断裂构造在南堡凹陷新生代火成岩形成中的作用

南堡凹陷在新生代有多期次的基性岩浆活动，形成大量玄武岩和少量次火成岩、火山碎屑岩，产状有岩被、岩株、岩床等。火成岩的形成期次及空间分布，与凹陷盆缘断层及基底断层的演化、空间分布规律一致。火成岩分析数据证实，基性岩浆起源于幔源型原生岩浆。凹陷内的深大断裂是上地幔部分熔融后岩浆上涌侵入或喷发的通道。断裂构造活动与基性岩浆形成的同一性，是南堡凹陷内火成岩的形成机制。岩浆活动的高温、高压，有利于源岩生成丰富的油气。广泛分布的火成岩，既可以作为储层，也可以作为盖层。南堡凹陷内已经发现基底深大断裂侧向遮挡，并由该断裂运移岩浆形成的玄武岩被做盖层，形成储量千万吨以上的馆陶组油气藏。

Effect of fault structure on generation of Cenozoic igneous rock in Nanpu sag

Multiphase basic magmatic activities had happened in Nanpu sag in Cenozoic, resulting in a large amount of basalt and a small amount of secondary volcanic and volcanoclastic rocks, with occurrence like rock quilt, stock and sill, etc. The generation periods and space distribution of volcanics had the same law with the evolution and space distribution of basin-margin fault and sole fault. Igneous rock analysis had proved that basic magma originated from mantle-derived primary magma. The deep fracture within the sag was the path of magma upwelling, invasion, or eruption after partially melting of upper mantle. The generation mechanism of volcanics in Nanpu sag was the homogeny of fault movement and forming of basic magma. The high temperature and high pressure magma action was beneficial for generating rich oil and gas in source rock. The extensively distributed volcanics can serve as both reservoirs and caprocks. In Guantao formation of Nanpu sag, a reservoir with reserves over 10 million tons, having lateral screen of the deep sole fracture, with basalt which was generated due to magma migration along the fault as caprock, has been discovered.