In Guangxi, the Lower-Middle Devonian boundary beds yield abundant corals, brachiopods,stromatoporoids and conodonts. The former three were common in tropical and subtropical zones, while thelast occurred only round t...In Guangxi, the Lower-Middle Devonian boundary beds yield abundant corals, brachiopods,stromatoporoids and conodonts. The former three were common in tropical and subtropical zones, while thelast occurred only round the equator. This reveals that the South China Plate in the Early-Middle Devonianwas at or near the equator, which was also supported by palaeomagnetic study giving the palaeolatitude of theGuangxi Region at the time to be 0°36′N.展开更多
Palaeoclimatic and palaeoenvironmental reconstructions of the Cryogenian Period have attracted attention in relation to the debated“Snowball Earth”hypothesis and the early evolution of metazoan life.The carbon cycle...Palaeoclimatic and palaeoenvironmental reconstructions of the Cryogenian Period have attracted attention in relation to the debated“Snowball Earth”hypothesis and the early evolution of metazoan life.The carbon cycle and redox conditions of the Sturtian-Marinoan non-glacial interval have been subjected to much controversy in the past decades because of the lack of a high-resolution stratigraphic correlation scheme.As one of the typical Sturtian-Marinoan interglacial deposits,the Datangpo Formation was widely distributed in South China with shales continuously deposited.The previous zircon dating data of the Datangpo Formation provide important ages for global constrain of the Sturtian-Marinoan non-glacial interval.Here we present a high-resolution straitigraphic study of the organic carbon isotopes of the Datangpo Formation from a drill core section in northern Guizhou Province.Based on measured episodicδ^(13)C_(org) perturbations,three positive shifts and three negative excursions are identified.Aδ^(13)C_(org)-based chemostratigraphic correlation scheme is proposed herein that works well for the Datangpo Formation regionally.Meanwhile,theδ^(13)C_(org) vertical gradients changed dynamically throughout the formation.This discovery implies that a significant ocean circulation overturn might have occurred in the upper Datangpo Formation,coinciding with the potential oxygenation.展开更多
Layer-block tectonics （LBT） concept, with the core of pluralistic geodynamic outlook and multilayer-sliding tectonic outlook, is one of new keys to study 3-dimensional solid and its 4-dimensional evolution history o...Layer-block tectonics （LBT） concept, with the core of pluralistic geodynamic outlook and multilayer-sliding tectonic outlook, is one of new keys to study 3-dimensional solid and its 4-dimensional evolution history of global tectonic system controlled by global geodynamics system. The LBT concept is applied to study the lithospheric tectonics of the southern South China Sea （SCS）. Based on the analysis of about 30 000 km of geophysical and geological data, some layer-blocks in the Nansha micro-plate can be divided as Nansha ultra-crustal layer-block, Zengmu crustal layer-block, Nanwei （Rifleman bank）-Andu （Ardasier bank） and Liyue （Reed bank） North Palawan crustal layer-blocks, Andu-Bisheng and Liyue-Banyue basemental layer-blocks. The basic characteristics of the basemental layer-blocks have been dicussed, and three intra-plate basin groups are identified. The intra-plate basins within Nansha micro-plate can be divided into three basin groups of Nanwei- Andu, Feixin-Nanhua, and Liyue-North Palawan based on the different geodynamics. In the light of pluralistic geodynamic concept, the upheaving force induced by the mid-crust plastic layer is proposed as the main dynamical force which causes the formation of the intra-plate basins within the Nansha micro-plate. Finally, models of a face-to-face dip-slip detachment of basemental layerblock and a unilateral dip-slip-detachment of basemental layer-block are put forward for the forming mechanisms of the Nanwei Andu and Liyue-North Palawan intra-plate basin groups, respectively.展开更多
