Fluid inclusions are commonly observed in various stages during the diagenetic evolution and the generation, migration and arcumulation of hydrocarbons in LowerPermian carbonate rocks in the Xichang Basin, providing d...Fluid inclusions are commonly observed in various stages during the diagenetic evolution and the generation, migration and arcumulation of hydrocarbons in LowerPermian carbonate rocks in the Xichang Basin, providing direct physico-chemical evidencefor the process. Altogether seven stages can be recognized, i.e., the penecontemporaneous, early and mid-late diagenetic stages, the epidiagenetic stage and the eary, middleand late reburying stages. Karst and dissolution pores and structural fissures developedduring the epidiagenetic and reburying stages constitute the major reservoirs for hydrocarbon accumulation. Oil generation and migration began in the early reburying stagein Late Permian time and decloped to its climax in the middle reburying stage in theTriassic period, followed by extensive generation and migration of natural gases duringthe late stage of reburying in tbe Jurassic and later periods. The generation, migrationand accumulation of hydrocarbons are closely related to Hercynian basalt eruption andIndosinian and Yenshanian tecto-magmatism.展开更多
Upper Triassic and Middle Jurassic strata of the Xichang Basin in Sichuan Province, southwestern China, yielded important dinosaur ichnofossils. From the Xujiahe Formation of the Yiguojiao tracksite, we report a Late ...Upper Triassic and Middle Jurassic strata of the Xichang Basin in Sichuan Province, southwestern China, yielded important dinosaur ichnofossils. From the Xujiahe Formation of the Yiguojiao tracksite, we report a Late Triassic footprint assemblage in China and the first discovery of diagnostic Triassic sauropodomorph tracks in this region. The tracks share a number of features in common with the ichnogenera Eosauropus(Late Triassic) and Liujianpus(Early Jurassic). The neighboring Bingtu tracksite is stratigraphically younger(Shaximiao Formation, Middle Jurassic) and preserves small tridactyl theropod tracks that represent the first occurrence of the ichnotaxon Carmelopodus in China and Asia. While these tracks are morphologically comparable to those from the Middle Jurassic type locality in North America, the specimens from China show the proximal margin of the digit IV impression in a more cranial position, which may indicate a trackmaker with a relatively short metatarsal IV. In addition to the skeletal record, the Carmelopodus footprints document the presence of small theropods in the dinosaur fauna of the Middle Jurassic Shaximiao Formation.展开更多
文摘Fluid inclusions are commonly observed in various stages during the diagenetic evolution and the generation, migration and arcumulation of hydrocarbons in LowerPermian carbonate rocks in the Xichang Basin, providing direct physico-chemical evidencefor the process. Altogether seven stages can be recognized, i.e., the penecontemporaneous, early and mid-late diagenetic stages, the epidiagenetic stage and the eary, middleand late reburying stages. Karst and dissolution pores and structural fissures developedduring the epidiagenetic and reburying stages constitute the major reservoirs for hydrocarbon accumulation. Oil generation and migration began in the early reburying stagein Late Permian time and decloped to its climax in the middle reburying stage in theTriassic period, followed by extensive generation and migration of natural gases duringthe late stage of reburying in tbe Jurassic and later periods. The generation, migrationand accumulation of hydrocarbons are closely related to Hercynian basalt eruption andIndosinian and Yenshanian tecto-magmatism.
基金supported by the National Natural Science Foundation of China (Grant No.41772008)the State Key Laboratory of Palaeobiology and Stratigraphy(Nanjing Institute of Geology and Palaeontology, CAS)(Grant No.173127)and the comprehensive geological and mineral survey in Wumeng mountainous area conducted by China Geological Survey (Grant No.121201010000150002)
文摘Upper Triassic and Middle Jurassic strata of the Xichang Basin in Sichuan Province, southwestern China, yielded important dinosaur ichnofossils. From the Xujiahe Formation of the Yiguojiao tracksite, we report a Late Triassic footprint assemblage in China and the first discovery of diagnostic Triassic sauropodomorph tracks in this region. The tracks share a number of features in common with the ichnogenera Eosauropus(Late Triassic) and Liujianpus(Early Jurassic). The neighboring Bingtu tracksite is stratigraphically younger(Shaximiao Formation, Middle Jurassic) and preserves small tridactyl theropod tracks that represent the first occurrence of the ichnotaxon Carmelopodus in China and Asia. While these tracks are morphologically comparable to those from the Middle Jurassic type locality in North America, the specimens from China show the proximal margin of the digit IV impression in a more cranial position, which may indicate a trackmaker with a relatively short metatarsal IV. In addition to the skeletal record, the Carmelopodus footprints document the presence of small theropods in the dinosaur fauna of the Middle Jurassic Shaximiao Formation.
