CLASSIFICATION AND TECTONIC CHARACTERISTICS OF BURIED HILLS IN THE SOUTH YELLOW SEA BASIN

The South Yellow Sea Basin, built upon the pre-Nanhua metamorphic basement of the Lower Yangtze platform, is a polycyclic basin with a type of sandwich architecture. The geologic evolution of the basin can be divided into three stages:the Nanhua-early and middle Triassic marine basin stage, the late Cretaceous-Paleogene graben fault basin stage and the Neogene-Quaternary depression basin stage. Buried hills are well developed due to complicated geological evolution of the Basin. Based on the former researches on buried hill classification and combined with the interpretation results of seismic profiles, this paper systematically studied the types of buried hills in the South Yellow Sea Basin and described the tectonic characteristics of typical buried hills. According to origin, buried hills can be divided into erosional, extensional, compressive and complex types. Based on shape, each type of buried hills could be further divided into erosional remnant, tilted fault block, step-fault block, fault horst, compressive fold, arch fold and fold-fault block hills. Buried hills are distributed in a zonal pattern in the basin. According to the structural position in the basin, a fault depression basin can be divided into convex buried hill belt, inner depression buried hill belt, steep slope buried hill belt and gentle slope buried hill belt. There are many types of buried hills in each buried hill belt. The researches indicated that Paleozoic and Mesozoic buried hills are well developed in the South Yellow Sea Basin and could be an important type of reservoir.