The Shanan sag in the central-western Bohai Bay Basin hosts high-quality Paleogene source rocks within the Shahejie Formation’s third member(E_(2)s_(3)).Despite hydrocarbon indications in Cenozoic strata,no commercia...The Shanan sag in the central-western Bohai Bay Basin hosts high-quality Paleogene source rocks within the Shahejie Formation’s third member(E_(2)s_(3)).Despite hydrocarbon indications in Cenozoic strata,no commercial accumulations have been discovered.An integrated approach combining geochemical analysis,fluid inclusion thermometry,apatite fission-track(AFT)thermochronology,and basin modeling was employed to unravel the paleo-geothermal regime and hydrocarbon generation history of E_(2)s_(3) source rocks.AFT data from the Shahejie Formation’s second member(E_(2)s_(2))reveal a tectonothermal event at 25 Ma that accelerated E_(2)s_(3) maturation.Outside three sub-sag depocenters,current E_(2)s_(2) reservoir temperatures remain below the 25 Ma paleo-geothermal maxima despite subsequent Neogene burial.Hydrocarbon-bearing brine inclusions in E_(2)s_(2) reservoirs exhibit peak homogenization temperatures(Th)at 25 Ma,with minimal high-temperature signals,indicating that E_(2)s_(3) hydrocarbon generation peaked during the Paleogene thermal event,with limited late-stage accumulation.The regional effects of the Dongying Movement necessitate thick Neogene sedimentation to compensate for the 25 Ma paleo-geothermal anomaly.Our findings emphasize targeting Neogene depocenters in petroleum exploration to mitigate the inhibitory effects of high paleo-heat flow on late hydrocarbon generation,thereby enhancing current accumulation potential.展开更多
Multi-dating on the same detrital grains allows for determining multiple different geo-thermochronological ages simultaneously and thus could provide more details about regional tectonics.In this paper,we carried out ...Multi-dating on the same detrital grains allows for determining multiple different geo-thermochronological ages simultaneously and thus could provide more details about regional tectonics.In this paper,we carried out detrital zircon fission-track and U-Pb double dating on the Permian-Middle Triassic sediments from the southern Ordos Basin to decipher the tectonic information archived in the sediments of intracratonic basins.The detrital zircon U-Pb ages and fission-track ages,together with lag time analyses,indicate that the Permian-Middle Triassic sediments in the southern Ordos Basin are characterized by multiple provenances.The crystalline basement of the North China Craton(NCC)and recycled materials from pre-Permian sediments that were ultimately sourced from the basement of the NCC are the primary provenance,while the Permian magmatites in the northern margin of NCC and Early Paleozoic crystalline rocks in Qinling Orogenic Collage act as minor provenance.In addition,the detrital zircon fission-track age peaks reveal four major tectonothermal events,including the Late Triassic-Early Jurassic post-depositional tectonothermal event and three other tectonothermal events associated with source terrains.The Late Triassic-Early Jurassic(225–179 Ma)tectonothermal event was closely related to the upwelling of deep material and energy beneath the southwestern Ordos Basin due to the coeval northward subduction of the Yangze Block and the following collision of the Yangze Block and the NCC.The Mid-Late Permian(275–263 Ma)tectonothermal event was associated with coeval denudation in the northern part of the NCC and North Qinling terrane,resulting from the subduction of the Paleo-Asian Ocean and Tethys Ocean toward the NCC.The Late Devonian-early Late Carboniferous(348±33 Ma)tectonothermal event corresponded the long-term denudation in the hinterland and periphery of the NCC because of the arc-continent collisions in the northern and southern margins of the NCC.The Late Neoproterozoic(813–565 Ma)tectonothermal event was associated with formation of the Great Unconformity within the NCC and may be causally related to the Rodinia supercontinent breakup driven by a large-scale mantle upwelling.展开更多
