The Growth of Archean Continental Crust in Aqtashtagh Area of Southeast Tarim, China: Constraints from Petrochemistry and Chronology about Milan Group and TTG-Gneiss
详细信息
- 责任者：Xin Houtian (China University of Geosciences ; Beijing 100083 ; China) ; Liu Yongshun
- 刊名：Earth Science Frontiers
- 出版年：2013
- 卷期：20(1)
- 关键词：片麻岩 ; gneisses ; 陆壳 ; continental crust ; 塔里木盆地 ; Tarim Basin
- 页码：p.240-259
- 图表：illus., 4 tables, 71 refs.
- 分类号：0802
- issnNo：ISSN1005-2321
- isbnNo：CN11-3370/P
摘要
In Aqtashtagh,southeastern margin of Tarim Basin,there are relatively well-preserved early Precambrian basement metamorphic rocks-Aqtashtagh complex,consisting of Milan Group,Neoarchean TTG gneisses and paleoproterozoic granitic gneiss intruding into them.With rheomorphic folding,Milan Group and TTG underwent high-amphibolite to granulite facies metamorphism,intensive migmatization and later alteration of amphibolite facies metamorphism.Their geochemical characteristics-low Si and Na,high Al and K content,enriched in LILEs and LREE,depleted in HFSE and HREE,heavy fractionation between LREE and HREE,and no obvious Eu anomaly,indicate that they are products of arc basalt melting after subducting beneath the lower continental crust.The zircon U-Pb SHRIMP ages of them are 2567±32 Ma and 2592±15 Ma respectively,suggesting that they are formed from the same magma stage,and hinting the assembly of Tarim Craton in the late Neoarchean and horizontal crust growth similar to the Japan arc model in southeastern margin of Tarim Craton in Wutai stage.Moreover,many xenocrystals of zircon with ages ranging from 2.67 to 2.8 Ga and two generation metamorphic zircon with the ages of 2.35-2.4 Ga and 1.9-2.0 Ga reflect the major magmatic event in the middle Neoarchean and the cratonization of Tarim platform in the Paleoproterozoic.