We applied the finite frequency tomography method to S wave data recorded by 350 broadband stations beneath the South China Block（SCB） and its surroundings from earthquakes occurring between July 2007 and July 2010,...We applied the finite frequency tomography method to S wave data recorded by 350 broadband stations beneath the South China Block（SCB） and its surroundings from earthquakes occurring between July 2007 and July 2010,to better understand upper mantle deformation.Differential travel-times in the pair of stations with appropriate weighting for each station are used in the inversion.Our results are consistent with previous tomography that show a high velocity anomaly beneath the Sichuan basin and a high velocity anomaly in the transition zone beneath the Yangtze Craton.However,the resolution of mantle heterogeneity provides new insight into the tectonic framework of subduction of Burmese lithosphere in the west part of the study region and subduction of oceanic lithosphere in the east.In the subduction realm,west of 107°E,a significant fast S-wave anomaly is located on the southeast of Sichuan Basin.East of 107°E,and two narrow and discontinuous fast S-wave anomalies occur at a depth of 400-600 km beneath the middle of the South China block overlain by the pronounced low S-wave anomalies at a depth of 100 and 400 km.If the fast anomalies located in the mantle transition zone represent stagnant slabs,their fragmented nature may suggest that they could be produced by different episodes of subduction beneath western Pacific island and the above slow velocity anomaly may associated with the back-arc regions of ongoing subduction.In addition,tomography also reveals an anomalously high S-wave velocity continental root extends eastward to a depth 400 km beneath the eastern Sichuan Basin.This anomaly may be related to eastern extrusion of Indian lithosphere associated with the collision of India and Eurasia.Moreover,our results also show large slow anomalies beneath the Red River fault region connected to deeper anomalies beneath the South China Fold Belt and South China Sea.AH these observations are consistent with the scenario that the South China block has been built by both of subduction of Paleopacific plate and eastward subduction of Burma microplate.展开更多
Detailed global plate motion models that provide a continuous description of plate boundaries through time are an effective tool for exploring processes both at and below the Earth's surface. A new generation of n...Detailed global plate motion models that provide a continuous description of plate boundaries through time are an effective tool for exploring processes both at and below the Earth's surface. A new generation of numerical models of mantle dynamics pre-and post-Pangea timeframes requires global kinematic descriptions with full plate reconstructions extending into the Paleozoic(410 Ma). Current plate models that cover Paleozoic times are characterised by large plate speeds and trench migration rates because they assume that lowermost mantle structures are rigid and fixed through time. When used as a surface boundary constraint in geodynamic models, these plate reconstructions do not accurately reproduce the present-day structure of the lowermost mantle. Building upon previous work, we present a global plate motion model with continuously closing plate boundaries ranging from the early Devonian at 410 Ma to present day.We analyse the model in terms of surface kinematics and predicted lower mantle structure. The magnitude of global plate speeds has been greatly reduced in our reconstruction by modifying the evolution of the synthetic Panthalassa oceanic plates, implementing a Paleozoic reference frame independent of any geodynamic assumptions, and implementing revised models for the Paleozoic evolution of North and South China and the closure of the Rheic Ocean. Paleozoic(410-250 Ma) RMS plate speeds are on average ～8 cm/yr, which is comparable to Mesozoic-Cenozoic rates of ～6 cm/yr on average.Paleozoic global median values of trench migration trend from higher speeds(～2.5 cm/yr) in the late Devonian to rates closer to 0 cm/yr at the end of the Permian(～250 Ma), and during the Mesozoic-Cenozoic(250-0 Ma) generally cluster tightly around ～1.1 cm/yr. Plate motions are best constrained over the past 130 Myr and calculations of global trench convergence rates over this period indicate median rates range between 3.2 cm/yr and 12.4 cm/yr with a present day median rate estimated at～5 cm/yr. For Paleozoic times(410-251 Ma) our model results in median convergence rates largely～5 cm/yr. Globally,～90% of subduction zones modelled in our reconstruction are determined to be in a convergent regime for the period of 120-0 Ma. Over the full span of the model, from 410 Ma to 0 Ma,～93% of subduction zones are calculated to be convergent, and at least 85% of subduction zones are converging for 97% of modelled times. Our changes improve global plate and trench kinematics since the late Paleozoic and our reconstructions of the lowermost mantle structure challenge the proposed fixity of lower mantle structures, suggesting that the eastern margin of the African LLSVP margin has moved by as much as ～1450 km since late Permian times(260 Ma). The model of the plate-mantle system we present suggests that during the Permian Period, South China was proximal to the eastern margin of the African LLSVP and not the western margin of the Pacific LLSVP as previous thought.展开更多
