The Gravity Characteristics Of The Middle And Upper YANGTZE Region And Its Geological Significance

The middle and upper YANGTZE is located in a low-latitude region, where the most oil and gas fields of the world are concentrated in. Its tectonic settings is very similar to global marine oil and gas's. So it is Chinese potential strategic oil and gas areas. For a long time, many studies about Southern China's continental tectonics have been carried out, but a comprehensive study of its three-dimensional structure must be further strengthened. Some crucial tectonic positions, which is closely related to oil and gas, is not studied clearly, which seriously restricts the research and exploration of Southern China's marine oil and gas resources. The studies about the current whole structure configuration and tectonic framework of Southern China's continental is necessary, which is of great significance to petroleum exploration in the middle and upper YANGTZE region.Making use of common processing (such as calculating upward continuation) and wavelet mult-resolution analysis, the data of Bouguer gravity anomalies of 1:2500000 scale in study area are carried through synthetic treatment. The apparent Bouguer anomaly datum are obtained by global gravity field model (GRACE) and GTOPO 30 digital elevation model. In combination with deep seismic sounding, magnetotelluric, seismic tomographic and geological data, analyzing those processing results, those structural problems, such as the relationship of the study area's different blocks and the distribution of the main faults, and so on, is described. The main conclusions are as following:(1) The faults are classified and the planar distribution characteristic of the faults is analyzed. The formation of the NW-trending and NE-trending faults in the study area is resulted from the interaction of the three tectonic dynamic systems.(2) Huayingshan Fault is tracked by apparent Bouguer anomalies, stretches to the northeast, inserts Southern Daba structural belt. At the same time, it is found that Longquanshan Fault diverges and becomes two branches, respectively stretches to Longmenshan and Micangshan southern edge.(3) The subduction of the YANGZE plate beneath Qinling tectonic belt, involved in the middle Trias, causes the lower Bouguer anomaly of Chengkou. It is infered that Sichuan basin northeast deep border locates along Ziyang-Langao.(4) Many kinds of information imply that the middle of Sichuan basin block is stable. It is preliminarily considered that Chishui EW structures develop in the caprock.