老挝琅勃拉邦构造带石英闪长岩锆石U-Pb定年:古特提斯洋东向俯冲启示  

Zircon U-Pb dating of quartz-diorite from Luang Prabang tectonic belt in Laos:Implication for eastward subduction of the Paleo-Tethys Ocean

作　　者：郭林楠 侯林[1] 聂飞[1] 刘书生[1] 徐思维 张启明[1] GUO Linnan;HOU Lin;NIE Fei;LIU Shusheng;Xu Siwei;ZHANG Qiming(Chengdu Center,China Geological Survey,Chengdu 610081,China)

机构地区：[1]中国地质调查局成都地质调查中心,四川成都610081

出　　处：《沉积与特提斯地质》2020年第1期68-75,共8页Sedimentary Geology and Tethyan Geology

基　　金：中国地质调查局地质调查项目“东南亚大型锡铜金矿资源基地评价”(DD2019444);“老挝、柬埔寨及邻区矿产资源潜力评价”(DD20160107)的资助。

摘　　要：老挝琅勃拉邦构造带位于印支板块西部,是东南亚特提斯域内的重要构造带之一。该地区多期次的岩浆活动记录了多阶段的构造岩浆演化,但与古特提斯洋闭合过程相关的岩浆活动报道相对较少,导致与该过程相关的构造-岩浆-成矿作用关系理解不清。本文在野外地质观察和岩相学研究的基础上,对老挝琅勃拉邦地区石英闪长岩开展了锆石U-Pb LA-ICP-MS定年,分析结果表明,石英闪长岩结晶年龄为260.5±1.8 Ma,表明琅勃拉邦构造带存在中晚二叠世岩浆活动。结合前人研究结果,本文认为该中酸性侵入体很可能是古特提斯洋板片东向俯冲,难河-沙缴弧后盆地关闭过程中岩浆活动的产物,且为琅勃拉邦构造带向南连接至难河-程逸结合带提供了新资料。The Luang Prabang tectonic belt in Laos is located in the western of Indo-China Plate,and it is one of the important tectonic belts in Southeast Asia-Tethys domain.Multi-stage magmatic activities in this area recorded multi-stage tectonic-magmatic evolutions.However,there are few reports on magmatic activity related to the closure process of Paleo-Tethys Ocean,thus the relationship of tectonic evolution-magmatism-metallogenesis in the process remain controversial.Based on field geological observations and petrographic studies,this article carried out zircon U-Pb LA-ICP-MS dating of quartz diorite in Luang Prabang,Laos.The results show that the crystalline age of the quartz diorite is 260.5±1.8 Ma,indicating a Middle-Late Permian magmatic activity in the Luang Prabang tectonic belt.Combine with previous studies,we believe the medium-acid intrusive rock is likely to be the product of magmatic activity during the eastward subduction of the Paleo-Tethys Ocean-plate and closure of the Nan-Sra Kaeo backarc basin.It also provides new data indicating that the Luang Prabang tectonic zone may link to the Nan-Uttaradit to the south.

关 键 词：锆石U-PB定年 琅勃拉邦构造带 石英闪长岩 古特提斯洋 

分 类 号：P597.3[天文地球—地球化学]