Abstract:

The Mesozoic volcanic rocks in Nanjing-Wuhu Basin originated from the mantle source.Maoshan and Chaoxian-Hanshan fold zones on both east and west sides of the basin are symmetrically distributed,with an overturned facies strike overthrusting to the Mesozoic-Cenozoic stratum.The intensely pressed,and the overturned facies strike,of Qinglong limestones from the middle-lower Triassic can be found on both flanks of median synclinorium in the west sectionof Ningzhen fold system.Continental clastics from the upper Triassic-lowermiddle Jurassic can be seen only in their core.Things for Nanjing-Wuhu Basin from the east foot of Chaoxian-Hanshan mountain system to the west foot of Maoshan mountain arc all just the same.It is believed that,according to the geological facts showing in the deep texture,fold systems on the east and west flanks of Nanjing-Wuhu Basin and southwestern end of Ningzhen fold on the north of the basins were previously connected with each other.It is because the subduction of the Pacific plate towards the Eurasian plate that brought about the upwarping of the mantle within the area,the extending,the thinning out and cracking of the crust,the exploiding of magama,the drifting of the basement and overlying sedimentary mantle to both east and west and then hiding,and the intensely folding and overturning of overlying formations on both sides,even overthrusting above a new formation within the basin and the volcanic system,thus forming the nappe structure of facies strike on the east and west flanks of the basin at last.This is the basin marginal ramp model formed by volcanic activity of rift type.