Granites sampled from Garzê-Litang thrust, Longmen Shan thrust, Garzê and Litang strike-slip faults in the eastern Tibetan Plateau have been analyzed with apatite fission track thermochronological method in ...Granites sampled from Garzê-Litang thrust, Longmen Shan thrust, Garzê and Litang strike-slip faults in the eastern Tibetan Plateau have been analyzed with apatite fission track thermochronological method in this study. The measured fission track apparent ages, combined with the simulated annealing mod- eling of the thermal history, have been used to reconstruct the thermal evolutionary histories of the samples and interpret the active history of the thrusts and faults in these areas. Thermal history mod- eling shows that earlier tectonic cooling occurred in the Garzê-Litang thrust in Miocene (~20―16 Ma) whereas the later cooling occurred mainly in the Longmen Shan thrust since ~5 Ma. Our study sug- gests that the margin of eastern Tibetan Plateau was extended by stages: through strike-slip faults deformations and related thrusts, the upper crust formed the Garzê-Litang margin in the Miocene epoch and then moved to the Longmen Shan margin since ~5 Ma. During this process, the deformations of different phases in the eastern Tibetan Plateau were absorbed by the thrusts within them and conse- quently the tectonic events of long-distance slip and extrusion up to hundreds of kilometers have not been found.展开更多
Basin modeling has become an important tool for analyzing sedimentary basins. The North Subbasin of the South Yellow Sea Basin is filled with thick Meso-Cenozoic terrigenous deposits during the rift evolution stage. T...Basin modeling has become an important tool for analyzing sedimentary basins. The North Subbasin of the South Yellow Sea Basin is filled with thick Meso-Cenozoic terrigenous deposits during the rift evolution stage. The accumulation of data and achievements of geological investigations in recent years have provided the preconditions for basin modeling. The necessary parameters and geological elements for simulations are collated and summarized. Modeling of tectono-thermal evolution is performed and the related trend in heat flow is reconstructed and calibrated. The heat flow value commences from an average level of 61 m W/m2during MiddleLate Jurassic, rises to about 80 m W/m2from circa 145 Ma to circa 74 Ma, and then undergoes a gradual decline to65 m W/m2until the end of Oligocene.Three evolutionary phases, namely, the initial rifting phase, syn-rifting phase, and post-rifting phase, have been identified. The modeling results show that the North Subbasin generally enters into a stage of strong rifting during Cretaceous and undergoes rapid subsidence until the Late Cretaceous,then follows by a stage of moderate rifting during the Paleogene. The input and general workflow involved in 3-D modeling are introduced. Reconstruction of the petroleum system in the North Subbasin reveals that the threshold depth of hydrocarbon generation is located near the top of the Paleogene Funing formation, and the underlying Jurassic and Cretaceous source rocks have reached or exceeded peak oil generation and have almost completed the generation and expulsion of hydrocarbons. The main generation and expulsion in the Jurassic source rocks take place during the syn-rifting and post-rifting phases, whereas the peak generation and expulsion in the Cretaceous and Paleogene source rocks take place during the post-rifting phase. Although the study area is still a relatively less explored sedimentary basin, the results of modeling can provide valuable information for exploration. A preliminary discussion of the main uncertainty factors is a展开更多
The contractional structures in the southern Ordos Basin recorded critical evidence for the interaction between Ordos Basin and Qinling Orogenic Collage. In this study, we performed apatite fission track （AFT） therm...The contractional structures in the southern Ordos Basin recorded critical evidence for the interaction between Ordos Basin and Qinling Orogenic Collage. In this study, we performed apatite fission track （AFT） thermochronology to unravel the timing of thrusting and exhumation for the Laolongshan-Shengrenqiao Fault （LSF） in the southern Ordos Basin. The AFT ages from opposite sides of the LSF reveal a significant latest Triassic to Early Jurassic time-temperature discontinuity across this structure. Thermal modeling reveals at the latest Triassic to Early Jurassic, a ~50~C difference in temperature between opposite sides of the LSF currently exposed at the surface. This discontinuity is best interpreted by an episode of thrusting and exhumation of the LSF with -1.7 km of net vertical displacement during the latest Triassic to Early Jurassic. These results, when combined with earlier thermochronological studies, stratigraphic contact relationship and tectono-sedimentary evolution, suggest that the southern Ordos Basin experienced coeval intense tectonic contraction and developed a north-vergent fold-and-thrust belt. Moreover, the southern Ordos Basin experienced a multi-stage differential exhumation during Mesozoic, including the latest Triassic to Early Jurassic and Late Jurassic to earliest Cretaceous thrust-driven exhumation as well as the Late Cretaceous overall exhumation. Specifically, the two thrust-driven exhumation events were related to tectonic stress propagation derived from the latest Triassic to Early Jurassic continued compression from Qinling Orogenic Collage and the Late Jurassic to earliest Cretaceous intracontinental orogeny of QinUng Orogenic Collage, respectively. By contrast, the Late Cretaceous overall exhumation event was related to the collision of an exotic terrain with the eastern margin of continental China at -100 Ma.展开更多
