Based on the test and experimental data from exploration well cores of the Upper Paleozoic in the central-eastern Ordos Basin,combined with structural,burial depth and fluid geochemistry analyses,this study reveals th...Based on the test and experimental data from exploration well cores of the Upper Paleozoic in the central-eastern Ordos Basin,combined with structural,burial depth and fluid geochemistry analyses,this study reveals the fluid characteristics,gas accumulation control factors and accumulation modes in the Upper Paleozoic coal reservoirs.The study indicates findings in two aspects.First,the 1500-1800 m interval represents the critical transition zone between open fluid system in shallow-medium depths and closed fluid system in deep depths.The reservoirs above 1500 m reflect intense water invasion,with discrete pressure gradient distribution,and the presence of methane mixed with varying degrees of secondary biogenic gas,and they generally exhibit high water saturation and adsorbed gas undersaturation.The reservoirs deeper than 1800 m,with extremely low permeability,are self-sealed,and contains closed fluid systems formed jointly by the hydrodynamic lateral blocking and tight caprock confinement.Within these systems,surface runoff infiltration is weak,the degree of secondary fluid transformation is minimal,and the pressure gradient is relatively uniform.The adsorbed gas saturation exceeds 100%in most seams,and the free gas content primarily ranges from 1 m^(3)/t to 8 m^(3)/t(greater than 10 m^(3)/t in some seams).Second,the gas accumulation in deep coals is primarily controlled by coal quality,reservoir-caprock assemblage,and structural position governed storage,wettability and sealing properties,under the constraints of the underground temperature and pressure conditions.High-rank,low-ash yield coals with limestone and mudstone caprocks show superior gas accumulation potential.Positive structural highs and wide and gentle negative structural lows are favorable sites for gas enrichment,while slope belts of fold limbs exhibit relatively lower gas content.This research enhances understanding of gas accumulation mechanisms in coal reservoirs and provides effective parameter reference for precise zone evaluation and innovation of adaptive stimulation technologies for deep resources.展开更多
The Yarlung Zangbo Suture Zone(YZSZ)on the southern margin of the Lhasa block and the Tangjia-Sumdo ultrahigh-pressure metamorphic belt(TSMB)within the block represent natural laboratories for the study of plate tecto...The Yarlung Zangbo Suture Zone(YZSZ)on the southern margin of the Lhasa block and the Tangjia-Sumdo ultrahigh-pressure metamorphic belt(TSMB)within the block represent natural laboratories for the study of plate tectonics and oceanic slab subduction.It is generally believed that these two zones represent the remnants of the ancient oceanic crust and upper mantle of the Yarlung Zangbo Neo-Tethys(YZNT)and the Tangjia-Sumdo Paleo-Tethys(TSPT).However,the evolutionary patterns and spatiotemporal relationships of the TSPT and the YZNT have been debated.展开更多
This study presents whole-rock major,trace elements and Sr-Nd-Hf isotopic compositions,as well as zircon UPb geochronological data,for the peraluminous and aluminous granitoids in northern Guangdong Province,South Chi...This study presents whole-rock major,trace elements and Sr-Nd-Hf isotopic compositions,as well as zircon UPb geochronological data,for the peraluminous and aluminous granitoids in northern Guangdong Province,South China,in order to investigate their petrogenesis and tectonic implications.The Qingzhou granodiorites(458.5-455.4 Ma)are peraluminous(A/CNK=1.05-1.96).They have relatively high initial^(87)Sr/^(86)Sr ratios(I_(Sr)=0.7087-0.7148),lowε_(Nd)(t)values(-11.2 to-10.1)and a variety of zirconε_(Hf)(t)values in the range-13.4 to+4.81.By contrast,the Damaoshan granodiorites(458.1 Ma)are metaluminous(A/CNK=0.79-0.94)in composition,with I_(Sr)values of 0.7083 to 0.7110,ε_(Nd)(t)values of-7.92 to-5.28 and zirconε_(Nf)(t)values of-8.69 to-2.06.The Gaoshou quartz diorites(449 Ma)are metaluminous-peraluminous.Their I_(Sr)values vary from 0.7104 to 0.7111 withε_(Nd)(t)values from-9.64 to-8.63.Geochemical data and Sr-Nd-Hf isotope compositions indicate that the Qingzhou,Damaoshan and Gaoshou intrusions are primarily derived from the partial melting of metagreywackes,tonalitic rocks and amphibolite,respectively.The crustal materials in northern Guangdong,from top to bottom consist of Paleozoic sequences,metasediments with a V_(p)of<6.0 km/s,metaigneous rocks with a V_(p)of 6.3-6.7 km/s and amphibolite with a V_(p)of~7.03 km/s.展开更多
