks older than 2.5 Ga inthe Sinokorean Craton are derived from a mantle source moredepleted than that defined by DePaolo’s depleted mantleevolution curve. Granitic magmatism peaked 2.5 Ga ago in the11Sinokorean Craton, affecting all the previously formed rocks.Nd isotopic data show significant crustal involvement information of some —2.5 Ga granites in the Sinokorean Craton.Early Proterozoic mafic volcanic rocks of the 2.3 to 2.4Ga Kuandian Complex in Liaoning Province and the Hutuo Complexin Shanxi Province, formed in a intra—continental environment.Kuandian granites have an anorogenic granite character. Theearly Proterozoic mantle magma source in the eastern LiaoningProvince is less depleted than the mantle of DePaolo’s (1981)average mantle evolution curve. This can be explained bycontamination of Archean basement or derivation from a differentmantle source.iiiTABLE OF CONTENTSABSTRACT iiLIST OF TABLES viiLIST OF FIGURES viiiACKOWLEGEMENTS XiI. INTRODUCTION 1II. EARLY PRECAMBRIAN ROCKS IN EASTERN HEBEI PROVINCE 611-1. Qianxi Complex 6Geological Background 6Isotopic Dating of the Qianxi Complex andAssociated Granitic Rocks 7Discussion 1211-2. Dantazi-Zhuzhangzi Group 14III. EARLY PRECAMBRIAN ROCKS IN LIAONING AND JILINPROVINCES 15111—1. Qingyuan Complex 15111-2. Tiejiashan and Lishan Granites 19Geological setting and Geochemistry 19Isotopic Dating of the Tiejiashan and LishanGranites 29Discussion 29111-3. Anshan Complex and Anshan Gneissic Granite 38Geological background 38Isotopic dating of the Anshan Complex andthe Anshan Gneissic Granite 39Discussion 43111-4. Longgang Complex 45Geology and Isotopic Dating 45Discussion 48111—5. Jianping Complex 50111—6. Kuandian Complex and Associated Rocks 50Geological Background and PreviousIsotopic Work 53Petrochemistry of Kuandian Complex andAssociated Rocks 60(1). Kuandian Amphibolite 60(2). Kuandian Granite 80(3). Other Granitic Bodies from the Area. . .81Isotopic Results 82Kuandian Complex 82Caohe Group 90Liaoyang Group 90Pre-Kuandian Granites 90Post—Kuandian Granites 96Age Interpretation 100Petrogenesis of Kuandian igneous rocks 109(1). Kuandian Amphibolite 109(2). Kuandian Granite 110Summary 112IV. EARLY PRECAMBRIAN ROCKS IN WUTAISHAN AND TAIHANGSHANivAREAS.114IV—1. Geological Background and PreviousIsotopic Work 114Fuping Complex 114Wutai Complex 117Hutuo Group 119Granitic Intrusions 119IV-2. Petrochemistry of Samples from the Wutaishan -Taihangshan Region 120(1). Metabasic Samples 120(2). Gneisses and Granites 147IV-3. Isotopic Results 149Fuping Complex 149Wutai Complex 149Hutuo Group 162Lanzishan Granite 169Chechang Granite and Wangjiahui Granite 169IV-4. Age Constraints 169Fuping Complex 175Wutai Complex 179Hutuo Group 179Granitic Intrusions 180IV—5. Discussion 181Alkali Metasomatism 181Resetting of Isotopic Systems 182Stratigraphic and Tectonic Revisions 183IV-6. Summary 184V. EARLY PRECAMBRIAN ROCKS IN SHANDONG PROVINCE 186V-l. Taishan Complex and Associated Granitic Rocks. . .186V-2. Jiaodong Complex 190VI. EARLY PRECAMBRIAN ROCKS IN NORTHERN SLOPE OFQINLING MOUNTAIN BELT 191VI—l. Taihua Complex 191VI-2. Dengfeng Complex 191VII. EARLY PRECAMBRIAN ROCKS IN INNER MONGOLIA 194Sanggan Complex 194VIII. CRUSTAL ACCRETION HISTORY OF THE SINOKOREAN CRATONIN THE EARLY PRECAMBRIAN 1961. Continental Nuclei Older than 3.0 Ga 1962. Late Archean High-grade metamorphic Complexes(2.5 to 2.8 Ga) 1963. Late Archean Greenstone Granite Belt (2.5 GA)....1994. Terminal Archean Granitic Magmatism (@ 2.5 Ga)....1995. Early Proterozoic Continental Rift(2.3 to 2.4 Ga) 199IX. Nd ISOTOPIC CHARACTER OF THE EARLY PRECAMBRIANROCKS IN THE SINOKOREAN CRATON 203X. CONCLUSION 208vBIBLIOGRAPHY.211APPENDIX 1. Sample description 222APPENDIX 2. Analytical methods for Rb-Sr, Sm-Nd,and Pb-Pb isotopes 229viLIST OF TABLESTable Page2—1. Isotopic dates of Early Precambrian rocks fromeastern Hebei Province 8—92-2. Sm-Nd isotopic date with 2cr errors for samplesfrom Qianxi Complex 103—1. Isotopic dates for Early Precambrian rocks fromLiaoning and Jilin provinces 16-183-2. Sm-Nd isotopic data with 2cr errors for samplesfrom Liaoning and Jilin provinces 20-223—3. Major element analyses for samples from Liaoningand Jilin provinces 24-253—4. Trace element analyses for samples from Liaoningand Jilin provinces 26-273-5. Pb—Sr isotopic data from samples from Liaoningand Jilin provinces 30-333-6. Pb isotopic data for samples from Liaoning andJilin provinces 363—7. U—Pb analyses of zircon fractions from Kuandiangranite and a felsic dike 88-894—1. Major element analyses for samples from theWutaishan and Taihangshan region 121-1224—2. Trace element concentrations for samples fromthe Wutaishan and Taihangshan region 123-1244-3. Summary of discrimination test formetabasic rocks 1334-4. Rb-Sr isotopic data for whole rock samples fromthe Wutaishan and Taihangshan region 151—1524-5. Sm-Nd isotopic data for whole rock samples fromthe Wutaishan and Taihangshan region 153-1544-6. Whole rock Pb isotopic data for samples fromthe Wutaishan and Taihangshan region 1554—7. Isotopic dates for Early Precambrian rocks fromWutaishan and Taihangshan region 156-1575—1. Isotopic dates for Early Precambrian rocks fromShandong Province 1875-2. Sm-Nd isotopic data with 2cr errors for samplesfrom Taishan Complex 1896—1. Isotopic dates fro Early Precambrian rocks fromHenan Province 1927—1. Isotopic dates for Early Precambrian rocks fromInner Mongolia 195viiLIST OF FIGURESFigure Page1—1. Exposures of Early Precambrian rocks in theSinokorean Craton 21-2. Political divisions of northern China 33-1. An - Ab - Or plot for Tiejiashan, Lishan, Kuandiangranites and some other granitic bodies from theeastern Liaoning Province 233-2. Rb - (Y+Nb) plot Tiejiashan, Lishan, Kuandiangranites and some other grariitic bodies from theeastern Liaoning Province 283-3. Rb - Sr isochron plot for the Lishan Granite 343-4. Sm — Nd isochron plot for the Lishan, Shisi, andMafeng granites 353-5. Whole rock Pb plot for the Lishan Granite 373-6. Sm-Nd isochron plot for the Anshan amphiboliteand fine grained gneiss 403-7. Pb-Pb isotopic plot for the Anshan amphibolites 413-8. Rb-Sr isochron plot for the Anshan amphiboliteand fine-grained gneiss 423-9. Pb-Pb isotopic plot for the Anshan fine-grainedgneisses 443-10. Rb-Sr isochron plot for the Longgang Complex 463-11. Sm-Nd isochron plot for the Longgang Complex 473-12. Pb-Pb isotopic plot for the Longgang Complex 493-13. Rb-Sr isochron plot for the Jianping Complex 513-14. Sm-Nd isochron plot for the Jianping Complex 523—15. Simplified geological map of eastern LiaoningProvince 543-16. Schematic stratigraphic section of Proterozoicgeological systems in the East Liaoning Province 553—17. Geological map showing sample localities foreastern Liaoning Province 563—18. Total alkali - Si02 plot for the Kuandianainphibolites and granites 623-19. OJi-Ne’-Q’ plot for the Kuandian amphibolitesand granites 633-20. A12O3 — Plagioclase plot for Kuandian Complex 643-21. AFMp1ot for Kuandian Complex 653—22. FeO /MgO - Ti02 plot for tholeiitic basaltsfrom the Kuandian Complex 673-23. F2 - F1 plot for basaltic rocks from KuandianComplex 683-24. F3 - F2 plot for basaltic rocks from KuandianComplex 693—25. Trace element plots (spider diagrams) for basalticamphibolites from Kuandian Complex 713-26. ThY - Nb/Y plot for tholeiitic Kuandian Complex 723—27. Ti/100- Zr - *3 plot for basaltic Kuandianamphibolites 733—28. Zr/Y— Zr plot for basaltic Kuandian amphibolites.. .743—29. Ti—Zr plot for basaltic Kuandian amphibolites 753—30. Ti/lOO — Zr— Sr/2 plot for Kuandian amphibolites. . .763—31. Ni - Y plot for Tholeiitic Kuandian amphibolites 773-32. Chondrite normalized REE plot for the Kuandianviiiamphibolites and granites .793-33. Rb - Sr isochron plot for the Kuandian Complex 843-34. Sm-Nd isochron plot for the Kuandian Complex 853-35. Whole rock Pb plot for the Kuandian Complex 873—36. U—Pb concordia plot for zircons from the Kuandiangranite 913—37. Rb — Sr isochron plot for metasedimentary rocksfrom Caohe Group 923—38. Sm — Nd isochron plot for metasedimentary samplesfrom Caohe and Liaoyang groups 933—39. Rb — Sr isochron plot for metasedimentary samplesfrom Liaoyang Group 943-40. Rb - Sr isochron plot for the Shisi Granite 953-41. Rb - Sr isochron plot for the Mafeng Granite 973-42. Whole rock Pb plot for the Mafeng Granite 983-43. U-Pb concordia plot for zircons from a felsic dyke. .993-44. Diagram for Nd depleted mantle dates 1023-45. Diagram showing scattering of Nd depleted mantlemodel dates by later event 1034-1. Simplified geological map of the region containingthe Wutaishan and Taihangshan areas 1154—2. Geological map of Wutaishan Area 1164—3. Total alkali — Si02 plot for metabasic samplesfrom the Wutaishan and Taihangshan region 1264—4. Ol’—Ne’—Q’ plot for metabasic samples from theWutaishan and Taihangshan region 1274-5. Average total alkali and K20/Na for metabasicrocks from Wutaishan and Taihangshan region 1284—6. Al203 — Plagioclase plot for metabasic samplesfrom Wutaishan and Taihangshan region 129-1304-7. AFM plot for metabasic samples from WutaishanandTaihangshan region 1314-8. FeO /MgO- Ti02 plot for metatholeiites fromWutaishan and Taihangshan region 1344-9. F2 - F1 plot for metabasic samples from theWutaishan and Taihangshan region 1364—10. F3 — F2 plot for metabasic samples from theWutaishan and Taihangshan region 1374—il. Trace element plots for metabasic samples fromthe Wutaishan and Taihangshan region 138-1404-12. Ti/Y - Nb/Y plot for matabasic samploes fromthe Wutaishan and Taihangshan region 1424-13. Ti/lOO - Zr - *3 plot for metabasic samplesfrom Wutaishan and Taihangshan region 1434-14. Zr/Y - Zr plot for metabasic samples from theWutaishan and Taihangshan region 1444-15. Ti/100 - Zr — Sr/2 plot for metabasic samplesfrom the Wutaishan and Taihangshan region 1454-16. Ni - Y plot for metatholeiites from Wutaishanand Taihangshan region 1464-17. An - Ab - Or plot for Precambrian granitesfrom the Wutaishan and Taihangshan region 1484-18. Rb - (Y+Nb) plot for Precambrian granitesfrom the Wutaishan and Taihangshan region 1504-19. Rb - Sr isochron plot for the Fuping Complex 158ix4-20. Sm-Nd isochron plot for the Fuping Complex 1594-21. Whole rock Pb plot for the Fuping Complex 1614—22. Rb - Sr isochron plot for the Wutai Complex 1614-23. Sm - Nd isochron plot for amphibolites fromthe Wutai Complex (W-l) 1634-24. Sm - Nd isochron plot for the greenschistsfrom the Wutai Complex (W-2) 1644-25. Composite Sm - Nd isochron plot for all themetabasic samples from the Wutai Complex 1654—26. Whole rock Pb plot for all the metabasicsamples from Wutai Complex 1664-27. Rb — Sr isochron plot for the Hutuo Group 1674-28. Sm - Nd isochron plot for the Hutuo Group 1684-29. Whole rock Pb plot for the Hutuo Group 1704-30. Rb — Sr isochron plot for the Lanzishan,Chechang, and Wangjiahui granitic bodies 1714-31. Sm - Nd isochron plot for the Lanzishan,and Chechang granitic bodies 1724-32. Whole rock Pb plot for the Lanzishan Granite 1734-33. Whole rock Pb plot for the Chechang Granite 1748-1. Isotopic dates for the Qianxi, Qingyuancomplexes, and Tiejiashan and Lishan granites 1978-2. Isotopic dates for the Anshan, Longgang, Jianping,Taishan, Jiaodong, and Taihua complexes 1988-3. Isotopic dates for the Fuping, Sanggan, Dengfengcomplexes 2008-4. Isotopic dates for the Kuandian Complex, Hutuometabasalts, and Dantazi-Zhuzhangzi Group 2019-1. 6Nd evolution diagram for rocks well definingSm-Nd isochrons 2049-2. Sm-Nd isochron plot for individual sample data .205-206xACKNOWLEDGEMENT SI wish to express sincere appreciation to Dr. Richard LeeArmstrong, thesis supervisor, for his support, supervision,advice and encouragement throughout the study.I am also grateful for supervision and support from Dr.Richard St J. Lambert during sample collection in China andisotopic analyses at the University of Alberta.Financial support was provided by graduate fellowships fromthe University of British Columbia and the University ofAlberta, an NSERC Operating Grant to R. St J. Lambert and anNSERC Operating Grant to R. L. Armstrong.Thanks also to Drs. Xinhua Zhou, Nolan E, Jiliang Li, KaiyiWang, Chunchao Jiang, Chaolei Xu, Jiahong Wu, Guangsheng Fengand Yinghui Li for their help and discussion during the fieldwork.xiACKNOWLEDGEMENTSI wish to express sincere appreciation to Dr. Richard LeeArmstrong, thesis supervisor, for his support, supervision,advice and encouragement throughout the study.I am also grateful for supervision and support from Dr.Richard St J. Lambert during sample collection in China andisotopic analyses at the University of Alberta.Financial support was provided by graduate fellowships fromthe University of British Columbia and the University ofAlberta, an NSERC Operating Grant to R. St J. Lambert and anNSERC Operating Grant to R. L. Armstrong.Thanks also to Drs. Xinhua Zhou, Molan E, Jiliang Li, KaiyiWang, Chunchao Jiang, Chaolei Xu, Jiahong Wu, Guangsheng Fengand Yinghui Li for their help and discussion during the fieldwork.xiI. INTRODUCTIONThe Sinokorean Craton (30-45°N, and 105-l28°E) includesmuch of the oldest crystalline basement in Asia. It containsrocks as old as 3.5 Ga, and was largely stabilized 2.4-2.5 Gaago. The Early Precambrian rocks have generally undergone high—to medium— grade metamorphism in Archean and Early Proterozoictimes. The main exposures along the north border of the cratonare, from west to east, in Inner Mongolia, eastern Hebei,eastern Liaoning and southeastern Jilin provinces; exposures ofthe centre of the craton in Shanxi, and Shandong provinces andnear to the south border of the craton, small exposures alongnorthern slope of the Qinling Mountain Range in Henan andadjacent provinces (Fig. 1-1 and 1—2).Recent geochemical and geochronological studies of theEarly Precambrian rocks in the Sinokorean Craton havesubstantially improved our understanding of its Precambrianhistory. However, conventional stratigraphic divisions are stillwidely used for Archean and Early Proterozoic systems in Chinaand great effort has been made to correlate the stratigraphicgroups and formations for different areas (e.g. Wang, 1988;Zhao, 1988). Such conventional stratigraphic divisions oftencreate contradictions even when applied to small areas, due toerasure of original petrology by superimposed high-grademetamorphism. Moreover stratigraphic schemes based solely onmetamorphic grade or structural complexity are generally notsubstantiated by firm geochronological data. For example, when1100°E11O°E120°E130°E_— Sheang__©4O°NsBeijingc:DYinchuang•0IJinan‘1Lanzhou0YellowXia.•.....:Sea\ng____Archaean—includingsomelowerProterozoic•Shanghai--30NWuhan0tN1Majordeepfractures+........+,r0400____Nationalboundaryi——kmFigure1-1.ExposuresofEarlyPrecambrianrocksintheSinokoreanCraton(adoptedfromJahn,1990a).Numberedregionsare1:easternHebe!Province;2:LiaoningandJilinprovinces;3:ShanxiProvince;4:ShandongProvince;5:HenanProvince;6:InnerMongolia.5O45.4O35.3OFigure 1-2. Political divisions of northern China showingtheir relationship to Sinokorean Craton (stippled). The map issimplified from CAGS, 1973.110 115 12O 1253compared with the Precambrian rocks in Liaoning and Jilinprovinces, the “Fuping Group” in Shanxi Province has beencorrelated either to the “Anshan Group” (Wang, 1988), or to the“Longgang Group” that was placed below the “Anshan Group” (Zhao,1988), or to the “Kuandian Group” which overlies the “AnshanGroup” (Jiang, 1987).Many Precambrian studies including our recent work (Sun etal., 1991a and 199lb) have revealed that Early Precambrian rockseven in vicinity locations may have formed in different tectonicenvironments and in different times, they may or may not havethe same lithological associations. Large proportion of metaigneous rocks also invalidates stratigraphic divisions. Thus theconventional stratigraphic divisions only lead tomisunderstanding of new data and of geological history.This thesis synthesizes published data and our own work todescribe the Early Precambrian crustal accretion history andmantle evolution for the entire Sinokorean Craton. We abandonthe conventional stratigraphic divisions where they are nolonger appropriate, instead the term “complex” has been used inthis study to refer to a rock system identified in the field bya close association of distinctive lithologies of similar age.Well—identified granitic intrusions are not included as membersof the named complexes but are named separately as plutons.Samples of our own analyses are described in Appendix 1.Methods for Rb-Sr, Sm-Nd and Pb-Pb isotopic analyses aredescribed in Appendix 2. Measured 87Sr/6, and 143Nd/’4d ratioshave been normalized to 86Sr/8r = 0.1194, and 146Nd/4 =40.7219, respectively. The U-Pb zircon analyses follow the methoddescribed in van der Heyden (1989). Tables of Rb-Sr, Sm-Nd, Pb-Pb, and U—Pb zircon isotopic data are incorporated inappropriate chapters. All errors reported are 2a.A York (1969) regression program was used for isochroncalculations in the course of this study. Sr and Nd depletedmantle model dates calculated according to DePaolo (1981) arelisted in Rb-Sr and Sm-Nd tables. Nd model dates calculatedaccording to Allegre and Rousseau (1984) are very similar tothose of DePaolo (1981) so are not tabulated. The nominalsingle, first stage growth j.t value is determined from theintersection of the whole rock Pb-Pb isochron and the 4.57 Gageochron. This p value is that of single-stage growth in auniform source, or is an overall average j of a multi—stagegrowth history prior to differentiation into rocks of diverseU/Pb ratios.The following Rb-Sr, Sm-Nd, and U-Pb constants have beenused in this study: A87Rb l.42xl011/yr, = 0.654xl011/yr,(147Sm/4Nd)CHUR = 0.1967, (143Nd/4d)CHUR 0.512626, A238U =l.55l25xl010/yr, A235u = 9.8485xl010/yr, 238U/5 = 137.88 atomratio. Primeval 206Pb/4 = 9.3066 and 207Pb/4 = 10.293.5II. EARLY PRECAMBRIAN ROCKS IN EASTERN HEBEI PROVINCE11—1. Qianxi ComplexGeological backgroundBecause of its granulite—facies metamorphism (which wasformerly thought to be restricted to the lowermost unit of thebasement), the oldest Rb-Sr and Sm-Nd dates reported in China,and economic importance (BIF), the Qianxi Complex has been thefocus of many recent papers on the early stages of SinokoreanCraton history (e.g. Zhao, 1988; Wang, 1988; Liu et al., 1990;Wang, 1990; Jahn, 1990a and b).The Qianxi Complex is mainly distributed in Qianan, Qianxiand Zunhua counties, Hebei Province (Fig. 1-1 and 1-2). TheComplex contains amphibolite, fuchsite quartzite, banded ironformation (BIF), kinzigite, diopsidite, fine-grained gneiss (theterm “leptynite” and “leptite” are widely used in China), greygneiss, biotite— and/or plagioclase—bearing pyroxene granuliteand marble. Qianxi rocks have undergone polyphase metamorphismand deformation, and been intruded by multiphase granitic rockswhich include gabbroic diorite, monzodiorite, granodiorite, K-rich granite, and charnockite.Most amphibolites have basic compositions and occur aslayers intercalated with fuchsite quartzite, BIF, marble anddiopsidite, or as enclaves in grey gneiss, either isolated meterto decimeter—sized blocks or meter—sized disrupted boudins. Theintercalated amphibolites have been considered to be, togetherwith the gneisses, of a bimodal volcanic suite. The amphibolite6blocks/boudins have been considered either disrupted pieces ofthe same origin or disrupted dykes (Liu et al., 1990).Granulite—facies rocks have basic, intermediate, acid andultrabasic igneous compositions (Jahn and Zhang, 1984).Isotopic dating of the Qianxi Complex and associatedgranitic rocksIsotopic dates for the Qianxi Complex and the associatedgranitic rocks are summarized in Table 2—1.a. Amphibolite:A 3.5 Ga Sm-Nd isochron, with an initial eNd(T) = +3, hasbeen obtained by three research groups (Huang et al., 1986; Qiaoet al., 1987; Jahn et al., 1987).b. Fuchs ite-quartz iteZircons from the Qianxi fuchsite-quartzite give 3.65 to3.67 Ga single zircon evaporation dates (Liu et al., 1990).These are the oldest dates reported so far for the SinokoreanCraton.c. Grey gneiss:Four biotite-plagioclase-gneiss samples plot on the 3.5 GaSm-Nd isochron for the Qianxi amphibolite (Qiao et al., 1987).The Nd depleted mantle model dates (TDM, all cited TDM’s have beenrecalculated according to DePaolo, 1981) for these samples arebetween 3.32 and 3.46 Ga, except for one 2.10 Ga. Three quartzdiorite gneisses fall close to the 3.5 Ga amphibolite Sm-Ndisochron (Huang et al., 1986), with TDM’s between 3.22 and 3.36Ga. One sample in the same study, off the 3.5 Ga isochron, has7Table 2-1. Isotopic dates for Early Precambrian rocks from eastern Hebei ProvinceRock type Date (Ga±2a) Method Source3.50±0.08 eNd=+3.3±0.33.47±0.11 eNd=+2.7±0.63.50±0.02 8eNd=+3.1±1.33.12 to 3.46(& one 2.1 & one 3.76)2.64±0.072.8, 2.6 and 2.32.31±0.12 gO.7020±83.3, 2.9-3.0, —2.53.65-3.67—3.02.79±0.07 ENd=+3.6±0.82.48±0.13 &IsNd=+2.7±2.22.53±0.06 SI=O.7Ol6±92.48±0.07 81s=O.0l462.51±0.022.4±0.3 Sr0701842.40 and 2.452.73±0.032.65±0.05 81Sr°702222.5 13±0.008—2.5Sm-Nd isochronSm-Nd isochronSm-Nd isochronTOMU-Pb zicon upper interceptsingle zircon evaporationRb-Sr isochronsingle zircon evaporationsingle zircon evaporationRb-Sr isochronSm-Nd isochronSm-Nd isochronRb-Sr isochronRb-Sr isochronU-Pb zircon upper interceptRb-Sr tsochronNd TOMU-Pb zicon upper interceptRb-Sr isochronU-Pb zircon upperU-Pb zircon upperHuang et at., 1986Jahn et at., 1987Qiao et at., 1987Huang et at., 1986Jahn et el., 1987Qiao et aL., 1987Liu et at., 1990Liu et at., 1990Sun et at., 1986Liu et at., 1990Liu et at., 1990Sun et at., 1986Jahn et at., 1990bJahn et at., 1990bCompston et al., 1983Jahn and Zhang, 1984Pidge, 1980Sun et at., 1986this studyLiu et at., 1990Wang et at., 1985Liu et at., 1990Yin, 1988Qianxi amphiboliteQianxi grey gneissQianxi fine-grainedgneissQianxi fuchsitequartzi teOianxi granutiteQianxi charnockiteinterceptintercept8continuedQianxi K-rich graniteQianxi granodioriteQianxi gabbroic dioriteQianxi monzodiorite3.0±0.1 U-Pb zircon upper intercept Liu et aL., 19902.980±0.008 and —2.5 sigte zircon evaporation Liu et aL., 19902.596±0.009 U-Pb zircon upper intercept Liu et aL, 19902.494±0.002 U-Pb zircon upper intercept Liu et al., 19902.48±0.01 single zircon evaporation Liu et al., 19902.45±0.03 U-Pb zircon upper intercept Liu et at., 19902.498±0.003 sigle zircon evaporation Liu et at., 19902.45±0.03 U-Pb zircon upper intercept Liu et at., 19902.495±0.001 U-Pb zircon upper intercept Liu et aL., 1990Dantazi-Zhuzhangzi—2.2 Rb-Sr isochron Lu and Huang, 1987metabasaltic rockDantazi-Zhuzhangzi 2.4 to 2.5 Rb-Sr isochrons Liu et at., 1981fine-grained gneiss Shen et at., 1981Luo et al., 1982Quartz diorite —2.4 Rb-Sr isochron Lu and Huang, 19879TDM 3.76 Ga.Two granodioritic gneisses give a 3.12 and a 3.13 Ga TDM(Jahn et al., 1987).Single—zircon evaporation dates of 2.8, 2.6 and 2.3 Ga, anda 2.64 ± 0.07 Ga U-Pb upper intercept date have been reportedfor the grey gneiss (Liu et al., 1990). Sun et al. (1986) haveobtained a 2.31 ± 0.12 Ga Rb—Sr isochron, with (87Sr/6)0 =0.7020 ± 0.0008, for the Qianxi gneiss.d. Fine-grained gneiss:Four zircons from the Qianxi fine—grained gneiss haveyielded 3.3, 2.9, and -2.5 Ga single—zircon evaporation dates(Liu et al. 1990).e. Granulite—facies rocks and charnockite:A 2.79 ± 0.07 Ga Sm—Nd isochron, with ENaCT) = +3.6 ± 0.8,has been obtained by Jahn (1990a) for the Qianxi granuliticrocks. Three basic enclaves in charnockite plot on the 3.5 Gaamphibolite Sm-Nd isochron (Jahn et al., 1987). A 2.73 ± 0.03Ga U-Pb zircon upper intercept date (Liu et al., 1990) and a2.65 ± 0.05 Ga Rb-Sr isochron (Wang et al., 1985) have beenreported for charnockites in the region. Rb-Sr study of Sun etal. (1985) also gave a hint of —3.0 Ga history for the Qianxigranulitic rocks. However, date around 2.5 Ga (from Sm—Nd, Rb—Sr and U-Pb) seems still prevailing for the granulite rocks(Pidgeon, 1980; Compston et al., 1983; Jahn and Zhang, 1984; Sunet al., 1985; 2.40 and 2.45 Ga Nd TDM in this study, Table 2—2)and for the charnockite (Yin, 1988; Liu et al., 1990).10Table 2-2. Sm-Nd isotopic data with 2Q errorsfor samples from Qianxi ComplexSample Sm ppm Nd ppm 147Sm/4Nd 143Nd/4 eNd(0) TDMOianxi ComplexHTB-4 7.628 37.45 0.1229 0.511606 -19.9 2.40i-f- 0.006 0.02 0.0002 0.000012 0.1 0.02HTB-5 1.316 10.85 0.0732 0.510778 -36.0 2.45+1- 0.002 0.04 0.0004 0.000020 0.1 0.07+ Sm and Nd concentrations were determined by isotopic dilution on aVG-30 mass spectrometer, 143Nd/4 ratios were measured by aVG-354 at the University of Alberta. 2 sigma errors listed in thistable do not include calibration and replication uncertainties.0.005% and 1.0% were used for 143Nd/4 and 147Smf4Nd inregression calculations.