Relationship Between Petroleum Accumulation of Mesozoic and Tectonic Movement in Ordos Basin
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摘要: 鄂尔多斯盆地是中国著名的大型中生代含油气盆地,上三叠统延长组和侏罗系延安组为盆地主要含油层系,该含油层系经历了印支、燕山和喜山三期大的构造运动。通过中、新生代不同地质历史时期应力场分析以及构造热事件研究,结合裂缝性质、裂缝方位及裂缝中包裹体特征等,讨论了中生界油气成藏与构造运动的关系。研究认为盆地主要发育E—W向、NNE向和NE向三组区域性裂缝。其中,弱充填的NE向剪裂缝为印支期S—N向挤压环境下形成的剪裂缝,或基底断裂形成的诱导张裂缝;近E—W向展布的弱充填裂缝为燕山期NW—SE挤压环境下形成的剪切裂缝;强烈充填的NNE向张裂缝形成于喜山期NNW—SSE拉张环境。盆地中、新生代地层所经历的每一期构造运动都对盆内油气的运移和聚集起控制作用。印支运动使得盆地沉积了中生界最为重要的一套烃源岩;燕山运动产生的构造热事件使烃源岩达到了生排烃高峰期,使得油气成藏大多定型于燕山期;喜山运动使油气进行大规模的运移和调整,从而使中生界上部油气的分布与基底断裂带走向相吻合。中、新生代这三期构造运动对鄂尔多斯盆地发展和油气成藏产生了重要影响。Abstract: Ordos Basin is the famous petroliferous basin of Mesozoic in China. Yanchang Formation of Upper Triassic and Yan'an Formation of Jurassic are the main oilbearing strata. The oilbearing strata got through IndoChina movement, Yanshanian movement and Himalayan movement. Based on the analyses of the tectonic stress field of Mesozoic and Cenozoic and the research of the tectonic heat events, combined with fracture property, fracture azimuth and characteristic of inclusion in fracture, the relationship between the petroleum accumulation of Mesozoic and tectonic movement was discussed. It is suggested that EW, NNE and NE striking fractures were developed in the basin. Among them, the NE striking shear fractures with thin filled were developed in the SN compression environment in IndoChina period, or the NE striking fractures induced tensional fracture formed by basement fault. The EW shear striking fractures with thin filled were developed in the NWSE compression environment in Yanshanian period.The NNE tensional striking fractures with strong filled were developed in the NNWSSE extensional environment in Himalayan period. Each tectonic movements occured in Mesozoic and Cenozoic controlled the migration and accumulation of the petroleum.Because of the IndoChina movement, Ordos Basin deposited the important hydrocarbon source rock in Mesozoic. The hydrocarbon source rock reached the peak of hydrocarbon generation and expulsion because of the tectonic heat event which was producted by Yanshanian movement, resulting in the petroleum accumulation during Yanshanian period. The petroleum undergone largescale migration and adjustment because of the Himalayan movement led to the petroleum distribution of upper Mesozoic consistent with the trend of basement fracture belt. These three Mesozoic and Cenozoic tectonic movements have signicantly influenced the development of Ordos Basin and hydrocarbon accumulation within it.
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Key words:
- Ordos Basin /
- IndoChina movement
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