| 冀东三屯营地区片麻岩的早太古宙全岩年龄 |
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| 引用本文： | 刘武旭,M.F.Thirlwall.冀东三屯营地区片麻岩的早太古宙全岩年龄[J].吉林大学学报(地球科学版),1992(1). |
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| 作者姓名： | 刘武旭 M.F.Thirlwall |
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| 作者单位： | 长春地质学院
(刘武旭)，伦敦大学R.H.B新立学院(M.F.Thirlwall) |
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| 摘 要： | 冀东三屯营地区麻粒岩相片麻岩由三组中酸性岩石组成。三组片麻岩Pb-Pb全岩等时线年龄为。三组片麻岩也各给自出了早太古宙年龄。岩石的这一年龄,是麻粒岩相变质过程中U和Th亏损之后发生均匀化的结果,因而表明麻粒岩相的变质作用结束于3563Ma之前。岩石在3563～2500Ma期间处于角闪岩相的环境。文中还给出了全岩Rb-Sr同位素的年龄成果,为2500～2800Ma。
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| 关 键 词： | 冀东 片麻岩 早太古宙 铅铅等时线 同位素年龄 |
EARLY ARCHAEAN WHOLE-ROCK ISOCHRON OF GNEISSES IN SANTUNYING, EASTERN HEBEI, CHINA |
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| Liu Wuxu M. F. Thirlwall.EARLY ARCHAEAN WHOLE-ROCK ISOCHRON OF GNEISSES IN SANTUNYING, EASTERN HEBEI, CHINA[J].Journal of Jilin Unviersity:Earth Science Edition,1992(1). |
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| Authors: | Liu Wuxu M F Thirlwall |
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| Institution: | Liu Wuxu M. F. Thirlwall(Changchun Univ. of Earth Science) (R. H. B. New College of London Univ. ) |
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| Abstract: | Archaean high-grade complex in Santunying of Qianxi,eastern Hebei,is dominantly composed of three Gneisses, Santunying Gneiss (Q-dioritic), Xiaoguanzhuang Gneiss (Q-dioritic) and Qiuhuayu Gneiss (tonalitic-trondjhimatic). The whole-rock Pb-Pb isochron of the three Gneisses produces an age of 3563+134- 145 Ma with a primary source *=9. 71.The three Gneisses also present ages around 3500 -3700 Ma respectively within errors. The Pb isotope system was homogenised among the Gnefsses after their depletion of U and Th under a granulite facies metamorphism. This is the earliest isochron age ever obtained from the Plutonic Gneisses in the Craton of North China.Whole-rock Rb-Sr isotopic system is also studied which snows ages around 2500 -2800 Ma with relatively high MSWD values which hint the system was homogenised poorly between the samples at end of Archaean.The isotope study suggests that granulite facies did not affect the Gneisses as a regional metamorpism after 3563Ma and an amphibolite facies dominated the terrain between 3563-2500. The initial isotopic rations show the sources of the Gneisses were Mantle. |
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| Keywords: | eastern Hebei gneiss early Archaean Pb-Pb isochron isotopic age |
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