鄂尔多斯盆地古生代原型盆地演化与构造沉积格局变迁

鄂尔多斯古生代盆地是在前寒武系裂陷体系上发育起来的克拉通盆地，经历了早古生代克拉通边缘拗陷和晚古生代克拉通内拗陷两个阶段。其中早古生代克拉通边缘拗陷阶段可细分为早—中寒武世张夏期、晚寒武世三山子期—早奥陶世亮甲山期、中奥陶世马家沟期、晚奥陶世平凉期—背锅山期等4个阶段；晚古生代克拉通内拗陷可细分为晚石炭世—早二叠世、中—晚二叠世等2个阶段。古生代盆地从早寒武世—中奥陶世被动大陆边缘伸展转变为晚奥陶世—二叠纪主动大陆边缘，构造变革受周缘大地构造体制转变控制，内部构造沉积格局具有从寒武纪早期西南“L”型伸展裂陷、中—晚寒武世“坳—坡—隆—坪”、奥陶纪“坳—坡—隆—坳”、石炭—二叠纪“一隆两坳”逐步演化的特征。古生代原型盆地演化和构造—沉积格局变迁过程中，派生了多套烃源岩和储层，其中盆地西—南缘持续沉降区域发育寒武系苏峪口组—辛集组、徐庄组、奥陶系平凉组、石炭—二叠系煤系烃源岩，盆地内部沉降区发育奥陶系徐庄组、马家沟组、石炭—二叠系煤系烃源岩；下古生界中央古隆起两侧古斜坡区发育张夏组高能鲕粒滩、克里摩里组生物礁滩—颗粒滩、马家沟组颗粒滩等有效储层。 

Evolution of prototype basin and change of tectonic-sedimentary pattern in Paleozoic,Ordos Basin

The Ordos Basin is a craton basin developed based on the Precambrian rift system during Permian. It has experienced two stages of evolution including the Early Paleozoic craton marginal depression and Late Paleozoic intra-craton depression. The former can be further divided into four periods, including the Zhangxia period of Early to Middle Cambrian, the Sanshanzi period of Late Cambrian to the Liangjiashan period of Early Ordovician, the Majiagou period of Middle Ordovician, and the Pingliang-Beiguoshan period of Late Ordovician. The latter can be further divided into two periods, including Late Carboniferous to Early Permian and Middle to Late Permian. Controlled by the transformation of surrounding tectonic system of North-China blocks, the Paleozoic Ordos Basin evolved from passive continental margin extension in the Early Cambrian and Middle Ordovician to active continental convergence in Late Ordovician and Permian. The internal tectonic sedimentary pattern gradually evolved from a "L-shaped" extensional rift in the southwest of the basin during Cambrian, to "depression-slope-uplift-plateau" druing the Middle-Late Cambrian, to "depression-slope-uplift-depression" during Ordovician, and to "one uplift and two depressions" duringJP] Carboniferous to Permian. During the evolution of Paleozoic prototype basin and the change of tectonic-sedimentary pattern, several sets of source rocks and reservoirs were derived. In the continuously subsiding region on the western and southern margin of the basin, coal-measure source rocks deposited in Cambrian Suyukou-Xinji formations, Xuzhuang Formation,JP]Ordovician Pingliang Formation, Carboniferous and Permian. In the subsiding region inside the basin, coal-measure source rocks deposited in Ordovician Xuzhuang Formation, Majigou Formation, Carboniferous and Permian. Effective reservoirs, such as high-energy oolitic beach of Zhangxia Formation, bioreef-granule beach of Krimori Formation and granulate beach of Majiagou Formation, were developed in the western and eastern paleoslope areas of the central paleouplift of the Paleozoic Ordos Basin.