Geochronology and petrogenesis of Eocene gabbros and granitic rocks of the eastern Gangdese belt, southern Tibet: Implications for the timing of India-Asia collision
Geochronology and petrogenesis of Eocene gabbros and granitic rocks of the eastern Gangdese belt, southern Tibet: Implications for the timing of India-Asia collision
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藏南冈底斯带东部始新世辉长岩和花岗岩的年代学和岩石成因：对印度-亚洲碰撞时间的启示
DOI：
10.1016/j.gr.2021.05.019
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发表时间：
2021-09
影响因子：
6.1
通讯作者：
Zhao Y.-Y.
中科院分区：
文献类型：
--
作者：
Shui X.-F.;Klemd R.;He Z.-Y.;Mao J.-W.;Zhao Y.-Y.
古新世-始新世（66-41 Ma）是藏南冈底斯带大规模岩浆活动最强烈的时期。然而，这条岩浆带的岩浆来源和构造背景一直是一个讨论了几十年的问题。本文对冈底斯造山带东段加查地区始新世辉长岩和花岗质岩石进行了锆石年代学和地球化学研究。激光烧蚀-ICP-MS锆石U-Pb定年结果表明，两种岩石的结晶年龄几乎同步，为50-47 Ma。地球化学特征表明，辉长岩具有较低的稀土元素总量和较高的锆石εHf（t）正值（+8.4 ~+15.0），表明其母岩浆来自同位素亏损的地幔。花岗质岩石为含镁钙碱性-钙质花岗岩，锆石εHf（t）值变化较大（+3.0 ~+10.8），表明岩浆是幔源岩浆分异作用的产物，古地壳物质的贡献也不相同。此外，扩大的66-41 Ma深成岩和共存的林子宗火山岩数据库揭示了从镁铁质岩到镁铁质岩的演化趋势。锆石Hf和Nd同位素组成随着全岩SiO2的增加而更加演化。66-41 Ma深成岩和林子宗火山岩的全岩和同位素地球化学研究表明，它们的形成和演化背景为活动大陆边缘环境。因此，我们认为，冈底斯带是与新特提斯洋板块俯冲在整个早始新世，从而意味着最初的印度-亚洲碰撞发生后~ 41 Ma。
The Palaeocene-Eocene (66–41 Ma) hosts the most intense stage of extensive magmatism in the Gangdese belt of southern Tibet. However, the magma sources and tectonic setting of this magmatic belt have been a matter of discussion for decades. In this study, we conducted zircon geochronological and geochemical studies on Eocene gabbroic rocks and granitic rocks from the Jiacha area in the eastern Gangdese belt. Laser ablation-ICP-MS zircon U–Pb dating suggests almost synchronous crystallization ages of 50–47 Ma for both rock types. Geochemically, the gabbroic rocks have low total rare earth elements and high positive zirconεHf(t) values (from +8.4 to +15.0), indicating that the parental magma was derived from an isotopically depleted mantle. The granitic rocks are magnesian calc-alkalic to calcic granites that are characterized by variable zirconεHf(t) values (from +3.0 to +10.8), indicating that the magmas were generated by differentiation of a mantle-derived magma with variable contributions from ancient crustal materials. Furthermore, an enlarged database of 66–41 Ma plutonic rocks and coexisting Linzizong volcanic rocks reveals an evolutionary trend from mafic to silicic rocks. The zircon Hf and Nd isotopic compositions become more evolved with increasing whole-rock SiO2. The whole-rock and isotope geochemistry of the 66–41 Ma plutonic rocks and the Linzizong volcanic rocks indicate an origin and evolution of these rocks in an active continental margin setting. Therefore, we argue that the Gangdese belt was associated with the subduction of the Neo-Tethyan Oceanic plate throughout the Early Eocene, thereby implying that the initial India-Asia collision occurred after ~ 41 Ma.
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影响因子：
3.5
作者：
Lin Ma;Qiang Wang;Zheng‐Xiang Li;D. Wyman;Zi-qi Jiang;Jin-Hui Yang;Guo-Ning Gou;H. Guo
通讯作者：
Lin Ma;Qiang Wang;Zheng‐Xiang Li;D. Wyman;Zi-qi Jiang;Jin-Hui Yang;Guo-Ning Gou;H. Guo
影响因子：
6.1
作者：
Yuanku Meng;Zhiqin Xu;M. Santosh;Xuxuan Ma;Xijie Chen;G. Guo;Fei Liu
通讯作者：
Yuanku Meng;Zhiqin Xu;M. Santosh;Xuxuan Ma;Xijie Chen;G. Guo;Fei Liu
影响因子：
3.5
作者：
Larocque, Jeff;Canil, Dante
通讯作者：
Canil, Dante
影响因子：
3.5
作者：
Lili Yan;Zhengjun He;C. Beier;R. Klemd
通讯作者：
Lili Yan;Zhengjun He;C. Beier;R. Klemd
藏南曲须侵入杂岩的岩浆混合起源：拉萨南部地下早始新世岩浆作用和地球动力学的见解
影响因子：
3.5
作者：
Wang Rui Qiang;Qiu Jian Sheng;Yu Si Bin;Lin Lei;Xu Hang
通讯作者：
Xu Hang