Middle-Late Cretaceous Basaltic rocks (85―110 Ma) are distributed in the contemporaneous downfaulted red basins and volcanic-sedimentary basins in South China (including Hunan, Jiangxi, Guangdong, Fujian, Zhejiang pr...Middle-Late Cretaceous Basaltic rocks (85―110 Ma) are distributed in the contemporaneous downfaulted red basins and volcanic-sedimentary basins in South China (including Hunan, Jiangxi, Guangdong, Fujian, Zhejiang provinces). They are geographically divided into two groups delimited by Wuyishan Range, namely the west area basaltic rocks (WABs) distributing over the west of Wuyishan Range and the east area basaltic rocks (EABs) distributing over the east of Wuyishan Range, and observed having distinct geochemical and isotopic characters. WABs are characterized by relatively low in K2O (0.44%―3.17%), alkalis (K2O+Na2O= 3.27%―6.80%) and Al2O3 (13.08%―16.75%) contents, but high in MgO (5.13%―8.78%) and TiO2 (1.12%―3.35%) contents. WABs are similar to ocean-island basalts (OIB) or intraplate basalts on trace elements and isotopes: no negative Nb and Ta anomalies, relatively low ∑REE (74.66 μg/g―287.72 μg/g) and LaN/YbN (4.49―22.10), low (87Sr/86Sr)i (average ratio is 0.704679), high εNd(t) (?1.81―8.00). In contrast, EABs display relatively high in K2O (0.55%―4.86%), alkalis (K2O+Na2O=2.95%―7.55%) and Al2O3 (15.80%―21.10%) contents, but low in MgO (2.63%―6.28%) and TiO2 (1.19%―1.86%) contents, strong negative Nb and Ta anomalies, enrichment in LILE (K, Rb, Ba and Th), relatively high ΣREE (79.68 μg/g―327.61 μg/g) and LaN/YbN (5.25―26.37), high (87Sr/86Sr)i (average ratio is 0.707658) and negative εNd(t) (?8.50― ?1.22), similar to that of IAB (island arc basalts) or CAB (continental arc basalts). Accordingly, WABs were probably generated under continental rifting tectonic setting related to asthenosphere upwelling, and hence their source was characterized by mixing between EMⅡ with DM. Source of EABs may be enriched lithoshperic mantle which had ever undergone the metasomatism of fluid/melt derived from the subducted Pacific plate.This indicates that subduction of a paleo-Pacific plate (Kula) beneath the Eurasian continent had ever occurred during the late Mesozoic period, but the metasomatism resulted from the subduction was only limited to the east of Wuyishan Range.展开更多
The past size and location of the hypothesized proto-South China Sea vanished ocean basin has important plate-tectonic implications for Southeast Asia since the Mesozoic. Here we present new details on proto-South Chi...The past size and location of the hypothesized proto-South China Sea vanished ocean basin has important plate-tectonic implications for Southeast Asia since the Mesozoic. Here we present new details on proto-South China Sea paleogeography using mapped and unfolded slabs from tomography. Mapped slabs included： the Eurasia-South China Sea slab subducting at the Manila trench; the northern Philippine Sea Plate slab subducting at the Ryukyu trench; and, a swath of detached, subhorizontal, slab-like tomographic anomalies directly under the South China Sea at 450 to 700 km depths that we show is subducted ‘northern proto-South China Sea’ lithosphere. Slab unfolding revealed that the South China Sea lay directly above the ‘northern Proto-South China Sea’ with both extending 400 to 500 km to the east of the present Manila trench prior to subduction. Our slab-based plate reconstruction indicated the proto-South China Sea was consumed by double-sided subduction, as follows：（1） The ‘northern proto-South China Sea’ subducted in the Oligo–Miocene under the Dangerous Grounds and southward expanding South China Sea by in-place ‘self subduction’ similar to the western Mediterranean basins;（2） limited southward subduction of the proto-South China Sea under Borneo occurred pre-Oligocene, represented by the 800–900 km deep ‘southern proto-South China Sea’ slab.展开更多
华南板块新元古代的兴凯地裂运动始于晋宁运动后(800 Ma B.P.),强烈活动于新元古代中期的苏雄—开建桥组火山岩喷发期(700 Ma B.P.),结束于中奥陶世的郁南运动(458 Ma B.P.)。演化历程大体相当于Rodinia(罗迪尼亚)超大陆解体时,应为Rodi...华南板块新元古代的兴凯地裂运动始于晋宁运动后(800 Ma B.P.),强烈活动于新元古代中期的苏雄—开建桥组火山岩喷发期(700 Ma B.P.),结束于中奥陶世的郁南运动(458 Ma B.P.)。演化历程大体相当于Rodinia(罗迪尼亚)超大陆解体时,应为Rodinia超大陆裂解期的组成部分。兴凯地裂运动在新元古代形成扬子板块的基底,对中上扬子区后期构造变形有重要的影响,为后兴凯期(加里东运动)形成大型古隆起和大形拗陷提供了基础;产生的基底断裂对四川盆地后期构造活动有控制作用;形成的稳定大陆边缘为下组合烃源岩发育提供了条件等。展开更多
基金The study was supported by the National Natural Science Foundaion of China the State Education Commission of China.