Subduction initiation is a critical part of the plate tectonic system,but its geodynamic process is still poorly understood due to the lack of well-preserved geological records.Based on new zircon U–Pb–Hf isotopic a...Subduction initiation is a critical part of the plate tectonic system,but its geodynamic process is still poorly understood due to the lack of well-preserved geological records.Based on new zircon U–Pb–Hf isotopic and whole-rock geochemical data,we report the first discovery of a latest Cambrian–Early Ordovician forearc-arc rock sequence in the Eastern Alps.This sequence includes granitic gneisses,amphibolites,and amphibole plagiogneisses from the ophiolitic Speik Complex and Gleinalpe Complex.These rocks exhibit geochemical affinities with typical oceanic plagiogranites,forearc basalts(FABs),and island arc basalts,respectively.The latest Cambrian plagiogranitic protoliths(491±2 Ma)are shearing-type plagiogranites that were formed in the tectonic setting of forearc spreading.The latest Cambrian FABs(496–489 Ma)have similar geochemical compositions and positiveεHf(t)values(+2.5 to+14.9)to the depleted mid-ocean ridge basalts.However,they show depletion in high field strength elements(HFSEs;e.g.,Nb,Ta,and Zr)and have relatively low Ti/V ratios.These features suggest that they were derived from a depleted mantle source modified by subducting slab-released components in a forearc environment.The Early Ordovician basaltic protoliths(476–472 Ma)of amphibole plagiogneisses show enrichment in large ion lithophile elements and depletion in HFSEs(e.g.Nb,Ta,Zr,and Hf),implying a mature island arc environment.These metaigneous rocks,along with the coeval boninite-like high-Mg amphibolites near the study area,form a typical rock sequence resembling that of the Izu–Bonin–Mariana(IBM)arc system.The Speik and Gleinalpe complexes document a complete magmatic evolution from subduction initiation to mature arc development within the West Proto-Tethys Ocean.Integrating our new data with published work,we reconstruct the late Ediacaran–early Paleozoic tectonic evolution of the northern Gondwana.During the late Ediacaran–early Cambrian,the rollback of the West Proto-Tethys oceanic plate triggered the separation of the Wechsel-Silvretta-Gleinalpe continental arc from the northern Gondwana.This process led to the formation of the Speik back-arc oceanic basin,a southwestern branch of the West Proto-Tethys Ocean.In the latest Cambrian–Early Ordovician,subduction initiation occurred in the Speik Ocean,which subsequently developed into an intra-oceanic arc system.During the Early Devonian,the Speik Ocean closed and the Wechsel-Silvretta-Gleinalpe continental arc reattached to the Gondwana,as evidenced by the metamorphic event at ca.400 Ma.展开更多
0 INTRODUCTION The Haidewula uranium deposit is located in the Haidewula volcanic basin,which hosts a suite of basic,intermediate to felsic volcanic and subvolcanic rocks,including basalt,trachyte,trachyandesite.Previ...0 INTRODUCTION The Haidewula uranium deposit is located in the Haidewula volcanic basin,which hosts a suite of basic,intermediate to felsic volcanic and subvolcanic rocks,including basalt,trachyte,trachyandesite.Previous geochronological studies of the intrusions within this volcanic basin suggest that they primarily formed during the Silurian and Triassic periods(Dai et al.,2025;Sun et al.,2024;Wang et al.,2024;Zhu et al.,2022;Lei et al.,2021).展开更多