The apatite fission track dating of samples from the Dabashan （i.e., the Langshan in the northeastern Alxa Block） by the laser ablation method and their thermal history modeling of AFT ages are conducted in this stu...The apatite fission track dating of samples from the Dabashan （i.e., the Langshan in the northeastern Alxa Block） by the laser ablation method and their thermal history modeling of AFT ages are conducted in this study. The obtained results and lines of geological evidence in the study region indicate that the Langshan has experienced complicated tectonic-thermal events during the the Late Cretaceous-Cenozoic. Firstly, it experienced a tectonic-thermal event in the Late Cretaceous （-90-70 Ma）. The event had little relation with the oblique subduction of the Izanagi Plate along the eastern Eurasian Plate, but was related to the Neo-Tethys subduction and compression between the Lhasa Block and Qiangtang Block. Secondly, it underwent the dextral slip faulting in the Eocene （-50-45 Ma）. The strike slip fault may develop in the same tectonic setting as sinistral slip faults in southern Mongolia and thrusts in West Qinling to the southwest Ordos Block in the same period, which is the remote far-field response to the India-Eurasia collision. Thirdly, the tectonic thermal event existed in the late Cenozoic （since -10 Ma）, thermal modeling shows that several samples began their denudation from upper region of partial annealing zone （PAZ）, and the denudation may have a great relationship with the growth of Qinghai-Tibetan Plateau to the northeast. In addition, the AFT ages of Langshan indicate that the main body of the Langshan may be an upper part of fossil PAZ of the Late Cretaceous （-70 Ma）. The fossil PAZ were destroyed and deformed by tectonic events repeatedly in the Cenozoic along with the denudation.展开更多
Mesozoic intracontinental orogeny and deformation were widespread within the southern Central Asian Orogenic Belt(CAOB). Chronological constraints remain unclear when assessing the Mesozoic evolution of the central se...Mesozoic intracontinental orogeny and deformation were widespread within the southern Central Asian Orogenic Belt(CAOB). Chronological constraints remain unclear when assessing the Mesozoic evolution of the central segment of this region. The tectonic belt of Shalazha Mountain located in the center of this region is an ideal place to decode the deformation process. Apatite fission-track(AFT) thermochronology in Shalazha Mountain is applied to constrain the Mesozoic tectonothermal evolution of the central segment of southern CAOB. The bedrock AFT ages range from 161.8 ± 6.9 to 137.0 ± 7.3 Ma, and the first reported detrital AFT obtained from Lower Cretaceous strata shows three age peaks: P1(ca. 178 Ma), P2(ca. 149 Ma) and P3(ca. 105.6 Ma). Bedrock thermal history modeling indicates that Shalazha Mountain have experienced three stages of differential cooling: Late Triassic–Early Jurassic(~230–174 Ma), Late Jurassic–Earliest Cretaceous(~174–135 Ma) and later(~135 Ma). The first two cooling stages are well preserved by the detrital AFT thermochronological result(P1, P2) from the adjacent Lower Cretaceous strata, while P3(ca. 105.6 Ma) records coeval volcanic activity. Furthermore, our data uncover that hanging wall samples cooled faster between the Late Triassic and the Early Cretaceous than those from the footwall of Shalazha thrust fault, which synchronizes with the cooling of the Shalazha Mountain and implies significant two-stage thrust fault activation between ca. 230 and 135 Ma. These new low-temperature thermochronological results from the Shalazha Mountain region and nearby reveal three main phases of differential tectonothermal events representing the Mesozoic reactivation of the central segment of the southern CAOB. In our interpretations, the initial rapid uplift in the Late Triassic was possibly associated with intracontinental orogenesis of the CAOB. Subsequent Middle Jurassic–Earliest Cretaceous cooling is highly consistent with the Mesozoic intense intraplate compression that occurred in th展开更多
基金Supported by Chinese Academy of Sciences (Grant No. KZCX3-SW-143)Chinese Ministry of Science and Technology (Grant No. 2002CB412602) the National Natural Science Foundation of China (Grant No. 40234049)
文摘Granites sampled from Garzê-Litang thrust, Longmen Shan thrust, Garzê and Litang strike-slip faults in the eastern Tibetan Plateau have been analyzed with apatite fission track thermochronological method in this study. The measured fission track apparent ages, combined with the simulated annealing mod- eling of the thermal history, have been used to reconstruct the thermal evolutionary histories of the samples and interpret the active history of the thrusts and faults in these areas. Thermal history mod- eling shows that earlier tectonic cooling occurred in the Garzê-Litang thrust in Miocene (~20―16 Ma) whereas the later cooling occurred mainly in the Longmen Shan thrust since ~5 Ma. Our study sug- gests that the margin of eastern Tibetan Plateau was extended by stages: through strike-slip faults deformations and related thrusts, the upper crust formed the Garzê-Litang margin in the Miocene epoch and then moved to the Longmen Shan margin since ~5 Ma. During this process, the deformations of different phases in the eastern Tibetan Plateau were absorbed by the thrusts within them and conse- quently the tectonic events of long-distance slip and extrusion up to hundreds of kilometers have not been found.