Apatite fission-track dating and thermal-history modeling were carried out on samples from the Dabashan （大巴山）, a fold-thrust belt, northeast of the Sichuan （四川） Basin and east of the Tibetan Plateau. A first ...Apatite fission-track dating and thermal-history modeling were carried out on samples from the Dabashan （大巴山）, a fold-thrust belt, northeast of the Sichuan （四川） Basin and east of the Tibetan Plateau. A first cooling event in the Late Cretaceous is followed by a prolonged period of ther- mal stability with exhumation rates of 〈0.025 mm/a, as determined from age vs. elevation relationships. The preservation of age vs. elevations relationships and the lack of distinct age changes across tectonic structures indicate that the Dabashan fold-thrust belt formed prior to the Late Cretaceous, consistent with the current view of Triassic-Early Cretaceous shortening. Relatively short mean track lengths （-12 μm） indicate that the samples remained in the partial annealing zone for a prolonged time. The knick points in the best-fitting temperature-time models suggest that the onset of late-stage accelerated cooling commenced at 〈11 Ma. Related exhumation rates are 0.3-0.2 mm/a assuming geothermal gra- dients of 20 and 30 ℃/km. We speculate that this late-stage event results from eastward growth of the Tibetan Plateau and overstepping of the Sichuan Basin, it is likely responsible for the youthful mor- phology of the Dabashan.展开更多
To reveal the Jurassic tectonothermal event occurring to the Nyainrong microcontinent which is gripped among the Bangong-Nujiang suture zone,^40Ar/^39Ar dating was carried out on the basement orthogneiss and Jurassic ...To reveal the Jurassic tectonothermal event occurring to the Nyainrong microcontinent which is gripped among the Bangong-Nujiang suture zone,^40Ar/^39Ar dating was carried out on the basement orthogneiss and Jurassic granitc gneiss in the microcontinent. In the heating stage, four sam- pies exhibited a flat plateau age, with the value Tp concentrated in the range of 166-176 Ma; isochron age Ti was concentrated in the range of 165-175 Ma, and their corresponding ages were the consistent within allowable range. The ages should be representative of the era of the final deformation of the Amdo gneiss and cooling emplacement of the magmatic rock in the Jurassic. The geochronological studies have shown that the final deformation of microcontinent crystalline basement and the cooling of the Mesozoic large-scale tectonothermal events occurred in late Middle Jurassic. In Middle Jurassic, Nyainrong microcontinent experienced strong tectonic movement. Combining with the geochronologi- cal with isotope geochemistry for the microcontinent, the cause of the tectonothermal event should be attributed to the collision between the Nyainrong microcontinent and South Qiangtang Block following the northward subduction of Bangong-Nujiang oceanic crust.展开更多
The Central Indian Tectonic Zone(CITZ)is a major E-W striking mobile belt dissecting the Indian Craton along which the northern and southern Indian cratonic blocks have joined to make the Greater Indian Landmass(GIL)....The Central Indian Tectonic Zone(CITZ)is a major E-W striking mobile belt dissecting the Indian Craton along which the northern and southern Indian cratonic blocks have joined to make the Greater Indian Landmass(GIL).CITZ has a long evolutionary history spanning over 1000 Myrs(2.1-0.9 Ga),overlapping with the assembly and dispersal of two supercontinents–Columbia and Rodinia.展开更多
Ordos Basin is a remnant cratonic basin undergone multiple tectonothermal cyles, by the comprehensive study of thermoluminescence combined with vitrinite reflectance,magmatism, metamorphism and tectonosedimentation in...Ordos Basin is a remnant cratonic basin undergone multiple tectonothermal cyles, by the comprehensive study of thermoluminescence combined with vitrinite reflectance,magmatism, metamorphism and tectonosedimentation in the basin. Highly geothermal field,strong crustal movement existed in the basin during Archean to Paleoproterozoic. Since Mesoproterozoic, the tectonothermal nature has been relatively stable in Ordos Basin, associating with constant subsidence or uplift sometimes,while heat flow has still been high in the vicinityof the basin with strong activation of graben structural system because of the upwarding mantle creep flow. Two tectonothermal evolution stages and four developing periods can be recongnized in Ordos Basin,i. e. Pre-Mesoproterozoic stage consisting of Archean much higher geothermal geodome period and Paleoproterozoic higher-Reothermal geosyncline period,Mesoproterozolc to present stage including Mesoproterozoic to early Triassic low-geothermal geodepression period and late Triassic to present lowugeothermal uplift-subsidence period. The tectonothermal event at middle Triassic caused the uplift of the basin and the formation of the central paleodome,indicating that the basin entered its residual developing period of the platform. During the residual stable developing period of plat form,the creeping of the mantle increased and the heat flow changed to be high,accompanied by wide spreading eruption of basalt, such as that in Yimeng Uplift area,while the tectonic activity has been quite strong in the surrounding of the basin and the surrounding obviously overthrusted over the basin. Since Triassic, the basin has been gradually uplifted and its tectonism has migrated westward. The tectonothermal event may predicted the breakup of ordos Basin.展开更多
