鄂尔多斯盆地及周缘岩相古地理与沉积演化

Lithofacies palaeogeography and sedimentary evolution ofOrdos Basin and its periphery

鄂尔多斯盆地的沉积演化起始于中元古代,发育陆缘裂谷和陆内拗拉槽,沉积滨海相碎屑岩和潮坪相碳酸盐岩,新元古代盆地性质为大陆边缘地堑型坳陷,沉积滞留海盆碎屑岩、冰水沉积物组合及陆棚碎屑岩;早古生代寒武纪和奥陶纪的克拉通盆地主要沉积浅海碳酸盐岩,在西南缘发育沟-弧-盆体系;经过加里东运动抬升剥蚀后,开始了华北克拉通坳陷盆地的沉积演化过程,晚石炭世和早二叠世发育了陆表海沉积,早二叠世晚期—中三叠世形成了近岸碎屑湖盆沉积;中晚三叠世延长期至早白垩世,鄂尔多斯盆地最终形成,进入大型内陆差异沉积盆地的形成和发展时期,上三叠统、侏罗系和下白垩统是在鄂尔多斯盆地缓慢沉降过程中堆积的以河流-三角洲-湖泊相为特征的陆源碎屑岩系;新生代进入周边断陷发育阶段,先后发育河流-湖泊及风成沉积。这一系列沉积演化过程揭示了鄂尔多斯盆地复杂的地质历史和多样的沉积环境。

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.