班公湖-怒江板块缝合带发现侏罗纪洋岛型岩石组合  

The discovery of the Jurassic OIB-type rocks in the Bangong Lake-Nujiang River suture zone

作　　者：巴桑玉珍[1] 李才[1] 徐梦婧[1] 徐建鑫[1] 范建军[1] 

机构地区：[1]吉林大学地球科学学院,长春130061

出　　处：《地质通报》2013年第4期563-566,共4页Geological Bulletin of China

基　　金：国家自然科学基金项目<羌塘中部早古生代蛇绿岩及其构造意义>(批准号:41072166);<青藏高原申扎地区寒武系及泛非-早古生代造山事件研究>(批准号:41272240);中国地质调查局项目<西藏达查沟1:5万地质调查>(编号:1212011121248)

摘　　要：那东洋岛大地构造位置位于班公湖-怒江板块缝合带西段,洋岛型岩石组合平行于蛇绿混杂岩带南侧展布,夹持于侏罗系木嘎岗日群之中。那东洋岛玄武岩与木嘎岗日群复理石砂板岩呈过渡接触关系。那东洋岛岩石组合主要由3种岩石组成:玄武岩、玄武质砾岩、灰岩或礁灰岩,那东洋岛的岩石组合具有多旋回性。对那东洋岛中的玄武岩进行地球化学分析,玄武岩为OIB型玄武岩。以往研究认为班公湖-怒江洋盆在侏罗纪处于大洋演化阶段,那东洋岛的发现对揭示班公湖-怒江洋在侏罗纪的演化历史具有重要意义。Nadong oceanic island is located in the western part of the Bangong Lake-Nujiang River suture zone. It occurs as an EW- trending belt in parallel with ophiolite and is associated with the Jurassic Muga Kangri Group. There exists transitional contact relation- ship between the OIB-type basalts and the flysch of the Muga Kangri Group. The OIB-type rocks are composed of basalt, basaltic conglomerate, limestone and/or reef limestone. Furthermore, these rocks display several volcanic eruption cycles. Geochemical data show that all the basalts have typical OIB features. Studies have also shown that a Jurassic ocean basin existed in the Bangong Lake- Nujiang River suture zone. Thus the discovery of the Nadong oceanic island plays a key role in revealing the evolutionary history of the Bangong-Nujiang Ocean during the Jurassic.

关 键 词：青藏高原 班公湖-怒江缝合带 那东洋岛 构造演化 

分 类 号：P534.52[天文地球—古生物学与地层学]