Discussion on the special gravity field across the north part of Middle Qinling Mt

In this paper,we discussed the special gravity anomaly in the Xianyang-Middle Qinling mountain section in the synthetical geophysical profile from Yulin to Chongqing.Our results suggest that the Northern Qinling fault lies in the gravity anomaly section.The shallow part of the Northern Qinling fault extends in a slightly north-dipping direction with a dip about 70 degrees,and the deep part dips slighty to the south with a dip of 70~80 degrees,while the middle part of it is almost in vertical direction.The big gravity anomaly zone may be caused by the Cenozoic sediments with thickness of 6km and width of 40km in the upper crust.The formation of the Northern Qinling fault belt and the thick sedimentary strata may result from the complicated tectonic movement,especially the thrust of North China plate and the Qinling orogenic movement.