Sedimentological Restriction During the Uplift Period in Micangshan

As the northern boundary of Sichuan Basin,The Micangshan locates in the north part of the upper Yangtze region,which is the basin and mountain transition area among the Longmenshan,Qinling orogen belt and Sichuan Basin.So it is important for researching the tectonic evolution of Qinling and upper Yangtze region in Mesozoic.The uplift period of Micangshan has a large connection with spatio-temporal boundary of Sichuan Basin and tectonic evolutional framework.We can ascertain the palaeogeographical topographic features and tectonic upwarping's feature of Jurassic in Micangshan from the research of Jurassic sediment of its both sides.Two cross sections were surveyed at Baishui and Ganchang to the south of Micangshan,another cross section in Yankou to the north of Micangshan,and lithological column of l Jurassic was made.There is no remarkable discrepancies in sediments to both sides of Micangshan from Lias to early phase of Mid-Jurassic.In a word,our research indicates that the Micang shan uplifted was later than the early phase of Mid-Jurassic and the sedimentary environment was not separated until then.