龙门山北段矿山梁构造解析及其油气勘探

Structural analysis of Kuangshanliang in the northern Longmenshan fold-thrust belt and its hydrocarbon exploration

矿山梁构造是龙门山冲断带北段典型的前锋构造之一,经历了晚三叠世和新生代两期构造挤压变形。矿山梁构造几何学上表现为一个双重构造:浅层是一个晚三叠世形成的断层转折褶皱;深层则是在新生代形成的三个逆冲岩片叠置所构成的隐伏堆垛背斜构造。深部构造的发育改造了上覆晚三叠世形成的浅层构造。矿山梁构造的有利勘探部位是深部的隐伏冲断构造,尤其是新生代构造变形中最早形成的构造岩片即岩片1,但该构造能否具有较好的油气潜力则取决于深部构造顶部滑脱层的封堵能力。分析认为新生代形成的隐伏冲断构造是龙门山冲断带前锋带中油气勘探的新领域。

The Kuangshanliang area in the northern Longmenshan fold-thrust belt,experienced two episodes of tectonic deformations in the Late Triassic and the Cenozoic, The key structure in this area is a duplex that comprises of a shallow fault-bend fold of the Late Triassic and a deep blind stacking anticline imbricated by three thrust sheets of Cenozoic age. The deep structure may provide a possible field in Kuangshanliang area where hydrocarbon potential is restrained by the fault-seal capacity of the roof-thrust fault （F1）. We suggest that the blind thrust structures in the Cenozoic can be a potential for hydrocarbon exploration in the front of Longmenshan fold-thrust belt.