The First Discovery of Early Carboniferous Gabbro in Xiongcun Area on the Southern Margin of Lhasa Terrane, Tibet: Remnants of Paleo-Tethys Ocean?
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摘要: 拉萨地块是研究特提斯洋形成演化和青藏高原陆内汇聚作用的关键地区,前人对拉萨地块中新生代构造演化过程进行了大量的研究,而对于古生代演化阶段研究较为薄弱.本文以拉萨地块南缘雄村矿集区新发现的辉长岩为研究对象,对雄村辉长岩进行锆石LA-ICP-MS U-Pb定年,探讨其反映的构造意义.雄村辉长岩中锆石LA-ICP-MS U-Pb年龄为(341.55±0.89)Ma,表明其形成于早石炭世.结合区域地质演化过程,认为早石炭世雄村辉长岩可能是古特提斯洋的残留,新的年龄数据将为研究拉萨地块和特提斯洋的演化过程提供重要的约束.Abstract: Lhasa terrane is a key area in studying the formation and evolution of Paleo-Tethys and the intra-continental convergence in the Tibetan Plateau. Lots of precious studies have been devoted to the Cenozoic geological evolution process in Lhasa terrane; nevertheless, the study of the Paleozoic evolution remains very insufficient. Focusing on the newly found Early Carboniferous gabbro in Xiongcun area on the southern margin of Lhasa terrane, the authors conducted zircon LA-ICP-MS U-Pb dating for gabbro in Xiongcun area, and investigated its tectonic significance. Zircon LA-ICP-MS U-Pb age of Xiongcun gabbro is (341.55±0.89) Ma, indicating that it was formed in Early Carboniferous epoch. Combining with the regional geological evolution process, the authors consider that Early Carboniferous Xiongcun gabbro might be the remnant of Paleo-Tethys Oceanic crust, and the newly presented dating data would provide significant constraint for studying the evolution process of Lhasa terrane and Paleo-Tethys Ocean.
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Key words:
- Lhasa terrane /
- Gangdise /
- gabbro /
- Paleo-Tethys Ocean /
- Xiongcun /
- Tibet
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