The continental marginal extension concept developed by Chinese geologists recently may be applied to the explanation about the Cenozoic extension and divergent movement of the Eastern Asian continental margin. From t...The continental marginal extension concept developed by Chinese geologists recently may be applied to the explanation about the Cenozoic extension and divergent movement of the Eastern Asian continental margin. From the viewpoint of continental marginal extension, this paper discusses the deep tectonothermal mechanism of the tectonic extension of the Eastern Asian continental margin.The Eastern Asian continental margin is an extensional belt with intensive magmatism and structural deformation, geophysically characterized by continual earthquakes and obvious geothermal anomaly.Seismic tomographical results about the Eastern Asian continental margin imply that the Pacific Plate is subducted toward the Eurasian Plate at a low angle and the diving Pacific Plate lies on the surface of the 670-km phase transitional zone. We interpret this feature to be resulted from retrogressive subduction followed by continental marginal extension. Our thermal modeling and geodynamical computation results suggest that the retrogressive subduction occurred at about 76Ma and the withdrawal of the trench served to supply the volume for the continental growth, which led to the formation of the growing front of the Eastern Asian continental margin. The growth width of the Eastern Asian continental margin is about 700 km.展开更多
The thermal evolution of source rocks in the Paleozoic stratigraphic sequences has been an outstanding problem for petroleum exploration in the Tarim Basin, as the thermal history of the Paleozoic could not be reconst...The thermal evolution of source rocks in the Paleozoic stratigraphic sequences has been an outstanding problem for petroleum exploration in the Tarim Basin, as the thermal history of the Paleozoic could not be reconstructed objectively due to the lack of effective thermal indicators in the early Paleozoic carbonate successions. The (U-Th)/He thermochronometry of apatite and zircon has recently been used as an effective tool to study the structural uplift and thermal history of sedimentary basins. The Paleozoic tectonothermal histories of two typical wells in the Tarim Basin were modeled using the thermal indicators of (U-Th)/He, apatite fission track (AFT), and vitrinite reflectance (Ro) data in this paper. The Paleozoic strata in the two wells were shallow due to persistent uplift and significant erosion during the Hercynian tectonic events (from Devonian to Triassic). Therefore, the paleothermal indicators in the Paleozoic strata may retain the original thermal evolution and can be used to re- construct the Paleozoic thermal history of the Tarim Basin. The apatite and zircon helium ages from core and cuttings samples were analyzed and the Paleozoic thermal histories of wells KQ1 and T1 were modeled by combining helium ages, AFT, and equivalence vitrinite reflectance (VRo) data. The modeling results show that the geothermal gradient evolution is different in the Kongquehe Slop and Bachu Uplift of Tarim Basin during the Paleozoic. The thermal gradient in Well T1 on the Bachu Up- lift was only 28–30°C/km in Cambrian, and it increased to 30–33°C/km in Ordovician and 31–34°C/km during the Silurian and Devonian. The thermal gradient of Ordovician in Well KQ1 on the Kongquehe Slope was 35°C/km and decreased to 32–35°C/km during the Silurian and Devonian. Therefore, the combined use of (U-Th)/He ages and other thermal indicators appears to be useful in reconstructing the basin thermal history and provides new insight into the understanding of the early Paleozoic thermal history of the Tarim Basin.展开更多
Analysis of tectonothermal history of the Yanchang Formation in the western Weibei Uplift and in the northwestern Weihe Basin can reconstruct the cooling history of the southwest most remained Upper Triassic source ro...Analysis of tectonothermal history of the Yanchang Formation in the western Weibei Uplift and in the northwestern Weihe Basin can reconstruct the cooling history of the southwest most remained Upper Triassic source rock of the North China Plate. Apatite fission-track(AFT) and(U-ThSm)/He(AHe) analysis were used to recover the cooling and uplift history of the Upper Triassic here. Ten sandstones from the Middle–Upper Triassic strata yield AFT ages between 179.8 ± 7.4 and 127.6 ± 8.1 Ma. AHe ages of two sandstones have the value of 37.7 ± 2.3–131.1 ± 8.1 and 45.7 ± 2.8–83.5 ± 5.2 Ma. Time-temperature modeling results showed that tectonothermal history of the Yanchang Formation was initially different in time-space