Abstract:

South China underwent the continental margin tectonism during the final Chinese continental collision and the intracontinental tectonism hereafter in the Mesozoic. In the Late Paleozoic, there was an oceanic basin opened to the west, which is called the Mianlue ocean, between the QinlingDabie plate and the Yangtze plate. From the latest Middle Triassic, the Yangtze plate obliquely subducted and collided towards the North China plate northwestward, and in the Late Triassic till the Middle Jurassic, the continental margin foreland fold and thrust belt and the foreland basin system were developed in the northern Yangtze. The tectonic setting of East China took an important change in the Late Jurassic and Early Cretaceous, and the MiddleUpper Yangtze was surrounded and contracted by mountains on three sides. Under this kind of tectonism, in the Late Jurassic and the Early Cretaceous, intracontinental combination and superposition structures and intracratonic basin with foredeep system were formed in the MiddleUpper Yangtze. Beginning at the latest Middle Jurassic, the northern Yangtze foreland belt and the XuefengshanMufushan fold and thrust belt were assembled from east to west, and the intracratonic basin migrated and shrank from east to west. The oblique collision of the Yangtze plate towards the North China plate resulted in the deep subduction of the northern Yangtze and the formation of ultrahigh pressure metamorphic rocks. The thrust of the Dabie ultrahigh pressure metamorphic block along the XiangGuang fault and Tanlu fault after the subduction brought about the covering and deforming of the Late Triassic and Middle Jurassic foreland basin in the northern Yangtze.

Key words: the northern margin of MiddleUpper Yangtze, basinmountain systems, oblique subduction, surround and assemble, geodynamic mechanism