*TOM: depleted mantle model date of DePaolo (1981), errors arepropagated from standard deviations of 147Sm/4Nd and 143Nd/4.11f. Archean granitic intrusions associated with the QianxiComplex:Liu et al. (1990) obtained the following U-Pb zircon datesfor granitic rocks associated with the Qianxi Complex: 2.980 ±0.008 and 2.5 Ga single-zircon evaporation dates, 3.0 ± 0.1 and2.6 Ga U-Pb zircon upper intercept dates for K-rich granites,and many --2.5 Ga U-Pb zircon upper intercept dates and single-zircon evaporation dates for granodiorite, monzodiorite, andgabbroic diorite.DiscussionThe well-defined 3.5 Ga Sm-Nd isochron for the Qianxiamphibolite evidently records an important crustaldifferentiation event in the area. The mantle source of themagma of the axnphibolite has very depleted Nd isotopic characteras revealed by a positive eNd(T). The 3.5 Ga amphibolites andtheir associated metasediments have been regarded as theearliest supracrustal rocks in Sinokorean Craton (e. g. Zhao,1988)The 3.3 Ga single—zircon evaporation date for the fine—grained gneiss has been considered as an evidence that the fine—grained gneiss is nearly as old as the amphibolite and togetherthey represent an Archean bimodal volcanic suite (Liu et al.,1990). Minimum age of the grey gneiss is defined by the 2.8Ga single—zircon evaporation date. The TDM values of the greygneiss, between 3.12 and 3.46 Ga, will be older if a moredepleted mantle source, as indicated by Sm-Nd isochron of the12amphibolites, is used in calculation of the model dates.Because of its close field relationship with the amphibolites,its chemical similarity to the fine-grained gneiss, and its TDMvalues, the grey gneiss has likewise been inferred to be an acidmember of an Archean bimodal magmatic suite (Jahn et al., 1987).The 3.65 Ga old detrital zircon from the fuchsite—guartziteimplies the existence of an early Archean sialic crust in theSinokorean Craton, although the field relationship suggestscontemporaneous formation of the quartzite and the 3.5 Gaamphibolite. The Cr in fuchsite is likely derived from detritalchromite which is eventually derived from ultramaf ic—basalticrocks (Fabries and Latouche, 1973). Liu et al. (1990)consequently inferred an Early Archean greenstone belt as thesource. Wang et al. (1990) considered the association ofshallow water sediments (quartzite, marble and BIF) and pointedout that this is similar to the Isua supracrustal rocks and thusimplies the existence of an even older, yet undiscovered sialicbasement.Most investigators have concluded that the granulitic rocksand charnockite were emplaced and metamorphosed in rapidsuccession about 2.5 Ga ago (Compston et al., 1983; Jahn andZhang, 1984; Liu et al., 1990). Based on the Nd isotopic data,however, we infer that the granulitic rocks in the region formedat more than two times, one group at least 2.8 Ga ago andanother around 2.5 Ga ago, and metamorphosed to granulite—grade2.5 Ga ago. Granitic intrusions also formed predominantly in atleast two periods,- 3 Ga and 2.5—2.6 Ga ago.1311-2. Dantazi-Zhuzhangzi GroupDantazi-Zhuzhangzi Group (Zhao, 1988) overlies the QianxiComplex in the north and east of the Qianxi Complex, in Chengde,Qinglong, Luanxian and Funing counties, Hebei Province. Thisgroup is made of metavolcanic, volcanoclastic, pelitic andsilicic rocks and BIF, which have undergone amphibolite togreenschist fades metamorphism. Presently these areamphibolite, fine-grained gneiss, schist, quartzite and BIF.Liu et al. (1981), Shen et al. (1981) and Luo et al. (1982)reported 2.5 to 2.4 Ga Rb-Sr isochrons for fine-grained gneiss(Table 2—1). Lu and Huang (1987) obtained a 2.2 Ga Rb-Srisochron for metabasaltic rocks of the Dantazi—Zhuzhangzi Group.A quartz diorite, intruding the Dantazi-Zhuzhangzi Group, givesa 2.4 Ga Rb-Sr isochron date (Lu and Huang, 1987). We inferthat the Dantazi-Zhuzhangzi Group is older than 2.4 Ga, butyounger than 2.5 Ga granulite—facies rocks of the QianxiComplex.14III. EARLY PRECAMBRIAN ROCKS IN LIAONING AND JILINPROVINCES111-1. Qingyuan ComplexWe use the term “Qingyuan Complex” for the high—gradegreenstone—granite association in the Qingyuan area, LiaoningProvince (Fig. 1-1 and 1-2). The same rock suite has beenreferred to “Qingyuan Group” (Yan et al., 1981), or “AnshanGroup” (e.g. Zhang, 1984; Jahn, l990b).The Qingyuan Complex contains granitic gneisses,inetavolcanic and metasedimentary rocks. The granitic gneissespossess tonalite-trondhjemite-granodiorite (TTG) and monzoniticcomposition (Zhai et al., 1985) and have undergone granuliticmetamorphism. The granitic gneisses are believed to be overlainby axnphibolitic rocks with ultrarnafic-basaltic and calcakalinecompositions, and fine—grained gneiss, schist, marble andquartzite (Yan and Li, 1981; Zhai et al., 1985).Isotopic dates for the Qingyuan Complex and associatedgranitic rocks are summarized in Table 3—1.Wang et al. (1987) obtained a 2.98 ± 0.07 Ga K-Ar and two2.99 Ga 40Ar/39r plateau dates for hornblendes separated from theQingyuan amphibolite. The Qingyuan amphibolite also gave 2.61± 0.1 Ga (Zhai et al., 1985) and 2.4 ± 0.1 Ga (Sun et al., 1989)Rb—Sr isochrons.The Qingyuan tonalitic gneiss gave 2.88 ± 0.17 Ga U-Pbzircon and 2.90±0.09 Ga K—Ar biotite dates (Zhai et al., 1985).Sun et al. (1989) obtained a 2.4 ± 0.1 Ga Rb—Sr isochron15Table 3-1. Isotopic dates for Early Precambrian rocks from Liaoning and Jilin provincesRock type Date (Ga±2) Method SourceQingyuan amphibotite 2.98±0.07 K-Ar hornblende Wang et al., 1987—2.99 40Ar/39r Wang et al., 19872.61±0.03 Rb-Sr isochron Zhai et al., 19852.4±0.1 Sr°70194 Rb-Sr isochron Sun et al., 1989Qingyuan tonalitic 2.88±0.17 U-Pb zircon upper intercept Zhai et al., 1985gneiss2.90±0.09 K-Ar biotite Zhai et al., 1985Qingyuan granulite —2.9 and —2.6 Rb-Sr isochron R.G.Sun & Armstrongunpublished data2.47 and 2.51 Nd TDM this studyQingyuan charnockite 2.4±0.18!Sr=OlO38±4 Rb-Sr isochron Sun et al., 1989Lijiapuzi granite 2.71±0.14 Rb-Sr muscovite Zhai et al., 1985Kongshilazi granite 2.73±0.16 U-Pb zircon Zhai et al., 1985Yangwangbizi granite 2.76±0.16 Th-Pb monazite Zhai et al., 1985Tiejiashan Granite 3.3 to 3.4 U-Pb upper intercept Chen and Zhong, 19812.83±0.06 Sr°70261 Rb-Sr isochron Zhong, 19842.86±0.05 Pb-Pb isochron Zhong, 19842.97 U-Pb zircon micro-probe Zhong, 1984Lishan Granite 2.97 to 3.34 Nd TDM this study3.1±0.1 8=8.55 Pb-Pb isochron this studyAnshan amphibolite 2.66±0.08 geNth+4.4±0.5 Sm-Nd isochron Jahn et al., 19902.73±0.25 &INd=+3.0±5.0 Sm-Nd isochron Qiao et at., 19902.72±0.10 geNd=+3.2±2.2 Sm-Nd isochron Qiao et al., 19903.1±0.1 g=9.13 Pb-Pb isochron This study16continued2.722.4±0.1 =8.51.9±0.4 Sr=°7092572.50 to 2.79(& one 2.0 & one 3.0)2.5±0.2 eNd=-8.7±2.93.22 to 3.61—2.5—2.5Nd TOMPb-Pb isochronRb-Sr isochronNd TOMSm-Nd isochronNd TOMU-Pb zircon upper intercept40Ar/39r plateauThis studyThis studyThis studyQiao et at., 1990Qiao et at., 1990Qiao et at., 1990Peucat et at., 1986Wang et al., 1986Anshan fine grainedgneissAnshan schistAnshan GneissicGraniteLonggang gneiss 2.97±0.19‘Sr=°70098 Rb-Sr isochron Jiang, 19872.5±0.1 U-Pb zircon upper intercept Jiang, 1987Longgang gneiss & 2.56 to 2.78 Nd TOM this studygranutite (one 2.27)3.3±0.1 a=8.58 Pb-Pb isochron this studyJianping amphibotite 2.68±0.16‘Sr=°70124 Rb-Sr isochron this study2.85±0.08 leNd(T)=+5.0 Nd isochron this study2.58 to 2.63 Nd TOM this studyKuandian amphibolite & 2.32±0.06 EeNd=+1.3±0.5 Sm-Nd isochron this studygranite2.10±0.04 lg’8.21 Pb-Pb isochron this study1.91±0.06 81Sr•70567 Rb-Sr isochron this study1.7-1.9 K-Ar dates Jiang, 1987—2.2 Rb-Sr Liu et al., 198117continuedKuandian arnphiboliteKuandian graniteCaohe GroupLiaoyang GroupShisi GraniteMafeng GraniteFelsi dyke2.46 to 2.751.96±0.22‘Sr°7052.46±0.14 &Nd=+1.8±0.81.85±0.120.23±0.022.36 to 2.53>2.141.8±0.12.4±2 eNd=+2.3±1.71.8, 2.1 and 2.32.23 & 2.53—2.01.86 and 1.901.81.55±0.06 Sr°7168252.54 & 2.731.48 and 1.451.62.44 & 3.072.17 & 2.580.210±0.025 Sr°716730.16±0.10 eNd=-20.3±0.9—0.120Nd TDMRb-Sr isochronSm-Nd isochronSm-Nd mineral isochronRb-Sr mineral isochronNd TDMU-Pb zircon upper interceptRb-Sr isochronSm-Nd isochronU-Pb zircon upper interceptsNd TDMPb-Pb isochronRb-Sr isochronK-Ar muscoviteRb-Sr isochronNd TDMRb-Sr isochronsK-Ar muscoviteNd TDMNd TDMRb-Sr isochronSm-Nd isochronU-Pb zirocn upper interceptthis studythis studythis studythis studythis studythis studythis studythis studythis studyJiang, 1987this studyChen and Zhong, 1981Jiang, 1987Jiang, 1987this studythis studyJiang, 1987Jiang, 1987this studythis studythis studythis studythis study18for charnockite from the Qingyuan Complex, their unpublished Rb-Sr data also indicate a -2.9 and a -2.6 Ga date for the Qingyuanbiotite granulites (personal communication). We have derived2.47 and 2.51 Ga Nd TDM for the Qingyuan biotite granulite (Table3—2)Granitic rocks intruding the Qingyuan Complex (Lijiapuzi,Hongshilazi, and Yangwangbizi granites) gave a 2.71 ± 0.14 GaRb—Sr muscovite, a 2.73 ± 0.16 Ga U—Pb zircon and a 2.76 ± 0.16Th—Pb monazite dates (Zhai et al., 1985).We interpret that the Qingyuan Complex formed about 3.0 Gaago and was intruded by 2.7 Ga granites.11—3. Tiejiashan and Lishan granitesGeological setting and geochemistryThe Tiejiashan and Lishan gneissic granites are exposed inAnshan City, Liaoning Province. They are overlain by the Anshansupracrustal rocks, and thus are considered to be basement forthe Anshan supracrustal rocks.The Tiejiashan Granite plots in the granite field in thenormative An-Ab-Or diagram (Fig. 3-1). This granite has an Stype granite character in major element composition withexception of lower Al203, and higher Na20 (Table 3-3). Incontrast, it has an A-type granite character in high fieldstrength trace elements (HFS), e.g. Zr, Nb, 1, and Ce (Table 3-4), and falls in the WPG field in Rb — (Y+Nb) plot (Fig. 3-2).The Lishan Granite plots in the trondhjemite field in thenormative An-Ab-Or diagram (Fig. 3-1). Its major composition is19Table 3-2. Sm-Nd isotopic data with 2 errors forsamples from Liaoning and Jilin provincesSample Sm ppm Nd ppm 147SmI4Nd 143Nd/4 eNd(O) TOMQingyuan ComoplexLG-2 5.453 34.21 0.0962 0.511134 -29.1 2.47/- 0.024 0.17 0.0006 0.000008 0.2 0.12LG-3 2.164 16.68 0.0783 0.510813 -35.4 2.51+1- 0.004 0.02 0.0002 0.000012 0.2 0.04Lishan Graniter86-159 2.985 24.91 0.0723 0.510056 -50.1 3.25÷1- 0.004 0.02 0.0002 0.000008 0.2 0.04r86-163 3.287 23.68 0.0837 0.510227 -46.8 3.341- 0.002 0.02 0.0001 0.000016 0.3 0.04r86-164 5.733 43.69 0.0792 0.510280 -45.8 3.15+1- 0.001 0.04 0.0001 0.000060 1.2 0.08r86-165 3.452 26.04 0.0800 0.510328 -44.8 3.121- 0.004 0.12 0.0004 0.000006 0.1 0.14r86-166 3.199 26.19 0.0737 0.510328 -44.8 2.97-‘-I- 0.004 0.06 0.0002 0.000008 0.2 0.06Anshan ComplexA86-129 0.761 2.24 0.2053 0.512834 4.11- 0.001 0.00 0.0005 0.000008 0.2A86-130 1.680 5.12 0.1980 0.512717 1.8 3.38+1- 0.000 0.00 0.0000 0.000042 0.8 0.36A86-136 1.885 5.89 0.1933 0.512817 3.7 1.571- 0.008 0.00 0.0008 0.000024 0.5 0.35A86-144 4.198 23.04 0.1100 0.511196 -27.9 2.72+1- 0.001 0.02 0.0001 0.000008 0.2 0.04Longgang ComplexLG-001 5.558 35.80 0.0937 0.511251 -26.8 2.27÷1- 0.005 0.00 0.0001 0.000012 0.2 0.03LG-003 12.482 81.32 0.0926 0.511012 -31.5 2.56+1- 0.033 0.24 0.0004 0.000006 0.1 0.14LG-009 7.099 42.60 0.1006 0.511011 -31.5 2.74+1- 0.011 0.03 0.0002 0.000006 0.1 0.07LG-034 0.885 6.16 0.0867 0.510854 -34.6 2.631- 0.001 0.00 0.0001 0.000014 0.3 0.05LG-035 1.793 9.47 0.1143 0.511235 -27.1 2.78+1- 0.002 0.00 0.0001 0.000016 0.3 0.0520continuedJianping Complex6341 0.563 1.54 0.2203 0.513324 13.6+1- 0.000 0.00 0.0000 0.000038 0.76354 4.025 19.90 0.1221 0.511493 -22.1 2.58+1- 0.000 0.00 0.0000 0.000008 0.2 0.016441 7.466 39.02 0.1155 0.511347 -24.9 2.63+1- 0.001 0.02 0.0001 0.000006 0.1 0.026496 9.154 42.25 0.1307 0.511624-19.5 2.61+1- 0.001 0.01 0.0000 0.000006 0.1 0.01Kuandian ComplexK86-027 8.370 49.80 0.1015 0.511206 -27.7 2.49+1- 0.004 0.04 0.0001 0.000004 0.1 0.04K86-086 7.736 35.59 0.1313 0.511729-17.5 2.42/- 0.032 0.10 0.0006 0.000012 0.2 0.26K86-088 8.639 42.00 0.1242 0.511577 -20.5 2.491- 0.046 0.10 0.0008 0.000008 0.2 0.28K86-089 6.989 39.87 0.1059 0.511290 -26.1 2.47+1- 0.008 0.08 0.0002 0.000008 0.2 0.10K86-090 9.174 56.92 0.0973 0.511184 -28.1 2.43+1- 0.038 0.10 0.0004 0.000012 0.2 0.18K86-091 9.238 41.84 0.1333 0.511706 -17.9 2.53+1- 0.042 0.04 0.0006 0.000010 0.2 0.24K86-093 3.381 17.90 0.1141 0.511493 -22.1 2.36+1- 0.006 0.01 0.0002 0.000018 0.4 0.10K86-083 3.043 10.97 0.1676 0.512222-7.9 2.71+1- 0.004 0.01 0.0002 0.000008 0.2 0.12K86-084 4.425 15,86 0.1686 0.512258 -7.2 2.64+1- 0.014 0,01 0.0006 0.000018 0.4 0.22K86-243 3.398 12.98 0.1581 0.512140 -9.5 2.461- 0.004 0.01 0.0002 0.000006 0.1 0.08K86-244 2.422 9.05 0.1616 0.512164 -9.0 2.56-i-I- 0.002 0.02 0.0006 0.000008 0.2 0.22K86-246 3.329 11.76 0.1710 0.512272 -6.9 2.75+1- 0.001 0.02 0.0004 0.000006 0.1 0.16K86-248 5.329 25.56 0.1259 0.511561 -20.8 2.57+1- 0.002 0.02 0.0001 0.000006 0.1 0.0421continued(244 plag 1.045 6.52 0.0967 0.511429 -23.4 2.09+1- 0.001 0.01 0.0001 0.000022 0.4 0.04K244 hbl 1.948 6.12 0.1922 0.512591 -0.7 3.361- 0.001 0.01 0.0001 0.000032 0.6 0.34Caohe GroupC87-020 14.908 85.18 0.1056 0.511451 -22.9 2.231- 0.010 0.08 0.0002 0.000026 0.5 0.06C87-076 4.096 22.45 0.1101 0.511321 -25.5 2.53+1- 0.004 0.02 0.0002 0.000008 0.2 0.06Liaoyang GroupL86-213 4.459 22.18 0.1214 0.511505 -21.9 2.54+1- 0.002 0.01 0.0001 0.000028 0.5 0.06L86-218 3.966 18.59 0.1287 0.511522 -21.5 2.73+1- 0.006 0.02 0.0002 0.000006 0.1 0.10Shisi Graniter86-173 3.935 20.54 0.1156 0.511082 -30.1 3.071- 0.002 0.02 0.0002 0.000008 0.2 0.06r86-174 1.522 10.03 0.0916 0.511083 -30.1 2.441- 0.004 0.02 0.0002 0.000056 1.1 0.12Mafeng Graniter86-183 2.502 14.57 0.1036 0.511465 -22.6 2.17+/- 0.002 0.02 0.0002 0.000008 0.2 0.08r86-187 0.359 1.78 0.1218 0.511484 -22.3 2.581- 0.002 0.01 0.0006 0.000010 0.2 0.24+ Sm and Nd concentrations were determined by isotopic dilution on aVG-30 mass spectrometer, 143Nd/4 ratios were measured by aVG-354 at the University of Alberta. 2 sigma errors listed in thistable do not include calibration and replication uncertainties.0.005% and 1.0% were used for 143Nd/4 and 147Smf4Nd inregression calculations.*TDM: depleted mantle model date of DePaolo (1981), errors arepropagated from standard deviations of 147Sm/4Nd and 143Nd!4.22Ano Kuanthan Granite* Tiejiashan GraniteA Lishan Granite* Shisi Granitee Mafeng Granite<> Dading GraniteAb OrFigure 3-1. An - Ab — Or plot for Tiejiashan, Lishan,Kuandian granites and some other granitic bodies from theeastern Liaoning Province. The dividing lines are from WConnor(1965)23Table 3-3. Major element analyses for samples from Liaoning and Jilin provinces* +Sample SIC2 TIC2 A1203 Fe203(as SFe) Mn0 Mg0 Ca0 Na20 K20 P205 L.0.I.Anshan ComplexA86-121 70.0 0.42 13.5A86-130 52.3 0.87 14.4A86-144 70.2 0.38 13.6Longgang ComplexLG-001 60.9 0.56 16.5LG-003 60.3 0.61 16.9LG-009 60.4 0.60 16.6LG-011 62.9 0.58 16.0LG-014 62.2 0.54 16.1LG-033 74.8 0.23 12.8LG-034 69.8 0.70 14.3LG-035 72.7 0.47 12.2Kuandian ComplexK86-027 74.7 0.27 11.4K86-086 72.8 0.31 11.8(86-088 73.9 0.30 11.7K86-089 73.7 0.23 12.5K86-090 74.1 0.30 11.6K86-091 73.4 0.29 11.5K86-093 75.1 0.11 12.7K86-084 50.4 1.29 14.7K86-244 48.9 1.05 15.3K86-246 49.1 0.95 14.4K86-248 74.3 0.58 11.9K87-079 69.1 0.66 16.7K87-125 64.3 0.47 13.7Caohe GroupC86-207 33.8 0.17 3.6C87-020 65.5 0.75 18.0C87-076 57.2 0.40 9.7C87-091 62.8 0.65 21.3C87-098 56.7 0.68 27.2Liaoyang GroupL86-213 63.5 0.71 17.2L86-218 64.9 0.75 16.9L86-222 59.9 0.67 17.3L87-107 61.7 0.65 22.0L87-108 61.1 0.64 21.6Tiejiashan GraniteTi 69.9 0.52 12.8Lishan Graniter86- 159r86- 163r86-164r86-165Shisi Graniter86- 173r86- 174r86- 175r87- 116r87- 1180.07 1.93 1.59 3.54 2.99 0.120.24 6.72 8.87 2.85 0.35 0.060.09 1.99 2.54 4.12 2.03 0.132.06 4.62 4.53 3.36 0.302.28 4.88 4.75 2.97 0.322.29 4.86 4.58 3.08 0.311.90 4.06 4.29 3.56 0.282.08 4.59 4.19 3.29 0.280.54 2.88 3.75 2.35 0.031.51 3.07 4.07 2.11 0.070.68 3.47 3.43 1.26 0.110.10 0.53 3.30 5.16 0.030.04 1.28 3.17 5.68 0.040.06 0.63 3.37 5.34 0.030.09 0.95 4.30 4.46 0.030.05 1.06 3.95 4.18 0.030.06 0.72 2.88 6.01 0.030.04 0.61 4.53 4.40 0.096.04 9.65 2.41 1.07 0.116.65 10.31 2.38 2.46 0.108.99 11.30 2.21 0.96 0.081.19 5.80 2.78 0.32 0.131.19 0.61 1.19 2.59 0.173.72 5.06 3.20 2.77 0.260.05 7.07 51.68 0.94 0.96 0.09 33.200.13 2.04 0.38 0.50 5.34 0.11 4.470.05 12.35 11.49 1.68 3.71 0.08 3.970.03 1.63 0.27 0.87 4.94 0.12 3.690.02 1.53 0.22 0.80 6.14 0.12 4.630.09 3.19 0.54 1.38 2.23 0.10 3.520.08 2.37 0.61 1.55 2.64 0.10 3.090.07 4.96 0.15 0.20 2.03 0.09 4.540.04 2.37 0.11 0.65 5.14 0.06 4.040.05 2.24 0.30 0.90 5.03 0.09 4.390.07 0.57 2.01 3.15 4.88 0.15 0.782.8 0.08 0.39 1.70 4.65 3.02 0.09 0.612.4 0.09 0.37 1.26 5.10 3.05 0.08 0.652.5 0.08 0.59 1.16 5.32 1.98 0.11 0.902.2 0.08 0.33 1.55 4.67 3.30 0.07 0.631.8 0.08 0.10 0.47 3.79 5.27 0.02 0.331.4 0.05 0.08 0.33 4.03 5.01 0.02 0.901.6 0.08 0.13 0.54 3.11 5.30 0.04 0.321.8 0.07 0.11 0.81 3.82 5.24 0.03 0.281.6 0.06 0.11 0.77 3.84 5.58 0.02 0.480. 0.27 14.373.5 0.24 13.973.6 0.29 14.473.5 0.20 14.176.1 0.09 12.376.5 0.07 12.578.0 0.12 11.175.6 0.12 12.474.8 0.08 13.124continuedMafeng Graniter86-183 74.0 0.17 13.9 1.8 0.06 0.20 1.48 4.09 4.31 0.04 1.32r86-187 74.2 0.13 13.6 2.1 0.12 0.13 1.16 4.18 4.34 0.03 1.11r86-188 76.1 0.05 13.0 1.0 0.06 0.04 1.12 4.00 4.55 0.02 0.59Dading GraniterD-002 72.7 0.09 15.5 1.8 0.06 0.27 1.76 5.39 2.42 0.04 0.61rD-005 72.5 0.10 15.2 1.6 0.06 0.30 2.35 5.39 2.44 0.04 0.86rD-008 72.6 0.10 15.3 1.6 0.06 0.30 2.32 5.34 2.30 0.03 0.54* All major element analyses are by a Philips PW-1400 XRF spectrometer, on ground fused glasspellets (Michael and Russell, 1989), reported in wt% and calculated to 100% volatile free.Estimated accuracy (1 sigma) from duplicated runs: Si02, 1%; K20, Ti02, 2%; Fe203, 7%; A1203,MgO, CaO, Na20, 5%; MnO, P205, ±0.01.+ L.0.I. = weight loss between 120 and 900°C.25Table 3-4. Trace element analyses for samplesfrom Liaoning and Jilin provinces*Ba Cr Nb Ni Rb Sr V Y ZrERR0R 7. 8.Anshan ComplexA86- 121A86-122A86- 130A86- 144Longgang ComplexLG-001 1016. 28.LG-003 835. 34.LG-009 930. 25.LG-011 1195. 27.LG-014 1110. 39.LG-033 718. 14.LG-034 502. 77.LG-035 196. 21.Kuandian ComplexK86- 027K86- 086K86- 088K86- 089K86- 090K86- 091K86- 093K86- 084K86- 244K86- 246K86- 248K87- 079K87-125Caohe GroupC86- 207C87- 020C87- 076C87- 091C87- 098Liaoyang GroupL86-213 229. 161.L86-218 232. 155.L86-222 162. 166.L87-107 540. 119.L87-108 654. 116.Tiejiashan GraniteTi 1358. 154.1585. 5.1356. 6.859. 15.1136. 14.Lishan Graniter86- 159r86- 163r86- 164r86- 165Shisi Graniter86- 173r86 -174r86- 175r87-115r87-116r87-1181. 5. 1. 6.6. 50. 100. 292.6. 42. 93. 282.4. 72. 20. 123.7. 44. 76. 301.9. 18. 72. 1114.13. 20. 65. 979.8. 17. 72. 1100.8. ii. 102. 1064.6. 14. 71. 947.6. 7. 59. 575.11. 17. 80. 602.7. 10. 58. 427.5. 152. 66.6. 222. 87.2. 200. 74.3. 166. 106.5. 162. 114.10. 202. 75.0. 161. 70.42. 48. 255.38. 131. 233.109. 25. 202.17. 5. 260.32. 159. 126.45. 115. 439.4. 4. 30. 700.15. 30. 188. 72.8. 20. 172. 149.13. 44. 246. 90.12. 33. 280. 103.6. 70. 71. 104.6. 63. 89. 128.6. 87. 56. 46.12. 37. 216. 40.12. 36. 218. 43.16. 156. 116.-3. 166. 513.0. 157. 326.2. 139. 249.2. 184. 382.2. 274. 85.-4. 202. 91.1. 276. 92.-0. 278. 116.3. 300. 108.2. 264. 94.37. 1. 3.65. 15. 138.71. 14. 134.176. 17. 57.63. 15. 137.89. 17. 171.86. 29. 162.88. 21. 173.88. 12. 224.89. 19. 187.21. 1. 143.59. 4. 55.58. 10. 240.27. 50. 324.34. 66. 298.29. 55. 270.21. 41. 220.22. 51. 261.31. 61. 349.8. 20. 59.221. 27. 92.185. 22. 75.176. 16. 60.50. 26. 224.77. 43. 158.75. 14. 127.22. 16. 152.iii. 35. 289.78. 23. 159.89. 37. 158.108. 39. 150.100. 22. 123.110. 22. 127.98. 19. 119.95. 40. 138.97. 30. 141.68. 80. 429.52. 6. 185.45. 7. 151.33. 11. 246.36. 10. 139.2. 13. 86.-3. 12. 79.7. 22. 109.0. 16. 78.2. 19. 91.12. 26. 79.831. 162.774. 167.129. 123.667. 13.1183. 12.1015. 17.649. 15.741. 3.1142. 12.491. 23.315. 97.250. 215.144. 534.93. 69.451. 60.800. 168.301. 31.1235. 80.277. 76.594. 116.768. 32.292. 25.348. 16.329. 23.331. 20.553. 16.26continuedMafeng Graniter86-183 1234. 13. 9. -1. 115. 473. 32. 14. 115.r86-187 1077. 33. 9. 8. 136. 402. 23. 26. 107.r86-188 655. 20. 6. -0. 135. 328. 7. 10. 63.Dading GraniterD-002 1288. 18. 3. 2. 97. 702. 32. 3. 81.rD-005 1234. 14. 3. 3. 97. 724. 26. 7. 85.rD-008 1240. 16. 4. 3. 98. 713. 26. 5. 80.* All trace element analyses are by a Philips PW-1400 XRF spectrometer,on pressed powder pellets (Armstrong and Nixon, 1980), reported as ppm.+ 1 sigma error estimated from scatter of standards about working curve.27Y+Nb (ppm)1000o Kuandian Granite* Tiejiashan GraniteA Lishan Granite* Shisi Granitee Mafeng Granite> Dading GraniteFigure 3-2. Rb - (Y+Nb) plot Tiejiashan, Lishan, Kuandiangranites and some other granitic bodies from the easternLiaoning Province. The dividing lines are from Pearce et al.(1984)1001 10 10028similar to I-type granite, but EFe2O3 and Na20 are higher, and Rbis lower than the average value of Whalen et al. (1987). Itplots in the VAG field in Rb-(Y+Nb) diagram (Fig. 3-2).Isotopic dating of the Tieliashan and Lishan GraniteChen and Zhong (1981) published a 3.3 to 3.4 Ga U—Pb zirconupper intercept date for the Tiejiashan Granite. Zhong (1984)reported a 2.83 Ga Rb-Sr, a 2.86 Ga Pb-Pb whole rock isochron,and a nearly concordant 2.97 Ga date by zircon ion probeanalyses for the Tiejiashan Granite (Table 3—1).Four Rb-Sr data from the Lishan Granite plot on a linewhich corresponds to 2.05 ± 0.09 Ga with (87Sr/6)0 = 0.7147± 0.0016 (Table 3—5, Fig. 3—3). One sample is far from theisochron. The Sr depleted mantle model dates are around 3.0 Gafor this granite (Table 3-5). Five whole rock samples arescattered in a Sm-Nd isochron diagram, but plot around 3.0 Gareference line through CHUR (Table 3-2 and Fig. 3-4). The Nddepleted mantle model dates are between 2.97 and 3.34 Ga. Fivewhole rock samples mostly plot right of the geochron, and definea Pb-Pb isochron of 3.1 ± 0.1 Ga, with a single stage, firststage growth ji = 8.55 (Table 3-6 and Fig. 3—5), second stage sare equal to or greater than 8.55.DiscussionThe minimum age of the Tiejiashan Granite is 2.97 Ga, theion probe U—Pb zircon concordia date.29Table 3-5. Rb-Sr isotopic data for samplesfrom Liaoning and Jilin provincesSample Rb ppm Sr pp 87Rb/6Sr 87Sr/6r TDM*Lishan Graniter86-159 164.76 508.34 0.941 0.74282 3.1+1- 0.34 0.42 0.002 0.00023 0.4r86-163 152.00 298.44 1.473 0.75728 2.7÷1- 1.71 1.96 0.007 0.00048 0.8r86-164 134.83 241.85 1.615 0.78232 3.5+1- 0.08 2.44 0.019 0.00011 0.9r86-165 180.90 305.91 1.721 0.76644 2.6+1- 0.30 0.24 0.003 0.00016 0.6r86-166 165.92 473.80 1.017 0.74462 3.0+1- 0.44 0.14 0.003 0.00017 0.6Anshan ComplexA86-002 3.56 28.70 0.359 0.72483 4.7+1- 0.01 0.00 0.001 0.00029 0.2A86-005 142.84 226.83 1.832 0.76126 2.3+1- 0.30 0.10 0.004 0.00007 0.9A86-129 25.87 125.44 0.599 0.74874 5.6+1- 0.05 0.03 0.001 0.00023 0.2A86-130 17.25 128.06 0.391 0.72909 5.11- 0.05 0.07 0.001 0.00010 0.2A86-136 16.59 385.15 0.125 0.71497 7.9+1- 0.03 4.53 0.003 0.00019 0.6A86-120 81.88 298.02 0.797 0.72734 2.3+1- 0.16 0.17 0.002 0.00030 0.3A86-121 102.61 292.41 1.018 0.73652 2.41- 0.22 0.09 0.002 0.00012 0.5A86-143 132.96 304.62 1.268 0.74589 2.51- 0.22 5.79 0.024 0.00059 0.9A86-144 75.55 288.79 0.759 0.73251 2.91- 0.13 0.16 0.001 0.00017 0.3A86-147 124.85 162.83 2.230 0.76312 1.91- 0.29 0.10 0.005 0.00016 0.930continuedLonggang ComplexLG-001 68.70 878.10 0.226 0.70803 1.9÷1- 0.12 0.33 0.001 0.00002 0.1LG-003 65.18 828.99 0.228 0.70882 2.2+1- 0.14 0.21 0.001 0.00001 0.1LG-009 74.61 929.40 0.232 0.71107 2.9+1- 0.12 3.91 0.001 0.00017 0.8LG-033 60.42 530.82 0.330 0.71320 2.5+1- 0.29 0.29 0.002 0.00007 0.3LG-034 81.05 605.26 0.388 0.71798 3.01- 0.14 0.17 0.001 0.00002 0.1LG-035 53.64 404.69 0.384 0.71550 2.51- 0.08 0.50 0.001 0.00016 0.2Jianping Complex6302 5.19 212.99 0.071 0.70403 2.31- 0.01 0.12 0.000 0.00006 0.16303 10.10 258.77 0.113 0.70597 2.8/- 0.09 0.06 0.001 0.00004 0.26341 1.72 56.63 0.088 0.70427 1.9÷1- 0.01 0.05 0.001 0.00023 0.36354 8.79 104.76 0.243 0.71042 2.5-‘-I- 0.14 0.02 0.004 0.00007 0.86441 76.88 706.22 0.315 0.71275 2.51- 0.12 0.02 0.001 0.00002 0.16496 17.40 173.88 0.296 0.71317 2.81- 0.05 0.02 0.001 0.00006 0.2Kuandian ComplexK86-026 169.32 68.92 7.237 0.89439 1.91- 0.38 0.04 0.017 0.00006 0.7K86-027 145.67 62.00 6.916 0.88517 1.91- 0.26 0.06 0.014 0.00026 0.9K86-086 209.74 78.94 7.888 0.92889 2.0+1- 0.36 0.74 0.029 0.00001 0.8K86-088 197.08 76.63 7.570 0.91253 2.0/- 1.98 0.01 0.033 0.00015 0.9K86-089 168.67 94.99 5.210 0.85237 2.01- 0.40 0.08 0.003 0.00020 0.6K86-090 153.88 98.89 4.561 0.83621 2.1-‘-1- 0.26 1.22 0.014 0.00061 0.8K86-091 188.16 67.65 8.239 0.93351 2.0+/- 0.32 0.14 0.028 0.00094 1.0K86-093 154.26 61.15 7.435 0.89864 1.9-i-I- 0.30 0.04 0.002 0.00019 0.431continuedK86-083 93.81 309.57 0.878 0.72811 2.1+f- 0.36 1.40 0.001 0.00007 02K86-084 53.18 273.33 0.564 0.72441 2.9+/- 0.10 0.06 0.001 0.00008 0.2K86-243 31.92 184.63 0.501 0.71648 2.1-i-f- 0.06 0.06 0.001 0.00024 0.2K86-244 133.10 234.20 1.652 0.75289 2.2-i-f- 0.40 0.44 0.004 0.00020 0.8K86-246 29.69 199.30 0.419 0.73248-i-I- 0.56 1.63 0.001 0.00045K86-248 5.26 248.29 0.061 0.70748-i-f- 0.02 0.58 0.003 0.00023K87-079 153.13 120.45 3.714 0.80654 2.0-i-f- 0.38 0.10 0.010 0.00035 0.9K87-125 104.19 374.11 0.808 0.73106 2.6-i-f- 0.28 0.44 0.002 0.00004 0.6K244 plag 563.18 598.54 2.740 0.77501 1.9+1- 2.94 1.18 0.015 0.00006 0.8K244 hbl 16.57 22.75 2.121 0.77302 2.4-i-f- 0.04 0.01 0.004 0.00006 0.9Caohe GroupC86-019 3.90 16.28 0.696 0.73743 37-i-I- 0.02 0.06 0.008 0.00608 0.9C86-020 2.00 26.74 0.217 0.73799-i-f- 0.01 0.08 0.001 0.00267C86-032 217.01 146.72 4.323 0.81204 1.8-I-f- 0.40 0.20 0.010 0.00048 0.9C86-037 159.67 239.74 1.940 0.77797 2.8+f- 0.30 0.26 0.004 0.00032 0.9C86-098 4.38 17.54 0.725 0.73068 2.8+f- 0.01 0.14 0.001 0.00156 0.2C86-099 2.01 11.32 0.514 0.73984 5.3-i-f- 0.01 0.02 0.002 0.00086 0.2C86-207 25.43 531.18 0.137 0.70898 4.0+f- 0.08 0.20 0.001 0.00006 0.1C87-020 172.66 71.05 7.126 0.84674 1.4-i-f- 0.34 0.24 0.028 0.00027 0.8C87-076 140.57 108.48 3.779 0.79006 1.6+1- 0.30 0.04 0.008 0.00005 0.5C87-091 251.05 135.31 5.487 0.93522 3.0-i-I- 0.84 1.04 0.046 0.00086 0.932continuedC87-098 267.73 128.17 6.171 0.92222 2.5+1- 0.66 0.16 0.020 0.00008 0.7Liaoyang GroupL86-213 72.26 106.27 1.977 0.75972 2.1+1- 0.30 0.24 0.001 0.00033 0.1L86-218 83.23 121.35 1.995 0.76307 2.2+1- 0.57 0.68 0.029 0.00089 0.9L86-222 54.17 42.65 3.707 0.79634 1.8+1- 0.22 0.22 0.001 0.00028 0.1L87-107 215.35 34.49 18.793 1.11874 1.6+1- 1.28 0.04 0.001 0.00076 0.1L87-108 219.38 44.28 14.833 1.06330 1.7+/ 0.52 0.16 0.067 0.00038 0.9Shisi Graniter86-172 253.08 79.17 9.457 0.93645 1.7+1- 0.52 0.10 0.022 0.00012 0.9r86-173 262.19 75.21 10.331 0.95627 1.7+1- 0.62 0.18 0.030 0.00070 1.0r86-174 201.44 90.79 6.509 0.85499 1.7+1- 0.42 0.28 0.198 0.00033 1.0r86-175 265.49 124.43 6.190 0.73672 0.4÷1- 0.50 0.56 0.012 0.00096 1.0Mafeng Graniter86-180 120.87 403.61 0.867 0.71933 1.4-‘-I- 0.26 0.24 0.002 0.00007 0.4r86-183 114.25 461.07 0.718 0.71904 1.7+1- 0.28 0.60 0.002 0.00020 0.4r86-184 111.72 453.73 0.713 0.71883 1.7+1- 0.24 0.32 0.002 0.00014 0.4r86-187 131.80 376.99 1.013 0.71955 1.2+1- 0.24 2.08 0.006 0.00040 0.9r86-188 131.06 296.49 1.281 0.72069 1.0-‘-1- 0.22 0.24 0.002 0.00021 0.6+ Rb and Sr concentrations were determined by isotopicdilution on a VG-30 spectrometer at the University ofAlberta. 2 sigma errors listed in this table do notinclude calibration and replication uncertainties.0.026% and 2% were used for 87Sr/6r and 87Rb!6Srin regression calculations.* TDM depleted mantle model date of DePaolo (1981),errors are propagated from standard deviations of87Rb/6Sr and 87Sr/65 .330.80000.79000.78000.77000.76000.75000.74000.73000.72000.7 1000.7000cn1f]87Rb/°6SrFigure 3-3.Lishan Granite.Rb - Sr isochron plot for samples from the34— ILIIIII IIIIIIII lIIIlIIIlIIIL iii I0.5125 Granites from Liaoning —-s’CHJJR0.5120 - //0.5115 0.15 Ga1ine/._-—0.5110 - ‘$—c-0 5105sigma error bar: +-A—‘?.-iL%>0.5100_., A A Lishan Granite— ‘.* Shisi Granitea Mafeng Granite0.5095 ./ c.c?.--- o’‘S.