Abstract:

The Tanlu fault belt, being a preNeogene giant fault belt located in the marginal Pacific area of East China, can be divided into southern, central and northern segments, and seven subsegments based on the geologic contexture shown in seismic data. In petroleum industry, there are two different views on the belt in terms of effective extension of the belt, i.e. the broad sense of Tanlu fault belt and the narrow sense of Tanlu fault belt. The geological contexture of the broad sense of preNeogene Tanlu fault belt includes two basins separated by the central uplift, and the geological contexture of the narrow sense of Tanlu fault belt consists of a central horst belt and the faults on its both sides. The broad sense of Tanlu fault belt is unacceptable because of its broadening the limitation of Tanlu fault belt and the existence of inversion and flower structures developed both inside and outside of the belt. The general extension of the narrow sense of Tanlu fault belt is NNE, and changes to NE on the south of Jiashan. The preNeogene faults (extending EW, NE and NEE) on both sides of the belt intersect the belt with acute angles. The boundary faults of all Paleogene halfgrabens developed on both sides of the belt from north to south are growth faults. It indicates that the Paleogene basins are extension basins rather than the pullapart basin. The dextral strikeslip stress superimposed on the paleogene structural layer was caused by the underthrusting of Pacific plate beneath the Eurasian plate. The left translational movement of the belt resulted from the north underthrusting of Kula plate beneath the Eurasian plate during the Mesozoic. The intersection position of Tanlu NE translational strikeslipping fault and the subtle faults extending NW is the structural position for earthquake generation. So, we should pay more attention to supervise the earthquake activity in the intersection position of Gaoliying growth fault (extending NE) and the subtle fault of BozhongSunheNankou which extending NW.

Key words:

Key words: broad sense Tanlu fault belt; narrow sense Tanlu fault belt; extensional stress; dextral strikeslip stress; supervise natural earthquake