Subduction and Collision of the Jinsha River Paleo-Tethys: Constraints from Zircon U-Pb Dating and Geochemistry of the Ludian Batholith in the Jiangda–Deqen–Weixi Continental Margin Arc  

作　　者：HE Juan WANG Baodi WANG Qiyu 

机构地区：[1]Chengdu Center,China Geological Survey,Chengdu 610081,China [2]College of Earth Sciences and Engineering,Shandong University of Science and Technology,Qingdao,Shandong 266590,China

出　　处：《Acta Geologica Sinica(English Edition)》2020年第4期972-987,共16页地质学报（英文版）

基　　金：funded by a grant from the National Key R&D Program of China(Grant No.2018YFC0604106 and 2016YFC0600305);the Program of the China Geological Survey(Grant No.DD20190053)。

摘　　要：The Jiangda–Deqen–Weixi continental margin arc(DWCA) developed along the base of the Changdu–Simao Block and was formed as a result of the subduction of the Jinsha River Ocean Slab and the subsequent collision. The Ludian batholith is located in the southern part of the DWCA and is the largest batholith in northwest Yunnan. Granite samples from the Ludian batholith yield an early Middle Permian age of 271.0 ± 2.8 Ma. The geochemical data of the early Middle Permian granitoids show high Si2 O, low P2 O5 and MgO contents that belong to calc-alkaline series and peraluminous I-type rocks. Their εHf(t) values range from-5.01 to +0.58, indicating that they were formed by hybrid magmas related to the subduction of the Jinsha River Tethys Ocean. The monzonite and monzogranite samples yield Late Permian ages of 250.6 ± 1.8 Ma and 252.1 ± 1.3 Ma, respectively. The Late Permian granitoids are high-K calc alkaline and shoshonite series metaluminous I-type rocks. Their εHf(t) values range from-4.12 to-1.68 and from-7.88 to-6.64, respectively. The mixing of crustal and mantle melts formed the parental magma of the Late Permian granitoids. This study, combined with previous work, demonstrates the process from subduction to collision of the Jinsha River Paleo-Tethys Ocean.

关 键 词：I-type granite Ludian batholith Jinsha River Paleo-Tethys Jiangda–Deqen–Weixi continental margin arc 

分 类 号：P597.3[天文地球—地球化学] P542[天文地球—地质学]