济阳坳陷内的负反转构造及其石油地质意义

济阳坳陷是中国东部一个重要的中新生代含油气盆地,过去一直认为该盆地为纯张裂成因,但近来盆地内负反转构造的发现和研究表明,该盆地在中生代发育早期曾经历了负反转、正反转交替的发育阶段,并总体呈现为负反转盆地特征。本文研究了负反转构造的类型和特征,识别出“薄底型”和“秃底型”两类负反转褶皱和“似正断层型”、“上正下逆混合型”等两类、4小类负反转断层;探讨了盆地与负反转构造的形成与演化,并指出了其在盆地成因、构造带演化、复式油气聚集带型式及油气藏形成与预测等诸多方面具有的重要意义。

NEGATIVE INVERSION STRUCTURE IN THE JIYANG DEPRESSION AND ITS PETROLEUM GEOLOGICAL SIGNIFICANCE

The Jiyang Depression is an important Mesozoic-Cenozoic petroliferous basin in East China. In the past, it is always considered as a pure tensional fault basin. However, the latest descovery of negative inversion structure in the basin and its study show that the basin experienced alternate negative inversion and positive inversion stages in the early development period of the Mesozoic, and presents the characteristics of negative inversion structure on the whole. In this paper, the types and characteristics of negative inversion structure are studied, the "thin based" and "bald based" two types of negative inversion folds as well as "paranormal fault type" and "upper normal and lower reversed mixed type" two categories and four subcategories of negative inversion faults are identified, and the formation and evolution of the basin and the negative inversion structure are discussed. It is pointed out that the negative inversion structure has important significance to basin genesis, tectonic belt evolution, complex hydrocarbon accumulation belt patterns, pool formation and prediction, etc.