Wugongshan in Jiangxi Province, China was a Mesozoic granitic dome-type extensional tectonics that is composed of metamorphic core complexes, ductile and brittle shear-deformed zones distributed around Mesozoic granit...Wugongshan in Jiangxi Province, China was a Mesozoic granitic dome-type extensional tectonics that is composed of metamorphic core complexes, ductile and brittle shear-deformed zones distributed around Mesozoic granites. Within it, the foliation defines an E-W elliptical shape and bears S-N stretching lineations. The axial part is located in Hongjiang-Wanlongshan area and occupied by oriented granites with coaxial symmetric shear fabrics. The southem and northern flanks, including rocks in the Anfu Basin to the south and the Pingxiang Basin to the north, display top-to-south and top-to-north motions, respectively. The ductile and brittle structures indicate a geometric and kinematic consistency. The extensional tectonics is developed on a Caledonian metamorphic basement and is unconformably covered by Late Cretaceous red beds. Isotopic ages on muscovite, biotite and whole rock by40Ar-39Ar, K-Ar and Rb-Sr suggest that the Wugongshan extensional doming began from the Triassic and ended in the Late Cretaceous. A geodynamic model is discussed.展开更多
A discussion of collision orogenic deformation has been made for the Middle Yangtze Region. Based on its deformation assemblage orders, three developing stages are classified successively as compression thrust uplift,...A discussion of collision orogenic deformation has been made for the Middle Yangtze Region. Based on its deformation assemblage orders, three developing stages are classified successively as compression thrust uplift, strike-slip escape rheology and tension extension inversion. The collision orogenesis of the studied region has been divided into three developing periods of initial, chief and late orogeny. Based on the data from Wugong Mts., Jiuling Mts. and Xuefeng Mts.,for each stage, its variation of stress and strain axes, the conversion of joint fractures and their relative tectonic evolution are described, models are plotted and corresponding explanations are made for the rock chronology dating value in the same tectonic period.展开更多
The authors select different grain size samples from granitic body in Weishan, central Hunan, to conduct mylonitization experiments under high temperature (HT) and high pressure (HP), by which the temperature and pres...The authors select different grain size samples from granitic body in Weishan, central Hunan, to conduct mylonitization experiments under high temperature (HT) and high pressure (HP), by which the temperature and pressure conditions of mylonitization and microstructures of deformation have been obtained. Through the transmission electron microscopy (TEM) observations of experimental mylonite, we calculate its dislocation density (D), differential rheological stress (Pd) and speed rate of strain (Rs): 3.20x109/cm2, 139.32 MPa and 6.39x10-10/s respectively. The results are in the same magnitude-order with those of natural mylonite from fault zones. By comparison and analysis of chemical compositions and microstructures of different structural environments, the authors establish approximate rheological parameters related to shallow structural level and also suggest the multiple rheological properties and total trend from deep structural level to shallow structural level.展开更多
文摘Wugongshan in Jiangxi Province, China was a Mesozoic granitic dome-type extensional tectonics that is composed of metamorphic core complexes, ductile and brittle shear-deformed zones distributed around Mesozoic granites. Within it, the foliation defines an E-W elliptical shape and bears S-N stretching lineations. The axial part is located in Hongjiang-Wanlongshan area and occupied by oriented granites with coaxial symmetric shear fabrics. The southem and northern flanks, including rocks in the Anfu Basin to the south and the Pingxiang Basin to the north, display top-to-south and top-to-north motions, respectively. The ductile and brittle structures indicate a geometric and kinematic consistency. The extensional tectonics is developed on a Caledonian metamorphic basement and is unconformably covered by Late Cretaceous red beds. Isotopic ages on muscovite, biotite and whole rock by40Ar-39Ar, K-Ar and Rb-Sr suggest that the Wugongshan extensional doming began from the Triassic and ended in the Late Cretaceous. A geodynamic model is discussed.
基金the National Natural Science Foundation of China (Grant No.49972069), the State Key Laboratory of Southwest Petroleum Institute, and Beijing Institute of Geomechanics. Thanks are due to the academician Guo Lingzhi of the Department of Earth Sciences of
文摘A discussion of collision orogenic deformation has been made for the Middle Yangtze Region. Based on its deformation assemblage orders, three developing stages are classified successively as compression thrust uplift, strike-slip escape rheology and tension extension inversion. The collision orogenesis of the studied region has been divided into three developing periods of initial, chief and late orogeny. Based on the data from Wugong Mts., Jiuling Mts. and Xuefeng Mts.,for each stage, its variation of stress and strain axes, the conversion of joint fractures and their relative tectonic evolution are described, models are plotted and corresponding explanations are made for the rock chronology dating value in the same tectonic period.
基金the National Natural Science Foundation of China (Grant No. 49972069), State Key Lab of Southwestern Petroleum Institute and Geomechanics Institute, CAGS.
文摘The authors select different grain size samples from granitic body in Weishan, central Hunan, to conduct mylonitization experiments under high temperature (HT) and high pressure (HP), by which the temperature and pressure conditions of mylonitization and microstructures of deformation have been obtained. Through the transmission electron microscopy (TEM) observations of experimental mylonite, we calculate its dislocation density (D), differential rheological stress (Pd) and speed rate of strain (Rs): 3.20x109/cm2, 139.32 MPa and 6.39x10-10/s respectively. The results are in the same magnitude-order with those of natural mylonite from fault zones. By comparison and analysis of chemical compositions and microstructures of different structural environments, the authors establish approximate rheological parameters related to shallow structural level and also suggest the multiple rheological properties and total trend from deep structural level to shallow structural level.