-’0.5090 - I I0.000 0.050 0.100 0.150 0.200147 144Sm/ NdFigure 3-4. Sm - Nd isochron plot for the Lishan, Shisi,and Mafeng granites.35Table 3-6. Pb isotopic data for samples fromLiaoning and Jilin provincesSample 2O6Pb/4# 207Pb/4 208Pb/4Anshan amphiboliteA86-128 19.21 16.27 37.44A86-129 18.55 16.15 37.09A86-130 18.53 16.10 37.25A86-133 21.30 16.82 38.45A86-136 17.81 15.96 36.70A86-137 18.69 16.26 37.07Anshan fine grained gneissA86-120 18.28 15.85 37.91A86-121 19.18 15.96 38.81A86-143 19.26 15.96 38.27A86-144 20.14 16.14 38.86A86-147 21.67 16.36 39.99Longgang ComplexLG-001 14.47 14.89 34.87LG-003 14.43 14.90 34.50LG-009 14.48 14.84 35.13LG-033 15.15 15.07 34.51LG-034 15.65 15.18 36.32LG-035 15.17 15.09 34.73Kuandian ComplexK86-026 48.46 19.56 72.78K86-027 34.52 17.82 53.45K86-086 26.60 16.70 50.12K86-089 34.08 17.85 72.95K86-093 21.30 16.04 42.56K86-083 17.34 15.57 36.49K86-084 17.43 15.51 37.46K86-243 23.96 16.47 44.08K86-244 21.88 16.19 41.91K86-248 28.70 16.86 51.82K244 plag 17.62 15.71 38.44K244 hbt 18.69 15.67 38.79Lishan Graniter86-159 18.81 15.99 40.85r86-163 18.09 15.82 40.90r86-164 19.93 16.26 45.01r86-165 19.88 16.20 39.68r86-166 18.69 1592 40.59Mafeng Graniter86-180 17.40 15.54 38.12r86-183 17.42 15.56 38.21r86-187 17.56 15.57 38.20r86-188 17.61 15.51 38.16# The 2 sigma errors for 206Pb/4, 207Pb!4 and208Pb/4 are 0.10, 0.15, and 0.16%, respectively.Error correlation coefficient CR) between 206Pb/4and 207Pb/4 is 0.8.3620.0019.0018.0017.0016.0015.0014.0013.0012.0010.00206Pb/204PbFigure 3-5. Whole rock Pb plot for samples from the LishanGranite. The 4.57 Ga geochrori is plotted for reference. Anominal single, first stage growth jI, 8.55, is calculated fromthe intersection of geochron and Pb—Pb isochron. This i valueis that of single—stage growth in a uniform source, or is anoverall average of a multi—stage growth history prior todifferentiation into rocks of diverse U/Pb ratio. Second stagej.’s are equal to or greater than 20.00 25.00 30.0037The 2.97 to 3.34 Ga Nd depleted mantle model dates for theLishan Granite indicate a mantle source older than the 2.7 GaAnshan Complex, which is the oldest supracrustal rock exposedin the area. The 2.05 ± 0.09 Ga Rb-Sr isochron date cannot bea differentiation age because the Anshan Complex overlies theLishan Granite. This young date is partly due to isotopicresetting, and the high initial Sr isotopic ratio is consistentwith this interpretation. The Sr depleted mantle model dates areconsistent with a pre-Anshan age. The 3.06 Ga whole rock Pb-Pbisochron date is probably close to the true age of the LishanGranite. First stage growth equals 8.55 and all the data plotto right of the geochron. This indicates a relatively high U/Pbsource and an overall enrichment of U/Pb in the rock suite atthe time of differentiation. In conclusion, we infer that theTiejiashan and Lishan granites are at least 3.0 Ga old.111-3. Anshan Complex and Anshan gneissic graniteGeological backgroundThe Anshan Complex is exposed in Anshan city and Benxicounty, Liaoning Province (Fig. 1-1 and 1-2). It overlies theTiejiashan and Lishan gneissic granites, and is composed ofmainly supracrustal rocks, i.e. amphibolites with komatiitic,caic—alkaline basaltic compositions (Zhang, 1984), fine—grainedgneiss, schist with greywacke and pelite compositions,quartzite, and BIF. In general, the BIF is closely associatedwith amphibolites, and makes a high proportion of China’s ironore. The rocks have undergone amphibolite (north) to38greenschist—facies metamorphism (south).The Anshan Complex is intruded by the Anshan gneissicgranite. Presently, the Anshan Complex occur as giant to smalllenses within the Anshan gneissic granite.Isotopic dating of the Anshan Complex and the Anshangneissic granitePublished isotopic dates and our results for the AnshanComplex and the Anshan gneissic granite are listed in Table 3-1.a. Amphibolites:Jahn and Ernst (1990) have obtained a 2.66 ± 0.08 Ga Sm-Ndisochron, with cNd(T) = +4.4 ± 0.5, for the Anshan amphibolite.Qiao et al. (1990) have analyzed two suites of amphiboliticsamples that are associated with two different BIF formationsin the Anshan area, and derived Sm—Nd isochrons of same date,2.7 Ga, with similar Nd(T), about +3. Our Sm-Nd data for threeamphibolites from two drill holes in the Anshan area plot closeto the 2.7 Ga Sm-Nd reference line (Table 3-2 and Figure 3-6).Our six Pb isotopic data for the Anshan amphibolites fromtwo drill holes give a 3.1 ± 0.1 Ga Pb-Pb isochron, with asingle stage i = 9.13 (Table 3—6, Fig. 3—7).Our Rb-Sr data for amphibolite are scattered (Table 3-5,Fig. 3—8), same as in the case of Qiao et al (1990).b. Fine—grained gneiss:One fine-grained gneiss sample with a granodioriticcomposition (Appendix 1) has a TDM of 2.72 Ga and falls close to390.51300.51250.51200.51150.5110z0.51050.51000.50950.50900.000Figure 3-6. Sm-Nd isochron plot for the Anshan amphiboliteand fine grained gneiss.0.050 0.100 0.150 0.200147 ‘1.4Sm/ Nd4018.0017.00. 16.00015.00014.0013.0012.00Figure 3-7. Pb-Pb isotopic plot for the Anshanaxnphibolites. The 4.57 Ga geochron is plotted for reference.Meaning of single stage p, 9.13, is same as for the LishanGranite (Figure 3—5). Second stage 1u’s are either smaller orgreater than 9.13.206Pb/4’Pb410.80000.79000.78000.7700-4 0.7600Cl)0.7500CI) 0.74000.73000.72000.71000.700087Rb/°6Sr2.50Figure 3-8.and fine—grainedthe fine-grainedRb-Sr isochron plot for the Anshan axnphibolitegneiss. 1.9 Ga errochron date is calculated forgneiss0.00 0.50 1.00 1.50 2.0042the 2.7 Ga Sm—Nd reference line (Table 3—2 and Fig. 3—6).Five fine-grained gneisses all plot right to the 4.57 Gageochron. This may imply that a U/Pb depleted component has beenleft since formation of the fine—grained gneiss, or this is dueto metamorphic U enrichment of the fine-grained gneiss. The fivedata define a 2.4±0.1 Ga Pb-Pb isochron, with a single stage i= 8.5 (Table 3—6, Fig. 3—9). These five samples poorly defineda Rb—Sr isochron of 1.9 ± 0.4 Ga, with initial (87Sr/6)0 =0.7092 ± 0.0057 (Table 3—5, Fig. 3—8).c. Pelitic schistQiao et al. (1990) published five Sm-Nd data for the Anshanmetapelitic rocks. The TDM’s of these rocks are between 2.50 and2.79 Ga, except for one 2.0 and one 3.0 Ga.d. Anshan gneissic graniteQiao et al. (1990) obtained a 2.5 ± 0.2 Ga Sm—Nd isochron,with cNd(T) = -8.7 ± 2.9, for the Anshan gneissic granite. Theof these rocks are between 3.22 to 3.61 Ga. 2.5 Ga dateshave also been obtained by U-Pb zircon (Peucat et al., 1986) and40Ar/39r methods (Wang et al., 1986).DiscussionThe 2.7 Ga Sm-Nd isochron, with a very depleted initial Ndisotopic ratio, reveals that the Anshan ainphibolites are mainlyderived from the mantle 2.7 Ga ago. Their tectonic environmenthas been inferred to be similar to modern island arcs (Zhai etal., 1990).431.8.00 I I ‘I’’ I17.00 Anshan fine—grained gneiss:14.00- Isochron date = 2.41 +1— 0.1 Ga13.00Single stage mu = 8.512.00 III I13.00 15.00 17.00 19.00 21.00206Pb/4Figure 3-9. Pb-Pb isotopic plot for the Anshan finegrained gneisses. Meaning of single stage bL, 8.5, is same as forthe Lishan granite (Figure 3-5). Second stage s are allgreater than 8.5. This may imply that these rocks came from aU/Pb enriched source, or this is due to metamorphic U enrichmentof the fine-grained gneiss.44The fine—grained gneiss and other supracrustal rocks mostlikely were also formed/deposited about 2.7 Ga ago. The Anshansupracrustal rocks are intruded by 2.5 Ga Anshan gneissicgranite, which was largely derived from partial melting of theexisted continental crust as evidenced by the Nd depleted mantlemodel dates.111-4. Longgang ComplexGeology and isotopic datingThe Longgang Complex is exposed in the Huadian-Jingyu area,Jilin Province (Fig. 1-_i and 1—2). It has also been referredto “Baishanzhen Group” (Jiang and Shen, 1980), “Anshan Group”(e.g. Jahn, 1990), or “Longgang Group” (Jiang, 1987).The Longgang Complex comprises amphibolite, grey gneiss,fine-grained gneiss, quartzite, Hyp-Hb-granulite and Cpx-Opxgranulite. The amphibolite and granulite have basic tointermediate compositions (Jiang, 1987).Jiang (1987) obtained a 2.97 ± 0.19 Ga Rb—Sr isochron, with(87Sr/6)0 = 0.7009 ± 0.0008, and a 2.5 ± 0.1 Ga U—Pb zirconupper intercept date for the Longgang grey gneisses (Table 3-1)We have done Rb-Sr, Sm-Nd and Pb-Pb isotopic analyses forthe Longgang grey gneiss and Longgang granulite withintermediate compositions (Table 3-3).The Rb-Sr and Sm-Nd data are scattered (Fig. 3—10 and 3-11). The Nd TDM’S for these rocks are between 2.56 and 2.78 Ga,except for one 2.27 Ga. Pb isotopic compositions for the450.72000.71800.71600.71400.7120CI)0.7100CI) 0.70800.70600.70400.70200.70000.00Figure 3-10. Rb-Sr isochron plot for the Longgang Complex.0.10 0.20 0.30 0.40 0.5087Rb ,86/ Sr460.51300.51250.51200.51150.5110z0.51050.51000.50950.50900.000Figure 3-11. Sm-Nd isochron plot for the Longgang Complex.0.050 0.100 0.150 0.200147 ‘144Sm/ Nd47Longgang granulite are nearly identical, and together with dataof grey gneiss plot on a 3.3 ± 0.1 Ga Pb-Pb line (Fig. 3-12).All these Pb data plot left of the geochron, the same asgranulites from the Qianxi Complex (Sun, 1987). This indicatesthat the Longgang Complex has a U/Pb depleted character whichis perhaps related to the granulite—facies metamorphism.DiscussionThe maximum formation age of the Longgang Complex isindicated by the maximum Nd TDM, 2.78 Ga. The only possibilitythat the Longgang Complex is older than 2.78 Ga, is that it isderived from a mantle source more depleted than DePaolo’s (1981)average mantle curve as seen in other Archean rocks of theSinokorean Craton. The 3.5 Ga Qianxi amphibolites have initialNd +2.0 E units higher than the mantle curve (Huang et al.,1986; Jahn et al., 1987; Qiao et al., 1987), 2.7 Ga Anshanamphibolites posses an initial Nd + 1.8 c units higher than themantle curve (Jahn et al., 1990; Qiao et al., 1990), and 2.7 GaTaishan amphibolites have initial Nd + 1.1 € units higher thanthe mantle curve (Jahn et al., 1988). However, even if themantle source for the Longgang Complex is + 2 higher than theaverage mantle curve, the calculated Nd TDM is still not greaterthan 3.0 Ga.We infer that the Longgang Complex was formed around 2.8Ga ago and metamorphosed 2.5 Ga ago. The 3.3 ± 0.1 Ga Pb-Pbisochron is considered as a mixing line between unrelated endmembers and thus of no age significance.4817.0016.5016.0015.5015.0014.5014.0013.5013.0012.5012.0012.00 20.00Figure 3-12. Pb-Pb isotopic plot for the Longgang Complex.Meaning of single stage p, 8.58, is same as for the LishanGranite (Figure 3-5). Second stage s are all smaller than8.58. This indicates that the Longgang Complex has a U/Pbdepleted character which is perhaps related to the granulitefacies metamorphism.14.00 16.00 18.00206Pb/449111-5. Jianping ComplexEarly Precambrian rocks exposed in the western LiaoningProvince, west of the Tan—Lu Fault, have been named the JianpingComplex (Fig. 1-1 and 2—2), which has also been referred as“Anshan Group” (Chinese Academy of Geological Sciences, 1973).The Jianping rocks have undergone granulitic—facies metamorphismand are considered, together with the Qianxi Complex, as partof the “granulitic belt” which continues west to the Yinshanregion of Inner Mongolia (Sanggan Complex) and east to the JilinProvince (the Longgang Complex).Rocks in the Jianping Complex are mainly ainphibolite,hornblendite, pyroxenite, gneiss and granulites with basic tointermediate compositions. Our Rb-Sr data of amphiboliticsamples from the Jianping Complex define a 2.68 ± 0.16 Gaisochron, with(87Sr/6)0= 0.7012 ± 0.0004 (Table 3—5, Fig. 3—13). Our four Sm—Nd samples lie on a 2.85 ± 0.08 Ga line, withENd(T) = + 5.0±0.3 (Table 3-2, Fig. 3—14). The Nd TDM’s for threeof the four samples are between 2.58 and 2.63 Ga (Table 3—2).One with a high Sm/Nd ratio (6341) does not give a reasonableTOM. Thus we infer that the Jianping Complex has formed 2.7 to2.85 Ga ago, perhaps contemporaneous with or not much older thanthe Anshan supracrustal rocks.11—6. Kuandian Complex and associated rocksA Proterozoic mobile belt is well exposed in the easternLiaoning Province and southern Jilin Province, China (Fig. 1-1,500.7200-________0.7175- VJianping Complex0.7150-0.7125CI)0.7100-0.7075 -2 sigma error bar: -+-0.7050Isochron age 2.68 +/— 0.18 Ga0.7025(Sr/Sr)0 = 0.7012 +/— 0.00040.7000- II I0.00 0.10 0.20 0.30 0.40 0.5087Rb/6SrFigure 3-13. Rb-Sr isochron plot for the Jianping Complex.510 5135 I I I I I I I I I I I I I0.5130 --Jianping Complex0.51250.51200.5115 - --0.5110 -— 0.5105 2 sigma error bar:0.5100 Isochron age 2.85 +/— 0.08 Ga-0.5095 - (1Nd/t”Nd)0 = 0.50918 +/— 0.00008 -0.5090 I I I I I I I I I I I I I I I I I I I I I I I I I I I I I I IE..0.000 0.050 0.100 0.150 0.200 0.250147 144-,Sm/ i’dFigure 3-14. Sm-Nd isochron plot for the Jianping Complex.521-2 and 3-15). The belt is bounded by the Archean Anshan Complexto the north and south, Tan—Lu Fault to the west, and continuesinto Korea on the east. The name, Liaohe Group, has been usedfor decades for the Proterozoic rocks in the area. Zharig (1984)pointed out that metapelitic, carbonate rocks are found in thenorth and that intrusive, volcanic rocks and turbidite are foundin the south of the Proterozoic belt. He proposed that amiogeosyncline (“North—Liaohe”) coexisted with an eugeosyncline(“South-Liaohe”, or “Liaojitite”) in the Early Proterozoic inthe area. Jiang and his colleagues, however, subdivided theProterozoic rocks into the following complex and groups (Fig.3-16): Kuandian Complex, Caohe Group, Dalizi Group, LiaoyangGroup, and Xutun Group (e.g. Jiang, 1987). The Kuandian Complexis composed of high grade metamorphosed rocks, such as gneissand axnphibolite, and granite. The other Proterozoic groups aremedium or low grade metasediments. They observed unconformitiesbetween the adjacent rock systems in the above sequence, andconcluded that these rocks formed in the Early to the MiddleProterozoic (Jiang, 1981) or from Late Archean to the MiddleProterozoic (Jiang, 1984; 1987) time. Figure 3-17 shows in moredetail the distribution of Proterozoic rocks in the study area,East Liaoning Province, and our sample localities.Geological background and previous isotopic workKuandian Complex:The Kuandian Complex unconformably overlies the ArcheanAnshan Complex (Jiang, 1984). The Kuandian Complex contains5342°400380Figure 3-15. Simplified geological map of eastern LiaoningProvince, China. Jilin Province is north of 41°N and east of126°E. The Proterozoic mobile belt is bounded by Archean rocksto the north and south, the Tan-Lu Fault to the west, andcontinues into Korea on the east (simplified from CAGS, 1973 andunpublished map of Jiang, 1987).0 50 100km54- Xutun -—www— LiaoyangDalizi.——Eo.. .CáoheC00.c._JJKuandian-Ku a rid iangranitef__I_r.t ,-.F__I I-SI •._I r.-F__I ,—, f-_i f__I c_i c_If__f__‘_ _i p_J r\’• •.._i . +• ‘.1 _? . .__J ___, . ji +Anshan‘Shisi, DadinggranitesTiejiashan, LishangranitesFigure 3-16. Schematic stratigraphic section showing therelationships of the Proterozoic geological systems in the EastLiaoning Province, China. The “thicknesses” are compiled fromJiang (1987). Unconformities have been observed between thedifferent systems. The Archean Anshan Complex unconformably lieson Tiejiashan Granite, and is mainly composed of amphibolitesand gneisses. The Kuandian Complex consists of axnphibolite,granite, limestone and fine—grain gneiss. The Caohe Group isintermediate grade rocks of meta—flysch facies and metapelite.Dalizi Group is mainly low-grade phyllite and meta-siltstone.Liaoyang Group is slate and carbonate. Xutun Group is slate,phyllite and quartzite.5541°20’40040’40000’Figure 3-17. Geological map showing sample localities. Themap shows the field occurrences of the Archean Anshan Complex,Proterozoic Kuandian complex, Caohe, Liaoyang, Dalizi, and Xutungroups, and granitic bodies of various ages (simplified fromunpublished map of Jiang, 1987).0 10 20km56fine-grained gneiss, amphibolite, olivine-phlogopite-marble andgranite with a low—Mg character.Protoliths of fine—grained gneisses are rocks withturbidite rhythmic layers, which consist of immature sandstone,siltstone, greywacke, and some pyroclastic rocks/components(Zhang, 1984; Jiang, 1987). The amphibolites are made of fineor medium grain—sized hornblende and plagioclase, with welldeveloped lineation and foliation.Controversy exists regarding the nature of the Kuandiangranite. The granite occurs as sheets or layers intercalatedwith amphibolite and gneiss. Jiang (1987) named the granite aslayered migmatite and implied a metamorphic origin. Zhang(1984), however, proposed an igneous origin for the granite. Ourpetrographic study indicates that the granite ishololeucocratic, mainly composed of fine to intermediate grain—sized microcline, oligoclase and quartz. Mafic minerals arearound 5%, which include biotite, blue amphibole (riebeckitic?)and locally dark green (aegirine?) augite. Magnetite, apatiteand zircon are the main accessory minerals. No fluorite has beenobserved. Quartz usually shows undulatory extinction. Fracturesare found inside zircon grains. K—feldspar porphyroclasts appearin one thin section. Perthitic textures are common inmicroclines, the exsolved albite has a stringer shape and isdistributed regularly through the K-feldspar. Gneissic textureis conspicuous for the granite. From the above observations androck chemistry discussed below, we infer that the Kuandiangranite has an igneous origin, either an orthogneiss or57metavolcanic rock.The previously published K-Ar dates are between 1.7 to 1.9Ga (compiled by Jiang, 1987). Liu et al. (1981) reported a 2.2Ga Rb—Sr whole rock isochron for the Kuandian gneissic rocks.U—Pb zircon upper intercept dates for the Kuandian granite arearound 1.8, 2.1, and 2.3 Ga (compiled and recalculated by Jiang,1987). Based on these isotopic data, Jiang and his colleaguesonce placed the Kuandian Complex in the Early Proterozoic (e.g.Jiang, 1981). However, by comparison of petrochemistry andlithologic assemblages with the Fuping Complex in theTaihangshan region, Shanxi and Hebei provinces, they latertentatively placed the Kuandian Complex in the Late Archean(Jiang, 1984; 1987)The Kuandian Complex contains two important type of borondeposits, i.e. ascharite type and ludwigite type, also massiveFe of metasediment type, fine-grained stratiform Pb-Zn,magnesite, and talc.Caohe Group:The Caohe Group unconformably overlies the Kuandian Group.Conglomerates are observed overlying the contact. The CaoheGroup consists of intermediate grade rocks of meta—flysch faciesand metapelite, now mainly fine—grained gneiss, schist andcarbonate. Chen and Zhong (1981) reported a 2.0 Ga Pb-Pb wholerock isochron. Jiang (1987) obtained 1.90 and 1.86 Ga Rb—Srwhole rock isochrons for the Caohe Group and a 1.8 Ga K—Ar datefor muscovite from a pegmatite intruding the Caohe Group. Theyproposed that the Caohe Group was deposited between 2.1 and 1.8558Ga, and underwent a metamorphic event at 1.85 ± 0.05 Ga.Dalizi Group:The Dalizi Group mainly crops out in the southeastern JilinProvince. This group consists of low grade phyllite and metasiltstone. The phyllite has a pelitic composition. Jiang (1987)reported a 1.73 Ga Rb-Sr whole rock isochron and interpreted thedate as a metamorphic age. They presumed that the Dalizi Groupwas deposited between 1.8 to 1.7 Ga. Dalizi stratiform irondeposit is confined in this group.Liaoyang Group:The Liaoyang Group is mainly made of slate and thick andmassive carbonates. The slate has a pelitic composition. Jiang(1987) obtained 1.48 and 1.45 Ga Rb-Sr whole rock isochrons anda 1.6 Ga K-Ar date for muscovite from a pegmatite intruding theLiaoyang Group. They interpreted the Rb-Sr isochron date as ametamorphic age and proposed that the Liaoyang Group wasdeposited between 1.7 to 1.5 Ga. Important inagnesite, talc, andmetasedimentary phosphorus deposits are found in this group.Xutun Group:The Xutun Group consists of slate, phyllite, and quartzite.The slate and phyllite have a pelitic composition. No isotopicages have been reported for this group to date. Fieldrelationships indicate that it is older than the Sinian.In summary, previous geochronological studies generallyagree on an Early Proterozoic age for the Kuandian Complex andCaohe Group, probable Early Proterozoic age for the DaliziGroup, and possible Middle Proterozoic age for the Liaoyang59Group.Granitic intrusions:Granitic bodies of different ages are widely distributedin the area, but very little isotopic dating has been done onthe granites.Pre—Kuandian granites:The Shisi Granite and the Dading Granite are overlain bythe Kuandian Complex and contain inclusions of the AnshanComplex. There are no isotopic data for these bodies.Post—Kuandian granite:The Mafeng granite was previously mapped as a Proterozoicgranite. Our new field observations indicate that the MafengGranite intrudes the Kuandian Complex. The isotopic data of thisstudy indicate a Mesozoic age.Petrochemistry of Kuandian Complex and associated rocksWe have done major and trace element XRF analyses for 4amphibolites, 7 granites, and 2 metasediments from the KuandianComplex, 5 metasediments from the Cache Group, 5 metasedimentsfrom the Liaoyang Group, and 12 samples from associated graniticbodies (Tables 1 and 2). Immobile elements have been givenspecial attention.(1). Kuandian amphibolitesEssential Classification:Volcanic rocks usually fall into basaltic, andesitic, andrhyolitic categories according to their Si02 concentrations.60They can be classified as subalkaline, alkaline, andperalkaline, according to their alkali contents. The subalkalinerocks can be further subdivided into tholeiitic and caic—alkaline series based on iron enrichment trends and A1203contents (Irvine and Baragar, 1971).Amphibolites from the Kuandian Complex are mostly basaltic,except for one sample, K86—248, of very different composition.This sample has high Si02 (74.3%), but extremely low K20 (0.32%)and Rb (5 ppm). CaO is higher than rocks with high Si02. It isfrom a leucocratic microlayer inside the foliated melanocraticamphibolite, and is mainly composed of fine grained quartz,minor alkali feldspar, hornblende, sphene, and apatite, with amylonitic fabric. The protolith of this rock is probably a Si02—enriched sediment, perhaps impure chert or siliceous exhalite,and is excluded from any further discussion.Major element data indicate that most of the Kuandianamphibolites have the chemical signature of subalkaline rocks(Figs. 3—18 and 3—19). The only exception is one sample, K86244,that plots at the boundary of alkaline and subalkaline rocks inAlkali-Si20diagram (Fig. 3—18) and falls in the alkaline fieldin Ol’-Ne’-Q’ plot (Fig. 3-19). Trace elements show asubalkaline character for all the amphibolites from the KuandianComplex, e.g. Y/Nb > 1.All the Kuandian amphibolites fall in the tholeiitic fieldin A1203 -normative plagioclase plot (Fig. 3-20) and AFM diagram(Fig. 3—21)61Figure 3-18. Total alkali- SiC2 plot showing thatKuandian amphibolites and granites fall in the subalkaline fieldwith the exception that one amphibolite plots near to theboundary of alkaline and subalkaline fields. The dividing lineis from Irvine and Baragar (1971).7-p6CC’2 5+CSi02 wt%6201’Figure 3—19. O1’-Ne’--Q’ plot showing that Kuandianaxnphibolites and granites fall in the subalkaline field with theexception that one axnphibolite plots slightly in the alkalinefield. The dividing line is from Irvine and Baragar (1971).O1’=Ol+3/4Opx, Ne’=Ne+3/5Ab, Q’=Q+2/5Ab+1/4Opx, cation norms.Kuandian ComplexOpx • Ainphibolite0 GraniteNe’AbQ’63250201510Normative PlagioclaseFigure 3-20. A1203 - Plagioclase plot for Kuandian Complex.All the amphibolites fall in the tholeiitic field.100 80 80 40 20 0Composition64FA MFigure 3-21. AFM plot for Kuandian Complex. Allamphibolites fall in the tholeiitic field. The dividing line isfrom Irvine and Baragar (1971). A=K20+Na, F=EFeO, M=MgO, allin wt%Kuandian Complex• Amphibolite0 GraniteCale—alk65In summary, the Kuandian amphibolites have basalticcompositions, and are subalkaline to transitional (subalkaline—alkaline) with a tholeiitic character.Tectonic Discriminant Plots:The tectonic settings for modern volcanic rocks are welldefined and numerous discriminant diagrams based on major andtrace elements have been proposed (e.g. Pearce, 1982). These maynot be exactly appropriate for Precambrian time but neverthelessprovide a basis for comparison between Precambrian inagmaticsuites and between Precambrian and modern analogues.Glassley (1974) proposed a FeO*/MgO — Ti02 diagram todistinguish tholeiitic rocks formed in the environments of midocean ridge (MORB), ocean island (OIB) and island arc (IAT). Twoamphibolites from the Kuandian Complex plot in the IAT field,and one in the MORB field (Fig. 3—22).Pearce (1976) proposed diagrams using discriminantfunctions F1, F2, and F3, calculated from major element data. InF2-F1 plot, two amphibolites plot in the field of CAB+LKT, andone more alkaline sample falls in the field of SHO (Fig. 3-23).In F3-F2 plot, two amphibolites plot in the LKT field, and theone with more alkaline composition falls near to the SHO field(Fig. 3—24)Pearce (1982) introduced N-type MORB normalized traceelement patterns (“spider diagrams”) for comparison of MORB,WPB, and VAB. The Kuandian amphibolites are highly enriched inK, Rb, Ba, and Th; slightly enriched in Nb and Ce; P, Zr, Hf,Sm, Ti, Y, Yb, and Sc are close to 1. The pattern is between66Kuandian amphiboliteI I—3-- ‘IAT , _—o L... -t, om2-- I0,jI* ‘.——0-•-,l———-“ MOTB-_fr——0- I I0 1 2 3 4Ti02 wt %Figure 3-22. FO/MgO - TiC2 plot for tholeiitic basalts(Glassley, 1974). FeC represents total iron in FeC form, all inwt%. Tholeiites can be discriminated as MORB, IAT, and CIB inthis diagram. Two tholeiitic axnphibolites from the KuandianComplex fall in the IAT filed, one in the MCRB field. Condie(1982) ‘s average value of continental rift and flood basalts isindicated by an open triangle. Average value of the high-MgPicture George basalt (BVSP, 1981; Bailey, 1989) is shown by anopen square.67Kuandian amphiboliteFig. 3-23. F - F plot for basaltic rocks (Pearce, 1976).Two basaltic axnphibolites from Kuandian Complex fall in thefield of CAB+LKT. One with more alkaline composition plots inSHO field. F1 = 0.0088SiO2 — 0.0774TiO2 + 0.0l02Al2O3+ 0.0066FeO— 0.OOl7MgO — 0.0l43CaO — 0.0l55Na— 0.00071<20, F2 = —0.Ol3OSiO2— 0.0l85Ti02 — 0.0l29AlO— 0.Ol34FeO— 0.OO300MgO— 0.0204CaO —0.048lNaO + 0.07151<20. Fe203 = Ti02 + 1.5 was assumed incalculating FeC. Meanings of open triangles and squares are thesame as on Figure 3—22.