东海陆架盆地瓯江凹陷构造单元属性讨论

为了明确东海陆架盆地西部瓯江凹陷的构造单元属性，指导下步油气勘探部署，本文在前人中生代构造单元划分和构造演化的研究基础上，开展了地震剖面解释、平衡剖面分析、海陆对比研究等工作。综合研究认为，瓯江凹陷为白垩纪断陷红盆，缺少侏罗纪地层，其断裂构造特征、白垩纪沉积建造和火山岩活动等类似于浙闽隆起带，而瓯江凹陷以东的闽江凹陷为白垩纪和侏罗纪的断坳转换盆地，沉积环境为海陆过渡相—海相。地震剖面上闽江凹陷与其东侧的基隆凹陷构成一个向东倾斜的整体。海陆对比显示，瓯江凹陷与浙闽隆起侏罗纪时均处于隆升剥蚀，白垩纪时均处于断裂拉张。因此，推测瓯江凹陷与浙闽隆起带具有相似的构造单元属性，属于浙闽隆起带的一部分，其中生代的油气资源潜力可能比闽江凹陷差。

Discussion on the tectonic attributes of Oujiang Sag,East China Sea Shelf Basin

In order to make clear the tectonic attributes of the Oujiang Sag in the western part of the East China Sea Shelf Basin so as to guide and arrange the next cycle of oil and gas exploration in the region, on the basis of previously studies on the Mesozoic tectonic division and evolution, seismic profile interpretation, balanced profile analysis and land-sea correlation research are conducted in this paper. Comprehensive study shows that the Oujiang Sag is a faulted Cretaceous red basin in which the Jurassic is missing. The structural characteristics of faults, the Cretaceous sedimentary sequences and magmatic activities in the sag are similar to those observed in the Zhejiang-Fujian uplift belt. The Minjiang Sag to the east of Oujiang Sag is a Cretaceous and Jurassic fault-depression and transformation basin filled with marine-terrestrial transitional facies and marine facies deposits. On the seismic profile, the Minjiang Sag and the Jilong Sag in the east constitute an entirety inclined eastward. Sea-land correlation shows that both the Oujiang Sag and the Zhejiang-Fujian Uplift belt were uplifted and denuded in Jurassic, and suffered from faulting and extension in Cretaceous. Therefore, it is inferred that the Oujiang Sag has similar tectonic attributes with the Zhejiang-Fujian uplift belt, and could be regarded as a part of the Zhejiang-Fujian uplift belt, in which the Mesozoic oil and gas resources potential is worse than that in the Minjiang Sag.