西南三江造山带早古生代岩浆事件及其对原特提斯大洋演化的响应  

Early Paleozoic magmatic event in the Sanjiang orogenic belt in southwest China and its response to the evolution of the Proto-Tethyan Ocean

作　　者：尹福光[1] 徐波 王冬兵[1] 王保弟[1] 唐渊[1] YIN Fuguang;XU Bo;WANG Dongbing;WANG Baodi;TANG Yuan(Chengdu Center,China Geological Suvey,Chengdu 610081,Sichuan,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：《地质通报》2021年第6期817-826,共10页Geological Bulletin of China

基　　金：中国地质调查局项目《西南基础地质综合调查与片区总结》(编号:1212011220412);《地质调查综合智能编图系统与应用》(编号:DD20190415)。

摘　　要：西南三江造山带由多条缝合带及其间多个大小不等的中间地块构成,大地构造位置处于欧亚板块和印度板块结合部位的特提斯构造域东段。在福贡县马吉乡古当河片麻状花岗岩、保山怒江坝镇西片麻岩、永德变质流纹岩、漕涧花岗岩岩体、西盟花岗片麻岩、澜沧基性-中基性火山岩中分别获得SHRIMP锆石U-Pb年龄为465±5 Ma、512±7 Ma、510±16 Ma、441~457Ma、454~456 Ma、456~459 Ma,结合前人的西南三江地区早古生代岩浆岩年龄数据,昌宁-孟连特提斯大洋东西两侧都有中—晚奥陶世侵入岩,岩石地球化学特征表明,侵入岩具岛弧特征。昌宁-孟连特提斯大洋西缘的保山地块内部及东部有寒武纪火山岩,具双峰式特征,为拉张环境形成,表明特提斯大洋在寒武纪还在扩张。至中奥陶世,构造体制开始转变,大洋板块向东、西两大陆开始俯冲,在其大陆边缘形成岛弧。The Sanjiang orogenic belt in southwest China is composed of several sutures and many intermediate massifs of different sizes.It is tectonically located in the eastern part of Tethys structural domain where Eurasia plate and India plate joint.Zircon U-Pb dating of samples collected from Gudanghe gneissic granite, Nujiangba Town gneiss, Yongde metamorphic rhyolite, Caojian granite, Ximeng granitic gneiss and Lancang basic medium basic volcanic rocks in Maji Town of Fugong County yielded 465±5 Ma, 512±7 Ma, 510±16 Ma, 441 ~ 457 Ma, 454 ~ 456 Ma, 456 ~ 459 Ma respectively. Combined with the age data of the early Paleozoic magmatic rocks in th Sanjiang area, Southwest China, middle Late Ordovician intrusives with island arc characteristics were emplaced on the east and west sides of the Changlian-menglian Tethys Ocean.The Cambrian volcanic rocks with two peaks in the interior and east of Baoshan massif in the western margin of Changlian-Menglian Tethys ocean revealing tension environment indicate that the Tethys ocean existed in Cambrian and is still expanding. In the Middle Ordovician, the tectonic system began to change, and the oceanic plates began to subduct toward east and west, forming island arcs on the continental margin.

关 键 词：三江 早古生代 岩浆事件 大地构造 

分 类 号：P534.4[天文地球—古生物学与地层学] P588.11[天文地球—地质学]