—1.3—1.5—1.7F168—2.3—2.5—2.7-——1.7Kuandian amphiboliteFigure 3-24. F3 - F2 plot for basaltic rocks (Pearce,1976). Two basaltic ainphibolites from Kuandian Complex fall inthe LKT field, one with more alkaline composition plots near toSHO field. F3 = —O.O22lSiO2— O.O532TiO2— O.036A123 —O.OOl6FeO— O.O3lOMgO — O.O237CaO— O.O614Na— 0.02891<20.Meanings of open triangles and squares are the same as on Figure3—22.‘ I I I I I—1.5—1.3F269typical caic-alkaline and typical arc tholeiitic basalts (Fig.3—25)Some trace element diagrams are effective in discriminatingWPB from non-WPB, e.g. Ti/Y - Nb/Y (Pearce, 1982), Ti/l00- Zr -Y*3 (Pearce and Cann, 1973), Zr/Y — Zr (Pearce and Norry,1979), and Ti—Zr (Pearce, 1982) diagrams. All the ainphibolitesfrom the Kuandian Complex plot in the fields of non-WPB (Figs.3—26, 3—27, 3—28, and 3—29).Ti/100— Zr — Sr/2 (Pearce and Cann, 1973) and Ni— Y(Capedri et al., 1980) have been suggested for the furtherdiscrimination of non—WPB. In a Ti/100 - Zr — Sr/2 diagram, allthe amphibolites plot in the LKT field (Fig. 3-30). In Ni- Ydiagram, two amphibolites plot in the LKT field, and one fallsin the MORB field (Fig. 3-31).In summary, the Kuandian amphibolites mostly show thecharacter of island arc Low—K tholeiites in the above major andtrace element tectonic discriminant diagrams. Nevertheless highK20 in the Kuandian amphibolites is strongly inconsistent withthe low-K tholeiite character. If this could be attributed toK—enrichment in a later metamorphic event, however, the low A1203and high FeO characters of Kuandian amphibolite would still beinconsistent with island arc low-K tholeiites. Comparing witharc low-K tholeiite (e.g. Sun, 1980), the Kuandian amphiboliteis also enriched in Rb, Ba, Sr, Cr, Ni, Y, and Zr. Sr/Nd ratiosof the Kuandian amphibolite are between 14.2 and 25.9, which arealso smaller than island arc basalts (30 to 35, McDonough,1990)7010010CC.)C10.1Figure 3-25. Trace element plots (spider diagrams) forbasaltic axnphibolites from Kuandian Complex. Meanings of opentriangles and squares are the same as on Figure 3—22.Sr K Rb Ba Th Ta Wb Ce P Zr Hf Sm Ti Y Yb Sc Cr71Kuandian amphibolite1000.-4100Figure 3-26. Ti/Y- Nb/Y plot for tholeiitic and alkalinebasalts (Pearce, 1982). Fields are divided into subalkaline,transitional, and alkaline mainly according to Nb/Y ratios. WPBcan be easily discriminated from the non-WPB that includes VABand MORB. But VAB and MORB fields largely overlap. The Kuandianamphibolites are non-WPB and subalkaline, in accord with majorelement plots. Meanings of open squares is the same as on Figure3—22.0.1 1Nb/Y72Ti/100Figure 3-27. Ti/lOO- Zr — *3 plot for basaltic rocks(Pearce and Cann, 1973). WPB plots uniquely in the field D, thuscan be discriminated from non-WPB. The Kuandian amphibolitesplot in non—WPB fields. Meaning of open squares is the same ason Figure 3—22.Kuandian amphibolite73Kuandian amphibolite10•11000Figure 3-28. Zr/Y - Zr plot for basaltic rocks (Pearce andNorry, 1979). WPB can be distinguished front non-WPB, but thefields of MORB and lAB partly overlap. The Kuandian amphibolitesplot in non—WPB fields. Meaning of open squares is the same ason Figure 3-22.10 100Zr ppm74Kuandian amphiboliteS‘-41Figure 3-29. Ti-Zr plot for basalts and secondary rocks(Pearce, 1982). The Kuandian amphibolites plot in the non-WPBfield. Meaning of open triangles and squares are the same as onFigure 3-22.1000010 100 1000Zr ppm75Ti/100Figure 3-30. Ti/lOO— Zr - Sr/2 plot for non-WPB basalts(Pearce and Cann, 1973) . Basalts formed in non—WP settings canbe easily distinguished, but subject to much uncertainty becauseof Sr mobility in metamorphic rocks. LKT plots in field A, CABin field B, and OFB in field C. The Kuandian amphibolites plotin the LKT field. Meaning of open triangles and squares arethe same as on Figure 3—22.ZrKuandian amphiboliteSr/276Kuandian amphibolitetooz10-100YppmFigure 3-31. Ni - Y plot for TH basalts (Capedri et al.,1980). The fields are divided into MORB and LKT. Two basalticamphibolites from Kuandian Complex plot in the LKT field, andone in the MORB field. Meaning of open squares is the same ason Figure 3-22.CLKT1077The REE pattern of the Kuandian amphibolites is relativeflat, with a slight enrichment of LREE (Fig. 32, unpublisheddata from Wu). No Eu anomaly was observed. This is alsodifferent from the arc low-K tholeiite. The latter has a slightLREE depletion (BVSP, 1981).The REE pattern of the Kuandian amphibolites is, however,similar to one of the most primitive members of the ColumbiaRiver Basalt Group (BVSP, 1981). Their major and other traceelements also resemble the High-Mg Picture George basalt (BVSP,1981; Bailey, 1989), except for higher K20 and Rb and lower P205in the Kuandian amphibolites.In terms of K20 and Rb, the Kuandian amphibolites are evenmore enriched than many continental rift and continental floodbasalts, e.g. those from Afar Rift in Ethiopia (Barberi et al.,1975), Southern Gregory (Kenya) Rift (Barker et al., 1977), Isleof Skye in Scotland (Thompson et al., 1972; 1980), ProterozoicKeweenawan basalt in the Lake Superior district (BVSP, 1981),basalt from Iceland (Wood, 1978; Sigvaldason and Oskarsson,1986), as well as Snake River basalt (Thompson et al., 1983).The basaltic formations in the 2.76 Ga Fortescue Group ofAustralia share the high K20 and Rb character but the latter aregenerally higher in Si02, lower in MgO, CaO and A1203 (Glikson etal., 1986).Compared with the above mentioned continental rift andcontinental flood basalts (CFB), the Kuandian amphibolites arealso in some degree enriched in EFeO (similar to Snake Riverbasalt, but the latter has a lower SiC2), and depleted in Zr, Nb781000‘• 100CL)C.) 101Figure 3-32. Chondrite normalized REE plot for theKuandian amphibolites and granites. Meanings of open trianglesand squares are the same as on Figure 3—22.La Ce Nd SmEu Th Yb Lu79and Ti. This can explain why the Kuandian axnphibolite falls inthe LKT fields in tectonic discriminant diagrams.In conclusion, the Kuandian amphibolites are most likelyflood basalts, and thus hot-spot related melts, incorporatingcontinental lithosphere (Duncan and Richards, 1991).(2). Kuandian graniteSamples from the Kuandian granite are metaluminous and plotin the granite field in the normative An-Ab-Or diagram (Fig. 3-1). They are chemically similar to A-type granite (Whalen etal., 1987; Eby, 1990), except that Ba and V are high, and Th andZn are low. K20 is often even higher, A1203, MgO/FeO and MgO areeven lower, K/Rb ratio is higher, and Rb/Sr and Rb/Ba ratios arelower than the average A—type granite. Zr, Nb, and Y arecompatible with A-type granite, although generally lower thanthe average value of Whalen et al. (1987) and White and Chappell(1983)The Kuandian granites show a REE pattern of enriched LREE,flat HREE, with slightly negative Eu anomaly (Fig. 3-32,unpublished data from Wu). This REE pattern is similar to theA-type granite (e.g. Collins et al., 1982), although REE islower.The Rb - (Y+Nb) diagram of Pearce et al. (1984) has beenused to discriminate tectonic environments of the Precambriangranites in this study. The Kuandian granites mostly plot inthe WPG field in the Rb - (Y+Nb) diagram (Fig. 3-2).80Compared with world—wide Proterozoic anorogenic granites(Anderson, 1983), except for higher FeO and Sr, the Kuandiangranites are close in composition to the Wolf River batholith,Wisconsin; Trial Creek granite, Wyoming; Ragunda biotitegranite, Sweden; the average Finish rapakivi granites; andSnegamook Lake biotite granite, Labrador.The Kuandian granites also show higher K20 and EFeO, lowerAl203 and NgO character when compared with the Cenozoic rhyolites(>69% Si02) from predominantly bimodal mafic—silicic volcanicassociations (Ewart, 1979), e.g. those from Yellowstone andSnake River Plain, western U. S. A.; Medicine Lake Centre, andSalton Sea Centre, California; Iceland (also see Wood, 1978);Western Scotland and Northern Ireland, Southern Queensland (alsosee Ewart, 1982); and Kenya Rift (Macdonald et al., 1987).(3). Other granitic bodies from the areaThe Shisi Granite falls in the granite field in thenormative An-Ab-Or diagram (Fig. 2-1). It is chemically similarto A—type granite in major elements and Ba, Sc and V1 butdepleted in Zr, Nb, Y, La, and Ce, which are critical for A-typegranite classification. So we interpret that the Shisi Graniteis a highly evolved I-type granite, instead of A—type granite.Its location on the boundary of VAG and Syn-COLG in the Rb -(Y+Nb) diagram (Fig. 3—2), also substantiates thisinterpretation.The Dading Granite plots in the trondhjemite field innormative An-Ab-Or diagram (Fig. 3-1). It has an I-type granite81chemistry except for high Na20 and low MgO and Rb. It plots inthe VAG field in Rb - (Y+Nb) plot (Fig. 3-2).The Mafeng granite plots in the granite field in thenormative An-Ab-Or diagram (Fig. 3-1). This granite has an I-type chemistry, except for high Na20, and low MgO and Rb. Itfalls in the VAG field in Rb - (Y+Nb) plot (Fig. 3—2).Combined with chemistry of the Archean Tiejiashan andLishan granites, we conclude that the granitic bodies from theeastern Liaoning Province have a variety of compositions, somewith contradictory major and trace elements signatures: (a) theArchean Tiejiashan Granite has an S—type character in term ofmajor elements and an A—type character in term of traceelements. We make this observation without providing anyexplanation. (b) the Archean Lishan Granite, Proterozoic DadingGranite, and Mesozoic Mafeng Granite all have an I—typecharacter. (c) the Proterozoic Shisi Granite has an A-typecharacter in major elements and I—type granite character intrace elements. We tentatively infer that these b and c categorygranites are normal to extremely evolved I—type granites. (d)the Kuandian granite has a unique A—type granite character forboth major and trace elements.Isotopic resultsPublished isotopic dates and our own results for theKuandian Complex and associated rocks are summarized in Table3—1.Kuandian Complex:82Five amphibolites and eight granites define a Rb-Srisochron of 1.91 ± 0.06 Ga, with (87Sr/6)0 = 0.7056 ± 0.0007(Table 3-5 and Fig. 33). One amphibolite (K86-246) was rejectedfrom the regression calculation. Two metasediments also plot onthe isochron. Hornblende and plagioclase separated from anamphibolite, K86-244, plot near to the isochron. The two-mineralisochron date is 0.23 ± 0.02 Ga with (87Sr/6)0 = 0.7662 ±0.0006. The reason that the two mineral separates plot above thewhole rock could be due to epidote alteration. Higher Rb/Srratio of plagioclase than the hornblende is tentativelyattributed to a possible K-feldspar component in the plagioclaseseparate. The low mineral isochron date is probably due toisotopic resetting by Mesozoic magmatic activity in the region.Separate regression of amphibolites and granites gives 1.96 ±0.22 and 1.8 ± 0.1 Ga, with (87Sr/6)0 = 0.705 ± 0.001 and0.717 ± 0.011, for the amphibolites and granites respectively.Six amphibolites and seven granites define a straight linein the Sm—Nd plot. The isochron date is 2.32 ± 0.06 Ga with(143Nd/4)0 0.50969 ± 0.00005 or ENd(T) = +1.3 ± 0.5 (Table 3—2 and Fig. 34). Hornblende separated from an amphibolite, K86-244, falls on the isochron, while plagioclase from the samesample plots above the isochron. The two—mineral isochron dateis 1.85 ± 0.12 Ga with(143Nd/’4 )0= 0.51025 ± 0.00014. Separateregression of amphibolites and granites gives 2.46 ± 0.14 and2.4 ± 0.2 Ga, with(143Nd/4)0 = 0.5095 ± 0.0001 and 0.5096 ±0.0001 or ENd(T) = +1.8 ± 0.8 and +2.3 ± 1.7, for theamphibolites and granites respectively. Nd depleted mantle model830.950 — if l?1L lii•lllliii,-Kuandian Complex0000.8500 0 granite/ • amphiboliteV x metasediment/ 0 K244 plag/ K244 hblcn o.aooo - /72 9igma error bar: —0.7500- 7’ Isochron date = 1.91 +/— 0.06 Ga - -4 /• I__(87S/6) = 0.7056 +/— 0.0007III ‘fill,,,’ ,,llllII,Ii,,, iii urn ii ii0.00 2.00 4.00 6.00 8.00 10.00°7Rb/86SrFigure 3-33. Rb - Sr isochron plot for the KuandianComplex.84zz‘-4Kuandian Complexo granite• amphibolite0K244 plagK244 hbl0.51300.51250.51200.5 1150.5 1100.51050.51000.50950.50902 sigma error bar: ÷Isochron date 2.32 +/— 0.06 Ga(“Nd/’”Nd)0 = 0.50969 +/— 0.000050.000147 144Sm/ Nd0.200Figure 3—34. Sm-Nd isochron plot for the amphibolites andgranites from the Kuandian Complex.85dates for amphibolites are 2.46 to 2.75 Ga, those for granitesare 2.36 to 2.53 Ga.Five amphibolites and five granites define a Pb-Pb isochronof 2.10 ± 0.04 Ga (Table 3—6 and Fig. 3—35). The 4.57 Gageochron has been plotted as a reference. Two amphibolites plotclose to the geochron, others plot far to the right of thegeochron. The calculated single, first stage growth = 8.21,second stage s are equal to or greater than 8.21.Zircons from the Kuandian granite are euhedral, prismatic,with dark or light pink colour or colourless. Length/width ratiois 1 to 3. No evidence is found from our analyses for inheritedPb, but our results show multiple Pb loss events. At least two,one Proterozoic and one modern Pb loss event, are needed toexplain the data. Abrasion of coarse—grained zircons resultedin drastic decreases in U and Pb concentrations and improvedconcordance (Table 3—7). If the U—gain in zircons is a recentevent, it would be difficult to explain the correlated high Pbcontent and high radiogenic Pb of unabraded samples. So we inferthat zircons from the Kuandian granite have undergone an ancientU—gain event, which is probably related to Proterozoicmetamorphism.Four coarse grain—sized (>149 ) zircon fractions from theKuandian granite with different colour, abraded or non—abraded,give an upper intercept date of 2.142 ± 0.005 Ga and a lowerintercept date of 0.438 ± 0.129 Ga. Two abraded coarse, oneunabraded intermediate, and two unabraded fine gain—sizedzircoris give a highly suspect upper intercept date of 2.25 ±8620.0019.0018.0017.00. 16.000N15.00t- 14.000N13.0012.0011.0010.009.00Figure 3—35. Whole rock Pb plot for the amphibolites andgranites from the Kuandian Complex. The first stage u same asfor the Lishan Granite (Figure 3-5). Second stage t’s are equalto or greater than 29.00 39.00 49.00206Pb/487T88104(Kuandiangranite)1NM1.5A13°0.8975>149,purple2NM1.5A/3°0.31775>149jt,pink3M1.5A/3°0.360964-74t,pink4M1.5A/3°0.137664-T4,purple5NM1.5A/3’-0.015642>149t,singtegrainpurple,abraded6NM1.5A/3°-0.04674>149it,3grainspurple,abraded7NM1A/5’0.237474-149i,pinkTable3-7.U-PbanalysesofzirconfractionsfromKuandiangraniteandafelsicdike(allMa,and2u)#Splitwt(mg)ppmUppmPb207Pb208Pb204PbMeasured206Pb/238UDate207Pb/235UDate207Pb/206PbDate206Pb100206Pb/204Pb36613.23610.49890.0040236170.3527±0.00721947±346.412±0.1302034±180.13183±0.000082122.5±1.250312.6917.64110.0091104710.2734±0.00941558±484.739±0.1611774±280.12572±0.000162038.9±2.422612.7988.16990.0073124120.3558±0.01011962±486.231±0.182009±260.12702±0.000102057.2±1.614012.7738.11650.0011209720.3574±0.00181970±86.288±0.0302017±40.12758±0.000082064.9±1.226713.48012.93500.015334830.3810±0.00322081±166.975±0.0662108±80.13279±0.000402135.2±5.426413.2159.48840.0004188110.3717±0.00262037±126.770±0.0422082±60.13210±0.000122126.0±1.614312.9698.56290.0049148990.3664±0.00242012±126.519±0.0422049±60,12905±0.000102085.0±1.4continuedT88102(Felsicdike)1NM1.5Af30.35178936.45.006020.3250.00986472.00.0188±0.0002120.2±1.00.1262±0.0012120.7±1.00.04861±0.00012129.2±6.274-149t,clear2M1.5A/3°0.4166134.95.011120.2340.00908286.50.0195±0.0002124.2±0.80.1309±0.0010124.9±0.80.04878±0.00006137.4±3.464-74JL,clearUandPbconcentrationsarecorrectedforblankPb.Isotopiccompositionof100picogramblankis206Pb:784b17.75±0.19:15.5O±0.17:37.30±0.29:1.00.ConinonPbassumedtobeStaceyandKramers(1975)modelPbof2200±100and120±5MaagesforT88104andT88102,respectively.IUGSconventionaldecayconstants(SteigerandJäger,1977)are:238U1.55125x100a,235U=9.8485x1010a,238U/5=137.88atomratio.0.05 Ga (Fig. 3-36). This array of analyses is probably thecombined result of Proterozoic and modern Pb loss so that theapparent upper intercept has no geological significance. Weconsider the minimum crystallization age of the Kuandian graniteis close to the 2.14 Ga upper intercept date from the coarse—grained zircons.Caohe Group:Eleven metasediment samples are scattered in a Rb—Srisochron plot (Fig. 3-37). This is likely due to differentprovenance and variable resetting. Two metasediments produce Nddepleted mantle model dates of 2.23 and 2.53 Ga. In the Sm—Ndisochron plot (Fig. 3-38), they are close to the isochron ofKuandian igneous rocks, so the provenance of Caohe sedimentscould have a large component of Kuandian rocks or other rockswith similar age.Liaoyang Group:Four metapelitic samples give a Rb-Sr isochron of 1.55 ±0.06 Ga with (87Sr/6)0 = 0.7168 ± 0.0025 (Fig. 3—39). Twosamples produce Nd depleted mantle model dates of 2.54 and 2.73Ga. In Sm-Nd isochron diagram (Fig. 3-38), they are close to theisochron of Ruandian igneous rocks, this could indicate that theKuandian rocks remain as an important source for Liaoyangsediments.Pre—Kuandian granite:Shisi Granite:Four whole rock samples are scattered in a Rb—Sr diagram(Fig. 3-40). Three of these give a 1.7 Ga depleted mantle model90Figure 3-36. U-Pb concordia plot for zircons from theKuandian granites. Zircon fractions: 1 and 2, unabraded >l49;3 and 4, unabraded 64 to 74i; 5 and 6, abraded > l49i ( 5 is asingle grain, 6 is three grains); 7, unabraded 74 to l49. Fourcoarse grain—sized fractions give an upper intercept date of2.142 ± 0.005 Ga and a lower intercept date of 0.438 ± 0.129 Ga.2.142 Ga is considered as the minimum crystallization age of theKuandian granite. Two abraded coarse, one unabradedintermediate, and two unabraded fine grain—sized zircons definea line with a highly suspected upper intercept date of 2.25 ±0.05 Ga. This line probably resulted from Proterozoic and modernPb loss.D 0.34(T)Cu-p0CD0CuB207Pb’35U91Caohe Group0.95000.9000 -..4 0.8500 -CI)CI) 0.8000 -F/D 0 ////2 sigma error bar: —2.00 4.00 6.000.75000.70000.00 8.00 10.0087Rb/6SrFigure 3-37. Rb- Sr isochron plot for metasedimentaryrocks from Caohe Group. The data are virtually indecipherablein terms of Rb-Sr ages.92513) IllIllIll 11111 hr hhIrhhhhI hhhhhhIr I0.5125 Caohe and Liaoyang groups0.5120 -Z 0.5115 Q40_-tJ—0.5110—--Z - 2 sigma error bar: +0.5105—4—— çQV0.51000 Caohe0.5095 * Liaoyang0.5090 hhbhhIhhhbhhIhbh I0.000 0.050 0.100 0.150 0.200147Sm/144NdFigure 3-38. Sm - Nd isochron plot for metasedixnentarysamples from Caohe and Liaoyang groups.93Liaoyang GroupC,)C’)1.15001.10001.05001.00000.95000.90000.85000.80000.75000.70002 sigma error bar: —0.00Isochron date = 1.55 +/— 0.06 Ga(Sr/°Sr)0 0.7168 +/— 0.00255.00 10.00°7Rb/86Sr15.00 20.00Figure 3-39. Rb- Sr isochron plot for metasedimentarysamples from Liaoyang Group.941.0000Shisi Granite*0.9500/ */0.9000 7-,U)0.8500 *—J.1.c —0.8000-‘7c3. 2 sigma error bar: —0.7500*7/F I I F F F F I F I iiiij iii IIIIIIII F0.00 2.00 4.00 6.00 8.00 10.0087Rb/°6SrFigure 3-40. Rb - Sr isochron plot for samples from theShisi Granite.95date, while one odd sample results in a 0.4 Ga model date.Samples from this granite are moderately weathered. K—feldsparand plagioclase are seriously saussuritized. Sr model dates areall younger than inferred from field relationships. We suspectthat this granite has been strongly isotopically reset by apost—Proterozoic event or recent weathering. Two samples withthe same 143Nd/4 ratio today give Nd depleted mantle modeldates of 2.44 and 3.07 Ga (Fig. 3—4).Post—Kuandian granite:Mafeng Granite:Five whole rock samples define a Rb-Sr isochron of 210 ±25 Ma with(87Sr/6)0= 0.7167 ± 0.0003 (Fig. 3—41) . Two samplesgive 2.17 and 2.58 Ga Nd depleted mantle model dates, and definea two point isochron of 0.16 ± 0.10 Ga with (143Nd/’44)0 =0.51138 ± 0.00014 or ENd(T) = —20.3 (Fig. 3—4). Four whole rocksamples are clustered in a Pb-Pb isotopic plot (Fig. 3-42),close to but left of the geochron. Calculated single stage,first stage p for one point on the geochron is 8.0, second stagejPs are equal or less.Felsic dyke intruding the Kuandian Complex:Two zircon fractions from a felsic dyke intruding theKuandian Complex have been analyzed. These zircons arecolourless, euhedral, prismatic crystals. Length/width ratio is2 to 3. The intermediate grain—sized zircons plot very close tothe concordia at 120 to 125 Ma (Fig. 3-43). The fine-grainzircons show a hint of Pb inheritance, probably from aPrecambrian precursor.960.73000.7250 Mafeng Granite0.7200C 0.7150 -0.7100 - 2 sigma error bar: —4—Isochron date = 210 +/— 25 Ma0.7050 -(7Sr/5)0 = 0.7167 +/— 0.00030.7000 — I iii, I0.00 0.50 1.00 1.50 2.00°7Rb/°6SrFigure 3-41. Rb - Sr isochron plot for samples from theMafeng Granite.9720.00•19.00 Mafeng Granite18.0017.000CQ16.0015.00 .-- //‘4014.00 ,“ First stage mu = 8.0I,/13.00 /12.03 liii. III10.00 15.00 20.00 25.00 30.00206Pb/4Figure 3-42. Whole rock Pb plot for the Mafeng Granite.a ‘ value of 8.0 is calculated for the point on the geochron.98DCD(1•)CU\0.018.00.CD0CuFigure 3—43. U—Pb concordia plot for zircons from a felsicdyke intruding the Kuandian Granite. Zircon fractions: 1, 74 tol49, 2, 64 to 74g.207Pb/35U99Age interpretationDifferent dating techniques give somewhat inconsistentdates for the Kuandian Complex and associated rocks from theeastern Liaoning Province (Table 3—1). The reason for this couldbe initial heterogeneity in isotopic composition or isotopicresetting(s) after rock formation. The region was tectonicallyactive over prolonged periods in the Precambrian and wasreactivated in the Mesozoic (Yanshanian orogeny) and Cenozoic.Many studies indicate that zircons can survive latedisturbance without completely losing their inherited Pb evenup to granulite facies (e.g. Koppel, 1974; Grauert and Wagner,1975; Schenk, 1980; Vidal et al., 1980; Coolen et al., 1982).So the upper intercept ages of U—Pb zircons have been emphasizedwhen we constrain the minimum formation age of a rock system.DePaolo (1981) derived a mantle Nd evolution curve bycompiling published 6Nd(T) values of samples of known age. Thedepleted mantle model date is calculated by extrapolating ameasured ENd(O) value to the mantle evolution curve according tothe measured 147Sm/’44Nd ratio. Nd depleted mantle model dates canbe used as an important tool when we constrain the maximumformation age of a rock system.For an undisturbed Sm—Nd system all cogenetic samples fromthe depleted mantle source will have the same Nd depleted mantlemodel dates which are equal to the true mantle separation ageand the Sm—Nd isochron date. There are several alternatives tothis ideal situation. If the source was more depleted than themantle curve (i.e. higher ENd(T)), the calculated model dates100will be younger than the true mantle separation age (Fig. 3-44).On the other hand, if the source was less depleted, thecalculated model dates will be older than the true mantleseparation age.If samples are contaminated by crustal material duringmagma ascent, the initial ENd will decrease and thus give oldermodel dates than the true igneous crystallization age.If the Sm—Nd isotopic system was reset at a later time T’,calculated model dates will all be older than T’ and scatteredaround the true mantle separation age T, either older or youngerthan T depending on whether the sample Sm/Nd ratio is higher orlower than the average Sm/Nd ratio (Fig. 3-45).Kuandian Complex:The minimum crystallization age for the Kuandian Complexis 2.14 Ga, the coarse zircon U—Pb upper intercept date.Considering the movement towards concordia of coarse grain—sizedzircons after abrasion, we expect that the intermediate and finegrain—sized grains would also become older and more concordantafter abrasion, thus Proterozoic Pb loss event may be betterdefined.The Kuandian granites give a Sm—Nd isochron date and apositive initial Nd similar to those of amphibolites. This couldindicate that the Kuandian granite and amphibolites have acommon mantle source. The Nd depleted mantle model dates foramphibolites are between 2.46 and 2.75 Ga, those of gneisses are2.36 to 2.53 Ga. Spread of Nd model dates could be due to thefollowing causes:10110.‘‘ 0H—2.00C)—4.00—6.00—8.00—10.00Figure 3-44. Diagram showing younger Nd depleted mantleages will be calculated if the source region was more depletedthan the average mantle evolution curve. T is true age. T1 andT2 are calculated Nd model ages. The higher the Sm/Nd ratio ofa rock, the lower the calculated Nd model age and greaterdiscrepancy with the true age.Time (Ga)10210.—2.00—4.00—6.00—8.00—10.000.00Figure 3-45. Diagram showing how Nd depleted mantle modelages (T1 and T2) will be scattered around true age (T), if theSm—Nd system was homogenized by a later event.1.00 2.00 3.00 4.00Time (Ga)103(1). Rocks are initially heterogeneous in isotopiccomposition or contaminated by crustal material in differentdegrees. Because the granite is more crustal in chemicalcomposition, erroneously old Nd model ages could arise for thegranite. For example, 2.7—2.8 Ga gneiss from Anshan Complex,also in the eastern Liaoning Province, gives Nd model dates upto 3.61 Ga (Qiao et al., 1990, recalculated according toDePaolo, 1981). The Kuandian granites, however, have youngermodel dates than the amphibolites. This makes heterogeneoussource or crustal contamination an unlikely explanation for thespread of Nd dates.(2). Rocks are from a common source defined by the averagemantle evolution curve, but isotopically reset or partiallyreset by a later metamorphic or alteration event. In this case,the model date calculated from true average Sm/Nd ratio andcNd(O) will be identical to the true age. The average Sm/Nd ofKuandian Complex probably lies close to the maximum value of thegranites and the minimum value of the amphibolites. So by thisinterpretation the Kuandian Complex formed around 2.5 Ga. The2.32 Ga Sm—Nd isochron date is somewhat related to a metamorphicevent. Considering the 2.14 Ga coarse zircon U—Pb upperintercept date, however, it is not very likely that the KuandianComplex is as old as 2.5 Ga.(3). Rocks are from a common source that is more depletedthan that defined by the average mantle evolution curve. Forexample, 3.5 Ga old amphibolites from Qianxi Complex, HebeiProvince, give initial 6Nd about +2 higher than the mantle curve104(Huang et al., 1986; Jahn et al., 1987; Qiao et al., 1987). Thecalculated Nd depleted mantle model date for a rock from thishighly depleted source will be younger than the true mantleseparation age, which can be defined by Sm-Nd isochron if thesystem remains closed after rock formation. Moreover, the higherthe Sm/Nd ratio of a rock, the younger the model date. Howeverthe Sm/Nd isochron date for the Kuandian Complex is younger thanthe calculated Nd model dates, and the Kuandian amphibolites(with high Sm/Nd ratios) yield old model dates while theKuandian granite (with low Sm/Nd ratios) give young model dates.This makes the more-depleted source hypothesis unlikely, andrules out the possibility that the Kuandian Complex formed inArchean.