Characteristics and nature of the Meso-Cenozoic great continental spreading basins in China and adjacent regions depend on the relative positions of the allied adjacent oceans. Intracontinental,epicontinental and marg...Characteristics and nature of the Meso-Cenozoic great continental spreading basins in China and adjacent regions depend on the relative positions of the allied adjacent oceans. Intracontinental,epicontinental and marginal basins were respectively developed from the inland to the Meso-Cenozoic Tethys coast and Northwest Pacific coast,each having three series. These series are symmetrically arranged in feather-form.The general thrend is that the closer they are to the coasts,the stronger their activity,and the newer their evolutionary generations. The basins were in a spreading state and belonged to geotectonic spreading units possessing orogeny in their devolopment period. They play a decisive role in mould-making of orogenic belt in detailed morphology and become the orogenic “mighty pillar” of mould-making.The Meso-Cenozoic orogeny of China and adjacent regions can be divided into three kinds:orogeny of continental spreading basin,orogeny of oceanic spreading basin and composite orogeny of oceanic-continental basin.展开更多
金沙江造山带是东特提斯复合造山带的重要组成部分,也是一条重要的内生金属矿床成矿带。金沙江造山带自泥盆纪至第四纪经历了弧后盆地扩张、弧后盆地俯冲消减、弧后碰撞造山、挤压隆升与前陆盆地演化等四个主要演化阶段(潘桂棠等,1997;W...金沙江造山带是东特提斯复合造山带的重要组成部分,也是一条重要的内生金属矿床成矿带。金沙江造山带自泥盆纪至第四纪经历了弧后盆地扩张、弧后盆地俯冲消减、弧后碰撞造山、挤压隆升与前陆盆地演化等四个主要演化阶段(潘桂棠等,1997;Wang et al.,1995;王立全等,1999;何龙清,1998;Kenneth et al.,1995),各阶段都有不同的成矿作用,形成不同类型的内生金属矿床。展开更多
Petrogeochemical data indicate that after the end of seafloor spreading,residual magmatic activity still exists in the deep basin of the South China Sea.By using different viscous structure models beneath the fossil s...Petrogeochemical data indicate that after the end of seafloor spreading,residual magmatic activity still exists in the deep basin of the South China Sea.By using different viscous structure models beneath the fossil spreading center of the Southwest sub-basin we simulated the amount of melt produced,the length of the melting period,and the thermal evolution process in terms of geothermics and the buoyant decompression melting mechanism.We compared the results of our model with observed heat flow,seismic,and petrogeochemistry data.The results show that depletion buoyancy induced by buoyant decompression melting plays an important role in the melting process,while retention buoyancy,thermal buoyancy,and viscous shear force have only a weak influence on the melting process.From the length of the melting period,we determined that for the three viscous structures models the magmatic activity lasted about 5,12,and 15 Ma.Under the effect of buoyant depression melting,local high-temperature areas will develop under the basin,which can explain the low-velocity layer detected by seismic exploration in the middle and upper lithosphere of the Southwest sub-basin.We also simulated the possible lithology distribution beneath the fossil spreading center with the physical conditions of different viscous structure,different temperature structure,and different melting fraction,which provided a greater understanding of the rock petrogeochemical data of the deep sea basin in the South China Sea.展开更多
文摘Characteristics and nature of the Meso-Cenozoic great continental spreading basins in China and adjacent regions depend on the relative positions of the allied adjacent oceans. Intracontinental,epicontinental and marginal basins were respectively developed from the inland to the Meso-Cenozoic Tethys coast and Northwest Pacific coast,each having three series. These series are symmetrically arranged in feather-form.The general thrend is that the closer they are to the coasts,the stronger their activity,and the newer their evolutionary generations. The basins were in a spreading state and belonged to geotectonic spreading units possessing orogeny in their devolopment period. They play a decisive role in mould-making of orogenic belt in detailed morphology and become the orogenic “mighty pillar” of mould-making.The Meso-Cenozoic orogeny of China and adjacent regions can be divided into three kinds:orogeny of continental spreading basin,orogeny of oceanic spreading basin and composite orogeny of oceanic-continental basin.
文摘金沙江造山带是东特提斯复合造山带的重要组成部分,也是一条重要的内生金属矿床成矿带。金沙江造山带自泥盆纪至第四纪经历了弧后盆地扩张、弧后盆地俯冲消减、弧后碰撞造山、挤压隆升与前陆盆地演化等四个主要演化阶段(潘桂棠等,1997;Wang et al.,1995;王立全等,1999;何龙清,1998;Kenneth et al.,1995),各阶段都有不同的成矿作用,形成不同类型的内生金属矿床。
基金supported by the National Natural Science Foundation of China (Grant No. 41174085)Research Subject of the Chinese Academy of Sciences (Grant No. KZZD-EW-TZ-19)China Geological Survey Project (Grant No. 12120113101400).
文摘Petrogeochemical data indicate that after the end of seafloor spreading,residual magmatic activity still exists in the deep basin of the South China Sea.By using different viscous structure models beneath the fossil spreading center of the Southwest sub-basin we simulated the amount of melt produced,the length of the melting period,and the thermal evolution process in terms of geothermics and the buoyant decompression melting mechanism.We compared the results of our model with observed heat flow,seismic,and petrogeochemistry data.The results show that depletion buoyancy induced by buoyant decompression melting plays an important role in the melting process,while retention buoyancy,thermal buoyancy,and viscous shear force have only a weak influence on the melting process.From the length of the melting period,we determined that for the three viscous structures models the magmatic activity lasted about 5,12,and 15 Ma.Under the effect of buoyant depression melting,local high-temperature areas will develop under the basin,which can explain the low-velocity layer detected by seismic exploration in the middle and upper lithosphere of the Southwest sub-basin.We also simulated the possible lithology distribution beneath the fossil spreading center with the physical conditions of different viscous structure,different temperature structure,and different melting fraction,which provided a greater understanding of the rock petrogeochemical data of the deep sea basin in the South China Sea.
