摘要:长城系是鄂尔多斯盆地太古界—古元古界统一的结晶基底形成后所发育的最早期的沉积盖层，主要形成于区域拉张的裂陷构造背景下，在盆地内部发育多个东北向延伸的次级裂陷槽，并伴随有同构造期的基性岩浆活动。综合分析认为，长城系主要发育海相陆源碎屑建造，而在充填深海、半深海—海湾沉积的裂陷槽区，可能发育有效的海相烃源层；长城系沉积后，盆地大部分地区处于长达9～10亿年的抬升剥蚀环境，利于在其顶部形成大面积分布的风化壳储层；对长城系埋藏史分析表明其具有跨越大构造期而晚期成藏的热演化史，并未发生区域变质而遭破坏，在盆地本部地区具有有利的成藏构造保存条件；深层长城系是下一步天然气勘探值得期待的潜在层系，而勘探的关键是针对盆地本部的次级裂陷槽部署探井以确证长城系烃源岩的有效性。
关键词: 鄂尔多斯盆地/
长城系/
元古界烃源岩/
超大陆裂解/
裂谷充填
Abstract:The Changcheng System is the earliest sedimentary caprock developed after the formation of Archean Paleoproterozoic crystalline basement in Ordos Basin, which is mainly formed in the context of regional extensional rifting structure. In the basin, there are many secondary rifting troughs extending to the northeast, accompanied by basic magmatic activities in the syntectonic period. According to the comprehensive analysis, the Changcheng System mainly developed marine terrigenous clastic formation, while in the rift trough area filled with deep-sea, bay and semi deep sea sediments, it was possible to develop effective marine source beds; After the deposition of the Changcheng System, most areas of the basin were in a uplift and denudation environment about 900 million to 1 billion years, which was conducive to the formation of a large area of weathered crust reservoir at the top of the Changcheng System. The analysis of burial history of the Changcheng System shows that it has a thermal evolution history of great leap tectonic period and late accumulation without regional metamorphism and destruction, and has favorable conditions for reservoir formation and preservation in Ordos Basin; The Changcheng System is a potential stratigraphic system to be expected of the next natural gas exploration in the deep system of the basin. The key of exploration is to arrange wells for the secondary rifting troughs in the basin to confirm the effectiveness of the source rocks of the Changcheng System.
Key words:Ordos Basin/
Changcheng System/
Source rock in proterozoic/
Breakup of supercontinent/
Rift filling
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