青藏高原羌塘盆地东部鄂尔陇巴组火山岩的锆石SHRIMP U-Pb年龄及其地质意义  

Zircon SHRIMP U-Pb age of volcanic rocks in E'erlongba Formation,eastern part of the Qiangtang basin,Qinghai-Tibet Plateau,China and its geological significance

作　　者：付修根[1] 王剑[1] 谭富文[1] 陈明[1] 王进军[1] 杜伯伟[1] 陈文彬[1] 

机构地区：[1]中国地质调查局成都地质矿产研究所,四川成都610081

出　　处：《地质通报》2009年第5期561-567,共7页Geological Bulletin of China

基　　金：国家油气专项<青藏高原油气资源战略选区调查与评价>项目(编号:XQ2004-06);国家自然科学基金(编号:40702020)资助

摘　　要：藏北羌塘盆地东部地区三叠系巴贡组之上沉积超覆了一套火山岩-火山碎屑岩.该套地层下部玄武岩的锆石SHRIMPU-Pb年龄明显可以分为2组,一组年龄相对年轻(220.4Ma±2.3Ma),代表了羌塘东部地区鄂尔陇巴组火山岩的喷发年龄;另外一组年龄相对较老(241.4Ma±3.6Ma),可能与中三叠世羌塘地区普遍存在的碰撞隆升事件有关。羌塘中生代(晚三叠世—早白垩世)盆地演化早期的沉积作用经历了由陆相至海相的超覆过程,沉积超覆作用从冲洪积相开始,伴随着岩浆侵入、火山爆发及火山碎屑沉积作用,总体上表现为一个向上变深的海侵序列,显示裂谷盆地的特征。A suite of volcanic rocks to volcaniclastic rocks overlie the Triassic E＇erlongba Formation in the eastern part of Qiangtang basin, northern Xizang, China. The SHRIMP zircon U-Pb ages of the lower basalt from this strata can be categorized into two groups： 220.4±2.3 Ma and 241.4±3.6 Ma respectively. The former represents magma emplacement age of the E＇erlongba Formation volcanic rocks in the eastern part of the Qiangtang basin region, while the latter is related to collision and upli~ events during Middle Triassic period. Early stage sedimentation of basin evolvement during Mesozoic went through an overlapping process from continental to marine facies, sedimentary overlap started from the alluvial/fluvial facies, along with intrusion, eruption and pyroclaistic sedimentation, reflecting a upward deepened transgression sequence, which indicates a rift basin.

关 键 词：锆石SHRIMP U-PB年龄 沉积超覆 火山-沉积事件 鄂尔陇巴组火山岩 羌塘盆地东部 

分 类 号：P597.3[天文地球—地球化学] P534.51[天文地球—地质学]