(4). Rocks are from a common source that is more enrichedthan the average mantle evolution curve. In this case, all themodel dates will be older than the true mantle separation age,and the higher the Sm/Nd ratio of a rock, the older the modelage. Hence, the true age may be close to the 2.32 Ga Sm—Ndisochron date. Lower initial ENd than the mantle evolution curveis consistent with this explanation.(5). Rocks were formed at different times. The Kuandianamphibolite and granite have identical Sm-Nd isochron dates(-2.4 Ga) and initial Nd isotopic compositions. If the Sm-Ndisochrons are related to their formation ages, it is unlikelythat the granites are much younger than the amphibolites. Theonly possibility that the Kuandian amphibolites are much olderthan the granites is that the amphibolites formed between 2.46105and 2.75 Ga, the Nd depleted mantle model dates, and the Sm-Ndisotopic system was isotopically reset or partially reset duringemplacement of the Kuandian granite at 2.4 Ga. In this case, theKuandian amphibolites could have formed in Late Archean, butyounger than 2.7 Ga, the age of underlying Anshan Complex.From the above reasoning, we derive the followingconclusions:(a). The Kuandian amphibolites and granites are derivedfrom a moderately but not highly depleted mantle source. Themantle depletion is presumably related to Archean crustalformation, but not necessarily creation of the Anshan Complexor in the same area.(b). The Kuandian Complex, at least the Kuandian granite,formed 2.3 to 2.4 Ga ago, near to the Sm—Nd isochron date andthe U-Pb zircon upper intercept date. The 1.9 Ga whole rock Rb-Sr isochron date is related to the isotopic resetting in latermetamorphic events. Considering that two metasediments fall onthe Rb-Sr isochron and that the two-mineral Sm-Nd isochron dateis close to 1.9 Ga, we infer that the Kuandian Complex wasmetamorphosed about 1.9 Ga ago. This date is also consistentwith the oldest K-Ar dates for hornblende (Jiang, 1987).The 2.1 Ga whole rock Pb-Pb and 2.14 Ga upper intercept UPb coarse zircon date are probably the result of partialresetting. An alternative explanation is that they record a pre—1.9 Ga metamorphic event. This date is close to the Rb-Sr(reset) isochron date for the Lishan Granite. Some previous Rb—Sr and U-Pb work also gave 2.1 Ga dates (Jiang, 1987). The106confirmation of the later explanation, however, awaits furtherstudy of the Kuandian Complex and study of granites intrudingthe Kuandian Complex.The first stage growth equals 8.21 for the Kuandian wholerock samples. Data plot to the right of the geochron, indicatingU/Pb enrichment of the rocks relative to their mantle sourcewhich was itself somewhat enriched. This U/Pb enrichment is inaccord with the less depleted mantle Nd character of the samesource. The only Precambrian rocks nearby with depletedradiogenic Pb are in the granulite—facies Archean LonggangComplex outcropping in Jilin Province (Table 3-6). Whether abasement rock like the Longgang Complex exists beneath theEastern Liaoning Province, which can balance the Pb budget, isa question worth further investigation.(c). The initial ENd of the Kuandian Complex is 1.5 E—unitslower than the model mantle evolution curve, indicating a lessdepleted mantle source. This phenomenon is contrast with theArchean rock systems in Sino—Korean craton, for example, 3.5 GaQianxi amphibolites have average ENd +2.0 higher than the mantlecurve, 2.7 Ga amphibolites from Anshan Complex possess an ENd+1.8 higher than the mantle curve (Jahn et al., 1990; Qiao etal., 1990), 2.7 Ga amphibolites from Taishan Complex, ShandongProvince have a 6Nd +1.1 higher than the mantle curve (Jahn etal., 1988). This reveals either an important chemical differencebetween the Archean and the Early Proterozoic mantle under theregion, or reflects an increase in direct crustal recyclingduring Proterozoic magma genesis, or contamination of the107Proterozoic magmas by Archean basement rocks. Modern CFB alsohave a less—depleted source than MORB or oceanic arc.Caohe Group:Rb-Sr data from this study are all scattered. We could notinfer the deposit age or metamorphic age for the Caohe Group.Two Nd depleted mantle model dates, 2.23 and 2.53 Ga, imply thatthe Caohe sediments are derived from Kuandian rocks or from asource with the Kuandian age.Liaoyang Group:We obtained a 1.55 ± 0.06 Ga Rb-Sr isochron with(87Sr/6)0= 0.7168 ± 0.0025. Considering the previous reported 1.6 Ga K-Ar muscovite date of pegmatite intruding the Liaoyang Group, weinterpret this as a metamorphic date for the Liaoyang Group. Thesedimentation age will be older. The two Nd depleted mantlemodel dates, 2.54 and 2.73 Ga, could indicate a slightly largerproportion of Archean rocks in their provenance. But again theKuandian or similar age rocks are likely dominant.Shisi Granite:Two Nd model dates have been obtained for the ShisiGranite, i.e. 2.44 and 3.07 Ga. We can only suspect this graniteformed about 2.4 Ga ago, consistent with the field relationshipsand may have involved melting or assimilation of older rocks..Maferig Granite:This granite gives a 210 ± 25 Ma Rb-Sr isochron withinitial Sr ratio of 0.7167 ± 0.0003. The two—sample Sm-Ndisochron date, 0.16 Ga, is very similar. We infer that theMafeng Granite formed in the Mesozoic, about 0.2 Ga ago. The1082.17 and 2.58 Ga Nd depleted mantle model dates imply aProterozoic to Archean crust as the dominant source of themagma. The Pb isotopic analyses are nearly identical, but plotjust to left of the geochron. The first stage u is 8.0, thesecond stage ii’s are equal or less. This is the only rock suitein the Liaoning Province showing a depleted U/Pb character. Theycould be derived from U/Pb depleted rocks, such as thegranulitic-facies Longgang Complex exposed in the JilinProvince.A felsic dyke intruding the Kuandian Complex gives a circa0.12 Ga U-Pb zircon concordia date, showing that it is anotherresult of Mesozoic magmatic activity.Petrogenesis of Kuandian igneous rocks(1). Kuandian amphiboliteThe Nd isotopic composition indicates that precursor magmaof the Kuandian amphibolite is from a mantle source. The low Mg#(49-63) and Fe enrichment are possibly a result of fractionalcrystallization of pyroxene and divine, which can be inferredfrom the AFM plot. The REE data indicate that this fractionationcould not be very extensive because the REE pattern is relativeprimitive.The high Rb character of the Kuandian amphibolite cannotbe explained by fractionation. Rb content in magma can onlyincrease by a factor of 2, with 50% crystallization, althoughRb partition coefficients for clinopyroxene, orthopyroxene anddivine are very small. The Rb concentrations of the Kuandian109amphibolite are 10 to 60 times higher than an E-MORB mantlesource (e.g. Proterozoic Keweenawan basalt). In order to accountfor the high Rb (and K20) contents in the Kuandian amphibolite,we need to invoke crustal contamination of the precursor magmaor alkali metasomatism, which either happened in the sourceregion or after emplacement. The crustal contaminationhypothesis is not in conflict with the initial Nd isotopicratio, but it could not explain the relative low A1203, and theREE pattern of the Kuandian axnphibolite. The alternativehypothesis, alkali metasomatism in a multi—stage evolutionaryprocess, can account for the trace element character of theKuandian amphibolite.We infer that the precursor magma of the Kuandianamphibolite was less evolved: the high K20 and Rb character ismost likely due to alkali metasomatism either in the mantlemagma source or post emplacement. If this interpretation iscorrect, it leads to the conclusion that the initial Nd isotopicratio of the Kuandian igneous rocks, more enriched than theArchean amphibolites, reflects an important chemical differencebetween the Archean and Early Proterozoic mantle in the region.This characteristic is shared by all CFB regardless of age.(2). Kuandian graniteThe Kuandian granite is genetically related to the Kuandianamphibolite, as evidenced by Nd isotopic data, REE pattern, andsame geochemical character of bimodal—suite rocks.110Trace element partition model calculations indicate thatdirect partial melting of the Kuandian amphibolite (202-260 ppmSr) cannot account for the Sr content in the Kuandian Granite(70-114 ppm Sr), due to an unrealistic bulk partitioncoefficient (1D > 2). Furthermore, a negative Eu anomaly of theKuandian granite rules out significant melting of plagioclase.Partial melting of a gabbroic or eclogite rock could not producea magma with lower Sr content than itself, due to small KDvalues of their component minerals. So magma of the Kuandiangranite is unlikely to have been derived from partial meltingof the Kuandian amphibolite or its chemical equivalent rocks.Extreme fractional crystallization (>>80%) is needed forRb and Ba to differentiate Kuandian granite from a parent magmawith composition of the Kuandian amphibolite, and those mineralwith very small KD’s for Rb and Ba have to be involved (e.g.olivine, pyroxene). However, Cr content of the Kuandian granitewill not allow extensive fractionation of pyroxene and Nicontent of the Kuandian granite excludes extensive fractionationof olivine. Moderate fractional crystallization of (50—60%) ofolivine and/or pyroxene, and plagioclase can explain Cr, Ni, REEand most other elements of the Kuandian granite. We propose thatthe high Rb and Ba concentrations in the Kuandian granite aredue to alkali metasomatisin. Although the Kuandian amphiboliteis also enriched in Rb compared with world-wide CFB, it is stilltoo low in Rb to be parent of the Kuandian granite. We inferthat the Rb enrichment for the Kuandian igneous rocks is mostlikely a post—emplacement event. This explanation can also111account for negative correlation of Rb and Si02 in the Kuandiangranite.In order to interpret the anhydrous character of A—typegranite, many researchers invoke partial melting of residualgranulitic lower crust (e.g. White, 1979; Collins et al., 1982;White and Chappell, 1983; Whalen et al., 1987). They considerthe residual lower crust has undergone a previous extraction ofan orogenic (N—, I—, or S—type) granite. Nevertheless theoverall source ,u value of the Kuandian igneous rocks does notindicate a long term U—depleted source. So we do not seeevidence for the residual crust anatexis model for the Kuandiangranite.It is worth mention that the only rock suite in theLiaoning Province with a U/Pb depleted source character, theMafeng Granite, has an I-type granite chemistry. Thiscontradiction invites future study.SummaryThe Kuandian Complex formed 2.3 to 2.4 Ga ago andexperienced a major metamorphic overprint about 2.0 Ga ago andmore recently.The Kuandian amphibolite and granite formed in anenvironment like modern CFB, and are genetically related. Theyare chemically similar to modern CFB and anorogenic granite, andthus probably were created by a mantle plume (Duncan andRichards, 1991). Nd isotope and REE chemistry indicate thatlittle (if any) crustal contamination was involved in creating112the Kuandian igneous rocks. Low Sr content in the Kuandiangranite rules out its derivation from partial melting of theKuandian amphibolites or their chemical equivalents. Fractionalcrystallization of precursor magma of the Kuandian amphibolitescan explain origin of the Kuandian granite. An alkalimetasomatisin is invoked to explain high Rb character of theKuandian igneous rocks. Pb isotopic character of the Kuandiangranite does not indicate a long term U/Pb-depleted source. Thisis not favourable to the residual crust anatexis model of A—typegranite.The Kuandian igneous rocks are from a depleted mantlesource. However the source is less depleted than DePaolo(1981) ‘s average mantle Nd evolution curve, which is in contrastwith the extremely depleted character of Archean mantle for theSino—Korean Craton. This is an important chemical differencebetween the Early Proterozoic and Archeari mantle in the region.The same mantle could not have produced both groups of rocks insuccession.Liaoyang Group is older than 1.55 Ga. The Kuandian or rocksof similar chemistry and age are a dominant component in theprovenance of Caohe and Liaoyang sedimentary rocks.Shisi Granite formed in the Early Proterozoic; MafengGranite formed in the Mesozoic by partial melting or extensiveassimilation of the old lower crust.113IV. EARLY PRECAMBRIAN ROCKS IN WUTAISHAN AND TAIHANGSHANAREAEarly Precambrian metamorphic rocks are well exposed in theWutaishan and Taihangshan (“shan” means mountain) areas, Shanxiand Hebei Provinces of China (Fig. 1-1, 1-2, 4-1 and 4-2). Astandard “stratigraphic succession” of Early Precambrian rockshas been established in this region by Chinese geologists (e.g.Ma et al., 1957). The lowermost high grade metamorphic complexof grey-gneiss and amphibolite is named “Fuping Group” andassigned to the Archean. The medium to low grade metavolcaniccomplex is named “Wutai Group” and assigned either to the EarlyProterozoic (e.g. Yang et al., 1986) or the Late Archean (Bai,1986). The low—grade metasediments are named “Hutuo Group” andassigned to the Early Proterozoic. All of these rock systems areoverlain by unmetamorphosed, little deformed siliceous dolomitesof the Sinian of North China. The unconformities between Fupingand Wutai, Wutai and Hutuo, Hutuo and Sinian are named asFuping, Wutai and Luliang Movements, respectively. The FupingMovement is considered to be related to the formation of Chinesecontinental nuclei. The Wutai Movement is attributed to theinitial consolidation of the basement of 5mb-Korean Platform.The Luliang Movement is believed to mark the completion of theassembly and stabilization of the Sino-Korean Platform.IV—1. Geological background and previous isotopic workFuping Complex:11440°LEGENDCzCenozoicMzMesozoicPzPaleozoicQIlIHutuoGroupWutalComplexFupingComplexotherp€gneissgranitoidof p€granitoldofMz/faultAsamplelocalityforFupingComplexFigure4—i.SimplifiedgeologicalmapoftheregioncontainingtheWutaishanandTaihangshanareas.TheareashowningreaterdetailonFigure4-2isoutlinedbyarectangle.SamplelocalitiesfortheFupingComplexarelabelled.MzJdCz ‘ Pz CzCzH H (Y1PzPzMzPz•Beijing/cz:.::•zci.Cz 1rcLHHiIIlPzI’112°rLIrCz050100kmIIII113°114°115°116°-39°P PWi113°30’Figure4—2.GeologicalmapofWutaishanarea.ThemapshowsthefieldoccurrencesoftheFupingComplex,Wutaicomplex,HutuoGroup,andPrecambriangranites.SamplelocalitiesfortheWutaiComplex,HutuoGroupandPrecambriangranitesarelabelled.39°1O’—39°OO’—38°50’38°40113°OO’LEGEND0QuaternaryPzPaleozoicZSinlanHutuoGroupWutaiComplex:EW3 FupingComplexgranltoidsofp€IfaultAsamplelocality1rJI(I_jIIIIIIIIIIIIIIIFuping Complex is exposed in Taihangshan region, along theboundary of Hebei and Shanxi Provinces (Fig. 4-1). It containsgrey—gneiss, amphibolite, fine—grained gneiss, and some marbles.The early application of K-Ar dating yielded minimum agesof 2300 Ma (compiled by Liu et al., 1985). Liu et al. (1985)reported zircon U—Pb isotopic analyses of six pink euhedralzircon fractions from a paragneiss sample which define(excluding one analysis) an upper intercept age of 2474 +1- 20Ma. This was interpreted by the authors as a metamorphic age.Sub—rounded, brownish and colourless detrital zircon fractionsfrom a similar paragneiss yielded an upper intercept age of 2800+1- Ma. Thus a 2800 Ma maximum age for the Fuping Complex wasassigned by Liu et al. (1985). However, based on the same data,Bai (1986) assigned a minimum age of 2.7 to 2.9 Ga to the FupingComplex by inferring the possibility of an igneous origin forthe “detrital zircon” of Liu et al. (1985).Wutai Complex:The Wutai Complex is mainly composed of medium—grademetavolcanic rocks and has been considered as an Archeangreenstone belt (Bai, 1986). It can be mapped as W-l, W-2 andW-3, according to the metamorphic grades (Fig. 4—2). The W-lconsists of amphibolite and fine-grained gneiss of medium P andT amphibolite facies. The W-2 consists of rocks of greenschistfacies, such as sericite— and chlorite— quartz schists,magnetite quartzite and locally marble. From the previous fieldand petrochemical studies, two volcanic cycles are recognized117in this subdivision (a lower W-2a and an upper W-2b). The W-3mainly consists of quartzite and metaturbidite of subgreenschistfacies.K-Ar dates for the Wutai Complex are mainly between 1400and 2000 Ma, with the highest value being 2300 Ma (Bai, 1986).Rb-Sr isochron dates of 1.8 Ga, 2.1—2.3 Ga and 2.5 Ga have beenreported (Bai, 1986). Liu et al. (1985) reported a 2522 +/—Ma upper intercept date for pink euhedral zircon fractions ofa felsic metavolcanic rock (keratophyre) from W—2 andinterpreted this as a volcanic crystallization age. They alsoreported 2508 +/— 2 Ma for purple zircon fractions from aquartofeldspathic fine grained gneiss from the Wutai Complex (W1) and interpreted it as a metamorphic age.Previous work indicated that one unconformity is locatedbetween the Fuping and “Longquanguan Group”, and one between the“Longquanguan” and Wutai Complex. The “Longquanguan Group”consists of augen—gneisses of the same composition as the FupingComplex. New field observation revealed that the “LongquanguanGroup” is a shear zone1. In such a case, the two unconformitiesneed to be reexamined, they may be merely structural contactsor zones of rapid changes in ductility. Further careful fieldwork is needed to settle uncertainties about the tectonicsettings of Fuping and Wutai Complexes and the tectonic historyof the region.1Field observation was made during sampling by Mm Sun, KaiyiWang and Ruqi Liu.118Hutuo Group:The Hutuo Group is composed of low—grade inetasedimentaryrocks, including inetaconglomerate, quartzite, phyllite, slate,dolomitic marble, and a small amount of metavolcanic rocks. K—Ar dates for the Hutuo Group are between 1250 and 1850 Ma, witha maximum of 1928 Ma (Bai, 1986). One Rb-Sr whole rock date of1851 Ma was reported by Bai (1986). Wu et al. (1986) reportedan upper intercept age of 2366 +/- Ma for zircon fractionsfrom metabasalts of the lower part of Hutuo Group. Theyinterpreted this age as the maximum formation age of the HutuoGroup. However, it is difficult to exclude the possibility thatthese zircons are of metamorphic origin.Granitic intrusions:In the Wutaishan and Taihangshan region Precambriangranitic intrusions are widely distributed. Liu et al. (1985)analyzed zircon fractions from the Lanzishan Granite, andobtained a 2560 +/— 6 Ma upper intercept age. Their fieldobservation confirmed that the Lanzishan Granite intrudes theFuping Complex and is unconforinably overlain by the WutaiComplex. They inferred 2560 Ma as the minimum age of the FupingComplex and the maximum age of the Wutai Complex. However, Bai(1986) argued that this intrusion is unconformably overlain bythe Hutuo Group and implied that the Wutai Complex is older than2560 Ma. But they did not make any direct observation of therelation between Wutai Complex and Lanzishan Granite.119Field observation indicates that the Wutai Complex isintruded by many granitic bodies, including the Shifo, Chechang,Wangjiahui and Ekou granites. Some of these granitic bodieshave also been dated by U-Pb zircons: Shifo Granite yielded a2507+!- Ma upper intercept age (Bai, 1986), Ekou Graniteyielded a 2520 +/- 30 Ma upper intercept age (Liu et al., 1985).In summary, previous geochronological studies generallyagree on an Archean age for both Fuping and Wutai Complexes andan early Proterozoic age for the Hutuo Group.In this area, there are also some younger Precambriangranitic bodies and mafic dykes intruding the Hutuo Group. Thesegranites can be chemically distinguished from 2.5 Ga granitesby higher total alkali and higher K20/Na ratio. One graniticbody, Fengkuangshan Granite, yields a K-Ar biotite date of 1810+1— 29 Ma (Bai, 1986). 1.9 Ga was assigned to the LuliangMovement corresponding to metamorphism and deformation of theHutuo Group (Bai, 1986). Mesozoic granitic intrusions ofYanshanian and Cenozoic plateau basalts are the only youngermagmatic units in this area.IV-2. Petrochemistry of samples from the WutaishanTaihangshan regionThe results of major and trace element analyses for 46samples from the Wutaishan and Taihangshan area are presentedin Tables 4—1 and 4—2. Immobile elements have been givenspecial attention in this study.(1). Metabasic samples120Table 4-1. Major element analyses for samples from the Wutaishan and Taihangshan region(recalculated to 100% volatile free)*+Sample Si02 TiC2 A1203 Fe203(as EFe) MnO MgO CaC Na20 K20 P205 L.O.I.Shifo Granite05405769.6 0.39 14.0 4.4 0.08 2.09 1.78 3.72 3.8470.3 0.34 13.8 3.5 0.07 1.47 2.51 3.62 4.320.11 0.650.10 0.82Fuping ComplexF1-3 60.0 0.75 14.5 7.7 0.13 4.96 6.42 3.63 1.64 0.25 0.32F2-2 48.8 1.27 14.6 14.4 0.23 5.95 10.36 2.92 1.32 0.16 0.53F4-2 48.5 1.00 15.0 13.2 0.24 6.67 11.18 2.84 1.23 0.10 0.65F4-3 48.8 0.99 14.6 13.9 0.23 6.37 10.72 3.08 1.20 0.10 0.52F6-1 74.0 0.09 13.5 1.6 0.06 0.17 1.99 3.47 5.13 0.06 0.21F6-3 73.0 0.12 13.8 1.9 0.05 0.36 2.00 3.40 5.31 0.06 0.25F6-4 73.6 0.13 13.5 1.7 0.04 0.26 1.83 3.36 5.50 0.05 0.25F6-5 72.0 0.28 13.9 2.8 0.05 0.73 2.42 3.76 3.92 0.11 0.29Wutai Complex (W-1)W84-1 50.1 1.28 15.3 13.3 0.20 6.35 9.66 3.38 0.25 0.10 0.33W84-4 53.2 1.08 19.1 8.9 0.18 3.35 11.60 1.97 0.47 0.20 1.65W84-51(felsic) 44.0 0.53 21.2 9.5 0.28 3.35 18.73 1.73 0.60 0.07 1.86W84-52(mafic) 49.8 0.60 20.4 9.1 0.21 4.76 11.88 3.06 0.22 0.04 0.36W84-7 49.7 1.03 15.1 13.7 0.22 6.29 11.14 2.11 0.58 0.12 2.47W84-8 53.3 0.60 20.7 7.6 0.11 3.26 9.74 3.52 1.02 0.23 0.78W84-9 65.4 0.63 15.4 6.0 0.09 1.86 4.73 3.76 1.87 0.22 1.25Wutai Complex (W-2a)W82-4 50.2 1.06 17.0 13.0 0.19 6.16 9.64 2.53 0.13 0.09 6.01W82-5 52.0 0.93 14.7 13.0 0.23 6.54 10.89 1.49 0.10 0.07 2.87W82-7 50.4 0.97 15.8 13.4 0.20 6.83 9.75 2.44 0.18 0.08 3.13W82-9 48.8 0.97 15.2 12.0 0.23 5.17 14.84 2.53 0.14 0.08 8.91Wutai Complex (W-2b)W81-1 63.6 0.54 16.5 7.9 0.04 8.64 0.37 0.0 2.33 0.08 5.15W81-2 64.9 0.55 15.7 7.3 0.06 6.27 1.21 3.05 0.80 0.14 4.30W81-6 59.3 0.73 18.2 7.4 0.10 3.64 5.05 4.47 0.89 0.19 3.24W81-7 55.3 1.17 16.7 10.0 0.16 3.24 9.37 3.22 0.67 0.17 5.94W81-8 55.3 0.79 17.4 8.7 0.13 6.75 6.11 4.48 0.15 0.13 5.13W81-11 52.3 0.90 18.4 11.0 0.13 5.26 8.91 2.09 0.87 0.16 2.32Wutai Complex (W-3)W85-2 46.5 1.10 18.0 12.8 0.18 7.11 11.44 2.34 0.40 0.09 0.93W85-4 48.0 1.11 17.6 11.5 0.19 6.53 12.85 1.75 0.41 0.10 0.67W85-6 48.6 1.03 17.4 12.0 0.17 7.14 10.74 2.54 0.30 0.09 0.88W85-8 48.1 1.10 17.4 11.6 0.18 7.29 11.23 2.68 0.32 0.10 0.56Hutuo GroupH-003 47.1 1.81 19.4 14.1 0.06 9.93 2.57 4.03 0.73 0.32 6.031-004 49.3 2.00 17.9 13.4 0.13 8.06 4.95 3.33 0.52 0.35 6.20H-007 50.0 1.76 18.4 13.9 0.09 10.22 2.31 2.60 0.48 0.31 5.55H-014 50.4 1.61 17.0 15.7 0.17 9.10 1.80 3.48 0.32 0.40 4.64H-017 51.5 1.61 17.6 12.6 0.18 7.56 3.07 5.17 0.32 0.40 3.91Lanzishan Granite076 73.6 0.21 13.5 2.1 0.04 0.31 1.39 3.80 4.99 0.07 0.38077 73.7 0.23 13.4 2.3 0.04 0.36 1.42 3.80 4.69 0.08 0.38078 73.7 0.19 13.5 2.1 0.04 0.26 1.39 3.93 4.80 0.06 0.31080 73.4 0.23 13.4 2.3 0.03 0.32 1.45 3.83 4.89 0.07 0.37121continuedChechang Granite083-1 73.9 0.23 13.5 3.0 0.05 0.63 2.25 4.73 1.62 0.07 1.27083-2 72.1 0.26 14.5 3.0 0.06 0.63 3.15 4.52 1.73 0.08 0.73083-4 72.8 0.26 14.2 2.7 0.03 0.85 2.53 5.24 1.35 0.08 1.004angjiahui Granite087-2 72.7 0.45 12.8 3.3 0.03 0.45 1.53 3.74 4.84 0.14 0.41087-3 72.0 0.45 12.8 3.6 0.03 0.45 1.64 3.70 5.18 0.13 0.35087-4 73.3 0.43 12.5 3.0 0.03 0.47 1.49 3.58 5.09 0.12 0.40* All major element analyses are by a Philips PW-1400 XRF spectrometer, on ground fused glasspellets (Michael and Russell, 1989), reported in wt%.Estimated accuracy (1 a) from duplicated runs: Si02, 1%; K20, Ti02, 2%; Fe203, 7%; A1203,MgO, CaD, Na20, 5%; MnO, P205, ±0.01.+ L.0.I. = weight loss between 120 and 900°C.122Table 4-2W Trace element concentrations (in ppm) for samplesfrom the Wutaishan and Taihangshan region*Ba Cr Nb Ni Rb Sr V Y ZrERROR (1) 7 8 1 5 1 6 37 1 3Wutai Complex (U-i)W84-i 114 170W84-4 55 268W84-51(felsic) 134 384W84-52(mafic) 52 472W84-7 228 176W84-8 578 211W84-9 708 154Wutai Complex (W-2a)U82-4 8 227U82-5 13 30W82-7 14 198W82-9 20 208Wutai Complex (W-2b)W81-1 435 561W81-2 175 70W81-6 237 73W81-7 67 26W81-8 8 293W81-11 250 122Wutai Complex (14-3)W85-2 118 172W85-4 111 173W85-6 78 171W85-8 96 160Hutuo GroupH -003H -004H-007H-014H-017360 90297 93228 9130 5846 565 74 7 136 235 26 728 229 19 189 129 23 925 228 41 262 149 13 315 299 6 175 171 15 275 76 10 164 182 24 825 71 26 1016 114 13 1117 58 52 501 94 17 1424 108 5 101 219 253 70 0 100 177 214 96 2 76 188 225 93 3 113 172 193 139 59 21 134 6 684 82 25 72 71 7 1045 76 21 364 100 16 1116 20 23 368 159 23 1175 199 3 351 118 16 915 168 34 471 148 22 1035 176 10 299 164 20 824 185 8 332 162 18 835 174 5 284 168 16 745 167 4 311 166 17 84Lanzishan Granite076 555 19077 532 17078 399 19080 516 209 31 271 15710 25 197 17712 24 314 1218 19 244 15819 8 13720 10 15212 9 12017 10 134Shifo Granite054057601 132 9 43 180 176796 130 8 51 170 35250 9 14743 12 121Fuping ComplexF1-3 345 320 6 147 63 496 97 14 121F2-2 165 93 6 40 19 134 247 26 110F4-2 63 153 4 57 20 173 179 20 69F4-3 70 141 5 57 18 164 183 19 65F6-1 1181 10 4 0 157 373 26 4 164F6-3 1044 18 3 1 163 360 25 3 154F6-4 1101 16 4 1 159 279 24 3 145F6-5 875 31 5 10 133 369 41 7 185595352579 134 9 64 214 23 14811 126 6 172 210 21 15710 119 5 44 222 21 1447 100 3 24 234 26 1418 103 5 40 231 26 135123cant i nuedChechang Granite083-1 383 20 6 29 49 238 15 6 106083-2 452 17 4 25 43 287 25 7 114083-4 244 34 4 34 37 338 18 3 94Uangjiahui Granite087-2 825 8 21 17 259 223 43 32 270087-3 846 13 21 27 255 236 34 27 257087-4 724 13 18 16 247 189 35 23 219* All trace element analyses are by a Philips PW-1400 XRF spectrometer,on pressed powder pellets (Armstrong and Nixon, 1980).