文摘In Guangxi, the Lower-Middle Devonian boundary beds yield abundant corals, brachiopods,stromatoporoids and conodonts. The former three were common in tropical and subtropical zones, while thelast occurred only round the equator. This reveals that the South China Plate in the Early-Middle Devonianwas at or near the equator, which was also supported by palaeomagnetic study giving the palaeolatitude of theGuangxi Region at the time to be 0°36′N.
基金Special thanks to Erik Tihelka for improving the English.This study was supported by the National Natural Science Foundation of China(41602126)the China Geological Survey(DD20160018,DD20221661)+1 种基金the Second Tibetan Plateau Scientific Expedition and Research Program(2019QZKK0706)Liu Bao-jun Academician Research Funds subsidized by Chengdu Center of China Geological Survey.
文摘Palaeoclimatic and palaeoenvironmental reconstructions of the Cryogenian Period have attracted attention in relation to the debated“Snowball Earth”hypothesis and the early evolution of metazoan life.The carbon cycle and redox conditions of the Sturtian-Marinoan non-glacial interval have been subjected to much controversy in the past decades because of the lack of a high-resolution stratigraphic correlation scheme.As one of the typical Sturtian-Marinoan interglacial deposits,the Datangpo Formation was widely distributed in South China with shales continuously deposited.The previous zircon dating data of the Datangpo Formation provide important ages for global constrain of the Sturtian-Marinoan non-glacial interval.Here we present a high-resolution straitigraphic study of the organic carbon isotopes of the Datangpo Formation from a drill core section in northern Guizhou Province.Based on measured episodicδ^(13)C_(org) perturbations,three positive shifts and three negative excursions are identified.Aδ^(13)C_(org)-based chemostratigraphic correlation scheme is proposed herein that works well for the Datangpo Formation regionally.Meanwhile,theδ^(13)C_(org) vertical gradients changed dynamically throughout the formation.This discovery implies that a significant ocean circulation overturn might have occurred in the upper Datangpo Formation,coinciding with the potential oxygenation.
基金The National Basic Research Program of China ("973") under contract Nos 2009CB2194 and 2007CB411700the Major Knowledge Innovation Programs of the Chinese Academy of Sciences under contract No. kzcx2-yw-203-01+2 种基金the National Natural Science Foundation of China of China under contract No. 40676039the National Program of Sustaining Science and Technology of China under contract No. 2006BAB19B02the Program of the Ministry of Land and Natural Resources of China under contract No. GT-YQ-QQ-2008-1-02
文摘Layer-block tectonics （LBT） concept, with the core of pluralistic geodynamic outlook and multilayer-sliding tectonic outlook, is one of new keys to study 3-dimensional solid and its 4-dimensional evolution history of global tectonic system controlled by global geodynamics system. The LBT concept is applied to study the lithospheric tectonics of the southern South China Sea （SCS）. Based on the analysis of about 30 000 km of geophysical and geological data, some layer-blocks in the Nansha micro-plate can be divided as Nansha ultra-crustal layer-block, Zengmu crustal layer-block, Nanwei （Rifleman bank）-Andu （Ardasier bank） and Liyue （Reed bank） North Palawan crustal layer-blocks, Andu-Bisheng and Liyue-Banyue basemental layer-blocks. The basic characteristics of the basemental layer-blocks have been dicussed, and three intra-plate basin groups are identified. The intra-plate basins within Nansha micro-plate can be divided into three basin groups of Nanwei- Andu, Feixin-Nanhua, and Liyue-North Palawan based on the different geodynamics. In the light of pluralistic geodynamic concept, the upheaving force induced by the mid-crust plastic layer is proposed as the main dynamical force which causes the formation of the intra-plate basins within the Nansha micro-plate. Finally, models of a face-to-face dip-slip detachment of basemental layerblock and a unilateral dip-slip-detachment of basemental layer-block are put forward for the forming mechanisms of the Nanwei Andu and Liyue-North Palawan intra-plate basin groups, respectively.