relationships but then became almost identical through time followed by different cooling rate. Modeling results of the Triassic strata in the Qianyang area and the Yaojiagou area revealed three different uplift-cooling stages commencing in the Late Jurassic at ~165 Ma and in Early Cretaceous at ~110 Ma, respectively, both followed by first similar cooling histories to the Early Miocene at ~20 – 23 Ma and then different since the Late Miocene. Uplift-cooling rate since the Late Miocene at ~8 Ma were different between the Western Weibei Uplift and the Northwestern Weihe Basin. The timing, cooling-uplift rates of the Yaojiagou area, which was mainly controlled by movements related to the Liupanshan Mountains, the Qinling Orogens and the Weibei Uplift, had the earliest onset of uplift-cooling for the Upper Triassic series compared to other regions within the Weibei Uplift. Cooling paths for the Upper Triassic series became uniform regionally in the Early Cretaceous marking a key time for the tectonothermal evolutionary history of Upper Triassic series in the southwestern North China Plate.展开更多
In this paper we reported the 40 Ar 39 Ar dating results of hornblendes in Grt Pl bearing amphibolite from the Larsemann Hills, East Antarctica. Their apparent ages respectively are 1586 Ma, 1011...In this paper we reported the 40 Ar 39 Ar dating results of hornblendes in Grt Pl bearing amphibolite from the Larsemann Hills, East Antarctica. Their apparent ages respectively are 1586 Ma, 1011 1080 Ma, 761 Ma, 529 582 Ma. Their plateau ages of 1036 Ma and 554 Ma as well as an Ar Ar isochron age of 1010 Ma have also been obtained respectively. These isotopic dating results for the first time by the Ar Ar method for hornblendes completely record almost all the structural metamorphic thermal events that this region experienced, and provide an answer to the controversial question on the structural metamorphic thermal events of this region in recent several years, namely, which one is more important, the late Proterozoic 1000 Ma event (Grenvillian) or the early Palaeozoic 500 Ma event ( Pan African), as well as whether the former exists or not. The 40 Ar 39 Ar dating results of hornblendes show that the Larsemann Hills experienced a complicated poly metamorphic evolutionary history, and their protoliths were probably formed in early to mid Proterozoic. The late Proterozoic 1000 Ma event (Grenvillian) has been confirmed to be a predominant tectonothermal event whilst the early Palaeozoic 500 Ma event (Pan African) has been confirmed just to be the last strong tectonothermal event in this region.展开更多
As the structural body related to temporal-spatial evolution and tectonic dynamic system, the orogenic belt and basin are not only dependent on each other in space but also closely related with each other in terms of ...As the structural body related to temporal-spatial evolution and tectonic dynamic system, the orogenic belt and basin are not only dependent on each other in space but also closely related with each other in terms of infrastructure, matter transference and dynamic mechanisms. By using apatite fission-track method, the authors firstly analyze the uplift and denudation ratios of the Qinling-Dabie orogenic belt, and by using tectonically deformed combination analysis and tectonic-thermal simulation the main geological occurrences are also illustrated. It is found that there must have had multi-phase differential uplift and denudation phenomena in the Qinling-Dabie orogenic belt during the Mesozoic-Cenozoic. Then, the regional evolution pattern of qualitative and quantitative denudation process is obtained during the post-orogenic period. On the basis of summarizing evolution process of the basin-range system in the Qinling-Dabie orogenic belt during the Mesozoic-Cenozoic and its effects on regional environment, the influence of evolution process on geomorphologic landscapes change, water system vicissitude, eco-environment succession and drainage basin system evolution is discussed.展开更多
Recently,fission track analysis has been widely used to solve the problems involved instudy of geothermal evolution of basins.Thermoluminescence is also applied totectonothermal evolution.This note focuses on the tect...Recently,fission track analysis has been widely used to solve the problems involved instudy of geothermal evolution of basins.Thermoluminescence is also applied totectonothermal evolution.This note focuses on the tectonothermal events and evaluationof petroleum by using the fission track analysis in combination with the method ofthermoluminesence in the basin.展开更多
基金the National Natural Science Foundation(41802169)Key Laboratory of Polar Geology and Marine Mineral Resources Foudation(HNPY-202506)for supporting this study.
