恒山杂岩中变基性岩包体的同位素年代学和地球化学研究

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	恒山杂岩中变基性岩包体的同位素年代学和地球化学研究
	常向阳
	1991
学位授予单位	中国科学院地球化学研究所
学位授予地点	中国科学院地球化学研究所
学位名称	博士
摘要	在前人有限工作的基础上，选择恒山杂岩，特别是其中的变基性岩包体，以多种同位素地质年代学方法，多元同位素体系制约关系和同位素示踪理论，结合岩石化学，微量元素地球化学对以下问题做出重点研究：1、通过对杂岩，特别是其中的包体的岩石化学，微量元素地球化学和Sm-Nd、RB-Sr、Pb-Pb同位素年代学方法以及Nd-Sr-Pb同位素体系的研究，恢复其原岩类型，判别其所处的构造环境，确定它们的形成时代和其它地质事件发生的时代；2、提出本区早前寒武纪年代地层划分的初步方案；3、讨论区域地壳形成演化历史。
其他摘要	Hengshan Complex——Archean metamorphic assenblage which is located in Hengshan region, northern Shanxi province, China, is the link between Sanggan River granulite-gneiss terrains and Wutaishan greenstone granite terrains. metamorphic basic rocks are common and generally occur as the enclaves typical of grey gneisses. Metamorphic basic rocks plus grey gneisses could represent an early Archean bimodal suite. The protolithes of metamorphic basic rocks are tholeiitic rocks from island are or continental margin, according to differentiation from petrochemical and trace element geochemical diagrams. Sm-Nd, Rb-Sr, Pb-Pb geochronological studies indicate that there existed an old continental crust in Hengshan region Metamorphic basic rocks were formed about 2700Ma ago and quite soon undergone granulite facies metamorphism during Fuping Movement, and retrogressed to amphibolite facies assemblages about the end of Archean (2300Ma) ago during Wutai Movement Heterogeneity of source probably is the reason why Sm-Nd isochron age is too old. Based on the review of precambrian geochronologic and chronostratigraphic division norm, I advance my opinion on early precambrian geochronologic and chronostratigraphic division of Hengshan region, and 2300Ma is the age of demarcation line of Archean-Proterozoic. Tectonic overprintings of subduction zone reflected by Nd-Sr-Pb isotopic systems indicate that there existed probably plate motion during Archean.
页数	65
语种	中文
文献类型	学位论文
条目标识符	http://ir.gyig.ac.cn/handle/352002/3840
专题	研究生_研究生_学位论文
推荐引用方式 GB/T 7714	常向阳. 恒山杂岩中变基性岩包体的同位素年代学和地球化学研究[D]. 中国科学院地球化学研究所. 中国科学院地球化学研究所,1991.

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