Transition of the Late Mesozoic-Cenozoic tectonic regimes and modification of the Ordos basin
ZHANG Yue-qiao1, LIAO Chang-zhen2 (1. Department of Earth Sciences, Nanjing University, Nanjing 210093, Jiangsu, China; 2. College of Earth Sciences and Resources, China Geoscience University, Beijing 100081, China)
The Ordos basin is a large Mesozoic intracontinental basin superimposed on the Paleozoic North China craton. The Late Mesozoic-Cenozoic were an important modification period of the basin, during which significant changes in tectonic regimes occurred and tectonic belts of different trends and styles were formed around the basin. The main phase of the Yanshanian movement that took place during the Mid-Late Jurassic is of great significance for the shaping and development of the Ordos basin. Compressive tectonic belts surrounding the Ordos basin were mostly formed during this Yanshanian phase. During the Early Cretaceous, in response to the tectonic stress regime transition, the Ordos basin was subjected to week extension, and extensional deformation was localized along its SW margin, resulting in the development of the Liupanshan paleo-graben. During the Cenozoic, tectonic deformation mainly occurred around the Ordos basin, resulting in the formation of the grabens. During the Neotectonic movement since the late Miocene or early Pliocene, owing to the influence of the rapid uplift of the Qinghai-Tibet Plateau and its eastward extrusion, the Liupanshan fold belt on the southwestern margin of the Ordos rose rapidly, while extensional deformation and differential uplift and subsidence of the blocks took place in other peripheral zones of the basin. Finally, the paper discusses the basin modification in different tectonic stress regimes and some basic tectonic problems in the study of the Ordos basin.