基金The National Special Project for Marine Geology of China under contract No.DD20160147the National Basic Research Program(973 Program) of China under contract No.2013CB429701the National Natural Science Foundation of China under contract No.41210005
文摘Basin modeling has become an important tool for analyzing sedimentary basins. The North Subbasin of the South Yellow Sea Basin is filled with thick Meso-Cenozoic terrigenous deposits during the rift evolution stage. The accumulation of data and achievements of geological investigations in recent years have provided the preconditions for basin modeling. The necessary parameters and geological elements for simulations are collated and summarized. Modeling of tectono-thermal evolution is performed and the related trend in heat flow is reconstructed and calibrated. The heat flow value commences from an average level of 61 m W/m2during MiddleLate Jurassic, rises to about 80 m W/m2from circa 145 Ma to circa 74 Ma, and then undergoes a gradual decline to65 m W/m2until the end of Oligocene.Three evolutionary phases, namely, the initial rifting phase, syn-rifting phase, and post-rifting phase, have been identified. The modeling results show that the North Subbasin generally enters into a stage of strong rifting during Cretaceous and undergoes rapid subsidence until the Late Cretaceous,then follows by a stage of moderate rifting during the Paleogene. The input and general workflow involved in 3-D modeling are introduced. Reconstruction of the petroleum system in the North Subbasin reveals that the threshold depth of hydrocarbon generation is located near the top of the Paleogene Funing formation, and the underlying Jurassic and Cretaceous source rocks have reached or exceeded peak oil generation and have almost completed the generation and expulsion of hydrocarbons. The main generation and expulsion in the Jurassic source rocks take place during the syn-rifting and post-rifting phases, whereas the peak generation and expulsion in the Cretaceous and Paleogene source rocks take place during the post-rifting phase. Although the study area is still a relatively less explored sedimentary basin, the results of modeling can provide valuable information for exploration. A preliminary discussion of the main uncertainty factors is a
基金supported by the National Natural Science Foundation of China (Grants No. 41572102, 41330315, 41102067, and 41172127)China Geological Survey project (Grant No. 121201011000161111-02)
文摘The contractional structures in the southern Ordos Basin recorded critical evidence for the interaction between Ordos Basin and Qinling Orogenic Collage. In this study, we performed apatite fission track （AFT） thermochronology to unravel the timing of thrusting and exhumation for the Laolongshan-Shengrenqiao Fault （LSF） in the southern Ordos Basin. The AFT ages from opposite sides of the LSF reveal a significant latest Triassic to Early Jurassic time-temperature discontinuity across this structure. Thermal modeling reveals at the latest Triassic to Early Jurassic, a ~50~C difference in temperature between opposite sides of the LSF currently exposed at the surface. This discontinuity is best interpreted by an episode of thrusting and exhumation of the LSF with -1.7 km of net vertical displacement during the latest Triassic to Early Jurassic. These results, when combined with earlier thermochronological studies, stratigraphic contact relationship and tectono-sedimentary evolution, suggest that the southern Ordos Basin experienced coeval intense tectonic contraction and developed a north-vergent fold-and-thrust belt. Moreover, the southern Ordos Basin experienced a multi-stage differential exhumation during Mesozoic, including the latest Triassic to Early Jurassic and Late Jurassic to earliest Cretaceous thrust-driven exhumation as well as the Late Cretaceous overall exhumation. Specifically, the two thrust-driven exhumation events were related to tectonic stress propagation derived from the latest Triassic to Early Jurassic continued compression from Qinling Orogenic Collage and the Late Jurassic to earliest Cretaceous intracontinental orogeny of QinUng Orogenic Collage, respectively. By contrast, the Late Cretaceous overall exhumation event was related to the collision of an exotic terrain with the eastern margin of continental China at -100 Ma.
