Petrogenesis of the Qiongduojiang Gabbro in Tethys Himalaya and Its Metallogenetic Implication
2023
Jianzhong Li | Yong Huang | Qingsong Wu | Li Zhang | Tao Xiong | Bing Wang | Zhiqiang Liang | Huawen Cao | Wei Liang | Zuowen Dai
With the northward subduction and final closure of the Neo-Tethyan oceanic crust, the Indian and Eurasian plates finally collided together and underwent a strong collision orogenic event, resulting in large-scale crust&ndash:mantle magmatic interactions. In order to clarify the controversies about tectono-magmatic activities after the Indian&ndash:Eurasian continental collision, we report the newly dated Eocene Qiongduojiang gabbro explored in the Tethyan&ndash:Himalaya belt, southern Tibet. LA-ICP-MS zircon U-Pb dating shows that the crystallization age of the Qiongduojiang gabbro is 46.1 ±: 1.7 Ma. The whole-rock major and trace elements, as well as Rb-Sr, Sm-Nd, and Pb isotopic data results, show that the Qiongduojiang gabbro is apparently depleted in Nd isotopes, is enriched in Pb isotopes, and has maintained a consistent 87Sr/86Sr(t) value. This paper argues that the E-MORB-like Qiongduojiang gabbro originated from asthenosphere upwelling caused by slab breakoff of the Neo-Tethyan oceanic plate. This event caused large-scale magmatic activities, a magmatic mixing process between ancient crust and deep mantle, and wild distribution of Eocene Gangdese plutons along the Yarlung&ndash:Tsangpo Suture Zone, and it rendered the subduction-modified Tibetan lithosphere fertile from the Gangdese porphyry Cu deposits.
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