藏北羌塘中部冈玛错—日湾茶卡地区下石炭统望果山组的建立及其地质意义  

The establishment of Early Carboniferous Wangguoshan Formation in Gangmar Co-Riwanchaka area, central Qiangtang, Tibetan Plateau

作　　者：许伟[1] 李才[1] 江庆源 胡培远[1] 吴浩[1] 解超明[1] 

机构地区：[1]吉林大学地球科学学院,吉林长春130061

出　　处：《地质通报》2014年第11期1696-1701,共6页Geological Bulletin of China

基　　金：国家自然科学基金项目(批准号:41272240;41072166;41273047);中国地质调查局项目(编号:1212011221093;12120113036700)

摘　　要：望果山组是发育在龙木错—双湖—澜沧江板块缝合带内的一套早石炭世基性—酸性火山岩沉积地层,以火山角砾岩、火山凝灰岩、安山岩及流纹岩为主,夹少量玄武岩,具有多旋回式喷发的特点,被下石炭统日湾茶卡组整合覆盖,总体为一套近火山口相的海相火山岩沉积地层,表现出扬子型地层的亲缘性。在青山梁地区获得的望果山组安山岩的LA-ICP-MS锆石U-Pb年龄为350Ma±1Ma,结合下石炭统日湾茶卡组砂岩碎屑锆石的最年轻年龄峰值(362Ma),认为望果山组应形成于早石炭世杜内阶。望果山组的建立对龙木错—双湖构造地层区地层系统的完善,以及探讨龙木错—双湖—澜沧江洋的演化历史等具有重要的地质意义。The Wangguoshan Formation developed in the Lungmu Co-Shuanghu Lake-Lancang River suture zone is a suite of Early Carboniferous basic-acid volcanic sedimentary strata consisting of volcanic breccia,volcanic tuff,andesite,rhyolite and minor basalt, has the features of polycyclic eruption,and is conformably overlain by the Early Carboniferous Riwanchaka Formation. On the whole, these strata are a set of marine facies volcanic sedimentary strata near the volcanic vent and exhibit Yangtze attribute. The andsesite of the Wangguoshan Formation in the Qingshanliang area has a LA-ICP-MS U-Pb zircon concordia age of 350Ma ± 1Ma. In combination with the youngest peak numerical value of sandstone detrital zircon in the Early Carboniferous Riwanchaka Formation, the authors hold that the Wangguoshan Formation should have been formed in the Early Carboniferous Tournaisian. The establishment of the Wangguoshan Formation has important geological significance for the completion of the stratigraphic system in Lungmu Co-Shuanghu tectonic-stratigraphic area and the discussion of the evolutionary history of the Lungmu Co-Shuanghu-Lancang River Ocean.

关 键 词：青藏高原 望果山组 火山岩沉积地层 早石炭世 LA-ICP-MS锆石U-PB年龄 

分 类 号：P534.45[天文地球—古生物学与地层学] P539.2[天文地球—地质学]