Laji Shan is located in the eastern part of Qinghai Province,sandwiched between Xining and Hualong Basins.It is about 250km long and 10～20km wide from Riyueshan in the west to Minheguanting in the east.Laji Shan belongs to the Caledonian orogenic belt.Its basement consists of the rocks of Palaeo|Protero zoic Hualong Group (Pt 1 hl ) and Neo|Proterozoic Huangzhong Group (Pt-3 h ).There are ptygmatic folds,closely linear type folds,strongly structural d ifferentiation and schistosity developed,suggesting that the basement underwent deep seated ductile deformation.The main part of Laji Shan is composed of Early|Palaeozoic marine facies volcanic rocks and clastic sedimentary rocks,and suffered greenschist facies metamorphism and brittle|ductile deformation.Others are composed of Ea rly|Palaeozoic basic and ultrabasic rocks,intermediate|acidic intruded rocks a nd dike rocks.Devonian molasse formation in Laji Shan is in uncomfortable contac t with underlying strata.Jurassic and Cretaceous systems are intermont basin dep osits,corresponding to a cover.
展开▼
