| 鄂尔多斯盆地西缘马家滩地区的构造样式与圈闭分布规律 |
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| 引用本文：何登发,邵东波,开百泽,包洪平,傅定伍,朱昊,马静辉.2019.鄂尔多斯盆地西缘马家滩地区的构造样式与圈闭分布规律[J].地球学报,40(1):219-235. |
| DOI：10.3975/cagsb.2018.100801 |
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| 基金项目:国家自然科学基金重点项目(编号: 41430316; 40739906);国家科技重大专项(编号: 2017ZX05001-001) |
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| 中文摘要:鄂尔多斯盆地西缘冲断带是我国南北构造带的重要组成部分, 是阿拉善地块与鄂尔多斯地块之间陆内构造变形的产物, 研究其地质结构与构造样式是探讨陆内构造变形机制的基础, 同时也是剖析地震活动与开展油气勘探的重要依据。本文基于该区近年来新的钻井、高精度二维与三维地震资料, 应用构造解析方法, 研究构造变形样式及圈闭分布特点。研究表明, 马家滩地区地处鄂尔多斯盆地西缘冲断带中段, 经历长期的伸展—聚敛旋回演化, 是贺兰山—六盘山陆内造山带变形系统的一部分。马家滩地区的地质结构具有“分带、分层、分段”特征, 自西向东发育后缘伸展带(银川地堑)、逆冲推覆构造带(包括韦州—苋麻湾冲断席、石沟驿向斜)、前缘过渡带和天环凹陷; 前缘过渡带以石炭—二叠系煤层或泥岩为区域滑脱层分为上、下构造变形系统, 下构造变形系统向西缓倾, 发育低幅度背斜; 上构造变形系统发育三排断层相关褶皱背斜带, 向南变窄, 上构造变形系统因滑脱层发育差异而南、北分段, 二者之间斜向过渡转换。马家滩地区及邻区主要发育伸展-聚敛旋回制约的反转构造系统、陆内造山变形制约的扩展式前陆变形系统和后陆造山后伸展变形系统等3种构造变形系统; 前缘过渡带上部构造系统经历印支晚期、燕山期和喜马拉雅期三期变形, 形成不同期次、不同方向的叠加构造。马家滩地区发育断层传播褶皱、双重构造、叠瓦构造、构造楔和反冲断裂组合(冲隆构造)等构造样式, 形成断背斜、断鼻及断块等油气圈闭类型, 圈闭分布受断层控制呈带展布。马家滩地区构造圈闭发育, 为西缘油气勘探的有利远景目标区。 |
| 中文关键词:陆内变形 分层滑脱 断层相关褶皱 构造样式 油气圈闭 马家滩地区 鄂尔多斯盆地西缘 |
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| Structural Style and Trap Distribution in Majiatan Area on the Western Margin of Ordos Basin |
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| Abstract:The thrust belt on the western margin of Ordos basin is an important element of the North-Southward Tectonic Zone in China, resulting from the intra-continental structural deformation between the Alax continental block and the Ordos continental block. The study of the geological architecture and structural style is not only a basis for exploring the mechanism for intra-continental deformation but also the key reference for addressing the earthquakes and the petroleum exploration. Based on the new boreholes, high-resolution 2-D and 3-D seismic data around this area, the authors investigated the structural deformation style and the oil and gas trap distribution by utilizing the method of structural analysis. It is shown that the Majiatan area is located in the middle segment of the thrust belt on the western margin of Ordos basin. Being a part of the Helanshan–Liupanshan intra-continental orogenic belt, it underwent a prolonged evolution from extension to compression. The geological architecture in this area is characterized by zonation, multi-level stratification, and segmentation. It has developed in the hinterland the extensional zone (i.e. the Yingchuan graben), the thrust and nappe structural zone (including the Weizhou–Xianmawan thrust sheet and the Shigouyi syncline), the foreland transitional zone, and the Tianhuan depression. The foreland transitional zone can be subdivided into the lower and the upper structural deformation systems by the regional detachment level of the Carboniferous to Permian coal or mudstone intervals. Dipping shallowly to the west, the lower one developed low-relief anticlines, while the upper one developed three belts of fault-related folding anticline, narrowing southward. The upper one is characterized by the south-northward segmentation due to the differentiation in detachment layers with the oblique transferring or transition. The Majiatan region and its adjacent areas are dominated typically by the three kinds of deformation, i.e., the inverted structural system controlled by the extensional-compressive cycle, the propagation deformation in the foreland system controlled by the intra-continental orogenic deformation, and the post-orogenic extensional system in the hinterland. The upper structural system in the foreland transitional zone underwent three periods of deformation, i.e., the late Indo-sinian, the Yanshanian, and the Himalayan tectonic movements, and gave rise to the superimposed structures of different periods in the varied direction. It has many types of structural styles such as the fault-propagation fold, the duplex, the imbricate, the tectonic wedge, and the backthrust composition (i.e. pop-up structure), with the faulted-anticline, the faulted-nose, and the fault blocks as the main oil and gas traps. The oil and gas traps are distributed in zonation owing to the fault array. The structural traps are especially well developed in Majiatan area, which is therefore the favorable prospective area for hydrocarbon exploration on the western margin of Ordos basin. |
| keywords:intra-continental deformation multi-level detachment fault-related folding structural style oil and gas trap Majiatan area western margin of Ordos basin |
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