鄂尔多斯盆地保德地区上古生界沉积相与沉积演化特征

山西组与下石盒子组是鄂尔多斯盆地上古生界主要的勘探目的层系，本溪组和太原组发育的煤层是主要的烃源岩，深入研究上古生界沉积相及沉积演化特征对油气勘探具有一定的指导意义。以保德地区扒楼沟剖面露头实测为基础，通过岩性和岩石组合、沉积相分析，建立了不同沉积体系的沉积序列，并进一步探讨了该区上古生界沉积演化过程。结果表明:保德地区上古生界自下而上发育本溪组、太原组、下石盒子组、上石盒子组、石千峰组，识别出障壁海岸、碳酸盐台地、曲流河和辫状河4种沉积相，并建立8种典型的沉积序列；受区域构造演化控制，本溪组与太原组时期发生大规模海侵，山西组至石千峰组时期海水逐渐退出盆地，研究区晚古生代经历了障壁海岸-碳酸盐台地-河流相的沉积演化过程。

Sedimentary Facies and Their Evolution in the Upper Paleozoic of Baode Area,Ordos Basin

Shanxi Formation and Xiashihezi Formation of Upper Paleozoic in Ordos Basin are the main exploration target zone. Coal seams of Benxi Formation and Taiyuan Formation are the main source rocks. The study of Upper Paleozoic sedimentary facies and evolution characteristics has some guidance significance for the oil and gas exploration. Based on the field measurement of Palougou outcrop profile in Baode area, by analyzing lithology and rock-association as well as the sedimentary facies, sedimentary sequences of different sedimentary systems have been built, and the sedimentary evolution of Upper Paleozoic in this area has been studied. The results show that the formations of Upper Paleozoic (Benxi Formation, Taiyuan Formation, lower Shihezi Formation, upper Shihezi Formation and Shiqianfeng Formation)develop from bottom to top in Baode area and 4 types of sedimentary facies (barrier beach, carbonate platform, meandering river and braided river) are identified as well as 8 typical sedimentary sequences. Controlled by the regional tectonic evolution, a large-scale seawater invasion takes place at the age of Benxi Formation and Taiyuan Formation, then seawater withdrawn from the basin gradually from Shanxi Formation to Shiqianfeng Formation. This area of late Paleozoic era experienced depositional process in the order of barrier beach, carbonate platform, and fluvial facies.