通过室内测井数据分析和野外露头观察测量,结合前人研究成果,对鄂尔多斯盆地南部中奥陶世马家沟期的岩相古地理进行了研究。中奥陶世的马家沟组沉积期间,华北海发生了广域性海侵,研究区的碳酸盐岩台地及潮坪主导了沉积相。在总的海侵背景下,跟随华北海变迁过程,形成了马一、马三、马五段相对海退期和马二、马四、马六段的相对海进期碳酸盐岩台地云灰坪相沉积。由于研究区南部位于华北海西南隅,同时也受来自秦岭-祁连海水的侵进和鄂尔多斯古隆起的影响,所以华北韵律海升降造成的三云三灰岩互层变化不很典型,但在平面上,不同时期的沉积微相以及岩性分布存在差异。 Through the logging data analysis and outcrop observation in the field, the lithofacies palaeogeography of the Middle Ordovician Majiagou period in the southern Ordos Basin was studied based on the previous research results. During the sedimentation of the Middle Ordovician Majiagou Formation, a wide-area transgression occurred in the North China Sea. The carbonate platform and the tidal flat dominated the sedimentary facies in the study area. Under the background of total transgression, following the change of North China Sea, the relative sea-receding carbonate platforms of the Mahai, Ma3 and Ma5 Member relative sea returns and the Ma2, Ma4 and Ma6 Member Plaster deposition. As the southern part of the study area is located in the southwestern part of the sea in the North China Sea and influenced by the encroachment of Qinling-Qilian seawater and the Ordos paleo-uplift, the inter-stratification of the Sanyun limestone caused by the rising of the North China rhythm sea is not typical. However, There are differences in the distribution of sedimentary microfacies and lithology in different periods.