基金supported by National Natural Science Foundation of China(Grand No.41404042,41504071,41274123)Postdoctoral Science Foundation of China(Grand Nos.2014M552147, 2015T80888)Innovation drive Foundation of Central South University(Grand No.2016CX005)
文摘We applied the finite frequency tomography method to S wave data recorded by 350 broadband stations beneath the South China Block（SCB） and its surroundings from earthquakes occurring between July 2007 and July 2010,to better understand upper mantle deformation.Differential travel-times in the pair of stations with appropriate weighting for each station are used in the inversion.Our results are consistent with previous tomography that show a high velocity anomaly beneath the Sichuan basin and a high velocity anomaly in the transition zone beneath the Yangtze Craton.However,the resolution of mantle heterogeneity provides new insight into the tectonic framework of subduction of Burmese lithosphere in the west part of the study region and subduction of oceanic lithosphere in the east.In the subduction realm,west of 107°E,a significant fast S-wave anomaly is located on the southeast of Sichuan Basin.East of 107°E,and two narrow and discontinuous fast S-wave anomalies occur at a depth of 400-600 km beneath the middle of the South China block overlain by the pronounced low S-wave anomalies at a depth of 100 and 400 km.If the fast anomalies located in the mantle transition zone represent stagnant slabs,their fragmented nature may suggest that they could be produced by different episodes of subduction beneath western Pacific island and the above slow velocity anomaly may associated with the back-arc regions of ongoing subduction.In addition,tomography also reveals an anomalously high S-wave velocity continental root extends eastward to a depth 400 km beneath the eastern Sichuan Basin.This anomaly may be related to eastern extrusion of Indian lithosphere associated with the collision of India and Eurasia.Moreover,our results also show large slow anomalies beneath the Red River fault region connected to deeper anomalies beneath the South China Fold Belt and South China Sea.AH these observations are consistent with the scenario that the South China block has been built by both of subduction of Paleopacific plate and eastward subduction of Burma microplate.
基金supported by the Australian Governmentsupport of the Australian Government Research Training Program Scholarship+1 种基金supported by Australian Research Council grant DE160101020supported by Australian Research Council grant IH130200012 and DP130101946
文摘Detailed global plate motion models that provide a continuous description of plate boundaries through time are an effective tool for exploring processes both at and below the Earth's surface. A new generation of numerical models of mantle dynamics pre-and post-Pangea timeframes requires global kinematic descriptions with full plate reconstructions extending into the Paleozoic(410 Ma). Current plate models that cover Paleozoic times are characterised by large plate speeds and trench migration rates because they assume that lowermost mantle structures are rigid and fixed through time. When used as a surface boundary constraint in geodynamic models, these plate reconstructions do not accurately reproduce the present-day structure of the lowermost mantle. Building upon previous work, we present a global plate motion model with continuously closing plate boundaries ranging from the early Devonian at 410 Ma to present day.We analyse the model in terms of surface kinematics and predicted lower mantle structure. The magnitude of global plate speeds has been greatly reduced in our reconstruction by modifying the evolution of the synthetic Panthalassa oceanic plates, implementing a Paleozoic reference frame independent of any geodynamic assumptions, and implementing revised models for the Paleozoic evolution of North and South China and the closure of the Rheic Ocean. Paleozoic(410-250 Ma) RMS plate speeds are on average ～8 cm/yr, which is comparable to Mesozoic-Cenozoic rates of ～6 cm/yr on average.Paleozoic global median values of trench migration trend from higher speeds(～2.5 cm/yr) in the late Devonian to rates closer to 0 cm/yr at the end of the Permian(～250 Ma), and during the Mesozoic-Cenozoic(250-0 Ma) generally cluster tightly around ～1.1 cm/yr. Plate motions are best constrained over the past 130 Myr and calculations of global trench convergence rates over this period indicate median rates range between 3.2 cm/yr and 12.4 cm/yr with a present day median rate estimated at～5 cm/yr. For Paleozoic times(410-251 Ma) our model results in median convergence rates largely～5 cm/yr. Globally,～90% of subduction zones modelled in our reconstruction are determined to be in a convergent regime for the period of 120-0 Ma. Over the full span of the model, from 410 Ma to 0 Ma,～93% of subduction zones are calculated to be convergent, and at least 85% of subduction zones are converging for 97% of modelled times. Our changes improve global plate and trench kinematics since the late Paleozoic and our reconstructions of the lowermost mantle structure challenge the proposed fixity of lower mantle structures, suggesting that the eastern margin of the African LLSVP margin has moved by as much as ～1450 km since late Permian times(260 Ma). The model of the plate-mantle system we present suggests that during the Permian Period, South China was proximal to the eastern margin of the African LLSVP and not the western margin of the Pacific LLSVP as previous thought.