+ Estimated from scatter of standards about working curve.124Essential Classification:One amphibolite from the Fuping Complex, one amphibolitefrom the Wutai Complex (W—l) and three greenschists from thebottom cycle of W—2 have andesitic compositions. All the otherinetabasic samples from the region are basaltic. Major elementdata indicate that these samples mostly have the chemicalsignature of subalkaline rocks (Fig. 4-3 and 4-4). Theexceptions are that one greenschist from the Hutuo Group is inthe alkaline field on an alkali-Si02 plot, and that twoamphibolites from the Fuping Complex, one felsic sample from W1 and one greenschist from W-2a plot in the alkaline field inOl’-N&-Q’ plot. Amphibolites of the Fuping Complex and themetabasalts of the Hutuo Group have higher alkali than the WutaiComplex. The greenschists from W-2b have the highest totalalkali content in the Wutai Complex (Fig. 4-5) and thus the namemetaspilite was given by some previous workers (e.g. Li et al.,1988). K20/Na ratio of metabasic rocks generally decreases fromthe Fuping Complex to the Hutuo Group with a minimum at W-2a(Fig. 4—5). Trace elements show a subalkaline character for allthe metabasic samples from the region, e.g. Y/Nb > 1.The few samples that are in alkaline fields can betentatively explained as due to the mobility of alkali elementsin metamorphic processes. We consider that the metabasic samplesfrom the region are essentially subalkaline.The Fuping amphibolites plot in the tholeiitic field inA1203 -normative plagioclase plot (Fig. 4-6a), but are in boththoleiitic and calc-alkaline fields in AFM diagram (Fig. 4-7).125I I I0- - $8- --*7- --Alkaline Subalkaiinex0- * Fuping-x Wutaj (W—1) o•Wutaj (W—2a)4- - OWutaj ?w-2b) * o o+ AWutaj W-3)o ‘HutuoCQ 3 -0A2- --.1--U- I I30 40 50 60 70 80Si02 wt%Figure 4-3. Total alkali - Si02 plot showing thatmetavolcanic samples fall in the subalkaline field with oneexception from the Hutuo Group. The dividing line is from Irvineand Baragar (1971).12601’Q,01’ 01’Q’ Ne’ Q’Fuping ComplexFigure 4-4. Ol’-Ne’-Q’ plot showing that most metavolcanicsamples fall in the subalkaline field. The dividing line is fromIrvine and Baragar (1971). Ol’=Ol+3/4Opx, Ne’=Ne+3/5Ab,Q’=Q+2/5Ab+l/4Opx, cation norms.‘Wutaj W—1)• Wutai W—2ao Wutal W—2bA Wutai W—3)AbWutai ComplexLb LbHutuo Group1270.6C0.3ZC0.0Figure 4-5. Average total alkali and K20/Na values ofmetavolcanic rocks from Fuping Complex, Wutai Complex, and HutuoGroup, all in wt%.Fupng W-1 W-2& W-Zb W-3 Hutuo1280,C—(a)25200,CC’21510100 60 60 40 20CompositionNormative Plagioclase(b)0Wutai Complexxxx25201510xWutaj W—1)• Wutaj W—2ao Wulai W—2bAWutaj W.-3)0A 000x 0Caic—alk100 60 60 40 20Normative Plagioclase Composition01292520C1510100(c)Figure 4-6. AlgO3 - Plagioclase plot for rnetavolcanicsamples from (a) Fuping Complex, (b) Wutai Complex, and (c)Hutuo Group. The dividing line is from Irvine and Baragar(1971)80 60 40 20 0Normative Plagioclase Composition130FA MF FA MA MFuping ComplexFigure 4-7. AFM plot for metavolcanic samples from FupingComplex, Wutai Complex, and Hutuo Group. The dividing line isfrom Irvine and Baragar (1971). A=K20+Na, FEFeO, and M=MgO,all in wt%.Wutai ComplexHutuo Group131The amphibolites from W-l plot mainly in the calc-al]calinefield in A1203 - normative plagioclase plot (Fig. 4-6b), but arein both tholeiitic and calc-alkaline fields in AFM diagram (Fig.4-7). The greenschists from W-2a plot mainly in tholeiitic fieldand those from W-2b mainly in the calc-alkaline field in bothAl203 - normative plagioclase and AFM diagrams (Fig. 4-6b and 4-7). The xnetabasalts from W-3 mainly are in the caic-alkalinefield in A1203 - normative plagioclase plot (Fig. 4-6b), but incontrast fall in the tholeiitic field of the AFM diagram (Fig.4—7)Metabasaltic samples from the Hutuo Group plot in the caicalkaline field in Al203 - normative plagioclase diagram, but mostsamples, in contrast, are in the tholeiitic field in AFM diagram(Fig. 4-6c and 4—7).In summary, Fuping amphibolites are more tholeiitic thancalc—alkaline. The greenschists samples from W—l have more calc—alkaline than tholeiitic character. The greenschists from W-2show a tholeiitic signature in the bottom cycle (W-2a) and acalc-alkaline character in the upper cycle (W-2b). Themetabasaltic samples from W-3 and from the Hutuo Group fall inthe contradictory fields in the two different plots (Table 4-3)Tectonic Discriminant Plots:All the metatholeiitic samples from the Fuping and theWutai complexes plot in the IAT field in a FeO*/MgO- Ti02diagram (Fig. 4—8).132Table 4-3. Sunlnary of discrimination test for metavolcanic rocksSubalk 4-Subalk1-AikSubalk SubalkSubalk Subalk3-CAB CAB1-boundaryCAB+TholThol 3-Thol2-CABboundary MORBIAT+MORB near CIBC+L C+LLKT 1-LKT4-CABCAB- IAT WPB1-(V+M) 3-WPB3-bound. 2-bound.MORB+WPB MORB+WPBnon-WPB boundary WPBWPB+non-WPBnon-WPB boundary WPBWPB+non-WPBCAB boundary N/ALKT+CABW-1 W-2a W-2b W-3 HutuoDiagrams FupingAlk-Si02 Subalk SubalkOt’-Ne1-Q 6-Subalk 6-Subalk2-Alk 1-AlkY/Nb Subalk SubalkA1203-Plag Thol(am.) 2-TholCAB(geiss) 5-CABAFM Thol & CAB(am.) 4-TholCAB(gneiss) 3-CABFeD /MgO-Ti02 IAT IATF2-F1 CAB+LKT 5-(C+L)(C+L) 1-WPBF3-F2 LKT 2-LKT4-CABSpider CAB- IAT CAB- IATdiagramTi/Y-Nb/Y VAB+MORB 3-MDRB(V+M) 3-(V+M)Subalk Subalk3-Subalk Subalk1-AlkSubalk Subalk3-Thol 1-Thol1-CAB 5-CABTho 3-Thot3-CABIAT N/AC+L C+LLKT 4-CAB1-outMORB CAB-IATV+M V+MTi/100— non-WPB non-WPB non-dPBZr - y3Zr/Y-Zr non-WPB non-WPB non-WPBTi/100-Zr- OFB 3-OFB OFBSr/2 1-CAB 2-LKT1- CABNi-Y 3-LKT 1-LKT1-MORB 5-MORBMORB N/A MORB N/A1333. - ITART’ 1C /X fr\j * Fuping2 - I * ‘ ‘oixWutai W—1)x* 1 AWutal W 3)C——-- Hutuo0 I I I0 1 2 3 4 5Ti02 wt %Figure 4-8. FeO*/MgO- TiC2 plot for TH basalts (Glassley,1974). FeC represents total iron in FeC form, all in wt%.Tholeiites can be discriminated as MORB, IAT, and OIB in thisdiagram. Metatholeiitic samples from the Fuping and the Wutaicomplexes fall in the IAT filed. Samples in MORB field are fromW—3 and the Hutuo Group, which are ambiguous in theclassification of tholeiitic and calc-alkaline series.134In F2—F1 plot, most metabasic samples from the region plotin the field of LKT+CAB (Fig. 4-9). In F3-F2 plot, Fupingamphibolites plot mainly in LKT, amphibolites from the W-lmainly in CAB, greenschists from the W-2a in LKT, greenschistsfrom the W-2b mainly in CAB, metabasaitic samples from the W-3in LKT, and the Hutuo metabasaits mainly in CAB field (Fig. 4-10)Fuping amphibolites are highly enriched in K, Rb, and Ba,slightly depleted in Ti, Y and Cr, Zr is close to 1. Two samplesshow high P and high Sm, respectively. The trace element patternis between typical caic-alkaline and typical arc thoieiiticbasaits (Fig. 4—ila).Two analyses from the same hand specimen (W84—5l and W84—52, one felsic and one mafic micro—layer) from W—1 show apattern similar to typical arc thoieiite, but with high Crvalues. Other amphibolites from the W-l behave like the Fupingamphibolites (Fig. 4—lib). The W—2a greenschists show a traceelement pattern similar to basalts formed in slow spreadingridges, such as Alula-Fartak trench, but with higher Nbconcentrations (Fig. 4-lic). The W-2b and W-3 metavolcanicsamples are similar to arc volcanics like the Fupingamphibolites (Fig. 4—lid and 4-lie).Metabasaltic samples from the Hutuo Group show the traceelement pattern of within—plate thoieiites (Fig. 4—hf).In Ti/Y — Nb/Y (Pearce, 1982) and Ti/100— Zr — *3 (Pearceand Cann, 1973) diagrams, amphibohites from the Fuping Complexand from W-l, and greenschists from W-2 plot in the fields of135—1.3* FupingxWutaj W—1)• Wutaj W-2ao Wutai W—2bAWutaj W—3)HutuoFigure 4—9. F2- F1 plot for basaltic rocks (Pearce, 1976).Most metabasaltic samples from the study region plot in thefield of CAB+LKT. F1 = O.OO88SiO2 — O.O774TiO2 + O.0102A123 +O.OO66FeO — O.OOl7MgO— O.O143CaO — O.0l55Na— O.0007K0, F2 =—O.Ol3OSiO2 — O.O185TiO2 — O.Ol29Al— O.Ol34FeO— O.OO300MgO—O.O2O4CaO — O.048lNa + 0.07151<20.—1.5—1.7136—2.3FupingxWutaj W.-1)• Wutal W—2aOWutai W—2bA Wutai W—3)HutuoFigure 4-10. F3 - F2 plot for basaltic rocks (Pearce,1976). The Fuping amphibolites, W-2a, and W-3 metabasalticsamples are in the LKT field. W-1, most W-2b, and the Hutuometabasaltic samples fall in the CAB filed. F3 = -0.022lSiO2 -O.O532TiO2 — O.036A123— 0.OOl6FeO — 0.O3lOMgO — 0.0237CaO —O.O6l4Na — 0.02891<20.—2.5 -—2.7- ——1.7 —1.5F2—1.3137p I-I-Rock/MORD00 0p I-Rock/MORBI-0I C CHI— CD CD H H H C) 0 H ‘p. Ctj pa pa CD N ‘1 C,) (12 C,(j2 pa CD (I) (12 C, C, ‘1Rock/MORBRock/MORBPI-0I-’0•00000I111111II111111IIIIII1111111ICD (n I--H H C)OHI0-0-H_HI-NN-(_)-Cd)ICd)Cf oCl)Cl)HC)C)C)C)C-IIIIIIIinutIIII?)II_______10010C0C0.110010C0C0.1(e)(f)Figure 4-ha to hf: trace element plots (spider diagrams)for metavolcanic rocks from Fuping Complex, Wutai Complex (foursubdivisions), and Hutuo Group.Sr KRb BaTh TaNbCe P ZrHf SmTI Y YbScCrSr KRb BaTh TaNbCe P ZrHf SmTi Y YbScCr140non-WPB. Metabasalts from the W-3 plot near to the boundary ofWPB and non-WPB. The Hutuo metabasaltic samples mostly plot inthe WPB field (Fig. 4-12 and 4-13).In a Zr/Y - Zr plot (Pearce and Norry, 1979), the Fupingamphibolites are in both WPB and non-WPB fields. Amphibolitesfrom the W-l mainly fall in the non-WPB field. Greenschists fromthe W-2a plot in the non-WPB field. Two greenschists from W-2bfall in the WPB field and other 4 out of the fields defined bythe original paper. Metabasalts from the W-3 plot near to theboundary of WPB and non-WPB and some out of the original fields.The Hutuo metabasalts plot in the WPB field (Fig. 4—14).Ti/lOO — Zr — Sr/2 (Pearce and Cann, 1973) and Ni— Y(Capedri et al., 1980) have been suggested for the furtherdiscrimination of non-WPB. The meta-WPB from Hutuo Group arealso plotted for comparison although not discussed below. In aTi/lOO - Zr - Sr/2 diagram, most Fuping amphibolites plot in theOFB field. Amphibolites from the W-1 plot in the OFB, CAB, andLKT fields. Greenschists from the W-2a fall in the OFB field,those from the W-2b mainly in the CAB field. Metabasalticsamples from the W-3 plot near to the boundary of OFB and CAB(Fig. 4—15)In Ni - Y diagram, most Fuping amphibolites plot in the LKTfield. Amphibolites from the W-1 mainly plot in MORB field.Greenschists from the W-2a plot in the MORB field, those fromthe W-2b in both LKT and MORB. Metabasalts from the W-3 fall inthe NORB field (Fig. 4-16).1411000100Figure 4-12. Ti/Y - Nb/Y plot for tholeiitic and alkalinebasalts (Pearce, 1982). Fields are divided into subalkaline,transitional, and alkaline mainly according to Nb/Y ratios. WPBcan be easily discriminated from the non-WPB that includes VABand MORB. But VAB and MORB fields largely overlap. Theamphibolites from the Fuping Complex and Wutai Complex (W-l),greerischists from W—2a are rion—WPB. W—3 metabasalts areambiguous. The metabasaltic samples from the Hutuo Group areWPB. All the inetabasic samples are subal]caline, in accord withmajor element plots.Nb/Y142Ti/100Figure 4—13. Ti/100 - Zr - *3 plot for basaltic rocks(Pearce and Cann, 1973). WPB plots uniquely in the field D, thuscan be discriminated from non-WPB. The amphibolitesfrom theFuping Complex and the Wutai Complex (W-l), greenschists fromthe W-2a and W—2b mostly in non-WPB fields. W—3 metabasalts plotnear to the boundary of WPB and non-WPB. The metabasalticsamples from the Hutuo Group fall in the WPB field.* FupingxWutaj W—i)•Wutai W-2ao Wutai W—2bA Wutaj W—3)A Hutuo14310-1-10 1000Figure 4-14. Zr/Y - Zr plot for basaltic rocks (Pearce andNorry, 1979). WPB can be distinguished from non-WPB, but thefields of MORB and lAB partly overlap. The Fuping amphibolitesplot in both WPB and non-WPB fields. Most W-l, and W-2a fall innon—WPB field. Two W-2b metavolcanic samples plot in WPB field,and other one out of the fields defined by the original paper.W—3 metavolcanic samples fall near to the boundary of WPB andnon—WPB, and some out of the original fields. The metavolcanicsamples from the Hutuo Group fall in the WPB field.* FupingxWutaj W—I)• Wutaj W-2ao Wutaj W—2bAWutaj W-3)Hutuo100Zr ppm144Ti/100Figure 4—15. Ti/100 - Zr - Sr/2 plot for non-WPB basalts(Pearce and Cann, 1973). Basalts formed in non—WP settings canbe easily distinguished, but subject to much uncertainty becauseof Sr mobility in metamorphic rocks. LKT plots in field A, CABin field B, and OFB in field C. Most Fuping amphibolites plotin the OFB field. W-1 aTnphibolites plot in OFB, CAB, and LKTfield, greenschists from the W-2a fall in the OFB field andthose of W-2b in CAB field, W-3 metavolcanic samples near to theboundary of OFB and CAB.* FupingxWutai W—1)• Wutaj W-2aOWutai W-2bA Wut.aj W—3)HutuoZr Sr/2145X100z10•100Figure 4-16. Ni- Y plot for TH basalts (Capedri et al.,1980). The fields are divided into MORB and LKT. The Fupingamphibolites plot in the LKT field. Most W-l amphibolites, andW-2a greenschists fall in the MORB field, W-2b greenschists inboth LKT and MORB fields, W-3 metabasalts in the MORB field.X XX XX** Fupmg gnex Wutai (W— 1)• Wutai (W—2a)A Wutai (W—3)LKT10Yppm146In summary (Table 4-3), the amphibolites from the FupingComplex and the Wutai Complex (W-l), and greenschists from theupper cycle of the W—2 show the character of island arctholeiites, but less commonly show a MORB-like signature. Thegreenschists from the lower cycle of the W-2 fall in MORB fieldin trace element plots but in contrast fall in the island arctholeiite field in major element plots. Metabasaltic samplesfrom W-3 plot ambiguously between WPB and non-WPB, with a slightaffinity to low—K tholeiites. Metabasaltic samples from theHutuo Group uniquely plot in the WPB field. Geochemistry clearlyindicates that metavolcanic samples from the Wutai and Taihangregion formed in a succession of different tectonicenvironments.(2) . Gneisses and granitesGneisses from the Fuping Complex and all the graniticbodies that we have analyzed are subalkaline, with a calc—alkaline character. Calculated discriminant function of Shaw(1972) indicates an igneous parentage for the Fuping gneiss.The Fuping gneiss and the Lanzishan, Wangjiahui and Shifogranites plot in the granite field, while the Chechang Graniteplots in trondhjemite and tonalite fields in normative An-Ab-Ordiagram (Fig. 4-17). These granites are I-type granitesaccording to their chemistry.In Rb - (Y+Nb) diagram, the Chechang trondhjemite—tonalitefalls in the VAG field, the Wangjiahui Granite plots on theboundary of VAG and WPG, the Lanzishan Granite on the VAG synCOLG boundary and the Shifo Granite nearby, just inside VAG147AnAb OrFigure 4-17. An - Ab- Or plot for some Precambriangranites from the Wutaishan and Taihangshan region. The dividinglines are from O’Connor (1965).* Fupuig gneseC) Lauzishan GraniteA Shifo GraniteC Chechang GraniteWangjiahui Granite148(Fig. 4—18)IV—3. Isotopic resultsRb—Sr isotopic results for samples from the Wutaishan andTaihangshan areas are represented in Table 4—4. Sm—Nd isotopicresults are in Table 4-5. Pb isotopic results are in Table 4-6.Our Rb-Sr, Sm-Nd, and Pb-Pb isochron dates, and published U-Pbzircon dates are summarized in Table 4—7.Fuping Complex:Two amphibolites and three gneisses are scattered in theRb-Sr isochron plot (Fig. 4-19). The poorly defined isochrondate is 2.3 +/— 0.4 Ga, with (87Sr/6)0 = 0.7036 +/— 0.0029.Three amphibolites and two gneisses define a straight line inthe Sm-Nd plot (Fig. 4-20). The isochron date is 2.37 +/- 0.07Ga with(143Nd/’4 )0 = 0.50963 +/— 0.00005 or ENd(T) = 1.5±0.9(Fletcher and Rosman, 1982). Nd depleted mantle model dates foraxnphibolites are 2.48 to 2.60 Ga, and those for gneisses are2.43 to 2.46 Ga. Three arnphibolites and three gneisses definea Pb-Pb isochron of 2.2 +/- 0.2 Ga with a first stage growth= 7.73, largely controlled by one sample (Fig. 4—21).Wutai Complex:All metavolcanic samples from the Wutai Complex define aRb—Sr isochron of 2.0 +/— 0.1 Ga with(87Sr/6)0 = 0.7025 +/—0.0002 (Fig. 4-22) but with large scatter about the line (MSWD= 72). Seven amphibolites from the Wutai Complex (W-l) alonedefine an isochron of 2.4 +/- 0.4 Ga with(87Sr/6)0 = 0.7021+1— 0.0008.149I p 11119 I 11111111 111111Syn—COLGWPGoVAG ORG1- I I IIIII I I1 10 100 1000Figure 4-18. Rb- (Y+Nb) plot for somegranites from the Wutaishan and Taihangshan region.lines are from Pearce et al. (1984).150PrecambrianThe dividing1000.10010o Ian2ihan Granite* Shifo GraniteChechanj GraniteWangJiahui GraniteY+Nb (ppm)Table 4-4. Rb-Sr isotopic data for whole rock samplesfrom the Wutaishan and Taihangshan regionSample Rb ppm Sr ppm 87Rb/6Sr 87sri6 eNd(O)Fuping ComplexF1-3 63.35 496.26 0.3695 0.71305 121. 2.1±0.00007 1. 0.2F4-2 19.62 173.81 0.3268 0.71529 153. 3.0±0.00002 0. 0.2F4-3 20.99 161.19 0.3772 0.71916 208. 3.3±0.00001 0. 0.2F6-1 147.75 348.92 1.2291 0.74116 520. 2.3±0.00072 10. 0.8F6-4 155.68 278.66 1.6245 0.75934 778. 2.5±0.00001 0. 0.6Wutai Complex (U-i)W84-1 4.19 128.94 0.0939 0.70479 4. 2.3±0.00019 3. 0.2W84-2 2.43 132.93 0.0531 0.70357 -13. 2.6±0.00005 1. 0.2W84-3 4.71 132.54 0.1028 0.70497 7. 2.2±0.00006 1. 0.2W84-4 20.24 197.96 0.2960 0.70966 73. 1.8±0.00005 1. 0.4W84-52 6.79 168.43 0.1166 0.70689 34. 3.4±0.00012 2. 0.2U84-7 10.55 169.70 0.1788 0.70879 61. 2.9±0.00016 2. 0.2W84-8 27.23 1028.54 0.0766 0.70562 16. 4.1±0.00007 1. 0.2W84-9 55.98 490.23 0.3306 0.71465 144. 2.8±0.00006 1. 0.2Wutal Complex (W-2a)W82-4 2.76 113.91 0.0701 0.70374 -11. 1.8±0.00008 1. 0.2W82-5 2.83 89.38 0.0916 0.70658 30. 4.2±0.00040 6. 0.4W82-7 1.36 73.33 0.0536 0.70366 -12. 2.8±0.00018 3. 0.4W82-9 4.05 133.24 0.0880 0.70610 23. 3.9±0.00005 1. 0.1Wutai Complex (W-2b)W81-1 54.99 23.66 6.8000 0.89691 2731. 2.0±0.00006 1. 3.4W81-2 24.82 73.64 0.9773 0.73161 385. 2.2±0.00006 1. 0.4W81-3 3.97 60.27 0.1906 0.70745 42. 2.1±0.00017 2. 0.2W81-6 24.16 380.91 0.1836 0.70705 36. 2.0±0.00009 1. 0.1W81-7 28.55 362.98 0.2275 0.70881 61. 2.2±0.00002 0. 0.2W81-8 4.80 472.40 0.0294 0.70438 -2. 8.2±0.00005 1. 0.1U81-11 33.39 471.12 0.2050 0.70773 46. 2.0±0.00007 1. 0.2W81-15 28.39 239.25 0.3434 0.71308 122. 2.3±0.00010 1. 0.2151continued4utai Complex (W-3)W85-1 6.62 302.07 0.0634 0.70440 -1. 3.4±0.00005 1. 0.2W85-2 10.06 231.45 0.1257 0.70497 7. 1.7±0.00007 1. 0.1J85-3 3.25 309.09 0.0305 0.70327 -17. 5.5±0.00004 1. 0.2W85-4 8.72 379.27 0.0665 0.70522 10. 4.4±0.00003 1. 0.1W85-6 3.11 308.68 0.0291 0.70328 -17. 5.8±0.00003 1. 0.2w85-7 9.41 307.72 0.0886 0.70486 5. 2.6±0.00003 1. 0.1W85-8 4.00 231.50 0.0500 0.70380 -10. 3.5±0.00022 3. 0.6Hutuo GroupH-003 8.54 59.79 0.4135 0.71292 120. 1.9±0.00028 4. 0.4H-004 6.82 170.32 0.1159 0.70572 17. 2.5±0.00014 2. 0.2H-014 3.53 28.57 0.3574 0.71767 187. 3.2±0.00006 1. 0.4H-017 6.87 53.13 0.3744 0.71728 181. 3.0±0.00013 2. 0.2Lanzishan Granite076 274.72 161.66 5.0039 0.88848 2612. 2.6±0.00005 1. 2.4077 191.23 269.27 2.0696 0.78185 1098. 2.7±0.00015 2. 1.0078 296.25 155.11 5.6356 0.91017 2919. 2.6±0.00013 2. 1.0079 225.18 125.19 5.3059 0.89718 2735. 2.6±0.00019 3. 1.1080 236.50 160.66 4.3212 0.86033 2212. 2.6±0.00019 3. 1.2Chechang Granite083-1 41.25 219.48 0.5445 0.71973 216. 2.3±0.00007 1. 0.2083-2 43.42 232.70 0.5410 0.71677 174. 1.9±0.00001 4. 0.6083-3 43.81 265.41 0.4780 0.71857 200. 2.5±0.00008 1. 0.2083-4 33.82 357.18 0.2740 0.71044 84. 2.2±0.00007 1. 0.2Wangjiahui Granite087-1 218.18 214.38 2.9690 0.79264 1251. 2.2±0.00006 1. 1.4087-2 242.86 218.00 3.2542 0.80620 1444. 2.3±0.00014 2. 1.4087-3 239.27 250.78 2.7819 0.78723 1174. 2.2±0.00005 1. 1.4+ 2u errors are listed in the table, 0.026% and 2% were used for87Sr/6r and 87RbI6Sr in the regression calculation.* TOM: depleted mantle model date of DePaolo (1981), the followingconstants have been used in the calculation: 87Rb/6Sr)UR=0.0827,(87SrI6r)R0.7045, 7Rb00142 AE1.152Table 4-5. Sm-Nd isotopic data for whole rock samplesfrom the Wutaishan and Taihangshan regionSample Sm ppm Nd ppm 147Sm/4Nd 143Nd/4 eNd(0) TOMFuping ComplexF1-3 5.558 29.94 0.1120 0.511317 -25.5 2.59±0.000008 0.2 0.02F4-2 2.597 9.35 0.1678 0.512257 -7.2 2.60±0.000016 0.3 0.06F4-3 2.717 10.05 0.1633 0.512219 -7.9 2.48±0.000012 0.2 0.04F6-1 2.665 27.02 0.0595 0.510586 -39.8 2.43±0.000012 0.2 0.08F6-4 1.962 18.94 0.0625 0.510604 -39.4 2.46±0.000016 0.3 0.08Wutai Complex (W-1)W84-1 3.254 9.33 0.2106 0.512900 5.3 --±0.000040 0.8--W84-4 3.094 11.92 0.1567 0.512052 -11.2 2.65±0.000020 0.4 0.10W84-7 2.509 9.80 0.1546 0.511994 -12.3 2.71±0.000006 0.1 0.96W84-8 5.470 28.76 0.1148 0.511524 -21.5 2.33±0.000016 0.3 0.08Wutai Complex (W2b)#W81-6 3.989 20.40 0.1180 0.511462 -22.7 2.51±0.000010 0.2 0.08W81-15 3.545 13.63 0.1570 0.512114 -10.0 2.48±0.000008 0.2 0.16Wutai Complex (W-3)W85-1 3.682 12.63 0.1760 0.512329 -5.8 2.91±0.000008 0.2 0.26W85-2 3.566 12.49 0.1724 0.512356 -5.3 2.52±0.000006 0.1 0.32Hutuo GroupH-003 5.133 23.38 0.1325 0.511799 -16.1 2.32±0.000006 0.1 0.22[1-004 7.344 32.69 0.1356 0.511837 -15.4 2.34±0.000014 0.3 0.08H-007 5.034 21.53 0.1411 0.511795 -16.2 2.62±0.000006 0.1 0.08153continuedLanzishan Granite076 2.558 19.11 0.0808 0.510813 -35.4 2.56±0.000014 0.3 0.06077 3.163 23.10 0.0826 0.510953 -32.6 2.43±0.000060 1.2 0.10078 2.988 19.41 0.0929 0.511027 -31.2 2.54±0.000008 0.2 0.02079 1.951 12.93 0.0910 0.510889 -33.9 2.68±0.000012 0.2 0.08080 4.353 33.66 0.0780 0.510803 -35.6 2.52±0.000008 0.2 0.10Chechang Granite083-4 2.133 12.01 0.1072 0.511321 -25.5 2.46±0.000016 0.3 0.36+ 146Nd,,4O 7219 has been used for normalization, 2 errors arelisted in the table, 0.005% and 1% were used for 143Nd/4 and147Sm/4Nd in the regression calculation.* TOM: depleted mantle model date of DePaolo (1981), the followingconstants have been used in the calculation: 143Nd/4d)HuR0.512626,(l47Sm/l’Nd)g=0.1967,‘147 =0.00654 AE1.Sm# Data for six additional samples of W-2 from Li et al. (1990) werealso plotted on the Sm-Nd diagram.154Table 4-6. Whole rock Pb isotopic data for samplesfrom the Wutaishan and Taihangshan regionSample 2OóPb/4Pb# 207Pb/4 208Pb/4Fuping ComplexF1-3 18.22 15.40 37.75F4-2 15.00 14.92 35.26F4-3 15.47 15.06 35.92F6-1 15.65 15.13 40.6116-3 15.71 15.10 42.35F6-4 15.34 15.03 39.85Wutai Complex (U-i)W84-1 15.59 15.07 35.44W84-4 15.60 15.01 35.04Wutai Complex (W-2a)W82-7 15.67 15.07 35.27W82-9 15.44 15.06 35.19Wutai Complex (W-2b)W81-1 21.71 15.84 40.43W81-2 30.21 17.17 50.53W81-6 17.80 15.28 37.91W81-8 18.21 15.48 37.74W81-11 17.02 15.16 36.58Wutai Complex (W-3)W85-2 17.83 15.42 36.59W85-8 17.86 15.46 37.16Hutuo GroupH-003 21.99 15.91 40.83H-004 18.79 15.52 38.35H-007 23.33 15.62 41.09H-014 18.55 15.52 39.11H-017 19.23 15.38 39.66Lanzishan Granite076 24.27 16.44 43.96077 28.67 16.96 46.63078 28.45 17.12 42.39079 28.62 16.84 46.87Chechang Granite083-1 30.16 17.00 46.39083-3 18.81 15.36 38.45083-4 23.94 16.23 43.10# The 2 errors for 206Pb/4, 207Pb/4 andare 0.10, 0.15, and 0.16%, respectively.Error correlation coefficient CR) between 206Pb/4and 207Pb/4 is 0.8. Pb standard NBS981 gave averageratios, ±2a, of 16.940±0.003, 15.495±0.003, and 36.731±0.017 for 206Pb/4, 207Pb/4, and 208Pb/4,respectively.155Table 4-7. Isotopic dates for Early Precambrian rocksfrom Wutaishan and Taihangshan region Ga ± 2overallRb-Sr Pb-Pb Sm-Nd Nd model dates Zircon U-Pb inferred age*Fuping 2.2 2.37 am. 2.48-2.60 detrital 2.8 —2.6Complex ±0.2 ±0.07 gn. 2.43-2.46 ±0.2euhedral 2.47*±0.9 ±0.02Lanzishan 2.48 2.52-2.56 & 2.560* —2.55Granite ±0.03 0.6 2.43,2.68 ±0.00680.7076±0.0014Wutai Complex*U-i 2.4 2.2 2.33,2.65 & 2.508 ?2.5±0.4 ±0.1 2.71 ±0.00280.7021 8ENd(T)=O.S±0.0008 ±1.0Wutai Complex*W-2 2.4 2.48 & 2.51 2.52 2.5±0.1 ±0.028ENd(T)l .2±0.9Wutai ComplexW-3 2.91,2.52 2.5Wutai Complexas a whole 2.0 2.26 2.5a whole ±0.1 O.O7 ±0.0680.7025 i1—7.73 &IENd(T)_l.l±0.0002 ±0.5*Ekou 2.52 2.5Granite ±3Shifo 2.5i 2.5Granite ±2156continuedChechang 2.3 2.3 2.46 2.3Granite ±0.5 ±0.1lO.7011 g17.51±0.0032Wangjiahui 2.2-2.3k 2.3GraniteHutuo 2.32,2.34 & 2.37# —2.4Group0 102.62 O.O9* data from Liu et al. (1985).data from Wu et at. (1986).$ data from Bai (1986).+ Sr depleted mantle model date.1570.77000.7600.Fuping Complex0.75000.7400 00.73000.7200**2 sigma error bar: —D gneiss0.7100 * amphibobte0.7000 I I0.00 0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.6087Rb/6SrFigure 4-19. Rb - Sr isochron plot for the amphibolitesand gneisses from the Fuping Complex.1580.51300.51250.51200.51150.5110z0.51050.51000.50950.50900.000 0.100 0.150147 144Sm/ NdFigure 4-20. Sm-Nd isochron plot for the amphibolites andgneisses from the Fuping Complex.Fuping ComplexD gneis* amphibolite2 sigma error bar: +Isochron date 2.37 +1— 0.07 Ga(1’Nd/” )0 = 0.50983 +/— 0.000050.050 0.20015918.0017.00p. 16.00015.0014.0013.0012.00Figure 4-21. Whole rock Pb plot for the amphibolites andgneisses from the Fuping Complex.208Pb/4160CIDC/)Wutai Complex0.90000.87500.73000.72500.72000.71500.71000.70500.7000x Wutai W—1)•Wutai W-2aOWutai W-2bAWutai W—3)2 sigma error bar: —Isochron date = 2.0 +/— 0.1 Ga(87Sr/Sr)o 0.7025 +/— 0.00020.00 0.20 0.40 0.60 6.000.8087Rb/6SrFigure 4—22. Rb - Sr isochron plot for the xnetavolcanicrocks from the Wutai Complex.7.00161Four amphibolites from the W-l define a Sm-Nd isochron of2.2 +/— 0.1 Ga with(143Nd/4)0= 0.50984 +/— 0.00015 or€Nd(T)= 0.5±1.0 (Fig. 4—23). Nd depleted mantle model dates are 2.33,2.65, 2.71 Ga. One sample with Sm/Nd greater than chondrite doesnot give a realistic model date.Li et al. (1990) reported a Sm-Nd isochron of 2.25 Ga forW—2b. We analyzed two greenschists from the same volcanic cycle.Combining our data with their data we derive a Sm-Nd isochronof 2.4 +/— 0.1 Ga with(143Nd/4)0= 0.5096 +/— 0.0001 or eNd(T)= 1.2±0.9 (Fig. 4—24). Nd depleted mantle model dates from allthese samples are between 2.39 and 2.51, with one exception of2.73 Ga.When plotting all the analyses of Wutai complex, includingtwo from metabasalts of the W—3, we derive a composite Sm—Ndisochron of 2.26 +1— 0.06 Ga with(143Nd/4)0 = 0.50974 +/—0.00006 or ENd(T) = 1.1±0.5 (Fig. 4—25).Two amphibolites from W-1, two greenschists from the W-2a,five from W-2b, and two metabasalts from the W-3 define a Pb-Pbisochron of 2.27--/- Ga with a first stage growth p = 7.73.(Fig. 4—26)Hutuo Group:Four metabasalts are scattered on the Rb—Sr isochron plot(Fig. 4-27). No Rb-Sr age can be calculated. Three metabasaltsare close to one another on the Sm-Nd isochron plot (Fig. 4-28)so no isochron is defined but all lie close to a 2.4 Gareference line. The Nd depleted mantle model dates are 2.32,2.34, and 2.62 Ga. Five metavolcanics are scattered on the Pb—1620.51300.51250.51200.51150.5110z0.51050.51000.50950.50900.000Figure 4-23. Sm - Nd isochron plot for the amphibolitesfrom the Wutai Complex (W-l).Wutai Complex (W— 1)2 sigma error bar: +Isoehron date = 2.2 +/— 0.1 Ga(“Nd/’”Nd)0 = 0.50984 +/— 0.000150.050 0.100 0.150 0.200147 ‘1Sm/ “Nd1630.51300.5125 Wutai Complex (W—2)0.51200.5115•W-20.5110 0 W—2 (Li ot al, 1990)Z 2 sigma error bar: +0.5105Isochron date = 2.4 +/— 0.1 Ga0.5100(‘Nd/’44N )0= 0.5096 +1— 0.00010.50950.5090 I.I I,0.000 0.050 0.100 0.150 0.200147Sm/’NdFigure 4-24. Sm - Nd isochron plot for the greensohistsfrom the Wutal Complex (W—2). Six analyses from Li (1986) arealso plotted.1640.5130 - lit 111111 lilililti iltiliiil1itlllitll Ix• W-20.5125- o W—2 (Li et aL 1990)A W-30.51200.5115 - -0.51102 !igma error bar: +‘. 