鄂尔多斯盆地西缘上奥陶统拉什仲组深水等深流沉积

为缩小等深流沉积研究中的现代海洋研究与地层记录研究之间的不平衡和探索中-晚奥陶世鄂尔多斯盆地西缘大洋环流体系在海相深水油气勘探中的意义，在详细的野外观测的基础上，对有关沉积构造进行了古水流和流体动力学分析.结果表明:（1）非水道环境下约有1/3的小型交错层理古水流方向与区域斜坡方向垂直；（2）水道环境下普遍发育双向递变沉积构造，包括平行层（沙纹层）-均匀层-平行层（沙纹层）、条纹条带和双向粒序层3种类型.上述特征可解释为深水斜坡环境下的等深流沉积，并识别出非水道型和水道型2类，后者又分为部分改造型和完全改造型2亚类. 

Deep-Water Contour Currents Deposits of Upper Ordovician Lashizhong Formation in Western Margin of Ordos Basin

In order to reduce the gap between contemporary oceanographic studies and geological records in the study area of deep-water contour currents deposits, and to explore the significance of ocean circulation system on marine deep water oil and gas exploration in Middle to Upper Ordovician of western margin of Ordos basin, it was perform paleo-currents-analyses and hydrodynamics using sedimentary structures based on detailed field observations. The results show that:(1)There are 1/3 small cross beddings with paleo-currents directions perpendicular to the regional slope direction; (2)sedimentary structures with bi-directional progressive grain-size change are ubiquitous in deep-water turbidity currents channel, which include parallel (ripple laminae)-homogeneous-parallel (ripple laminae) sequence, stripped-and-banded structures and inverse to normal grading sequence (grain size). All these sedimentary characteristics maybe suggest the deep-water contour currents deposits according to the perpendicular flow direction and the rhythmic lithologic properties which coincide with the period of contour currents. Here it was also recognized two contourites types:deep-water non-channel contourites and turbidity currents channel contourites, and the latter includes two subtypes with partial reaction and entire reaction.