基金This research was supported by the National Natural Science Foundation of China(Grant Nos.40125007 and 40132010).
文摘Middle-Late Cretaceous Basaltic rocks (85―110 Ma) are distributed in the contemporaneous downfaulted red basins and volcanic-sedimentary basins in South China (including Hunan, Jiangxi, Guangdong, Fujian, Zhejiang provinces). They are geographically divided into two groups delimited by Wuyishan Range, namely the west area basaltic rocks (WABs) distributing over the west of Wuyishan Range and the east area basaltic rocks (EABs) distributing over the east of Wuyishan Range, and observed having distinct geochemical and isotopic characters. WABs are characterized by relatively low in K2O (0.44%―3.17%), alkalis (K2O+Na2O= 3.27%―6.80%) and Al2O3 (13.08%―16.75%) contents, but high in MgO (5.13%―8.78%) and TiO2 (1.12%―3.35%) contents. WABs are similar to ocean-island basalts (OIB) or intraplate basalts on trace elements and isotopes: no negative Nb and Ta anomalies, relatively low ∑REE (74.66 μg/g―287.72 μg/g) and LaN/YbN (4.49―22.10), low (87Sr/86Sr)i (average ratio is 0.704679), high εNd(t) (?1.81―8.00). In contrast, EABs display relatively high in K2O (0.55%―4.86%), alkalis (K2O+Na2O=2.95%―7.55%) and Al2O3 (15.80%―21.10%) contents, but low in MgO (2.63%―6.28%) and TiO2 (1.19%―1.86%) contents, strong negative Nb and Ta anomalies, enrichment in LILE (K, Rb, Ba and Th), relatively high ΣREE (79.68 μg/g―327.61 μg/g) and LaN/YbN (5.25―26.37), high (87Sr/86Sr)i (average ratio is 0.707658) and negative εNd(t) (?8.50― ?1.22), similar to that of IAB (island arc basalts) or CAB (continental arc basalts). Accordingly, WABs were probably generated under continental rifting tectonic setting related to asthenosphere upwelling, and hence their source was characterized by mixing between EMⅡ with DM. Source of EABs may be enriched lithoshperic mantle which had ever undergone the metasomatism of fluid/melt derived from the subducted Pacific plate.This indicates that subduction of a paleo-Pacific plate (Kula) beneath the Eurasian continent had ever occurred during the late Mesozoic period, but the metasomatism resulted from the subduction was only limited to the east of Wuyishan Range.
文摘The past size and location of the hypothesized proto-South China Sea vanished ocean basin has important plate-tectonic implications for Southeast Asia since the Mesozoic. Here we present new details on proto-South China Sea paleogeography using mapped and unfolded slabs from tomography. Mapped slabs included： the Eurasia-South China Sea slab subducting at the Manila trench; the northern Philippine Sea Plate slab subducting at the Ryukyu trench; and, a swath of detached, subhorizontal, slab-like tomographic anomalies directly under the South China Sea at 450 to 700 km depths that we show is subducted ‘northern proto-South China Sea’ lithosphere. Slab unfolding revealed that the South China Sea lay directly above the ‘northern Proto-South China Sea’ with both extending 400 to 500 km to the east of the present Manila trench prior to subduction. Our slab-based plate reconstruction indicated the proto-South China Sea was consumed by double-sided subduction, as follows：（1） The ‘northern proto-South China Sea’ subducted in the Oligo–Miocene under the Dangerous Grounds and southward expanding South China Sea by in-place ‘self subduction’ similar to the western Mediterranean basins;（2） limited southward subduction of the proto-South China Sea under Borneo occurred pre-Oligocene, represented by the 800–900 km deep ‘southern proto-South China Sea’ slab.
文摘华南板块新元古代的兴凯地裂运动始于晋宁运动后(800 Ma B.P.),强烈活动于新元古代中期的苏雄—开建桥组火山岩喷发期(700 Ma B.P.),结束于中奥陶世的郁南运动(458 Ma B.P.)。演化历程大体相当于Rodinia(罗迪尼亚)超大陆解体时,应为Rodinia超大陆裂解期的组成部分。兴凯地裂运动在新元古代形成扬子板块的基底,对中上扬子区后期构造变形有重要的影响,为后兴凯期(加里东运动)形成大型古隆起和大形拗陷提供了基础;产生的基底断裂对四川盆地后期构造活动有控制作用;形成的稳定大陆边缘为下组合烃源岩发育提供了条件等。
