六盘山盆地构造变形分析:来自地震剖面的约束

    Tectonic deformation analysis of Liupanshan Basin: Constraints from seismic profiles

    • 摘要: 六盘山盆地先后经历早古生代克拉通碳酸盐岩台地、古生代海陆交互、中生代内陆湖盆等过程,发育石炭系、三叠系—侏罗系和白垩系3套烃源岩,是当下可拓展的油气有利区之一。但是,该盆地所处大地构造位置特殊,受青藏高原、阿拉善、鄂尔多斯等块体相互作用,经历多期构造运动,发育大量褶皱与断裂等构造,地壳结构及盆地属性经历强烈改造,在一定程度上制约了六盘山盆地油气资源评价和有利区带优选。基于此,选择六盘山盆地3条关键地震剖面,结合野外构造变形特征和钻井信息,讨论了六盘山盆地中生代以来多期构造事件下的盆山演化过程,主要包括中生代早期(三叠纪/侏罗纪)局部伸展断陷,早白垩世早期挤压与晚期伸展,新生代以来受青藏高原增生扩展,六盘山地区强烈挤压,造就了现今六盘山褶皱逆冲带。

       

      Abstract: The Liupanshan Basin has undergone multi−processes such as Early Paleozoic craton carbonate platform, Paleozoic marine to terrestrial, and Mesozoic lacustrine environment, developing three sets of hydrocarbon source rocks: Carboniferous, Triassic−Jurassic, and Cretaceous. It is one of the potential target areas for new hydrocarbon exploration. However, located in such a critical tectonic location, Liupanshan basin is affected by the interaction of multiple blocks such as the Qinghai Tibet Plateau, Alxa, and Ordos. It has undergone multiple tectonic periods, developed numerous folds and faults, and undergone high modifications in crustal structure and basin properties, seriously hindering the hydrocarbon evaluation and target zones selection. Based on this, this study uses three key seismic profiles from the Liupanshan area and comprehensively analyzes the basin mountain evolution process. The main processes include early Mesozoic (Triassic/Jurassic) local extensional faulting, early Early Cretaceous compression and late Early Cretaceous extension. Since the Cenozoic era, the Liupanshan Basin has been strongly compressed by the Qinghai Tibet Plateau growth, creating the current Liupanshan fold and thrust belt.

       

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