The Queshan MCC is an important example of a crustal extensional structure in the eastern Jiaodong Peninsula along the southeastern margin of the NCC in the Early Cretaceous. The MCC is a typical Cordilleran-type core...The Queshan MCC is an important example of a crustal extensional structure in the eastern Jiaodong Peninsula along the southeastern margin of the NCC in the Early Cretaceous. The MCC is a typical Cordilleran-type core complex with a three-layered structure:(1) the upper plate is constituted by the Cretaceous supradetachment basin and Paleoproterozoic basement;(2) the lower plate comprises the Neoarchean high-grade metamorphic complexes and late Mesozoic granitic intrusions; and(3) the two plates are separated by a master detachment fault. A series of late NEN-oriented brittle faults superimposed on and destructed the early MCC. Petrology, geometry, kinematics, macro- and micro-structures and quartz c-axis fabrics imply that the MCC has a progressive exhumation history from middle-lower to subsurface level(via middle-upper crustal level) under the nearly WNW-ESE regional extensional regime. We present structural and geochronological evidence to constrain the exhumation of the Queshan MCC from ca. 135 to 113 Ma. Based on the comprehensive analysis of the different patterns of extensional structures in the Jiaodong and Liaodong Peninsula, we have defined the Jiao-Liao Early Cretaceou extensional province and further divided the crustal extension of it into two stages: the first stage was the intense flow of the middle-lower crust and the second stage was the extension of the middle-upper crust. Combining the tectonic setting, the lithosphere thinning in the Jiao-Liao Early Cretaceous extensional province can be considered a typical model for the response of crust-mantle detachment faulting under regional extension in East Asia.展开更多
Extracts from manganese nodules and ooze from the Central Pacific deep sea floor were analyzed using the chromatogram-mass spectrum, and it was found that most of the biomarker molecules are of the low-mature type (so...Extracts from manganese nodules and ooze from the Central Pacific deep sea floor were analyzed using the chromatogram-mass spectrum, and it was found that most of the biomarker molecules are of the low-mature type (some have characteristics of mature): the ratio of 'A'/C is high between 11.4%-19.75%; CPI is 1.22-1.23; C31-22S/ (22S+22R) hopane is 0.59-0.60, Tm/Ts is 0.99-1.99; pa moretane/(αβ+βα) hopane is 0.12-0.14; C29 sterane 20S/(20S+20R) is 0.35-0.41; ββ/(ββ+αα) is 0.38-0.45; arene TA(I)/TA(I+Ⅱ) is 0.16-0.21; methyl-phenanthrene index (MPI1) is 0.35-0.67. According to the geological settings of the sampling area and its organic geochemical characteristics, it is considered that the hydrothermal activities on the ocean floor facilitate the decomposition of organic matter in the sediment, which leads to the generation and migration of hydrocarbon into manganese nodules and ooze. This discovery is important for understanding the mechanisms of hydrocarbon generation in the ocean floor and展开更多
基金supported by the National Natural Science Foundation of China (Grant Nos. 41430211, 90814006 & 91214301)Doctoral Foundation of Ministry of Education of China (Grant No. 20110022130001)
文摘The Queshan MCC is an important example of a crustal extensional structure in the eastern Jiaodong Peninsula along the southeastern margin of the NCC in the Early Cretaceous. The MCC is a typical Cordilleran-type core complex with a three-layered structure:(1) the upper plate is constituted by the Cretaceous supradetachment basin and Paleoproterozoic basement;(2) the lower plate comprises the Neoarchean high-grade metamorphic complexes and late Mesozoic granitic intrusions; and(3) the two plates are separated by a master detachment fault. A series of late NEN-oriented brittle faults superimposed on and destructed the early MCC. Petrology, geometry, kinematics, macro- and micro-structures and quartz c-axis fabrics imply that the MCC has a progressive exhumation history from middle-lower to subsurface level(via middle-upper crustal level) under the nearly WNW-ESE regional extensional regime. We present structural and geochronological evidence to constrain the exhumation of the Queshan MCC from ca. 135 to 113 Ma. Based on the comprehensive analysis of the different patterns of extensional structures in the Jiaodong and Liaodong Peninsula, we have defined the Jiao-Liao Early Cretaceou extensional province and further divided the crustal extension of it into two stages: the first stage was the intense flow of the middle-lower crust and the second stage was the extension of the middle-upper crust. Combining the tectonic setting, the lithosphere thinning in the Jiao-Liao Early Cretaceous extensional province can be considered a typical model for the response of crust-mantle detachment faulting under regional extension in East Asia.
基金This work was supported by the National Basic Research and Development Project (Grant No. G199944309).
文摘Extracts from manganese nodules and ooze from the Central Pacific deep sea floor were analyzed using the chromatogram-mass spectrum, and it was found that most of the biomarker molecules are of the low-mature type (some have characteristics of mature): the ratio of 'A'/C is high between 11.4%-19.75%; CPI is 1.22-1.23; C31-22S/ (22S+22R) hopane is 0.59-0.60, Tm/Ts is 0.99-1.99; pa moretane/(αβ+βα) hopane is 0.12-0.14; C29 sterane 20S/(20S+20R) is 0.35-0.41; ββ/(ββ+αα) is 0.38-0.45; arene TA(I)/TA(I+Ⅱ) is 0.16-0.21; methyl-phenanthrene index (MPI1) is 0.35-0.67. According to the geological settings of the sampling area and its organic geochemical characteristics, it is considered that the hydrothermal activities on the ocean floor facilitate the decomposition of organic matter in the sediment, which leads to the generation and migration of hydrocarbon into manganese nodules and ooze. This discovery is important for understanding the mechanisms of hydrocarbon generation in the ocean floor and