0.5105-4Isochron date = 2.26 +/— 0.08 Ga0.5100(1Nd/”Nd)9 = 0.50974 +1— 0.000060.50950.5090 I..0.000 0.050 0.100 0.150 0.200147Sm/NdFigure 4—25. Composite Sm- Nd isochron plot for all themetabasic samples from the Wutai Complex.16518.0017.00, 16.00C’215.00N014.0013.0012.0010.00Figure 4-26. Whole rock Pb plot for all the metabasicsamples from Wutai Complex.208Pb/41660.7400 I lilt I 1111111110.7350 Hutuo Group0.7300 -e-0.7250 ,. -CI)9.—0.7200 ——— 2 sigma error bar: —r- 0.7150— 00.7100,0.70500.7000 .1 II.0.00 0.20 0.40 0.60 0.80 1.0087Rb/6SrFigure 4-27. Rb - Sr isochron plot for the inebasalticsamples from the Hutuo Group.1670.51300.51250.5120Z 0.51150.5110z0.51050.51000.50950.50900.000Figure 4-28. Sm - Nd isochron plot for the metabasalticsamples from the Hutuo Group.0.050 0.100 0.150 0.200147 ‘1Sm/ Nd168Pb plot (Fig. 4-29) so isochron date and model cannot becalculated.Lanz ishan Granite:Five samples from Lanzishan Granite define a 2.48 +/— 0.03Ga Rb—Sr isochron with(87Sr/6)0 = 0.7076 +/— 0.0014 (Fig. 4—30). Its Sr depleted mantle dates are 2.6 to 2.7 Ga. Fivesamples from this granite are close to one another in Sm—Ndisochron plot (Fig. 4-31). The Nd depleted mantle model datesare 2.43 to 2.68 Ga. Four samples from the Lanzishan Granitedefine an isochron on the Pb-Pb plot which gives a date of 1.9Ga with a first stage growth ,u = 8.38 (Fig. 4—32), theline being largely controlled by a single point.Chechang Granite and Wangjiahui Granite:Four samples from the Chechang Granite define a 2.3 +/- 0.5Ga Rb—Sr isochron with(875r/6S )0 = 0.7011 +/— 0.0032 (Fig. 4—30), largely controlled by one point. Its Sr depleted mantlemodel dates are 1.9 to 2.5 Ga. Three samples from the WangjiahuiGranite do not define a Rb-Sr isochron with a reasonable initialratio. A maximum age 2.24 Ga is calculated by assuming aninitial ratio 0.701. The Sr depleted mantle model dates are 2.2to 2.3 Ga (Fig. 4-30). One sample from the Chechang Granite hasbeen analyzed for Sm-Nd isotopic composition which yield a Nddepleted mantle model date of 2.46 Ga. Three samples fromChechang Granite define a Pb-Pb isochron of 2.3 +/-0.1 Ga witha first stage growth = 7.51 (Fig. 4-33).IV-4. Age constraints16900I i__i I IHutuo Group18.0017.0016.0015.0014.0013.00-12.00 -10.00208Pb/4Figure 4—29. Whole rock Pb plot for the metabasalticsamples from the Hutuo Group.Reference first stage mu = 7.7315.00 20.00 25.00 30.001700.90000.87500.8500C/) 0.82500.80000.77500.75000.72500.70000.00Figure 4—30. Rb - Sr isochron plot for samples fromLanzishan, Chechang, and Wangjiahui granitic bodies. The 2.48Ga isochron is defined by five samples from the LanzishanGranite. Four samples from the Chechang Granite give a crude ageof 2.3 +/— 0.5 Ga with lower initial ratio 0.7011 +/- 0.0032.A maximum age for the Wangjiahui Granite, represented by threesamples, is 2.24 Ga (0.701 initial ratio assumed).1.00 2.00 3.00 4.00 5.00 6.0087Rb/86Sr171) 5130 — I I Il I!0.5125 Pre C granites0.5120 - 0 LanzishanD Chechang .-0.5115 -0.5110-Z W0.51050.5100 2 sigma error bar: +0.5095 -0.5090- IlL H0.000 0.050 0.100 0.150 0.200147 144Sm/ NdFigure 4-31. Sm - Nd isochron plot for Lanzishan, andChechang granitic bodies.17218.0017.0016.0015.00CQ 14.0013.0012.00Figure 4—32. Whole rock Pb plot for the Lanzishan Granite.206Pb/417318.0017.00PD 16.00015.00CQ 14.0013.0012.00Figure 4-33. Whole rock Pb plot for the Chechang Granite.10.00 15.00 20.00 25.00 30.00206Pb/4174Different dating techniques give somewhat inconsistentdates for the Precambrian rock systems in the Wutaishan andTaihangshan region. The reason for this could be, as in case ofthe Kuandian Complex, isotopic resetting or post maginatic opensystem behaviour. The region was also tectonically active overprolonged periods in the Precambrian and was reactivated in theMesozoic (Yanshanian orogeny) and Cenozoic. We will use the samecriteria as for the Kuandian Complex to constrain the age ofEarly Precambrian rocks from the Wutaishan and Taihangshanregion.Fuping Complex:The maximum depositional age for the Fuping Complex is 2.8Ga, the detrital zircon U-Pb upper intercept age (Liu et al.,1985). The minimum formation age is 2.47 Ga, the euhedral zirconU—Pb upper intercept age interpreted as a metamorphic event (Liuet al., 1985). The Nd depleted mantle model dates for theamphibolites are between 2.48 and 2.60 Ga, those of gneissesare 2.43 to 2.46 Ga. Spread of Nd model dates could be due tothe following causes:(1). Rocks were formed at different times. Fieldobservations, however, indicate that it is unlikely that theFuping gneisses are much younger than the amphibolites.(2) . Rocks are heterogeneously contaminated or they camefrom different sources. Because the gneiss is more crustal inchemical composition, erroneously old Nd model ages could arisefor the gneiss. For example, 2.7—2.8 Ga gneiss from Anshan175Complex, Liaoning Province, NE China, gives Nd model dates upto 3.61 Ga (Qiao et al., 1990). The Fuping gneisses, however,have younger model dates than the Fuping amphibolites. Thismakes contamination an unlikely explanation for the spread ofNd dates.(3). Rocks are from a common source defined by the averagemantle evolution curve, but isotopically reset or partiallyreset by a later event (Fig. 3-45). In this case, the model datecalculated from true average Sm/Nd ratio and ENd(O) will beidentical to the true age. The average Sm/Nd of Fuping complexprobably lies between the ratios of the gneisses and theamphibolites. Thus the Fuping gneiss may yield model dateyounger than their true mantle separation age, and the Fupingamphibolites may produce model dates older than their truemantle separation age. By this interpretation the formation ageof the Fuping Complex is possibly older than 2.46 and youngerthan 2.60 Ga. It is unlikely that the average Sm/Nd ratio of theprotolith of Fuping Complex was higher than that of anyamphibolite, which would be required to suggest a true mantleseparation age older than 2.6 Ga. This interpretation is alsosupported by the younger Sm-Nd isochron date (2.37 Ga).(4). Rocks are from a common source that is more enrichedthan the average mantle evolution curve. In this case, all thedepleted mantle model dates will be older than the true mantleseparation age, and the higher the Sm/Nd ratio of a rock, theolder the model dates. Given a 2.47 Ga euhedral zircon upperintercept age, it is unlikely that the true age of Fuping176Complex is younger than 2.43 Ga, the youngest Nd model date, sothis explanation is ruled out.(5). Rocks are from a common source that is more depletedthan that defined by the average mantle evolution curve (Fig.3—44). For example, 3.5 Ga old amphibolites from Qianxi Complex,Hebei Province, 450 km northeast of the study region, giveinitial 6wd about +2 higher than the mantle curve (Huang et al.,1986; Jahn et al., 1987; Qiao et al., 1987). The calculated Nddepleted mantle model date for a rock from this highly depletedsource will be younger than the true mantle separation age,which can be defined by Sm-Nd isochron if the system remainsclosed after rock formation. Moreover, the higher the Sm/Ndratio of a rock, the younger the model date. However the Sm/Ndisochron date for the Fuping Complex is younger than thecalculated Nd model dates, and the Fuping amphibolites (withhigh Sm/Nd ratios) yield old model dates while the Fupinggneisses (with low Sm/Nd ratios) give young model dates. Thismakes the more depleted source hypothesis unlikely.The only possibility that the Fuping Complex is older than2.6 Ga is that its source was more depleted than the depletedmantle curve (Fig. 3-44) and isotopically reset or partly resetby a later event. In this case, the true age will be older thanall the model ages and rocks with higher Sm/Nd ratio may giveNd model ages older than those with low Sm/Nd.The other Archean rocks from the 5mb—Korea Craton showhigh initial ENd. The 3.5 Ga Qianxi amphibolites have average Nd+2.0 higher than the mantle curve. 2.7 Ga amphibolites from177Liaoning and Jilin Provinces, NE China possess an ENd +1.8 higherthan the mantle curve (Jahn and Ernst, 1990; Qiao et al., 1990).2.7 Ga amphibolites from Taishan Complex, Shandong Province havea ENd +1.1 higher than the mantle curve (Jahn et al., 1988). Theaverage Fuping Sm/Nd and 6Nd extrapolates to 2.62 Ga with Nd =+4.3, which is +2 higher than the mantle curve. Even if highdepleted Archean mantle is present in the Fuping area, we canstill conclude that the Complex is very unlikely to be olderthan 2.62 Ga.From the above reasoning, we infer that the mantleseparation time for the Fuping Complex is about 2.6 Ga, slightlyolder than the 2.56 Ga Lanzishan Granite. The 2.5 Ga upperintercept U-Pb age of euhedral zircons is probably related toa metamorphic event.Constrained by the 2.47 Ga U-Pb zircon upper intercept age,and the Nd model dates and their relationship to Sm/Nd ratios,the 2.37 +/— 0.07 Ga Sm—Nd and 2.34 +/— 0.42 Rb—Sr isochrondates can not be treated as true formation age of the FupingComplex. Instead the isochron dates can be interpreted as aconsequence of isotopic resetting at some equal or younger timeor artifacts of mixing lines. We infer that the isochron datesprobably represent the formation age reset by a latermetamorphic event or events, or even recent alteration. TheFuping amphibolite and gneiss, separately, have similar Nd modeldates, and this makes a mixing line hypothesis unlikely. Uniforminitial Nd isotopic ratios in different rock types have beenobserved in several studies, for instance, different komatiites178of the Onverwacht Group (Hamilton et a., 1979a; Jahn et al.,1982) and amphibolites and gneisses from the Taishan Complex(Jahn et al., 1988).The 2.2 +/- 0.2 Ga Pb-Pb isochron, likewise, must be theresult of younger metamorphic events in the region.Wutai Complex:The Nd depleted mantle dates are very close to 2.5 Ga inthe W-2 (including data from Li et al., 1988). The 2.3 to 2.4Ga isochron dates of Sm-Nd and Pb-Pb have probably been resetto some degree by later metamorphic events in the region. Analternative explanation is that the Wutai Complex formed 2.3 to2.4 Ga ago from partial melting of the underlying FupingComplex. However, the chemical composition of the Wutai rocksdoes not favour this suggestion and the two published 2.5 Ga U-Pb zircon upper intercept ages support the conclusion that theWutai Complex formed 2.5 Ga ago, and is not much younger thanthe Fuping Complex.Hutuo Group:The previously published U-Pb upper intercept age ofzircons from a metabasalt is 2.37 Ga (Wu et al., 1986). Nddepleted mantle model dates are 2.32, 2.34 and 2.62 Ga. We inferthat the lower part (volcanic series) of the Hutuo Group formedabout 2.4 Ga ago, very early in the Proterozoic, in a within—plate environment, as indicated by its petrochemistry. Thescatter in Nd model dates, and Rb-Sr, Pb-Pb isochron plots is179probably due to crustal contamination and post—emplacementregional metamorphism.Granitic intrusions:A 2.48 +/- 0.03 Ga Rb-Sr isochron is well defined for theLanzishan Granite, with(87Sr/6r)0= 0.7076 +/— 0.0014. The Nddepleted mantle dates of the Lanzishan Granite are 2.43 to 2.68and average 2.55 Ga. The published U-Pb zircon age for thisgranite is 2.56 Ga (Liu et al., 1985). For Rb-Sr system of thisgranite, only 0.1 Ga is needed to change 87Sr/6r from the mantlecurve to 0.7076 at 2.48 Ga. We thus interpret that this granitewas formed around 2.56 Ga, with the Rb—Sr systems reset about0.1 Ga later. The 2.56 Ga age separates the Fuping Complex andWutai Complex. The Pb-Pb isochron age for this granite, 1.9 +/-Ga, is presumably reset by later metamorphic events.As mentioned above, two granites, the Ekou Granite andShifo Granite, both intruding the Wutai Complex, have 2.52 and2.51 Ga zircon U-Pb ages, respectively.We also obtained a 2.46 Ga Nd depleted mantle model dateand 2.3 Ga Rb-Sr and Pb-Pb isochron dates for the ChechangGranite. As in other suites, the Rb-Sr and Pb-Pb isochrons areprobably somewhat reset by later events.The maximum Sr model date for the Wangjiahui Granite is2.24 Ga. Such 2.3 to 2.4 Ga dates are not only shown in theselater granites, but they also frequently appear as times ofresetting in the Fuping and the Wutai complexes. Widespreadresetting evidently ceased at about volcanic eruption time of180the Hutuo Group.There is geochronological evidence that Archeansupracrustal rocks are intruded by multiple granites in arelatively short time. For example, both 2.6 Ga and 2.4-2.5 Gagranites intrude the 2.7 to 2.75 Ga Taishan Complex (Jahn etal., 1988). We postulate that in the Wutaishan and Taihangshanarea at least three Precambrian granitic events can be inferred,one at 2.56 Ga (intruding the Fuping Complex), others at 2.3 to2.5 Ga (intruding Wutai Complex), and the final one at 1.9 Ga(high-K, intruding Hutuo Group, Bai, 1986, not studied in thisinvestigation).IV—5. DiscussionAlkali metasomatism:The amphibolitic samples from the Fuping and the Wutaicomplexes (W—1), and the greenschists from the upper cycle ofthe W-2 possess high alkali, high K20/Na ratio, and high Rbcontent. Sr concentrations are generally comparable with commonArchean basalts (e.g. Jahn and Sun, 1979). High-Rb is alsoobserved in the Qianxi amphibolites (Jahn et al., 1987), theTaishan amphibolite (Jahn et al., 1988), and the KuandianComplex (this study). The cause can be attributed to metamorphicand metasomatic effects of later intrusion of granitic magmas.For the Fuping gneisses, chondrite normalized NdN/SmN = 3.11to 3.26, and Sm = 10.22 to 13.88. This might reflect anextremely fractionated REE pattern with HREE depletion. This REEcharacter is typical for Archean gneisses of TTG composition181(Arth and Hanson, 1975; Glikson, 1976, 1979; Tarney et al.,1979). However they plot in the granite (s.s.) field in Ab-AnOr plot of WConnor (1965). This feature is also found in theQianxi gneiss (Jahn et al., 1987) and the Lanzishan Granite inthis study. Weaver (1980) invoked a metasomatic fluid to explainhigh K and Rb feature of acid charnockite from Madras. Jahn etal. (1987) interpreted that the Qianxi gneiss had an originalTTG composition but was modified through assimilation,contamination, or veining by late granite and pegmatite. Weaccept this explanation for the Fuping gneiss based on thewidely distributed red granitic and pegmatitic veins in theFuping gneiss.Resetting of isotopic systems:An alkali element metasomatic redistribution event can betentatively invoked as one cause of the isotopic resetting ofRb-Sr, Pb-Pb, and probably Sm-Nd systems in the Archean rocksof study area. Rb-Sr and Pb-Pb isotopic resetting are quitecommon for high—grade metamorphic rock systems (e.g. Jahn etal., 1987). But the Sm-Nd system can either remain littledisturbed up to granulite facies, e.g. in case of the Lewisiangneiss (Hamilton et al., 1979b) and the retrogressed Qianxiamphibolite (Jahn et al., 1987), or significantly disturbed inthe granulite facies, e.g. in case of the Napier Complex,Antarctica (DePaolo et al., 1982; McCulloch and Black, 1984).The Sm—Nd systems of Archean metabasic rocks, either inamphibolite or greenshist facies, from the Wutaishan and182Taihangshan area have been significantly disturbed. The Sm-Ndisochron dates are all younger than the U—Pb zircon upperintercept ages. In contrast, Archean samples from other partsof the Sinokorean Craton mostly give old Sm—Nd isochron dates,i.e. 3.5 Ga Qianxi Complex, the 2.7—2.8 Ga Taishan Complex, andthe 2.7-2.8 Ga Anshan Complex.Although the Sm-Nd systems were disturbed, the resetisochrons still give positive ENd values for the Fuping and theWutai complexes. The true initial ENd at their formation timeswill be even higher. This indicates that igneous precursors forthe Fuping and the Wutai complexes are derived from a depletedmantle source.Stratigraphic and tectonic revisions:The high-grade Fuping Complex is not much older than thelower—grade Wutai Complex. This does not agree with the attemptto make the age of Fuping Complex 2.8 Ga or older (Bai, 1986);the Fuping Complex is not one of the older continental nucleiof Sinokorean Craton, as previously suggested by Ren (1987). Theold nuclei of the 5mb—Korean Craton are 3.5 Ga old Qianxisupracrustal rocks in eastern Hebei Province, and 3.O GaQingyuan Complex and Tiejiashan and Lishan granites in theLiaoning Province. The Taishan Complex farther south, and theAnshan Complex farther northeast, formed at 2.7 to 2.8 Ga ago.The Fuping complex to the southwest formed about 2.6 Ga ago. Ndisotopes reveal that there was no significant amount ofcontinental crust present before 2.6 Ga in the Wutaishan and183Taihangshan region.Some authors have put the Wutai Complex in the EarlyProterozoic (e.g. Yang et al., 1986). Accumulated isotopic datarender this hypothesis obsolete. The Wutai complex formed atleast 2.5 Ga ago, and is thus Archean by modern definitions(Plumb, 1986)IV-6. SummaryThe Fuping Complex was derived from mantle about 2.6 Gaago and experienced a major metamorphic overprint about 2.4 Gaago and/or more recently.The Wutai Complex was derived from mantle 2.5 Ga ago andwas likewise metamorphosed about 2.4 Ga ago and/or morerecently.Metabasaltic rocks of the Hutuo Group were derived fromthe mantle nearly 2.4 Ga ago.No significant amount of continental crust existed before2.6 Ga in this region. From 2.6 to 2.5 Ga is the majorcontinental growth period in the Wutaishan and Taihangshan Area.In this period, Fuping and Wutai complexes formed sequentiallyfrom depleted mantle sources. The Fuping Complex and most of theWutai Complex formed in a modern island arc—like environment,with exception that the lower cycle of the W-2 formed in amodern MOR—like environment (rifted oceanic arc?) and thatsubgreenschist-facies rocks of the Wutai Complex (W-3) formedin an environment transitional between modern within plate andplate margin settings. Many calcalkaline I-type granitic bodies184formed in this region at about 2.55 and 2.50 Ga, the older onesintruding Fuping Complex and the later ones intruding bothFuping and Wutai complexes.About 2.4 Ga a major period of deformation and metamorphismaffected in the region. Some granites may have formed between2.3 and 2.5 Ga. At that time, the Fuping and the Wutai complexeswere under greenschist to amphibolite facies metamorphicconditions. They were deeply eroded before the Hutuo Groupmetasediments were deposited just after 2.4 Ga ago, with minorassociated within—plate volcanic rocks. The Hutuo Group, andpresumably its basement, underwent a later low—greenschistmetamorphic and high-K granite emplacement event about 1.8 to1.9 Ga ago.This study adds new evidence that Chinese Archean mantlehas positive cNd(T) values. The Archean igneous rocks from theSinokorean Craton formed at different times from heterogeneousand depleted mantle sources.185V. EARLY PRECAMBRIAN ROCKS IN SHANDONG PROVINCEThe Early Precambrian rocks in the Shandong Province arecalled Taishan Complex, west of the Tan-Lu Fault, and JiaodongComplex, east of the Tan-Lu Fault (Fig. 1-1 and 1-2).V—i. Taishan Complex and associated granitic rocksThe Taishan Complex is exposed in the Taishan, Mengshan andLushan area, western Shandong Province. It is composed of greygneiss, amphibolite, fine-grained gneiss, schist and quartzite.These rocks have generally undergone amphibolite—faciesmetamorphism.The Taishan gneisses have TTG compositions and have beeninterpreted by Ying (1980) to be metamorphosed volcano-sedimentary piles, and the arnphibolites that occur as enclavesin the Taishan gneiss to be residue of partial melting of theTaishan gneiss. Nevertheless, based on the isotopic and rareearth geochemical character of the Taishan amphibolite andgneiss, Jahn et al. (1988) considered that the Taishanamphibolite and gneiss are a possible bimodal magmatic suite.Jahn et al. (1988) reported a 2.69 ± 0.08 Ga Rb—Srisochron, with(87Sr/6)0 = 0.7006 ± 0.0004, and a 2.70 ± 0.04Ga Sm-Nd isochron, with€Nd(T) = + 3.3 ± 0.3, for the Taishanamphibolite and gneiss (Table 5-1). The Taishan amphibolitealone defined 2.77 Ga Rb-Sr and 2.74 Ga Sm-Nd isochrons. Theauthors inferred that the precursor basic and tonalitic magmasof the Taishan Complex were derived from the mantle and emplaced186Table 5-1. Isotopic dates for Early Precambrian rocks from Shandong ProvinceRock type Date (Ga±2a) Method SourceTaishan amphibolite & 2.69±0.08I5=O.7O6±4 Rb-Sr isochron Jahn et aL., 1988gnei ss2.70±0.04 ieNd(T)=+3.3±O.3 Sm-Nd isochron Jahn et al., 1988Taishan amphibolite 2.69 Nd TOM this study2.3±0.2 Sr°702414 Rb-Sr isochron Sun and Armstrong,19862.41±0.07 K-Ar hornblende Sun and Armstrong,1986Puzhaosi Diorite & 2.6±0.1 Sr°70088 Rb-Sr isochron Jahn et aL, 1988Zhongtainmen Granite2.45 to 2.55 Nd TDM Jahn et al., 1988Hushan Granite 2.56±0.01 U-Pb zircon upper intercept Jahn et al., 1988Aolaishan Granite 2.49±0.05‘sr=0702811 Rb-Sr isochron Jahn et al., 19882.45±0.14 Nd(T)=+1.0±1.7 Sm-Nd isochron Jahn et al., 19882.52 to 2.76 Nd TOM Jahn et al., 1988Taishan pegmatite 2.4±0.1 115r=°•73318 Rb-Sr isochron Sun and Armstrong,19862.30±0.06 K-Ar muscovite Sun and Armstrong,1986Jiaodong gneiss 2.6 to 2.8 U-Pb zircon Liu (unpublished)187about 2.7—2.75 Ga ago. We also obtained a 2.69 Ga Nd TDM for theTaishan amphibolite (Table 5-2). Sun and Armstrong (1986)obtained a 2.3 ± 0.2 Ga Rb—Sr isochron, with(87Sr/6)0= 0.7024± 0.0014, for the Taishan amphibolites (Table 5—1).The Taishan amphibolites mostly have a flat REE patternsimilar to Archean low—K tholeiites. However, the Taishanamphibolites have much more Rb and higher Rb/Sr ratio thanmodern arc tholeiite. Jahn et al. (1988) considered twopossible causes for this phenomenon, mantle metasomatism shortlybefore the melting event and metamorphic enrichment. In favourof the latter possibility, and considering the low initial Srisotopic ratio, they proposed that the Rb enrichment is due toamphibolite-facies metamorphism that happened shortly aftermagma emplacement.Sun and Armstrong (1986) reported a 2.41 ± 0.07 Ga K-Arhornblende date for the Taishan arnphibolite. This indicatesthat the amphibolite—facies metamorphism ended by 2.4 Ga ago.Granitic rocks intruding the Taishan Complex:Jahn et al. (1988) obtained a 2.6 ± 0.1 Ga Rb—Sr isochron,with(87Sr/6)0 = 0.7008 ± 0.0008 for the Puzhaosi Diorite andZhongtiarimen Granodiorite. The Nd TDM’s of these rocks arebetween 2.45 and 2.55 Ga. The authors inferred that thesedioritic rocks were mantle—derived. They also reported a 2.56± 0.01 Ga U-Pb zircon upper intercept date for the HushanGranite.188Table 5-2. Sm-Nd isotopic data with 2c errorsfor samples from Taishan ComplexSample Sm ppm Nd ppm 147Smf4Nd 143Nd/4 eNd(0) TOMTaishan ComplexSYB-5 2.698 8.72 0.1868 0.512562 -1.2 2.73+1- 0.002 0.01 0.0003 0.000014 0.3 0.09SYE-1 2.108 6.22 0.2047 0.512819 3.8 --+1- 0.002 0.01 0.0004 0.000014 0.3 --+ Sm and Nd concentrations were determined by isotopic dilution on aVG-30 mass spectrometer, 143Nd/4 ratios were measured by aVG-354 at the University of Alberta. 2 sigma errors listed in thistable do not include calibration and replication uncertainties.0.005% and 1.0% were used for 143Nd/4 and 147Sm/4Nd inregression calculations.