A systematic study of early Paleozoic S-type granites in Pinghe enhances our understanding of the tectonic evolution of proto-Tethys and provides a foundation for exploring rare metal deposits in the region.The Pinghe...A systematic study of early Paleozoic S-type granites in Pinghe enhances our understanding of the tectonic evolution of proto-Tethys and provides a foundation for exploring rare metal deposits in the region.The Pinghe granites consist of monzogranite and leucogranite.Zircon U-Pb dating shows that the emplacement ages of the monzogranite and leucogranite are 502.0 Ma and 500.9 Ma,respectively.All samples have high SiO_(2) content and a weakly to strongly peraluminous character(A/CNK=1.08-1.23),consistent with S-type granites.The monzogranite has relatively high CaO,Sr,Ba,and CaO/Na_(2)O ratios but lower Rb.In contrast,the leucogranite has lower CaO,Sr,Ba,and CaO/Na_(2)O ratios but higher Rb.The similar ε_(Nd)(t)values(−9.3 to−8.4)and Pb isotopic compositions((^(206)Pb/^(204)Pb)t=18.03-19.36,(^(207)Pb/^(204)Pb)t=15.66-15.76,(^(208)Pb/^(204)Pb)t=37.97-38.55)suggest that the monzogranite formed through partial melting of crustal greywacke,while the leucogranite originated from partial melting of crustal pelite.Regional geological studies suggest that these S-type granites in Pinghe were emplaced in an active continental margin setting,associated with the westward subduction of the proto-Tethys oceanic slab.The geochemical characteristics of leucogranite are consistent with those of tungsten-tin-related granites,indicating significant metallogenic potential for W and Sn deposits.展开更多
According to the complex differential accumulation history of deep marine oil and gas in superimposed basins,the Lower Paleozoic petroleum system in Tahe Oilfield of Tarim Basin is selected as a typical case,and the p...According to the complex differential accumulation history of deep marine oil and gas in superimposed basins,the Lower Paleozoic petroleum system in Tahe Oilfield of Tarim Basin is selected as a typical case,and the process of hydrocarbon generation and expulsion,migration and accumulation,adjustment and transformation of deep oil and gas is restored by means of reservoine-forming dynamics simulation.The thermal evolution history of the Lower Cambrian source rocks in Tahe Oilfield reflects the obvious differences in hydrocarbon generation and expulsion process and intensity in different tectonic zones,which is the main reason controlling the differences in deep oil and gas phases.The complex transport system composed of strike-slip fault and unconformity,etc.controlled early migration and accumulation and late adjustment of deep oil and gas,while the Middle Cambrian gypsum-salt rock in inner carbonate platform prevented vertical migration and accumulation of deep oil and gas,resulting in an obvious"fault-controlled"feature of deep oil and gas,in which the low potential area superimposed by the NE-strike-slip fault zone and deep oil and gas migration was conducive to accumulation,and it is mainly beaded along the strike-slip fault zone in the northeast direction.The dynamic simulation of reservoir formation reveals that the spatio-temporal configuration of"source-fault-fracture-gypsum-preservation"controls the differential accumulation of deep oil and gas in Tahe Oilfield.The Ordovician has experienced the accumulation history of multiple periods of charging,vertical migration and accumulation,and lateral adjustment and transformation,and deep oil and gas have always been in the dynamic equilibrium of migration,accumulation and escape.The statistics of residual oil and gas show that the deep stratum of Tahe Oilfield still has exploration and development potential in the Ordovician Yingshan Formation and Penglaiba Formation,and the Middle and Upper Cambrian ultra-deep stratum has a certain oil and gas resource prospect.This study provides a reference for the dynamic quantitative evaluation of deep oil and gas in the Tarim Basin,and also provides a reference for the study of reservoir formation and evolution in carbonate reservoir of paleo-craton basin.展开更多
