Lithofacies palaeogeography and sedimentary evolution of Ordos Basin and its periphery

The sedimentary evolution of the Ordos Basin began in the Mesoproterozoic, characterized by the development of continental marginal rift and intracontinental aulacogen. During this time, clastic rocks of the coastal facies and tidal flat carbonatites were deposited. In the Neoproterozoic, the basin evolved into a continental margin graben-type depression, resulting in the deposition of clastic rocks indicative of a stagnant environment, glacial sediments, and shelf clastic rocks. Throughout the Early Paleozoic Cambrian and Ordovician periods, the cratonic basin primarily accumulated shallow marine carbonates, with a trench-arc-basin system distributed along its southwestern margin. Following the uplift and denudation related with the Caledonian orogeny, the sedimentary evolution of North China Craton depression basin commenced. During the Late Carboniferous and Early Permian periods, the Ordos area was dominated by epicontinental sea deposits, succeeded by nearshore clastic lake basin from the late Early Permian to the Middle Triassic. From the Yanchang Period of the Middle-Late Triassic to the Early Cretaceous, the Ordos Basin underwent significant development and ultimately evolved into a large-scale, differentiated inland sedimentary basin. The Upper Triassic, Jurassic, and Lower Cretaceous strata primarily composed of fluvio-deltaic-lacustrine clastic rocks, accumulated during the slow subsidence of the Ordos Basin. In the Cenozoic, Ordos Basin entered the stage of peripheral fault development, with the successive accumulation of fluvial, lacustrine and aeolian deposits. The sedimentary evolution processes reveal the complex geological history and diverse sedimentary environments of the Ordos Basin.