*TOM: depleted mantle model date of DePaolo (1981), errors arepropagated from standard deviations of 147Sm/4Nd and 143Nd/4.189Jahn et al. (1988) derived a 2.49 ± 0.05 Ga Rb-Sr isochron,with(87Sr/6)0 = 0.7028 ± 0.0011, and a 2.45 ± 0.14 Ga Sm—Ndisochron, with €Nd(T) = + 1.0 ± 1.7, for the Aolaishan Granite.Nd TDM’S for this granite are between 2.52 and 2.76 Ga. Theyinterpreted the Aolaishan Granite to be derived from the partialmelting of the Taishan grey gneisses. Sun and Armstrong (1986)obtained a 2.4 ± 0.1 Ga Rb—Sr isochron, with(87Sr/6)0= 0.733±0.018, and a 2.30 ± 0.06 Ga muscovite K-Ar date for a pegmatiteintruding the Taishan Complex.In summary, the Taishan complex was formed 2.7 to 2.75 Gaago and has been intruded by mantle-derived granitic rocks -2.56Ga ago, and then intruded by the S-type Aolaishan Granite 2.45to 2.5 Ga ago. The magmatic activity in the area ended —2.4 Gaago.V-2. Jiaodong ComplexThe Jiaodong Complex is exposed in eastern ShandongProvince. It consists of gneiss, ainphibolite, fine—grainedgneiss, and some marble. These rocks have undergone amphibolitefacies metamorphism.Recent U—Pb analyses confirmed Archean ages of 2.6 to 2.8Ga for the Jiaodong Complex (Liu, personal communication).190VI. EARLY PRECAMBRIAN ROCKS IN NORTHERN SLOPE OF QINLINGMOUNTAIN BELTVI-l. Taihua ComplexThe Taihua Complex is exposed along the northern slope ofthe eastern Qinhing Mountain Belt in Henan Province and adjacentprovinces (Fig. 1-1 and 1-2). The Qinling Mountain Belt has beenconsidered a result of continental collision in the Proterozoic(Xu and Wang, 1990), the Paleozoic (e.g. Mattauer et al., 1985)or the Mesozoic (e.g. Sengor, 1985). Amphibolites from centreof the Qinling Mountain Belt give 1.2 Ga Sm-Nd isochron, withENd(T) = +5.7, and 1.13 to 1.19 Ga Nd TDM (Chen et al., 1991).The Taihua Complex consists primarily of tonalitic gneissesand tectonically interbedded upper amphibolite to granulitegrade supracrustals, e.g. metatholeiites, metapelites, andlenses of komatiitic amphibolites (Zhang et al., 1985).Single—grain evaporation of zircons from a tonalitic gneissof the Taihua Complex gave dates of 2.84 ± 0.01 and 2.81 ± 0.01Ga (Kröner et al., 1986, Table 6—1).We infer that the Taihua Complex formed 2.8 Ga ago.VI-2. Dengfeng ComplexThe Dengfeng Complex, surrounded by the Taihua Complexalong the northern slope of the eastern Qinling Mountain Beltin Henan Province and adjacent provinces (Fig. 1—1 and 1—2),consists of amphibolite—grade metavolcanic and metasedimentaryrocks. These rocks were intruded by large volumes of TTG and K—191Table 6-I. Isotopic dates for Early Precambrian rocks from Henan ProvinceRock type Date (Ga±2a) Method SourceTaihua tonalitic 2.84±0.01 & 2.81±0.01 single zircon evaporation Krbner et aL., 1986gnei ssDengfeng amphibolite & 2.51±0.03 lsNd(T)=2.2±0.8 Sm-Nd isochron Li et al., 1987acid metavolcanicsDengfeng metarhyodacite 2.51±0.02 U-Pb zircon concordia Kröner et al., 1986Shipaihe pluton -2.52 U-Pb zircon upper intercept Wang et al., 1987192rich granite (Zhang et al., 1985).Li et al. (1987) obtained a 2.51 ± 0.03 Ga Sm—Nd isochron,with ENd(T) = 2.2 ± 0.8, for six amphibolites and two acidrnetavolcanic rocks from the Dengfeng Complex (Table 6—1). Kröneret al. (1988) derived a 2.51 ± 0.02 Ga concordia U-Pb age forsingle zircons from a metarhyodacite of the Dengfeng Complex.A monzonite from the Shipaihe pluton intruding the DengfengComplex gave a -2.52 Ga U-Pb upper intercept date (Wang et al.,1987)We infer that the Dengfeng Complex formed 2.5 Ga ago.193VII. EARLY PRECAMBRIAN ROCKS IN INNER MONGOLIASanggan ComplexThe Sanggan Complex is exposed along the eastern YinshanRange, Inner Mongolia (Fig. 1-1 and 1-2). The Sanggan Complexhas been once subdivided into “Jining Group” and “WulashanGroup”, which has been proven to be without sound field evidence(Yang et al., 1986).The Sanggan Complex mainly consists of gneiss, amphibolite,quartzite, marble, semipelitic rocks and cherty iron beds. Theserocks have undergone a granulite to amphibolite—faciesmetamorphism. Migmatite and granitic intrusions are extensivethroughout.Whole rock Rb-Sr dates of 2.45 to 2.6 Ga have been obtainedfor the Sanggan Complex by previous studies (Cheng et al., 1984,Table 7—1).Sun et al. (1989) derived a 2.5 ± 0.1 Ga Rb—Sr isochron,with(87Sr/6)0 = 0.701 ± 0.002, for granulitic rocks from theSanggan Complex, and a 2.4 ± 0.1 Ga Rb-Sr isochron, with(87Sr/6)0= 0.703 ± 0.003 for the amphibolites from the SangganComplex. Model dates calculated from the average ratios of87Rb/6Sr and 87Sr/6r and bulk earth (Cameron et al., 1981) or0.701 Sr initial ratio (Hart and Brooks, 1977; Glikson, 1979)are both 2.6 Ga for the Sanggan granulites.We infer that the Sanggan Complex was formed 2.5 to 2.6 Gaago. Further Sm-Nd and U-Pb zircon work may prove that theSanggan Complex could be as old as the Fuping Complex or evenas old as the Jianping Complex.194Table 7-1. Isotopft dates for Early Precambrian rocks from Inner MongoliaRock type Date (Ga±2a) Method SourceSanggan Complex 2.45 to 2.6 Rb-Sr isochrons Cheng et al., 1984Sanggan amphibolite 2.4±0.1‘Sr=°7013 Rb-Sr isochron Sun et al., 1989Sanggang granulite 2.5±0.1 Sr°702 Rb-Sr isochron Sun et at., 1989195VIII. CRUSTAL ACCRETION HISTORY OF THE SINOKOREAN CRATONIN EARLY PRECAMBRIAN TIME1. Continental nuclei older than 3.0 GaThe oldest supracrustal rocks of the Sinokorean Craton areshallow water deposits about 3.5 Ga old in the eastern HebeiProvince (Table 2-1 and Fig. 8-1). Extensive basaltic volcanismaccompanied the deposition of the sedimentary rocks. Felsicmagmas intruded as plutons and erupted as volcanic layers whichhave been metamorphosed to grey gneiss and fine—grained gneiss.Magmatic and sedimentary processes may have lasted from 3.5 to3.0 Ga.Another continental nucleus has been identified in theQingyuan area where amphibolites and grey gneiss have given 3.0Ga ages (Table 3—i and Fig. 8-1). This nucleus may extend to theAnshan area to include the 3.0 Tieiashan and Lishan granites(Table 3—1 and Fig. 8—1).2. Late Archean high-grade metamorphic complexes (2.5 to2.8 Ga)The Late Archean high—grade rocks are extensive in theSinokorean Craton, surrounding the >3.0 Ga nuclei and along thesouth margin of the craton. These include the 2.7 to 2.8 Ga oldAnshan, Longgang, and Jianping complexes in the Liaoning andJilin provinces, Taishan and Jiaodong Complexes in the ShandongProvince, and the Taihua Complex in the Henan Province (Tables3—1, 5—1, and 6—1, and Fig. 8—2)1962.0 2.5 3.0 3.5 4.0 Ga1,111 iii liii III* Qianxi amphiboliteOJ 0 t Qianxi grey gneiss0 00 0 Qianxi fine—rained gneiss* Qianxi fuchsite—quartzite* x Qianxi granuliteo xc Qianxi charnockiteCD associated granitic rocksX ‘< Qingyuan amphiboliteQingyuan gneiss& X X Qingyuan granuliteX Qingyuan charnockiteassociated granitic rocks* c cc Tiejiashan Granite* Lishan GraniteFigure 8-1. Isotopic dating results from differenttechniques for rocks from the Qianxi, Qingyuan complexes andassociated granitic rocks, and Tiejiashan and Lishan granites.Asterisks stand for Sm-Nd isochron dates, triangles for Nddepleted mantle model dates, squares for U—Pb zircon upperintercept dates, diamonds for single zircon evaporation dates,crosses for Rb—Sr isochron dates, open circles for K—Ar dates,solid dots for 40Ar/39r dates, pluses for Tb—Pb dates, stars forPb—Pb whole rock isochron dates.1972.0 2.5 3.0 3.5 4.0 Ga1,11111 I Ii run iii** * Anshan amphibolitex * Anshan fine—grained gneissAnshan schist.. Anshan gneissic granitec x Longgang gneiss* Longgang gneiss & granulite< * Jianping amphibolite* Taishan amphibolite & gneissX Taishan amphiboliteO)<— associated granitic rocksJiaodong gneissTaihua gneissFigure 8-2. Isotopic dating results from differenttechniques for the Anshan, Longgang, Jianping, Taishan,Jiaodong, and Taihua complexes and associated granitic rocks.Symbols for different techniques are the same as in Figure 8-1.198The > 3.0 Ga continental nuclei have been also intruded bythe 2.7 to 2.8 Ga granitic rocks.The high-grade Fuping Complex formed -2.6 Ga ago in Shanxiand western Hebei provinces (Table 4-7 and Fig. 8—3). Age of theDengfeng Complex in Henan and adjacent provinces has beendetermined by the 2.51 Ga U-Pb zircon concordia date (Table. 6-1 and Fig. 8—3). The Sanggan Complex formed at least 2.5 to 2.6Ga ago in Inner Mongolia (Table 7-1 and Fig. 8-3).3. Late Archean greenstone-granite belt (2.5 Ga)The Wutai Complex formed 2.5 Ga ago as a greenstone—granite belt in Shanxi Province (Table 4-7 and Fig. 8-3).4. Terminal Archean granitic magmatism (-2.5 Ga)Granitic magmatism peaked about 2.5 Ga ago in theSinokorean Craton. These plutons overprinted all the previouslyformed complexes. After 2.5 Ga, inagmatic activity was greatlyrestricted in the Sinokorean Craton.5. Early Proterozoic continental rift (2.3 to 2.4 Ga)Early Proterozoic volcanic rocks in the Sinokorean Cratonare mainly found in the Kuandian Complex in the eastern LiaoningProvince, bottom of the Hutuo Group in Shanxi Province, and theDantazi—Zhuzhangzi Group in eastern Hebei Province.Metavolcanic rocks of the Kuandian Complex have acomposition similar to modern continental flood basalt. Granitesfrom the Kuandian Complex have an anorogenic granite chemistry.The Kuandian Complex formed 2.3 to 2.4 Ga ago (Table 3-1 andFig. 8-4). The Hutuo metavolcanic rocks have a within-platecharacter and most likely also formed 2.3 to 2.4 Ga ago (Table1992.0 2.5 3.0 3.5 4.0 Ga1111)1111 iiiit iiiFuping amphibolite‘ C Fuping gneissxc Lanzislan GraniteSanggan Complexx Sanggan amphiboliteSanggan granulite* Dengfeng amp. & acid metavolcanicsC Dengfeng metarhyodaciteC Shipaihe plutono Wutai metakeratophyreo Wutai fine—grained gneiss* Wutai metavolcanicso associated granitic rocksFigure 8—3. Isotopic dating results from differenttechniques for the Fuping, Sanggan, Dengfeng and Wutai complexesand associated granitic rocks. Symbols for different techniquesare same as in Figure 8—1.2002.0 2.5 3.0 4.0 Ga* * Kuandian amphibolite & graniteKuandian amphiboliteD Kuanthan graniteHutuo metabasaltic rocksx Dantazi—Zhuzhangzi metabasaltic rocksDantazi—Zhuzhangzi fine—grained gneissx associated granitic rocksFigure 8—4. Isotopic dating results from differenttechniques for the Kuandian Complex, Hutuo metabasalts, Dantazi—Zhuzhangzi Group and associated granitic rocks. Symbols fordifferent techniques are same as in Figure 8—1.2014-7 and Fig. 8-4). The Dantazi-Zhuzhangzi Group is lessextensively studied. It is younger than 2.5 Ga and probablyolder than 2.4 Ga (Table 4—7 and Fig. 8-4).We conclude that the Sinokorean Craton contains relicts of3.5 Ga crust and was largely consolidated about 2.5 Ga ago. Inthe Early Proterozoic the craton was only disrupted locally bycontinental rifts or aulacogens in which Early Proterozoicsedimentary rocks were deposited.All the Archean and Early Proterozoic rocks in theSinokorean Craton underwent a thermal event about 1.8 to 1.9 Gaago, which has been recorded by K-Ar and Rb-Sr isotopic systems.In the Middle and Late Proterozoic times, platform-typecarboniferous rocks were deposited along east, southwestmargins, and in the Yinshan—Yanshan area (Inner Mongolia—HebeiProvince) of the Sinokorean Craton.202IX. ND ISOTOPIC CHARACTER OF THE EARLY PRECANBRIAN ROCKSIN THE SINOKOREAN CRATONInitial ENd values determined from well defined Sm-Ndisochrons have been plotted in Figure 9-1. Sm-Nd isotopiccompositions for individual samples have been plotted in Figure9—2a, b, c, and d.Precambrian rocks older than 2.5 Ga in the SinokoreanCraton, whether of basic or granitic composition, plot aboveDePaolo’s (1981) depleted mantle evolution curve (Fig. 9-1), andmostly are above their reference lines, which are drawn throughthe initial ratios calculated from the mantle curve, on Sm—Ndisochron plots (Fig. 9-2a and b). This indicates that the basicrocks are derived from a mantle source more depleted than thatdefined by the mantle curve. Granitic rocks are also derivedfrom the depleted mantle source or are products of the formerbasic rocks with short crustal residence times. The mantledepletion can be related to extraction of old continentalmaterials. The Nd isotopic character, however, implies thatpreservation of the old continental material was not much before2.5 Ga ago.Some —2.5 Ga granitic rocks in the Sinokorean Craton,especially the Anshan gneissic granite, show an enriched Ndcharacter (Fig. 9-1 and Fig. 9-2c), which can be explained bysignificant involvement of old continental material in theirorigin. This indicates that a large proportion of the SinokoreanCraton has been formed since 2.5 Ga ago.2038.06.0AovZoDcr!e—4 0 * Qianxi Complex• Anshan Complex• Jianping Complex—6.0 Taishan ComplexDengfeng Complex* 2.5 Ga granites—8.0*Kuandian Complex—10.0—12.02.0 2.5 3.0 3.5 4.0 4.5Time (Ga)Figure 9-1. ENd evolution diagram for rocks well definingSm—Nd isochrons. All rocks older than 2.5 Ga show a moredepleted character than DePaolo’s (1981) depleted mantle curve.Some —2.5 Ga granitic rocks plot below the mantle curve, whichcan be explained by involvement of old continental material. The2.3—2.4 Ga Kuandian Complex came from a mantle source lessdepleted than that defined by the mantle curve. This is due tocontamination of Archean basement or derivation from a differentmantle source.2040.51400.5130F 0.51200.5110zc,z— 0.51000.50900.50800.000 0.050 0.100 0.150 0.200147 144Sm/ Nd0.250zzC,-l0.51400.51300.51200.51 100.51000.50900.50800.000 0.050 0.100 0.150 0.200 0.250147 /144-STSm INdFigures 9-2a and 9—2b, caption in p.206.2050.5140 — I I I IWutai Complex and 2.5 Ga granitic rocks0.5130 --0.5120 -:105hb0 + +±+ (C)— 0.5100*-2.5 Ga Wutal Complex+ -2.5 Ga Anshaii Granitefl fl9Q CD 2.5-2.6 Ga granites intrudingthe Taishan Complex* 2.56 Ga Lanzishan Granite0.5080 — I I I I I I I III 1111 I I I I I —0.000 0.050 0.100 0.150 0.200 0.250147 144Sm/ Nd0.5140 I I I I I I 11111111 I I I —2.3—2.4 Ga Kuandian Complex and Hutuo Group1::: (d)Kuandian Complexa Hutuo Group0.5090 -0.5080— I I I I I—0.000 0.050 0.100 0.150 0.200 0.250Figure 9—2a, b, c, and d. Sm—Nd isochron plot forindividual sample data of (a) Qianxi and Qingyuan complexes, andLishan Granite; (b) Anshan, Longgang, Jianping, Taishan, andFuping complexes; (c) Wutai Complex and —2.5 Ga granitic rocks,and (d) Kuandian Complex and Hutuo Group. The reference linesare drawn through initial Nd isotopic ratios that are calculatedfrom the depleted mantle evolution curve (DePaolo, 1981). Rocksmore depleted will plot above their reference lines and thoseless depleted will plot below their reference lines.206The 2.3 to 2.4 Ga old continental rift-related KuandianComplex show a Nd isotopic character less depleted than themantle curve (Fig. 9-1 and 9-2d). This is due to contaminationof Archean continental crust or to derivation of a differentmantle source.207X. CONCLUSIONContinental nuclei of the Sinokorean Craton include the 3.5Ga amphibolites and grey gneisses of the Qianxi Complex in theeastern Hebei Province, and the 3.0 Ga Qingyuan Complex in theeastern Liaoning Province. The latter may extend to the Anshanarea to include the 3.0 Ga Tiejiashan Granite and LishanGranite. There is little evidence for the existence of theSinokorean Craton before 3.5 Ga; either not much crustalmaterial formed earlier than 3.5 Ga ago in the area or most ofrocks older than 3.5 Ga have been recycled back to the mantleor buried in the lower crust.Younger Archean rocks in the Sinokorean Craton occur mainlyas high-grade metamorphic complexes, including the 2.7 to 2.8Ga old Anshan Complex in eastern Liaoning Province, LonggangComplex in southern Jilin Province, Jianping Complex in westernLiaoning Province, Taishan Complex in western Shandong Province,Jiaodong Complex in eastern Shandong Province, and TaihuaComplex in Henan Province; 2.6 Ga Fuping Complex in westernHebei and Shanxi Province; and 2.5 Ga Sanggan Complex in theInner Mongolia and Dengfeng Complex in Henan Province. TheWutai Complex and associated granites in Shanxi Province, a wellpreserved Early Precambrian greenstone—granite belt, are 2.5Ga old, and are not of Early Proterozoic age as suggested byYang et al. (1986). There is no evidence for continental crustbefore 2.6 Ga in the Wutaishan and Taihangshan regions, and asyet there are no data greater than 2.5 Ga in the Inner Mongolia208region.Nd isotopic data indicate that the Early Precambrian rocksolder than 2.5 Ga in the Sinokorean Craton are mainly derivedfrom a very depleted mantle source.Granitic magmatism peaked about 2.5 Ga ago in theSinokorean Craton, affecting all previously formed rocks. Some-2.5 Ga granites are partly derived from older continentalcrust, as shown by Nd isotopic compositions. After 2.5 Ga, thecraton was largely consolidated and magmatic activity wasgreatly reduced.In the Early Proterozoic the craton was disrupted locallyby continental rifts or aulacogens in which Early Proterozoicsedimentary rocks were deposited. The Early Proterozoicvolcanic rocks in the Sinokorean Craton, those in the 2.3 to 2.4Ga old Kuandian Complex and Mutuo Group, were derived from anintra—continental environment. Nd isotopic compositionsindicate that either the mantle source for the Kuandianamphibolite is less depleted than that for the Archean rocks,or precursor magmas were contaminated by Archean basement.Granites from the Kuandian Complex have an anorogenic character.Fractional crystallization of olivine, pyroxene and plagioclasefrom the precursor magma of the Kuandian amphibolite can producea magma with a chemical composition similar to that of theKuandian granite.All Archean and Early Proterozoic rocks in the SinokoreanCraton were affected by a thermal event about 1.8 to 1.9 Ga ago,as shown by K-Ar and Rb-Sr isotopic systems. 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Geochimica, 1:195—205.221APPENDIX 1SAMPLE DESCRIPTIONSample Locality Latitude DescriptionLongitudeQianxi ComplexHTB-4 Taipingzhai,Qianxi, HebeiHTB-5 Same as above.ComplexGounaidianz i,Qingyuan,LiaoningSame as above.Tiej iashan GraniteT—l Tiejiashan,Anshan,Liaoning.Lishan Graniter86—159 Lishan ParkAnshan,Liaoning.Same as above.Same as above.Same as above.Same as above.ComplexLaoj inchangHuadianJilin.Same as above.Same as above.Same as above.Erdaogou,Huadian,Jilin.LG-033 Quanhuizhan,Huadian,Jilin.LG-034 Same as above.LG—035 Same as above.Anshan ComplexA86-002 Cigou, Anshan,Liaoning.A86—005 Same as above.Biotite granulite.Migmatitic.Biotite granulite/gneiss.Leucocratic.Same as above.Same as above.Same as above.Same as above.Light-grey granulite.Medium grain sized.Light-reddish granulite.Granulite.Same as above.Biotite-hornblende—plagioclase gneiss.Coarse grain sized.Grey gneiss. Medium grainsizedDark—grey gneiss.Light-grey gneiss.Magnet ite amphibolite.Amphibolite. Fine grainsized.QingyuanLG-2LG-3400151118° 3642°4’124 °54’Grey plagioclase granulite.Grey plagioclase granulite.4106 I Leucocratic granite.123°2’r86—l63r86—l64r86—165r86—166Dark-grey trondhjemite.LonggangLG-001LG- 003LG-009LG- 011LG-01441°8l23°242°53’127 °27’42°51127 °17’42°48’127 °l4’41031123 °30’222oooO:lI111111oooooooH0DQco PT 00 oJ Ct)cI)H-0)(DCDNO)H-U)H-02<LCDCD•O0)t’JHO0)(I) 0) CD 0) CO 0) 0 CDC!)Cl)Cl)Cl)0)0)0)CDCDCDCD0)0)0)0)U)(0(1)Cl)0)0)0)0)o000<<<CDCDCDCD0ODH00001UiH00oCl)Cl)t-lC)0)0)H-0CDCD0CD0)0)H-H0)0)-’00CDCDU) 0)oooIIIIIIHHHHHHo.i0DCI)tC)0)H-0CDOCD0)0)0)01H-HCO(I)U)U)H i-Q00)0)0)0).-0000(D(DCDCDU)••••0)ooooooIIIIIHOC(‘Jt’JJH000o><Cl)H-0)0)CDCD)H-U)H-0H<I—’CDH-‘pH tJ00O’ioq._)c)JU1000)HHH‘pt1jH-CDC)H- CD-‘pH-CD°‘pH- CD‘‘pCD0H-H0)CD0C1)’ItCJ)0)H-CDH-0)CD0‘-PLi-CDC)H-0)H-0)0)Cl)CDdC))LP0)’-P-0)-00DDH 00H-H-H-00 H-H-CD‘-p’p0 N 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CDPOC))O)OOO’pObidØCflC!)‘pbICflCl)Cf)C!)“ICl)HO)CDHF-1H-HO)0)0)H-0)O)HO)O)H-HP)‘ZIO)ctH-Ibrt1H-H-0)ctOO)F1CDQP)ZH-<’ftCDCDH-rtCD(D’PCDCDCDPCDH-00CDH-00H-0H-H-CDU)H-H-HOrt0)0)U)rtP)0)O0)0)‘-P00)OH<k<I0’.<‘<CDH-HCDC)IU)U)•CDCOCOOCOU)C)U)Hrt1t-—1’p1Ic-tO)IHQHP)HH-CD00H-H0OOCDU)’O)H-0)0)I-tP)0)0)0)P)H-PlO)rt-XXOrtX0)’<1•CD<COOb’b’H-b’b’U)b’b’U)b’CDCDCDrtCDCDH-CDrtIdCDd0000CDO0(DO•H-’CD1(0<<CD<<<<CO<CDCDrtCD(DOi—I1P)H-(DIDICDCD0)CDCDH-P)(DIlCDID)bO)U)-‘p•-N.IflH•’b<‘prt‘dCDCD’dHHN<t1H-’I0)P)H-CD100CDHH-H-•H‘-PPOXC)bbH-O<CDHCD0CD000‘tCD0)1HHHC)<CDCOH-H-H-HH-ICDCtCt)0çICDCDCDU)><CD-CDCD CDhj(t)C/)H-0)0)CDCDCD‘-P0)0)U)U)0) H-0)0)Z CDOOP<<(DIDp..ID H CO CO9) HH-f-iO(flNH-CD-Q0-0:, H t’J 01or)on0)0)03030303030)IIIIDI000(DH 0Q 00)H-H-0)9)9)CD009)H-9)Q0)•0 CDH.M0C..)00010.H t’3000H 00H t%J000010H 00P t’3000H t.J000ticn-l-lt-tC’)C’)0)C’)no)O30303030303H-0303030303030303030303GH-——.)aOO0)—.1—.)OO-.3o’a’GID)IIII10IIIIIIIIIIIPH-HPCJJ0000J00J—)00s3PP9)‘.D‘.0—.)0’.).-.Pt’JQ03—)0303H00—1’.0‘.0030ti 0) H-0)H-9)H-0)03)ti0)H-H-H-0)0)H9)H-0)H-H-00)H-(D0)0)CD0)0)0)H-H-ct9)Cfl0)0)U)00H-U)9J0)Z’-J-CDCD00CDCD0U)CDOCDCDCDCD0H-H-D)H-bH-H-ZH-H-ZH-H-ZH-‘<C)O<9)03H-i.QH-0)0)H-Q0)9)H-Q0)H-<H-i.Q0)H-9)H-0)9)H-9)CD<‘<9)9)9)H-0bU)H-.Q(9(9H-(I)H-’dH-H-<H-9)U)9)U)CD9)(1)0H-(J)U)U)-Q0)0Q9)-.Q’.Ci‘.H-9)’0C0)0)00)’0-•0•0-•09)Qb0)-tiQ0)9)0)’--bbb’-----b-b-b--bbb000000-000<<<<<<H-<<<Ct)(DIDCDCDCD(DO)CDCDCD......0•HHPHMpLJ0WO000000M00P0101.C..)I—0000P0101G()1O1-----o.0EjcI)t33CI)tZOOQ(DH-0)tiH-0)CDHH-0H0HP9’00tiO)H9)9)9)O(D(DHrt(DOH-CtCl0ti0IH-0CtH-HH•ctH-HQ9)(OCt03OCDCt(DOtiNO0titiU)Cl(DU)tiCDtiC)009)0)IIH-HH9)PHctH-0)‘.H9)CtH’CtO)O)0)9)H-bH-bH-0CDU)’<dU)U)OCDOCD0OCDICDCDCDCD•Cl<H-CD<•IbCDU)CDbH-9)’b9)0)L.U)•P00Z•0)CDrtdPdCDH-H-H-H•ClrtH-CtH-H-U)CDCDCDbCDbU)Cl0•00.(nPPHOH-H-HCDCtH-CtCtCDH-H-CD‘.QCDCDH-(9(fl•‘U)U)r1CI-U)(I)QtCfl(i)bCI3Cn‘TJQ.!jQcnCDCD0)ti9)9)HbH-H-rI-H-tiH-H-ti9)ClCI(D<009)9)00)H-ClCD‘<PCDCD(DrI-CDctCD’bCI-CD’bCDH-IPIrt-H-IiHU)9)‘.H-9)0)CD-QCt0H-CI-‘.QH-9)U)tiCtU)U)tiCltiCDPtiCtCT)tiCtrilCDH-CD9)1H-0)(DIOJCDti.Q03(DQ039CD’bH-U)CtH-I(I)H-I9)9)tit3OCDZct0CtbH-Cl)0H-U)00H-<IItiIIi0<U)H<<WP(flH-bU)CDH-U)CD<H-CD9)CDCDHH-U)H-H-U)H-CD(9rI-•Ct’•H-NCt0NOCtNO’H-CDCDCt(•CtCDP•CDHN.•H-ClH-ClH-ClHCD0•Ct‘CI-•CtClCDH-H•U)ICtCtP(9CDCD9)C)Ct CDH.U) CtQtI(fl0CDI—--’HH-t-HP1P1P1J0H-0‘.QH-0C)1HH-Hb1c-I-H-H-000o(Dctct000I-’HH-H-HHI-’H-P1p1NNP1P1P1CDCDU)U)U)CDCDC5PCDCDCDH)P)P1P1Hb 0ddCtHCDH-H-H-HCtHCD000P1•HHHH-H-H-CDtIIH-(DCDCDCDc Ct1.jH-HCD HPIHH-P1U)lCDU) H-P1NH 0 H H Ct CDHCDF-H-H(flCtU)CDHHHP1P10H-H-H0OCtoOCDHHIP1P1U)U)0CDCDP1P1b’CDH-H-P.bbCD001HHH-HCtCtCDCD‘-3CI)CJcCI)CI)11P1P10CDCDCDCDPIQIPJPILi-U)U)U)U)CDP1P11Q1H- Ct0000CDCDCDCDCD0H-0CtU)H-CDCt’<CDiLIHt1CtP11H-H-P10HcnctH-CDN.CDIIIIUiIPIHH-I•Tj15j1TJt\)IIIII’ZH1ts)II0000P10Ht%JLQ() 0(1)Cl)CsiCtP1P1IP1PIOOHPICDCDCDCDCDCDNCtXP1P1P11P1H-0----.U)U)NIP1P1P1PIPICflH-ZH00000P1P1<<<<<z‘<CDCDCDCDCD<0H HL.)LD00HCl)CtC!)H-0P10H-0:-P;o0P1P1H-P1CD0U)XP1dJ0HP10CD-P1--.CtP1LQb000pIPICDOOOOO3IIIIIHHHHHoGUi4()Cl)I:-’C!)C):::Tz•’P1oH-P1H <H-edcX H-P101CDtLl•0X‘1--H CDGP1lCD00 I-it-lC/)P1H-P1P1P1H-I-bH-HOOCDP1Ct CDH-CDLN;QQH-GooIIIIHHHHooooO-L)CPiC!)Critl)P1P1P1P1CDCDCDCDP1P1Q1PIU)U)U)U)DlP1P1P10000CDCDCDCDI-QP1P1H-CDDlP1H-CDCD0‘-QH-Ct0CDP1P1H-QU)U)CDP1P1•‘ —00CDCDI•j•x•jI•ijIIIU14wC!)CrJCI)’1P1P1P1CDCDCDHP1P1P1QU)C))U)P1010I000b<<<CDCDCDCDH-000t1CDCDCD<I<1<LPLQ’QCDCDCDH-H-HU)Cl)U)U)Cl)U)t%)UIH H)000(J)Cl)Ci)CI)P1P1P1CDCDCDP1P1P1U)(flU)P1P1P1btb000<<<CDCDCDCl)C!)P1P1HCDCDOP1P1HU)U)P1P1•00CDCDHHHHHHHb)H1H()DD(lQ(-.10L)0000000000000HOHOt’J0Ui.0101O0-Q4HU1HW—101cl)Ci)01P1CDCDP1P1U)U)P1P100CDCDH 0 H H Ct CD U) CD ‘1 H (2 H Ct H- N CDC!)Cl)C!)C!)C/)C/)P1P1P1P1P1P1CDCDCDCDCDCDPIP1PIPIP1P1Cl)U)U)U)U)U)P1P1P1P1P1P1000000CDCDCDCDCDCDW84—7W8 4—8W84—9Same as aboveSame as aboveSame as aboveComplex (W-2b)SE 6km ofTaipinggou,Fanzhi, Shanxi.Same as aboveW81-3 Same as aboveW81-6 Same as aboveW81—7 Same as aboveW8l-8 Same as aboveW8l-ll Same as aboveW81-15 Same as aboveWutai Complex (W-3)W85—l NE 700m ofYaozichun,Daixian, ShanxiW85—2 Same as aboveW85-4 Same as aboveW85-6 Same as aboveW85—8 Same as abovewith W84-51.Amphibolite.Amphibolite.hornblende.Amphibolite.hornblende.Chlorite greenschist. Alsoconsists of epidote,plagioclase, quartz andcalcite. Fine—grain sized.Micro—veins of calcite.Epidote-chloritegreenschist.Chlorite greenschist. Fine-grain sized. Poorschistosity.Chlorite greenschist.Micro-folded. Calciteveins.39°04’ Chlorite greenschist. Goodl13°4l’ schistosity.Chlorite greenschist.schistosity.Chlorite greenschist.schistosity.Chlorite greenschist.schistosity.Chlorite greenschist.schistosity.Chlorite greenschist.Medium-grain sized.Chlorite greenschist.schistosity.Chlorite greenschist.38°58’ Actinolite amphibolite.113°04’ Also consists of epidote,plagioclase, quartz. Fine—grain sized.Actinolite amphibolite.medium—grain sized.Actinolite amphibolite.medium—grain sized.Actinolite amphibolite.medium—grain sized.Actinolite amphibolite.medium to coarse—grainsized.WutaiW82—4Complex (W—2a)SE 2km ofTaipinggou,Fanzhi, Shanxi.Biotite aroundBiotite around39° 05113 °39’W82-5 Same as aboveW82-7 Same as aboveW82—9 Same as aboveWutaiW81—lW81—2 GoodFairPoorPoorPoor226GroupS lOOm ofHuilongdi,Wutai, Shanxi.S 150m ofHuilongdi,Wutai, Shanxi.Same as aboveE 500m ofLiudingsi,Wutai, Shanxi.Same as aboveLanzishan Granite076 E 500m of 38°45’Changchengling, 113°45’Wutai, Shanxi.077 Same as aboveShifo Granite054 SW 500m ofXiaomati,Wutai, Shanxi.057 Same as above38°51’ Chlorite greenschist.113 °35’38°51’ Chlorite greenschist.113 °40’Chlorite greenschist.Fine—grain sized. Poorschistosity.Chlorite greenschist.Chlorite greenschist. Wellpreserved ophitic texture.Gneissic granite.Gneissic granite.grain sized.Gneissic granite.Gneissic granite.Gneissic granite.Chechang083—1083—208 3—308 3—4GraniteTaipinggou,Fanzhi, Shanxi.Same as aboveSame as aboveSame as above39°06’ Gneissic trondhjemite—1l3°38’ tonalite.Gneissic trondhjemitetonalite.Gneissic trondhj emitetonalite.Gneissic trondhj emite—tonalite.Wangj iahui Granite087—1 SW 4km ofWangj iahui,Daixian, Shanxi.Same as aboveSame as aboveSame as aboveTaishan ComplexSYB-5 0.5 km S ofYanhingguan,Xintai,Shandong.39°01’ Granitic gneiss.113 °06’Granitic gneiss.Granitic gneiss.Granitic gneiss.HutuoH— 003H—004H—007H—014H—01738°01113 °34’078079080Same as aboveSame as aboveSame as aboveMedium-38°55’ Granitic gneiss.113 °38’Granitic grieiss.087—2087—3087—436°5’11703Q’Plagioclase amphibolite.227SYE-1 1 km N of Plagioclase amphibolite.Yanhingguan,Xintai,Shandong228APPENDIX 2.ANALYTICAL METHODS FOR RB-SR, SM-ND and PB—PB ISOTOPES:Rb-Sr and Sm-Nd:Optimum amounts of 87Rb and 84Sr spikes were added to 200mg of whole rock powder for Rb and Sr isotopic dilution and Ndisotopic ratio analyses. Sm and Nd isotopic dilution analyseswere done separately, using another 200 mg whole rock powderaliquot mixed with an optimum amount of mixed spike containing149and 145Nd.Samples were digested with double-distilled HF and 16 NHNO3 (7:3) in a 15 ml screw—capped Savillex vial on a hotplate for over 24 hours. After drying the dissolved sampleswere extracted in 2.3 N HC1 and any residue was treated withmore HF and HNO3 in the closed Savillex vial on a hot platefor over 5 hours for a complete dissolution and taken up againin 2.3 N HC1 after drying.After the sample had been totally dissolved in 2.3 NHC1, the solution was dried again and then redissolved in 2 ml2.3 HC1 and centrifuged. The supernatant was loaded into acation exchange resin column (20 cm long 1 cm wide) for Rb, Srand REE separation by elution with 2.3 N and 6 N HC1.The REE aliquot was dried on a hot plate and loaded in0.1 N HC1 into a second cation exchange resin column (30 cmlong 0.1 cm wide) for Sm and Nd separation by MLA elution. Theflow rate was controlled by adjusting the height of MLAreservoir. An automatic counting collector was used for Sm andNd collection.229Rb, Sr, Sm, and Nd fractions were dried and furthercleaned by using a small cation resin column (7 cm long 0.5 cmwide) and HC1 elution.Rb, Sr, Sm, and Nd isotopic dilution analyses were madeusing a VG — MM3O mass spectrometer at the University ofAlberta. Nd isotopic ratio was measured using a VG— 354 massspectrometer, equipped with a multiple collector, at theUniversity of Alberta. Double Re filaments were used for Rb,Sr, Sm and Nd isotopic analyses. 87Sr/6r ratios arenormalized to 88Sr/6r = 8.3752 and corrected for 87Rb (87Rb/5ratio of the same spiked sample was used, Rb in any Sr run wasnegligible). Sr standard NBS-987 gave an average 87Sr/6r =0.71020 +/- 0.00002 (2u) during the course of this work.143Nd/4 was normalized to‘46Nd/144 = 0.7219. La Jollastandard Nd metal 143Nd/4 gave an average 0.511856 +/-0.000004 (2a) during the course of this work. The 2aprecisions estimated from duplicated runs are as follows: 2.0%for 87Rb/6Sr, 1.0% for 147Sm/4Nd, 0.026% for 87Sr/6r and0.005% for 143Nd/’4 . The blanks for the total procedure are0.2—0.3 ng for Rb, 3—4 ng for Sr, 0.2—0.3 ng for Sm, and 0.5—0.9 ng for Nd.Whole rock Pb:200 mg of rock powder was dissolved by the same methoddescribed above using triple distilled HF and 16 N HNO3. Thesample was taken up in 5 ml dilute HNO3 and centrifuged. 1 mlpurified BaNO3 solution was added to the supernatant for Pbcoprecipitation. The precipitate was taken up in 1.5 N HC1 and230loaded into an anion exchange resin column (5 cm long 0.5 cmwide) for Pb separation by 1.5 N HC1 and H20 elution.A silica gel - phosphoric acid loading method was usedwhen measuring the Pb isotopic ratios on a VG — MM3O massspectrometer at the University of Alberta. The 2a precisionestimated from duplicated runs is 0.10%, 0.15%, and 0.16% for206Pb/4, 207Pb/4, and 208Pb/4 respectively. Errorcorrelations between any two of these ratios are 0.8. Pbstandard NBS-98l gave average ratios, +1- 2a, of 16.940 +1-0.003, 15.495 +/— 0.003, and 36.731 +/— 0.017 for 206Pb/4,207Pb/4, 208Pb/4, respectively. Blank for the totalprocedure is 2 ng.231


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