The Songliao Basin(SLB)covers an area of approximately 260,000 km2in northeastern Asia and preserves a continuous and complete Cretaceous terrestrial record(Wang et al.,2021).The region is the most important petrolife...The Songliao Basin(SLB)covers an area of approximately 260,000 km2in northeastern Asia and preserves a continuous and complete Cretaceous terrestrial record(Wang et al.,2021).The region is the most important petroliferous sedimentary basin in China because of its continual annual oil and gas equivalent production of tens of millions of tons(ca.220–440 million barrels per year)since 1959.The SLB was previously thought to have developed on Hercynian basement and accumulated continuous sedimentary deposits during the Late Jurassic and Cretaceous(Wan et al.,2013;Wang et al.,2016).展开更多
Reconstructing the thermal evolution of the eastern Qaidam Basin is important for gaining a deeper understanding of its lithospheric geodynamics and for more accurate hydrocarbon evaluation and prediction.This article...Reconstructing the thermal evolution of the eastern Qaidam Basin is important for gaining a deeper understanding of its lithospheric geodynamics and for more accurate hydrocarbon evaluation and prediction.This article presents a set of new apatite and zircon(U-Th)/He thermochronological ages.Combined with 336 vitrinite reflectance(R_(o))data,the thermal history of the Ouanan Sag in the eastern Qaidam Basin has been reconstructed using inversion models.Three detrital samples from the Ounan Sag shows that the apatite(U-Th)/He ages are primarily concentrated in the range of 17.0 Ma to 76.5 Ma and that the zircon(U-Th)/He ages range from 200 Ma to 289.3 Ma.The time-temperature models demonstrate that the Ounan Sag experienced rapid subsidence and heating from the Carboniferous to late Permian,and exhumation/cooling events from the end of Permian to the Triassic.This thermal evolution was influenced by the widespread intrusion of plutons,and the collision and orogenesis caused by asthenosphere upwelling below the Qaidam arc,and slab rollback of the Southern Kunlun oceanic lithosphere,respectively.Additionally,our models depict the main exhumation/cooling stages since the Paleogene and a reheating event in the Miocene as a result of the intensifying growth of the Qinghai-Tibet Plateau and local sedimentary loading,followed by the initial India-Eurasia collision.Furthermore,the eastern Qaidam Basin experienced consistent heating during the late Paleozoic,reaching the maximum paleotemperature and geothermal gradient in the late Permian,with values of~230℃and~43-44℃/km,respectively.This study suggests that the source rocks in the most upper member of upper Carboniferous Keluke(C_(2)k)Formations in the Ounan Sag reached the gas generation stage in the late Permian.展开更多
The detailed description of two granite complexes in the Olkhon subterrane is given.The Early Paleozoic Sharanur complex was formed by granitization of gneisses of the Olkhon series.It includes migmatites,granite-gnei...The detailed description of two granite complexes in the Olkhon subterrane is given.The Early Paleozoic Sharanur complex was formed by granitization of gneisses of the Olkhon series.It includes migmatites,granite-gneisses,granites and pegmatites of normal alkalinity;they belong to the type of syncollisional granites.The Middle Paleozoic Aya granite complex includes mother Aya massif of amazonite-bearing granites and several types of rare-metal pegmatites.They have elevated alkalinity,low of Ba,Sr,and high LILE and HFSE elements contents.The Aya pegmatites lie in northwest cracks of stretching and associated with the rise of the territory under the influence of the North Asian plume.These cracks and pegmatites mark the beginning of a new intraplate geodynamic setting.Two geochemical types are distinguished among the pegmatites of this complex.These are amazonite pegmatites of Li-F type with Ta mineralization and complex type pegmatite with Be-Rb-Nb-Ta and Li-F mineralization(the Ilixin vein).The Tashkiney pegmatite vein is similar to Ilixin,but lies in the gneisses of the Olkhon series.It shows high concentrations of Be,Nb,Ta,as well as W,Sn,but lacks Li and F,due to a greater depth and higher temperature of the melt crystallization of this pegmatite.展开更多
