Temporo‐spatial Coordinates of Evolution of the Ordos Basin and Its Mineralization Responses

Abstract: The Ordos basin was developed from Mid‐Late Triassic to Early Cretaceous, and then entered into its later reformation period since the Late Cretaceous. Its main body bears the features of an intra‐cratonic basin. The basin also belongs to a multi‐superposed basin which has overlapped on the large‐scale basins of the Early and Late Paleozoic. Currently, Ordos basin has become a residual basin experienced reformation of various styles since the Late Cretaceous. It's suggested that there were at least four obvious stages of tectonic deformations existing during the basin's evolution, dividing the evolution and sedimentation into four stages. The prior two stages were of the most prosperous, during which the lake basin was broad, the deposition range was more than twice larger than the current residual basin, resulting in major oil‐ and coal‐bearing strata. The two stages were separated by regional uplift fluctuations in the area. At the end of the Yan'an Stage, the depositional interruption and erosion were lasting for a short period of time. The third one is the Mid‐ Jurassic Zhiluo‐Anding stage, in which the sedimentation extent was still broad but the lake area was obviously reduced. In the Late Jurassic tectonic deformation was intensive. A thrust‐nappe belt was formed on the basin's western margin while conglomerate of different thickness were accumulated within the foredeep of the eastern side. The central and eastern parts of the basin were subject to erosion and reformation. A regional framework with “uplift in the east and depression in the west” took shape in the area west of the Yellow River. In the Early Cretaceous sediments were widely distributed, unconformably overlapping the former western margin thrust belt and the ridges on the northern and southern borders. There are abundant energy resources such as oil, natural gas, coal and uranium deposits formed in Ordos Basin. The main stages of generation, mineralization and positioning of the multiple energy resources have obvious responding connection and close coupling relationships with those of the Mesozoic and Cenozoic evolution and reformation in Ordos Basin.