鄂东南地区印支期以来构造变形特征及油气意义

利用区域地震大剖面及MT资料,结合地面地质调查成果,对鄂东南地区的深部地质结构及典型构造样式进行了分析,认为该区发育以基底岩系顶面和志留系顶面为主滑脱面的大型逆冲推覆构造,并识别出双重逆冲构造、叠瓦状构造、台阶式结构、对冲构造及反冲断层等典型构造样式;同时对上下地质结构的变异进行了探讨,提出志留系滑脱层之下的“原地体”具有变形相对较弱、褶皱宽缓开阔的特点,在后期拉张改造中受到上盘“异地体”的保护,应是有利的油气勘探领域,双重逆冲构造内部发育的断层相关褶皱(如随阳构造)是重点勘探目标。

TECTONIC DEFORMATION SINCE INDOSINIAN PERIOD AND ITS SIGNIFICANCE FOR HYDROCARBON IN SOUTHEAST HUBEI

Based on a combination of the regional seismic sections with surface geologic surveys, we analyzed the deep geologic architecture and typical tectonic styles in Southeast Hubei. There occurred a large-scale thrust-nappe system, and its two main decollement units are Silurian surface and middle Proterozoic surface. Typical tectonic styles such as duplex of thrust-nappe, imbricated structure, bedding step model, opposite thrust structure and backthrust etc. were identified. Meanwhile, we discussed differentiation in geologic architecture between upper and lower strata and concluded that the "original geobody" under the Silurian detached layer, which is characterized by relatively weak deformation, and broad, gentle folds, should be favorable for hydrocarbon exploration, due to the protection by the "foreign geobody" in the upside during the latter extensional reformation, and especially, the intra duplex of fault-relative folds (e.g. Suiyang fold) should be the key exploration target.