As one of the most important constitutes of shales/mudstones,quartz has received increasing interests in the last decades,because productive shale gas successions are generally rich in quartz content.This study critic...As one of the most important constitutes of shales/mudstones,quartz has received increasing interests in the last decades,because productive shale gas successions are generally rich in quartz content.This study critically documents quartz types,silica source for quartz cementation and effect of quartz cementation on reservoir quality in the Lower Paleozoic shales,Middle Yangtze region,South China,including the Lower Cambrian Niutitang Formation and the Upper Ordovician-Lower Silurian Wufeng-Longmaxi formations.Our results suggest that high-resolution scanning electron microscopy combined with cathodoluminescene techniques are necessary for identifying quartz types in shales.Integrations of high-resolution imaging technique and detailed geochemical analysis are able to document silica source for quartz cementation and silica diagenetic processes.Six types of quartz can be identified in the Paleozoic shales,primarily including detrital quartz silt,siliceous skeletons,quartz overgrowth,microcrystalline quartz(matrix-dispersed microquartz and aggregated microquartz),silica nanospheres and fracture-filling quartz veins.Dissolution of siliceous skeletons provides the principal silica sources for authigenic quartz formation in the Paleozoic shales.Authigenic quartz has dual effects on porosity development.Quartz overgrowth definitely occupies interparticle pores and possibly squeeze spaces,whereas aggregated microquartz can form rigid framework that is favorable for generating and preserving intercrystalline pores and organic pores.展开更多
基金Supported by the National Natural Science Foundation of China(42130802,42272200)CNPC Science and Technology Major Project(2023ZZ18)+1 种基金PetroChina Changqing Oilfield Major Science and Technology Project(2023DZZ01)Technology Project of PetroChina Coalbed Methane Company Limited(2023-KJ-18)。
文摘Based on the test and experimental data from exploration well cores of the Upper Paleozoic in the central-eastern Ordos Basin,combined with structural,burial depth and fluid geochemistry analyses,this study reveals the fluid characteristics,gas accumulation control factors and accumulation modes in the Upper Paleozoic coal reservoirs.The study indicates findings in two aspects.First,the 1500-1800 m interval represents the critical transition zone between open fluid system in shallow-medium depths and closed fluid system in deep depths.The reservoirs above 1500 m reflect intense water invasion,with discrete pressure gradient distribution,and the presence of methane mixed with varying degrees of secondary biogenic gas,and they generally exhibit high water saturation and adsorbed gas undersaturation.The reservoirs deeper than 1800 m,with extremely low permeability,are self-sealed,and contains closed fluid systems formed jointly by the hydrodynamic lateral blocking and tight caprock confinement.Within these systems,surface runoff infiltration is weak,the degree of secondary fluid transformation is minimal,and the pressure gradient is relatively uniform.The adsorbed gas saturation exceeds 100%in most seams,and the free gas content primarily ranges from 1 m^(3)/t to 8 m^(3)/t(greater than 10 m^(3)/t in some seams).Second,the gas accumulation in deep coals is primarily controlled by coal quality,reservoir-caprock assemblage,and structural position governed storage,wettability and sealing properties,under the constraints of the underground temperature and pressure conditions.High-rank,low-ash yield coals with limestone and mudstone caprocks show superior gas accumulation potential.Positive structural highs and wide and gentle negative structural lows are favorable sites for gas enrichment,while slope belts of fold limbs exhibit relatively lower gas content.This research enhances understanding of gas accumulation mechanisms in coal reservoirs and provides effective parameter reference for precise zone evaluation and innovation of adaptive stimulation technologies for deep resources.
基金supported by the Science and Technology Research Program of Chongqing Municipal Education Commission(Grant No.KJQN202404310,KJQN202304302)National Natural Science Foundation of China(41972118).