文摘The Shanan sag in the central-western Bohai Bay Basin hosts high-quality Paleogene source rocks within the Shahejie Formation’s third member(E_(2)s_(3)).Despite hydrocarbon indications in Cenozoic strata,no commercial accumulations have been discovered.An integrated approach combining geochemical analysis,fluid inclusion thermometry,apatite fission-track(AFT)thermochronology,and basin modeling was employed to unravel the paleo-geothermal regime and hydrocarbon generation history of E_(2)s_(3) source rocks.AFT data from the Shahejie Formation’s second member(E_(2)s_(2))reveal a tectonothermal event at 25 Ma that accelerated E_(2)s_(3) maturation.Outside three sub-sag depocenters,current E_(2)s_(2) reservoir temperatures remain below the 25 Ma paleo-geothermal maxima despite subsequent Neogene burial.Hydrocarbon-bearing brine inclusions in E_(2)s_(2) reservoirs exhibit peak homogenization temperatures(Th)at 25 Ma,with minimal high-temperature signals,indicating that E_(2)s_(3) hydrocarbon generation peaked during the Paleogene thermal event,with limited late-stage accumulation.The regional effects of the Dongying Movement necessitate thick Neogene sedimentation to compensate for the 25 Ma paleo-geothermal anomaly.Our findings emphasize targeting Neogene depocenters in petroleum exploration to mitigate the inhibitory effects of high paleo-heat flow on late hydrocarbon generation,thereby enhancing current accumulation potential.
基金supported by the National Natural Science Foundation of China(Grants No.41572102,41330315,41102067,and 41172127)Natural Science Foundation of Shaanxi Province(Grant No.2018JM4001)
文摘Multi-dating on the same detrital grains allows for determining multiple different geo-thermochronological ages simultaneously and thus could provide more details about regional tectonics.In this paper,we carried out detrital zircon fission-track and U-Pb double dating on the Permian-Middle Triassic sediments from the southern Ordos Basin to decipher the tectonic information archived in the sediments of intracratonic basins.The detrital zircon U-Pb ages and fission-track ages,together with lag time analyses,indicate that the Permian-Middle Triassic sediments in the southern Ordos Basin are characterized by multiple provenances.The crystalline basement of the North China Craton(NCC)and recycled materials from pre-Permian sediments that were ultimately sourced from the basement of the NCC are the primary provenance,while the Permian magmatites in the northern margin of NCC and Early Paleozoic crystalline rocks in Qinling Orogenic Collage act as minor provenance.In addition,the detrital zircon fission-track age peaks reveal four major tectonothermal events,including the Late Triassic-Early Jurassic post-depositional tectonothermal event and three other tectonothermal events associated with source terrains.The Late Triassic-Early Jurassic(225–179 Ma)tectonothermal event was closely related to the upwelling of deep material and energy beneath the southwestern Ordos Basin due to the coeval northward subduction of the Yangze Block and the following collision of the Yangze Block and the NCC.The Mid-Late Permian(275–263 Ma)tectonothermal event was associated with coeval denudation in the northern part of the NCC and North Qinling terrane,resulting from the subduction of the Paleo-Asian Ocean and Tethys Ocean toward the NCC.The Late Devonian-early Late Carboniferous(348±33 Ma)tectonothermal event corresponded the long-term denudation in the hinterland and periphery of the NCC because of the arc-continent collisions in the northern and southern margins of the NCC.The Late Neoproterozoic(813–565 Ma)tectonothermal event was associated with formation of the Great Unconformity within the NCC and may be causally related to the Rodinia supercontinent breakup driven by a large-scale mantle upwelling.
