【作者】 邓昆；

【导师】 周立发；

【作者基本信息】 西北大学 ， 矿产普查与勘探， 2008， 博士

【摘要】 鄂尔多斯盆地中央古隆起的形成与演化在整个盆地的地质构造演化过程中占据着重要地位。它与天然气聚集有着十分密切的关系,控制着古生界油气地质条件,而中央古隆起及其周缘是天然气聚集的有利地区。研究中央古隆起的形成与演化可为古生界天然气藏的勘探提供理论依据和翔实资料。本文重点从以下几个方面展开:不同沉积期中央古隆起的形成演化,中央古隆起主要构造界面演化、古隆起形成演化的地质约束条件、古隆起形成机制及中央古隆起构造演化对古生界油气地质条件的控制等。运用盆地分析、地层学、石油地质学和地球物理学的新理论和新方法,结合华北板块、秦祁海槽、贺兰坳拉谷的形成演化与中央古隆起相互关系的认识,有步骤、分层次地开展《鄂尔多斯盆地中央古隆起形成演化与天然气聚集关系》研究。研究表明:鄂尔多斯及邻区中新元古代整体处于地壳伸展的构造背景,鄂尔多斯盆地内部不存在一个统一的中新元古界盖层,而是由多个相互分隔的盆地与块体组成。新元古纪末的晋宁运动在鄂尔多斯西缘和南缘及其北秦岭的构造表现形式有较大差异。寒武纪开始,鄂尔多斯才逐渐形成统一的地台盖层,中新元古代不存在中央古隆起,相对独立的中央古隆起始于晚寒武世。中央古隆起在马家沟组沉积期反映最为明显,主要表现为马家沟组在镇探2-镇探1-宁探1-灵1中央古隆起顶部缺失,表明了中央古隆起在马家沟期隆升,并遭受长期剥蚀。马家沟期,鄂尔多斯地区中央古隆起、伊盟隆起和三门峡隆起三个古隆起的共存,控制着华北海、祁连海和秦岭海的分布。石炭纪本溪期至二叠纪山西期仍有明显的显示,但古隆起的形态与位置均发生了较大变化与奥陶纪马家沟期的中央古隆起有较大差别。在晚二叠世以来不存在中央古隆起,故晚二叠世以来也不存在一个与前陆盆地系统有关的前缘隆起。就中央古隆起而言,奥陶系项面构造格局在不同构造层转换时期其特征不同,从山西期到延安期经历了从斜坡-低缓隆起-坳陷的构造转换,早白垩世末东隆西坳的格局基本定型。以奥陶系顶面所刻画的中央古隆起显示:中央古隆起仅在晚寒武世-石盒子期末有所显示。通过对宁夏香山群地质特征、北祁连寒武纪-奥陶纪构造背景、北秦岭与鄂尔多斯南缘加里东期花岗岩、秦祁结合带及商丹缝合带等进行探讨,从而为揭示中央古隆起形成演化的构造背景提供佐证。中央古隆起是在伸展构造背景下形成,在挤压构造背景下继续发育。加里东运动早期,西部祁连海槽扩张产生由西向东的挤压应力和加里东运动晚期秦岭海槽自南向北的挤压应力的共同作用形成“L”型古隆起。中央古隆起的形成演化对油气地质条件的控制作用体现在对沉积格局、残余生烃坳陷、储集条件、盖层圈闭条件及油气运聚等几个方面。更多还原

【Abstract】 The Central Paleouplift plays a central role in the formation and tectonic evolution of Ordos Basin, and it is closely related to gas accumulation in the basin. The Central Paleouplift constructions are suitable for hydrocarbon migration and accumulation. This study conducted a multiple disciplinary approach and provides supportive and detailed data for exploration of oil and gas formed during Palaeozoic eon.This study investigated the formation and tectonic evolution of Central Paleouplift in different sedimentary periods, evolution of important tectonic boundaries, geological constraints of tectonic setting, formation mechanism of Central Paleouplift, and their contributions to the basic conditions for oil and gas accumulation. Based on the theory of basin analysis, stratigraphy, petroleum geology, geophysics approaches of this region and the connection among North China Plate, Qin-Qi Trough, He-Lan Aulacogen and Central Paleouplift the Formation and tectonic evolution of Central Paleouplift are clarified such as it is indicated that the background of Mesoproterozoic and Neoproterozoic of Ordos Basin is extensional setting. The whole set of caprocks of Mesoproterozoic and Neoproterozoic basin cannot be observed, but several separated basins and bock can be identified. Besides, Jinning movement happened at the end of Neoproterozoic shows substantial differences at south and western margin of Ordos Basin. The caprock of platform in Ordos Basin as a whole was gradually formed from Cambrian. It implies that Central Paleouplift was nonexistent during Mesoproterozoic and Neoproterozoic, and the Central Paleouplift was formed from the late Cambrian. Its formation was featudred by the Majiagou formation, with the lack of Well Zhentan2- Zhentan1-Ningtan1-Ling1 which experienced long term extrusion and rising stage. Consequently, the distribution of North China Sea, Qi Lian Sea and Qin Ling Sea was influenced by the existence of Central Paleouplift, Yi Meng uplift, San Men Xia uplift. In addition, although Central Paleouplift existed during Benxi age of Carboniferous and Shanxi age of Permian, its structure and setting implies difference in comparison with Majiagou formation. As the Central Paleouplift was nonexistent during the Late Permian, the uplift with relevance to fore deep of foreland basin did not exist. Within the Central Paleouplift, the geological structure of Ordovician top was changed with the evolution of tectonic sequences. The developing stages of Ordovician top surface were characterized by slope, low-angle uplift and depression from Shanxi to Yanan periods. Ordovician top surface failed into a structural pattern of uplift in the east and depression in the west part of Ordos Basin in last stage of early Cretaceous. The Central Paleouplift described by Ordovician top surface was merely present during late Cambrian to last stage of Shihezi. Discussion on characteristics of Xiangshan Group, tectonic setting in Northern Qi-Lian mountains in Cambrian-Ordovician, granites of Caledonian in the north QinLing mountains and the south margin of Ordos Basin, suture zone of Qin-Qi mountains, of Shang-Dan mountains. Evidence could be provided to show tectonic setting of Central Paleouplift. The Central Paleouplift was formed at an extensional setting and developed during the transpressional stage. L-Shaped Paleouplift therefore was formed under compression environment produced by Qi-Lian Trough extension from west to east during the early Caledonian, and in the mean time, the Qin-Ling Trough extension from south to north directions during the late Caledonian.Its relation to gas accumulation in Ordos Basin is also suggested such as Formation and tectonic evolution of Central Paleouplift mainly controlled the development of sedimentary condition, depression for the generation of hydrocarbon, conditions for accumulation, formations of caprock and traps, immigration and storage of oil-gas.更多还原