鄂尔多斯盆地西南缘上奥陶统平凉组岩石特征及沉积环境

为研究鄂尔多斯盆地西南缘上奥陶统平凉组岩石特征及沉积环境，基于沉积学相关理论和方法，根据野外露头、古生物及粒度分析等资料，对研究区岩石特征、沉积相及主控因素开展了研究。结果表明：①研究区平凉组可划分3种岩相和2种岩相组合。②通过综合研究岩性、古生物、沉积构造及粒度参数等资料，确定平凉组沉积环境为深水斜坡。③沉积相为海底扇，在此基础上可划分为中扇和下扇2个亚相，近端朵叶和远端朵叶2个微相。④海底扇的主控因素为相对海平面升降、构造运动和物源供给。

Petrological Characteristics and Sedimentary Environment of the Upper Ordovician Pingliang Formation in the Southwestern Margin of Ordos Basin

In order to study the petrological characteristics and sedimentary environment of the Upper Ordovician Pingliang Formation in the southwest margin of Ordos basin, the petrological characteristics, sedimentary facies, and main controlling factors of the study area were studied by using sedimentology theories and methods based on outcrops, paleontology and grain–size analysis data. The result shows that: ① The Pingliang Formation in the study area can be divided into three lithofacies and two lithofacies associations. ② Based on an analysis of the lithologic character, sedimentary structure, palaeobiologic fossils and grain size parameters, it is believed that the sedimentary environment of Pingliang Formation is mainly deep–water slope. ③ The sedimentary facies is submarine fan, which can be further divided into two subfacies (middle fan and lower fan) and two microfacies (proximal lobe and distal lobe). ④ The main controlling factors of submarine fan include relative sea level, tectonic movement and provenance supply.