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Li S.Z.,Ocean University of China | Li S.Z.,The Key Laboratory of Submarine Geosciences and Exploration Techniques | Zhao G.C.,University of Hong Kong | Zhang G.W.,Northwest University, China | And 21 more authors.
Geological Journal | Year: 2010

The Yangtze foreland fold-and-thrust belt is located between the Mesozoic Dabie collisional orogen and the Mesozoic Jiangnan intraplate orogen in east-central China. Three regional deformation events are recognized in the Dabie Orogen north of the Yangtze River. The earliest regional deformation (D1) corresponded to a southeastward compression that occurred during the subduction of the South China Plate below the North China Plate. Top-to-the-southeast shearing coeval with Late Permian-Early Triassic blueschist facies metamorphism, was possibly associated with the development of regional gneissosity in the Dabie complexes and flat-ramp-style thrusts within the Neoproterozoic- Palaeozoic sedimentary cover, north of the Yangtze River. The main ductile deformation (D2) is also characterized by southeast-verging overturned and recumbent folds, coeval with the early stage of exhumation of the high-pressure rocks. A top-to-the-SW thrusting and WNW- striking open folds belong to a separate, later deformation phase, D3. Previous 40Ar-39Ar mica dates ranging between 245 and 205 Ma suggest Late Permian-Early Jurassic ages for the D1 to D3 events. The foreland folds and thrusts related to these deformations in the Dabie Orogen flank the eastern and western 'limbs' of the Dabie Orogen but are absent in the front of it. In contrast to the deformation north of the Yangtze River, the deformation of Neoproterozoic-Palaeozoic sedimentary cover in the Jiangnan Orogen south of the Yangtze River is generally characterized by north-verging folding and top-to-the-north thrusting from Triassic to Jurassic times. Based on the differences of deformation and structural polarity between the south and north areas of the Yangtze River, we propose that the Yangtze foreland fold-and-thrust belt in the direct front of the Dabie Orogen is unrelated to the Dabie Orogen but resulted from the Jiangnan Orogen. © 2010 John Wiley & Sons, Ltd.

Yang Z.,Ocean University of China | Yang Z.,The Key Laboratory of Submarine Geosciences and Exploration Techniques | Zhao S.,Ocean University of China | Zhao S.,The Key Laboratory of Submarine Geosciences and Exploration Techniques | And 15 more authors.
Scientia Geologica Sinica | Year: 2015

As geological investigation of the Wulungu depression in the Northeast Junggar Basin goes on in recent years, rich oil and gas resources are founded in the depression. But compared with the other part of the basin, the investigative level of oil and gas in the Wulungu depression is still low. This article systematically explores the law of oil and gas accumulation based on the structural characteristics and fault evolution. The Wulungu depression developed three sets of source rocks. The Dishuiquan Group and Batamayineishan group of Carboniferous dark mudstone is the most important source rock. According to the structural characteristics and evolution, the piedmont of Kelameili Mountain is the favorable oil and gas accumulation areas. The Wulungu depression is the oil-gas accumulation zone controlled by thrust faults, the oil and gas reservoirs in this area are characterized by zonal distribution along the NW-striking faults. The active deep-seated faults are the major hydrocarbon migration paths; the shallow faults mostly distributed in the Kalasayi fault, may damaged the early oil and gas reservoirs but benefit to the formation of secondary reservoirs in some degree. As the tectonic migration from north to south, the fault intensely active period matched well with the hydrocarbon generation. Structural traps in the root zone in the north developed from Late Indocinian stage to Early Yanshan stage, the main hydrocarbon reservoir types are faulted noses and faulted blocks related to the thrusting and secondary lithofacies reservoirs. Structural traps in the front zone in the south formed at Middle-Late Yanshan stage, the main hydrocarbon reservoir types are fault- related bends, fault-propagation folds, angular unconformity reservoirs and lithofacies reservoirs, but most of them are damaged by normal faulting during Himalayan period. ©, 2015, Science Press. All right reserved.

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