The Lajishan orogenic belt is one of the E-W-trending Caledonian orogenicbelts within the Qinling-Qilian orogenic system. It was formed upon the Jiningian basement byintensive taphrogenesis. Its major characteristics ...The Lajishan orogenic belt is one of the E-W-trending Caledonian orogenicbelts within the Qinling-Qilian orogenic system. It was formed upon the Jiningian basement byintensive taphrogenesis. Its major characteristics comprise the prominent faulting along the northand south boundaries, the highly complicated petrological and petro-geochemical features of thevolcanic rock series, and the development of a new type of ophiolite suite. In terms of tectonicanalysis and the sequential analysis of tectonic settings of magmatic rocks, it is suggested thatthe Lajishan orogenic belt has undergone a complete 'opening-closing' cycle, which can be furtherdivided into 3 second-order 'opening-closing' cycles. The composite characteristics of the'opening-closing' movement show that Laji Mountain is a typical fault orogenic belt. The faultorogenic belt is one of the most important types of intracontinental orogens. It is of criticaltheoretical and practical significance to summarize the characteristics and the diagnostic criteriaof this kind of orogenic belts, and study the mechanism of their formation and build models of theirevolution.展开更多
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 belo...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.展开更多
基金the Doctoral Programme of Higher Education 97049119 the National Natural Science Foundation of China grant 40072062.
文摘The Lajishan orogenic belt is one of the E-W-trending Caledonian orogenicbelts within the Qinling-Qilian orogenic system. It was formed upon the Jiningian basement byintensive taphrogenesis. Its major characteristics comprise the prominent faulting along the northand south boundaries, the highly complicated petrological and petro-geochemical features of thevolcanic rock series, and the development of a new type of ophiolite suite. In terms of tectonicanalysis and the sequential analysis of tectonic settings of magmatic rocks, it is suggested thatthe Lajishan orogenic belt has undergone a complete 'opening-closing' cycle, which can be furtherdivided into 3 second-order 'opening-closing' cycles. The composite characteristics of the'opening-closing' movement show that Laji Mountain is a typical fault orogenic belt. The faultorogenic belt is one of the most important types of intracontinental orogens. It is of criticaltheoretical and practical significance to summarize the characteristics and the diagnostic criteriaof this kind of orogenic belts, and study the mechanism of their formation and build models of theirevolution.
文摘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.
