祁连造山带及邻区前寒武纪深变质基底的时代和组成
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引用本文:万渝生,许志琴,杨经绥,张建新.2003.祁连造山带及邻区前寒武纪深变质基底的时代和组成[J].地球学报,24(4):319-324.
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作者单位E-mail
万渝生 中国地质科学院地质研究所北京100037 wanysh@21cn.com 
许志琴 中国地质科学院地质研究所北京100037  
杨经绥 中国地质科学院地质研究所北京100037  
张建新 中国地质科学院地质研究所北京100037  
基金项目:国家自然科学基金项目(49732070)
中文摘要:本文对祁连造山带及邻区前寒武纪深变质基底变泥砂质岩石和壳源花岗质岩石的地质、年代学、地球化学和Nd同位素组成进行了研究。主要结论为:①祁连造山带深变质基底主要由变泥砂质岩石和壳源花岗岩组成,主体形成于0.8~1.0Ga(晋宁期);②大多数变泥砂质岩石和壳源花岗岩具有较强的负铕和负钡异常,tDM和εNd(1.0Ga)分别为1.87~2.26Ga和-8.54~-4.06,显示出较高的成熟度;③花岗质岩石为典型的陆—陆碰撞产物,可能与全球新元古代Rodinia超大陆形成事件有关。本文还探讨了祁连造山带及邻区深变质基底的构造归属,认为祁连—柴北缘地体和阿拉善—敦煌地体在晋宁期以前相互分离,分属华北克拉通和扬子地台不同的板块体系。祁连造山带和秦岭造山带至少在晋宁期就有相同或相似的演化历史。
中文关键词:祁连造山带  年代学  Nd同位素  地球化学  前寒武纪基底
 
The Precambrian High-grade Basement of the Qilian Terrane and Neighboring Areas: Its Ages and Compositions
Abstract:Based on geological, chronological, geochemical and Nd isotopic studies of the high-grade basement of the Qilian terrane, the authors have drawn the following main conclusions: (1) the high-grade basement of the Qilian terrane consists mainly of meta-argillo-arenaceous rocks and granites and its bulk part was formed in the period of 0.8-1.0 Ga (the Jinningian period);(2)most of the meta-argillo-arenaceous rocks and granitic rocks have strong negative Eu and Ba anomalies (Eu/Eu * = 0.47-0.71 and Ba/Ba * = 0. 16 - 0.64), with tDMand εNd(1.0 Ga) ranging from 1.87 to 2.26 Ga and from -8.54to -4.06 respectively, showing relatively high maturity; and (3) the Jinningian granitic rocks seem to be a typical product of continent-continent collision, probably related to the formation of the supercontinent Rodinia. The above understanding, combined with the study of high-grade basement rocks near the Qilian terrane, has led the authors to believe that the Qilian-Qaidam northern-margin terrane and Dunhuang-Alxa terrane were separated from each other before the Jinningian period, belonging respectively to the plate system of the North China craton and that of the Yangtze platform. The Qilian orogenic belt was the same as or similar to the Qiling orogenic belt in terms of the geological evolution history at least before the Jinningian period.
keywords:Qilian orogenic belt  chronology  Nd isotope  geochemistry  Precambrian basement
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