基金funded by Natural Science Foundation of China(41572190)National Basic Research Program of Ministry of Science and Technology of the People's Republic of China(2015CB453002)China Geological Survey(121201102000150009-16,12120115069601)
文摘The apatite fission track dating of samples from the Dabashan （i.e., the Langshan in the northeastern Alxa Block） by the laser ablation method and their thermal history modeling of AFT ages are conducted in this study. The obtained results and lines of geological evidence in the study region indicate that the Langshan has experienced complicated tectonic-thermal events during the the Late Cretaceous-Cenozoic. Firstly, it experienced a tectonic-thermal event in the Late Cretaceous （-90-70 Ma）. The event had little relation with the oblique subduction of the Izanagi Plate along the eastern Eurasian Plate, but was related to the Neo-Tethys subduction and compression between the Lhasa Block and Qiangtang Block. Secondly, it underwent the dextral slip faulting in the Eocene （-50-45 Ma）. The strike slip fault may develop in the same tectonic setting as sinistral slip faults in southern Mongolia and thrusts in West Qinling to the southwest Ordos Block in the same period, which is the remote far-field response to the India-Eurasia collision. Thirdly, the tectonic thermal event existed in the late Cenozoic （since -10 Ma）, thermal modeling shows that several samples began their denudation from upper region of partial annealing zone （PAZ）, and the denudation may have a great relationship with the growth of Qinghai-Tibetan Plateau to the northeast. In addition, the AFT ages of Langshan indicate that the main body of the Langshan may be an upper part of fossil PAZ of the Late Cretaceous （-70 Ma）. The fossil PAZ were destroyed and deformed by tectonic events repeatedly in the Cenozoic along with the denudation.
基金supported by the National Natural Science Foundation of China (No. 41972153)the Geological Survey Project of China Geological Survey (No. DD20160172)the Science and Technology Department of China National Petroleum Corporation (No. 2018A-0104)。
文摘Mesozoic intracontinental orogeny and deformation were widespread within the southern Central Asian Orogenic Belt(CAOB). Chronological constraints remain unclear when assessing the Mesozoic evolution of the central segment of this region. The tectonic belt of Shalazha Mountain located in the center of this region is an ideal place to decode the deformation process. Apatite fission-track(AFT) thermochronology in Shalazha Mountain is applied to constrain the Mesozoic tectonothermal evolution of the central segment of southern CAOB. The bedrock AFT ages range from 161.8 ± 6.9 to 137.0 ± 7.3 Ma, and the first reported detrital AFT obtained from Lower Cretaceous strata shows three age peaks: P1(ca. 178 Ma), P2(ca. 149 Ma) and P3(ca. 105.6 Ma). Bedrock thermal history modeling indicates that Shalazha Mountain have experienced three stages of differential cooling: Late Triassic–Early Jurassic(~230–174 Ma), Late Jurassic–Earliest Cretaceous(~174–135 Ma) and later(~135 Ma). The first two cooling stages are well preserved by the detrital AFT thermochronological result(P1, P2) from the adjacent Lower Cretaceous strata, while P3(ca. 105.6 Ma) records coeval volcanic activity. Furthermore, our data uncover that hanging wall samples cooled faster between the Late Triassic and the Early Cretaceous than those from the footwall of Shalazha thrust fault, which synchronizes with the cooling of the Shalazha Mountain and implies significant two-stage thrust fault activation between ca. 230 and 135 Ma. These new low-temperature thermochronological results from the Shalazha Mountain region and nearby reveal three main phases of differential tectonothermal events representing the Mesozoic reactivation of the central segment of the southern CAOB. In our interpretations, the initial rapid uplift in the Late Triassic was possibly associated with intracontinental orogenesis of the CAOB. Subsequent Middle Jurassic–Earliest Cretaceous cooling is highly consistent with the Mesozoic intense intraplate compression that occurred in th