基金supported by the National Natural Science Foundation of China (No. 40902038)the Petro China Innova-tion Foundation (No. 2009D-5006-01-08)the Project of China Geological Survey (No. 12120113094200)
文摘Apatite fission-track dating and thermal-history modeling were carried out on samples from the Dabashan （大巴山）, a fold-thrust belt, northeast of the Sichuan （四川） Basin and east of the Tibetan Plateau. A first cooling event in the Late Cretaceous is followed by a prolonged period of ther- mal stability with exhumation rates of 〈0.025 mm/a, as determined from age vs. elevation relationships. The preservation of age vs. elevations relationships and the lack of distinct age changes across tectonic structures indicate that the Dabashan fold-thrust belt formed prior to the Late Cretaceous, consistent with the current view of Triassic-Early Cretaceous shortening. Relatively short mean track lengths （-12 μm） indicate that the samples remained in the partial annealing zone for a prolonged time. The knick points in the best-fitting temperature-time models suggest that the onset of late-stage accelerated cooling commenced at 〈11 Ma. Related exhumation rates are 0.3-0.2 mm/a assuming geothermal gra- dients of 20 and 30 ℃/km. We speculate that this late-stage event results from eastward growth of the Tibetan Plateau and overstepping of the Sichuan Basin, it is likely responsible for the youthful mor- phology of the Dabashan.
基金supported by the National Natural Science Foundation of China(Nos.41272240 and 41072166)China Geological Survey(Nos.1212011121248 and 1212011221093)
文摘To reveal the Jurassic tectonothermal event occurring to the Nyainrong microcontinent which is gripped among the Bangong-Nujiang suture zone,^40Ar/^39Ar dating was carried out on the basement orthogneiss and Jurassic granitc gneiss in the microcontinent. In the heating stage, four sam- pies exhibited a flat plateau age, with the value Tp concentrated in the range of 166-176 Ma; isochron age Ti was concentrated in the range of 165-175 Ma, and their corresponding ages were the consistent within allowable range. The ages should be representative of the era of the final deformation of the Amdo gneiss and cooling emplacement of the magmatic rock in the Jurassic. The geochronological studies have shown that the final deformation of microcontinent crystalline basement and the cooling of the Mesozoic large-scale tectonothermal events occurred in late Middle Jurassic. In Middle Jurassic, Nyainrong microcontinent experienced strong tectonic movement. Combining with the geochronologi- cal with isotope geochemistry for the microcontinent, the cause of the tectonothermal event should be attributed to the collision between the Nyainrong microcontinent and South Qiangtang Block following the northward subduction of Bangong-Nujiang oceanic crust.
文摘The Central Indian Tectonic Zone(CITZ)is a major E-W striking mobile belt dissecting the Indian Craton along which the northern and southern Indian cratonic blocks have joined to make the Greater Indian Landmass(GIL).CITZ has a long evolutionary history spanning over 1000 Myrs(2.1-0.9 Ga),overlapping with the assembly and dispersal of two supercontinents–Columbia and Rodinia.
文摘Ordos Basin is a remnant cratonic basin undergone multiple tectonothermal cyles, by the comprehensive study of thermoluminescence combined with vitrinite reflectance,magmatism, metamorphism and tectonosedimentation in the basin. Highly geothermal field,strong crustal movement existed in the basin during Archean to Paleoproterozoic. Since Mesoproterozoic, the tectonothermal nature has been relatively stable in Ordos Basin, associating with constant subsidence or uplift sometimes,while heat flow has still been high in the vicinityof the basin with strong activation of graben structural system because of the upwarding mantle creep flow. Two tectonothermal evolution stages and four developing periods can be recongnized in Ordos Basin,i. e. Pre-Mesoproterozoic stage consisting of Archean much higher geothermal geodome period and Paleoproterozoic higher-Reothermal geosyncline period,Mesoproterozolc to present stage including Mesoproterozoic to early Triassic low-geothermal geodepression period and late Triassic to present lowugeothermal uplift-subsidence period. The tectonothermal event at middle Triassic caused the uplift of the basin and the formation of the central paleodome,indicating that the basin entered its residual developing period of the platform. During the residual stable developing period of plat form,the creeping of the mantle increased and the heat flow changed to be high,accompanied by wide spreading eruption of basalt, such as that in Yimeng Uplift area,while the tectonic activity has been quite strong in the surrounding of the basin and the surrounding obviously overthrusted over the basin. Since Triassic, the basin has been gradually uplifted and its tectonism has migrated westward. The tectonothermal event may predicted the breakup of ordos Basin.
