The Baiyun sag is a deep one developing on the slope of the Pearl River Mouth Basin. It occurs as a composite graben horizontally, and is composed of two sub-sags versus one low uplift. Vertically, the sedimentary arc...The Baiyun sag is a deep one developing on the slope of the Pearl River Mouth Basin. It occurs as a composite graben horizontally, and is composed of two sub-sags versus one low uplift. Vertically, the sedimentary architecture could be divided into three layers, i.e. the faulted layer on the bottom, the faulted-ductile stretching layer in the middle and the draping layer on the top. The main rifting stage of the sag is supposed to be characterized by ductile extension and thinning of the crust. The special deformation pattern is probably attributed to the fact that the Baiyun sag is located in the transfer zone of the pre-existing weak zone, which made the sag a strongly deformed area, characterized by the greatly thinned lithosphere and active magmatism. The highly rising mantle under the Baiyun sag should be an important mechanism responsible for the ductile deformation, which caused partial melting of the upper mantle. Upweiling to the upper crust and the sedimentary layers, the partial melting materials accommodated extensional strain and caused non-faulted vertical subsidence. Magma was collected under the transfer zone after the first stage of rifting, and transferred laterally in a direction perpendicular to the extension to the ENE and WSW parts of the sag and upwelled along the NW-trending basal faults, where WNW-trending shear faults developed in swarms. The faulting activity and sedimentation history of the Baiyun sag may have been affected by the ocean ridge jump around 24 Ma and the cessation of sea floor spreading around 16 Ma.展开更多
The Sichuan Basin, located in the western margin of Yangtze Plate, is one of the important oil-gas-bearing basins in China. During the Early Permian-Middle Triassic, the Sichuan Basin experienced regional lithospheric...The Sichuan Basin, located in the western margin of Yangtze Plate, is one of the important oil-gas-bearing basins in China. During the Early Permian-Middle Triassic, the Sichuan Basin experienced regional lithospheric extension and Emeishan basalt activities, both of which influenced the basin development and thermal evolution. Here we simulated the thermal effects of lithospheric extension and the Emeishan mantle plume based on different geodynamical models. Modeling results indicated that the lithospheric temperature together with the basement heat flow was generally increasing with time due to extension. As the stretching factor was relatively small, the thinning of lithosphere, and consequently the thermal disturbance, was not great. The lithospheric extension yielded about 20% increase of the basement heat flow, with maximum value of 60?62 mW m?2 in the Early Triassic. Mantle plume model shows that the thermal evolution of the inner zone above the plume head was influenced greatly by plume activity. But the outer zone and its outside area where the Sichuan Basin is located were affected only slightly. The basalts that had erupted in the southwestern basin might disturb the basin temperature significantly, although shortly and locally. Generally, the thermal history of the Sichuan basin during the Early Permian-Middle Triassic was controlled by the lithospheric extension, but locally it superimposed thermal effects of basalt activities in its southwestern area.展开更多
基金国家自然科学基金项目(41874099,41474065,41981240687,41606080)日本科学技术研究经费支援项目(JSPS KAKENHI Grant Number JP16H04065)+1 种基金南方海洋科学与工程广东省实验室(广州)人才团队引进重大专项(GML2019ZD0104)中国台湾科技部项目(MOST 106-2116-M-003-003)资助.
文摘The Baiyun sag is a deep one developing on the slope of the Pearl River Mouth Basin. It occurs as a composite graben horizontally, and is composed of two sub-sags versus one low uplift. Vertically, the sedimentary architecture could be divided into three layers, i.e. the faulted layer on the bottom, the faulted-ductile stretching layer in the middle and the draping layer on the top. The main rifting stage of the sag is supposed to be characterized by ductile extension and thinning of the crust. The special deformation pattern is probably attributed to the fact that the Baiyun sag is located in the transfer zone of the pre-existing weak zone, which made the sag a strongly deformed area, characterized by the greatly thinned lithosphere and active magmatism. The highly rising mantle under the Baiyun sag should be an important mechanism responsible for the ductile deformation, which caused partial melting of the upper mantle. Upweiling to the upper crust and the sedimentary layers, the partial melting materials accommodated extensional strain and caused non-faulted vertical subsidence. Magma was collected under the transfer zone after the first stage of rifting, and transferred laterally in a direction perpendicular to the extension to the ENE and WSW parts of the sag and upwelled along the NW-trending basal faults, where WNW-trending shear faults developed in swarms. The faulting activity and sedimentation history of the Baiyun sag may have been affected by the ocean ridge jump around 24 Ma and the cessation of sea floor spreading around 16 Ma.
基金Instrument Developing Project of the Chinese Academy of Sciences(YZ201136)National Natural Science Foundation of China(41106086,41474065,41376059,41376061,91428205,41576036,41076028,41476167,and 41606080)Chinese Academy of Sciences Scholarship,the Strat
基金supported by Sinopec Marine Forward-looking Projects (Grant No. YPH08101)
文摘The Sichuan Basin, located in the western margin of Yangtze Plate, is one of the important oil-gas-bearing basins in China. During the Early Permian-Middle Triassic, the Sichuan Basin experienced regional lithospheric extension and Emeishan basalt activities, both of which influenced the basin development and thermal evolution. Here we simulated the thermal effects of lithospheric extension and the Emeishan mantle plume based on different geodynamical models. Modeling results indicated that the lithospheric temperature together with the basement heat flow was generally increasing with time due to extension. As the stretching factor was relatively small, the thinning of lithosphere, and consequently the thermal disturbance, was not great. The lithospheric extension yielded about 20% increase of the basement heat flow, with maximum value of 60?62 mW m?2 in the Early Triassic. Mantle plume model shows that the thermal evolution of the inner zone above the plume head was influenced greatly by plume activity. But the outer zone and its outside area where the Sichuan Basin is located were affected only slightly. The basalts that had erupted in the southwestern basin might disturb the basin temperature significantly, although shortly and locally. Generally, the thermal history of the Sichuan basin during the Early Permian-Middle Triassic was controlled by the lithospheric extension, but locally it superimposed thermal effects of basalt activities in its southwestern area.
