鄂尔多斯盆地西南缘晚三叠世早期沉积体系分析

依据露头剖面实测及钻井资料，运用岩相古地理研究方法，从盆地构造演化背景分析入手，综合蚀源区与沉积区岩石粒度、轻重矿物组合特征、剖面古流向特征、沉积构造现象及古生物特征，对该区晚三叠世早期沉积体系进行了剖析。认为该区晚三叠世早期存在着两个不同的沉积体系，即来自西部古陆粱区物源的扇三角洲沉积体系和来自南部秦岭物源区的辩状河三角洲沉积体系；不同沉积体系沉积模式不同，砂体展布特点不同。辨状河三角洲前缘砂体沿分流河道方向稳定性好，有利于石油大规模聚集。而扇三角洲有利砂体在桐川西南的向源方向。

Analyzing sedimentary system of early stage of late Triassic in southwest of Ordos basin

According to 4 sections of outcrop and 86 drill cores, using the palaeogeography research approach, starts with analysis of the background of constructing and evolving of the basin, synthesizes the characters of provenance and sedimentary province rock particles, the distribution characteristics of light and heavy minerals, the sections characteristics of paleocurrent direction, sedimentary structure phenomena and paleontology characteristics, and analyzes sedimentary systems in early stage of late Triassic in this district.Considering in this district there are two different sedimentary systems in early days of late Triassic, namely GuLuLiang district proved fan delta from the west and QinLing provenance braided delta from the south. Different sedimentary systems have different modes of sendimentary facies and distribution characteristics of sand bodies.The sand bodies in the foreside of braided delta has good stability along distributary channel and is in favor of oil accumulation. And fan delta is in favor of the distribution of sand bodies in southwest of Tongchuan.