基金supported by China National Natural Science Foundation(Grants No.40074022 and No.40174027)the“973”State Key Basic Research and Development Planning Program(Grant No.G200004670401)
文摘The continental marginal extension concept developed by Chinese geologists recently may be applied to the explanation about the Cenozoic extension and divergent movement of the Eastern Asian continental margin. From the viewpoint of continental marginal extension, this paper discusses the deep tectonothermal mechanism of the tectonic extension of the Eastern Asian continental margin.The Eastern Asian continental margin is an extensional belt with intensive magmatism and structural deformation, geophysically characterized by continual earthquakes and obvious geothermal anomaly.Seismic tomographical results about the Eastern Asian continental margin imply that the Pacific Plate is subducted toward the Eurasian Plate at a low angle and the diving Pacific Plate lies on the surface of the 670-km phase transitional zone. We interpret this feature to be resulted from retrogressive subduction followed by continental marginal extension. Our thermal modeling and geodynamical computation results suggest that the retrogressive subduction occurred at about 76Ma and the withdrawal of the trench served to supply the volume for the continental growth, which led to the formation of the growing front of the Eastern Asian continental margin. The growth width of the Eastern Asian continental margin is about 700 km.
基金supported by Key Project of Ministry of Education of China (Grant No. 308005)National Basic Research Program of China (Grant No. 2005CB422102)State Key Laboratory of Petroleum Resource and Prospecting (Grant No. PRPJC2008-01)
文摘The thermal evolution of source rocks in the Paleozoic stratigraphic sequences has been an outstanding problem for petroleum exploration in the Tarim Basin, as the thermal history of the Paleozoic could not be reconstructed objectively due to the lack of effective thermal indicators in the early Paleozoic carbonate successions. The (U-Th)/He thermochronometry of apatite and zircon has recently been used as an effective tool to study the structural uplift and thermal history of sedimentary basins. The Paleozoic tectonothermal histories of two typical wells in the Tarim Basin were modeled using the thermal indicators of (U-Th)/He, apatite fission track (AFT), and vitrinite reflectance (Ro) data in this paper. The Paleozoic strata in the two wells were shallow due to persistent uplift and significant erosion during the Hercynian tectonic events (from Devonian to Triassic). Therefore, the paleothermal indicators in the Paleozoic strata may retain the original thermal evolution and can be used to re- construct the Paleozoic thermal history of the Tarim Basin. The apatite and zircon helium ages from core and cuttings samples were analyzed and the Paleozoic thermal histories of wells KQ1 and T1 were modeled by combining helium ages, AFT, and equivalence vitrinite reflectance (VRo) data. The modeling results show that the geothermal gradient evolution is different in the Kongquehe Slop and Bachu Uplift of Tarim Basin during the Paleozoic. The thermal gradient in Well T1 on the Bachu Up- lift was only 28–30°C/km in Cambrian, and it increased to 30–33°C/km in Ordovician and 31–34°C/km during the Silurian and Devonian. The thermal gradient of Ordovician in Well KQ1 on the Kongquehe Slope was 35°C/km and decreased to 32–35°C/km during the Silurian and Devonian. Therefore, the combined use of (U-Th)/He ages and other thermal indicators appears to be useful in reconstructing the basin thermal history and provides new insight into the understanding of the early Paleozoic thermal history of the Tarim Basin.
