Magmatic and Metamorphic Events Recorded in Granitic Gneisses from the Qimantag, East Kunlun Mountains, Northwest China
详细信息
- 责任者：Meng Fancong (State Key Laboratory for Continental Tectonics and Dynamics ; Institute of Geology ; Chinese Academy of Geological Sciences ; Beijing 100037 ; China) ; Cui Meihui
- 刊名：Acta Petrologica Sinica
- 出版年：2013
- 卷期：29(6)
- 关键词：花岗质片麻岩 ; granitic gneiss ; 昆仑山 ; Kunlun Mountains
- 页码：p.2107-2122
- 图表：illus., 5 tables, 75 refs.
- 分类号：0802
- issnNo：ISSN1000-0569
- isbnNo：CN11-1922/P
摘要
SHRIMP and LA-ICP-MS U-Pb analyses of zirons from granitic gneisses from Jinshuikou Group in the East Kunlun Mountains Qimantag belt indicate magmatic crystallization at 938 ± 5Ma and 938 ±2Ma. Major elements,trace elements,and Sm-Nd isotopic data also indicate that all these Early-Neoproterozoic granites are characterized by the features of crust-derived and typical continent-continent syn-collisional granites. We infer that source of the granites similar to Baishahe Formation of the Proterozoic Jinshuikou Group. ( Meta-) granitoids of similar ages,1000～900Ma,occurred in further eastern segment of East Kunlun,the North Qaidam terrane and the Altyn Tagh Fault,suggesting this magmatic activity is widespread,that might be related to the assemble of different blocks,marking basement formation of Neoproterozoic craton in the North west China; this event might be the response of the formation of Rodinia Supercontinent. Zircon rims in one of these samples yield younger ages (416 ± 11Ma) compatible with zircon from Silurian-Divonian granites.40 Ar /39 Ardating of muscovite from granitic gneisses is 406 ±2Ma. These ages revealed distinct metamorphic and cooling events of Early-Neoproterozoic granitesduring Silurian-Divonian. This tectono-thermal event is related to the closure of the Qimantag oceanic basin or marginal sea basin.
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