西藏改则东上侏罗统-下白垩统沙木罗组沉积环境分析

Sedimentary Environment Analysis for Sha Mu Luo Formation of Upper-Jurassic to Lower- Cretaceous,Eastern Gaize,Tibet

研究区位于青藏高原腹地改则县境内,大地构造归属于班公湖-怒江-昌宁-孟连对接带内,包含南羌塘残余弧盆地。北部为北羌塘-甜水海陆块,南部为冈底斯陆块。论文以改则地区侏罗纪-早白垩纪沙木罗组为研究对象,在野外踏勘与实测剖面调查基础上,通过地层划分对比、沉积相分析方法,建立盆地充填序列,进而探讨控盆机理与大地构造背景。通过研究确定沙木罗组时代为晚侏罗世-早白垩世。沙木罗组分为混积陆棚相和斜坡相。认为晚侏罗世-早白垩世班公湖-怒江洋为残余海盆地。

The research area is in Gaize, located in the hinterland of Qinghai-Tibet Plateau. The location in geotectonic belongs to combination belt of Bangong lake- Nu river-Changning-Menglian, including residual arc basin of south Qiangtang. North Qiangtang-Tian shui sea plate in north and Gangdese plate in south. This paper concentrate on the Shamuluo formation of Jurassic- Early Cretaceous in Gaize, in the hinterland of Qinghai-Tibet Plateau. On the basis of field reconnaissance and measured profile, by differenciating ＆amp; contrast of layers and sedimentary facies analysis, we have built the order of basin filling, then discuss the mechanism of basin controlling and geotectonic background. With research, the Shamuluo formation’s time is fixed between later Jurassic and early Cretaceous. Shamuluo formation contains continental shelf face with complex sediments and continental slope face. We propose that the ocean of Bangonghu-Nu river is residual basin of ancient ocean.