基金supported by the National Natural Science Foundation of China (Nos.41630312,41602128,41703055)the “Research Grants by China Geological Survey (No.DD20160060)”+2 种基金the “Fundamental Research Funds for the Central UniversitiesCHD (Nos.300102279206,300102278204)”the fund from China Scholarship Council。
文摘Analysis of tectonothermal history of the Yanchang Formation in the western Weibei Uplift and in the northwestern Weihe Basin can reconstruct the cooling history of the southwest most remained Upper Triassic source rock of the North China Plate. Apatite fission-track(AFT) and(U-ThSm)/He(AHe) analysis were used to recover the cooling and uplift history of the Upper Triassic here. Ten sandstones from the Middle–Upper Triassic strata yield AFT ages between 179.8 ± 7.4 and 127.6 ± 8.1 Ma. AHe ages of two sandstones have the value of 37.7 ± 2.3–131.1 ± 8.1 and 45.7 ± 2.8–83.5 ± 5.2 Ma. Time-temperature modeling results showed that tectonothermal history of the Yanchang Formation was initially different in time-space relationships but then became almost identical through time followed by different cooling rate. Modeling results of the Triassic strata in the Qianyang area and the Yaojiagou area revealed three different uplift-cooling stages commencing in the Late Jurassic at ~165 Ma and in Early Cretaceous at ~110 Ma, respectively, both followed by first similar cooling histories to the Early Miocene at ~20 – 23 Ma and then different since the Late Miocene. Uplift-cooling rate since the Late Miocene at ~8 Ma were different between the Western Weibei Uplift and the Northwestern Weihe Basin. The timing, cooling-uplift rates of the Yaojiagou area, which was mainly controlled by movements related to the Liupanshan Mountains, the Qinling Orogens and the Weibei Uplift, had the earliest onset of uplift-cooling for the Upper Triassic series compared to other regions within the Weibei Uplift. Cooling paths for the Upper Triassic series became uniform regionally in the Early Cretaceous marking a key time for the tectonothermal evolutionary history of Upper Triassic series in the southwestern North China Plate.
文摘In this paper we reported the 40 Ar 39 Ar dating results of hornblendes in Grt Pl bearing amphibolite from the Larsemann Hills, East Antarctica. Their apparent ages respectively are 1586 Ma, 1011 1080 Ma, 761 Ma, 529 582 Ma. Their plateau ages of 1036 Ma and 554 Ma as well as an Ar Ar isochron age of 1010 Ma have also been obtained respectively. These isotopic dating results for the first time by the Ar Ar method for hornblendes completely record almost all the structural metamorphic thermal events that this region experienced, and provide an answer to the controversial question on the structural metamorphic thermal events of this region in recent several years, namely, which one is more important, the late Proterozoic 1000 Ma event (Grenvillian) or the early Palaeozoic 500 Ma event ( Pan African), as well as whether the former exists or not. The 40 Ar 39 Ar dating results of hornblendes show that the Larsemann Hills experienced a complicated poly metamorphic evolutionary history, and their protoliths were probably formed in early to mid Proterozoic. The late Proterozoic 1000 Ma event (Grenvillian) has been confirmed to be a predominant tectonothermal event whilst the early Palaeozoic 500 Ma event (Pan African) has been confirmed just to be the last strong tectonothermal event in this region.
文摘As the structural body related to temporal-spatial evolution and tectonic dynamic system, the orogenic belt and basin are not only dependent on each other in space but also closely related with each other in terms of infrastructure, matter transference and dynamic mechanisms. By using apatite fission-track method, the authors firstly analyze the uplift and denudation ratios of the Qinling-Dabie orogenic belt, and by using tectonically deformed combination analysis and tectonic-thermal simulation the main geological occurrences are also illustrated. It is found that there must have had multi-phase differential uplift and denudation phenomena in the Qinling-Dabie orogenic belt during the Mesozoic-Cenozoic. Then, the regional evolution pattern of qualitative and quantitative denudation process is obtained during the post-orogenic period. On the basis of summarizing evolution process of the basin-range system in the Qinling-Dabie orogenic belt during the Mesozoic-Cenozoic and its effects on regional environment, the influence of evolution process on geomorphologic landscapes change, water system vicissitude, eco-environment succession and drainage basin system evolution is discussed.
基金Project supported by the National Natural Science Foundation of China.
文摘Recently,fission track analysis has been widely used to solve the problems involved instudy of geothermal evolution of basins.Thermoluminescence is also applied totectonothermal evolution.This note focuses on the tectonothermal events and evaluationof petroleum by using the fission track analysis in combination with the method ofthermoluminesence in the basin.