文摘The Yarlung Zangbo Suture Zone(YZSZ)on the southern margin of the Lhasa block and the Tangjia-Sumdo ultrahigh-pressure metamorphic belt(TSMB)within the block represent natural laboratories for the study of plate tectonics and oceanic slab subduction.It is generally believed that these two zones represent the remnants of the ancient oceanic crust and upper mantle of the Yarlung Zangbo Neo-Tethys(YZNT)and the Tangjia-Sumdo Paleo-Tethys(TSPT).However,the evolutionary patterns and spatiotemporal relationships of the TSPT and the YZNT have been debated.
基金supported by the China Geological Survey Project(No.DD20243455)the National Natural Science Foundation of China(NSFC Project 41302046)。
文摘This study presents whole-rock major,trace elements and Sr-Nd-Hf isotopic compositions,as well as zircon UPb geochronological data,for the peraluminous and aluminous granitoids in northern Guangdong Province,South China,in order to investigate their petrogenesis and tectonic implications.The Qingzhou granodiorites(458.5-455.4 Ma)are peraluminous(A/CNK=1.05-1.96).They have relatively high initial^(87)Sr/^(86)Sr ratios(I_(Sr)=0.7087-0.7148),lowε_(Nd)(t)values(-11.2 to-10.1)and a variety of zirconε_(Hf)(t)values in the range-13.4 to+4.81.By contrast,the Damaoshan granodiorites(458.1 Ma)are metaluminous(A/CNK=0.79-0.94)in composition,with I_(Sr)values of 0.7083 to 0.7110,ε_(Nd)(t)values of-7.92 to-5.28 and zirconε_(Nf)(t)values of-8.69 to-2.06.The Gaoshou quartz diorites(449 Ma)are metaluminous-peraluminous.Their I_(Sr)values vary from 0.7104 to 0.7111 withε_(Nd)(t)values from-9.64 to-8.63.Geochemical data and Sr-Nd-Hf isotope compositions indicate that the Qingzhou,Damaoshan and Gaoshou intrusions are primarily derived from the partial melting of metagreywackes,tonalitic rocks and amphibolite,respectively.The crustal materials in northern Guangdong,from top to bottom consist of Paleozoic sequences,metasediments with a V_(p)of<6.0 km/s,metaigneous rocks with a V_(p)of 6.3-6.7 km/s and amphibolite with a V_(p)of~7.03 km/s.
基金supported by the National Natural Science Foundation of China(Grant Nos.42272244 and 91755212)Taishan Scholars(Grant No.ts20190918).
文摘Subduction initiation is a critical part of the plate tectonic system,but its geodynamic process is still poorly understood due to the lack of well-preserved geological records.Based on new zircon U–Pb–Hf isotopic and whole-rock geochemical data,we report the first discovery of a latest Cambrian–Early Ordovician forearc-arc rock sequence in the Eastern Alps.This sequence includes granitic gneisses,amphibolites,and amphibole plagiogneisses from the ophiolitic Speik Complex and Gleinalpe Complex.These rocks exhibit geochemical affinities with typical oceanic plagiogranites,forearc basalts(FABs),and island arc basalts,respectively.The latest Cambrian plagiogranitic protoliths(491±2 Ma)are shearing-type plagiogranites that were formed in the tectonic setting of forearc spreading.The latest Cambrian FABs(496–489 Ma)have similar geochemical compositions and positiveεHf(t)values(+2.5 to+14.9)to the depleted mid-ocean ridge basalts.However,they show depletion in high field strength elements(HFSEs;e.g.,Nb,Ta,and Zr)and have relatively low Ti/V ratios.These features suggest that they were derived from a depleted mantle source modified by subducting slab-released components in a forearc environment.The Early Ordovician basaltic protoliths(476–472 Ma)of amphibole plagiogneisses show enrichment in large ion lithophile elements and depletion in HFSEs(e.g.Nb,Ta,Zr,and Hf),implying a mature island arc environment.These metaigneous rocks,along with the coeval boninite-like high-Mg amphibolites near the study area,form a typical rock sequence resembling that of the Izu–Bonin–Mariana(IBM)arc system.The Speik and Gleinalpe complexes document a complete magmatic evolution from subduction initiation to mature arc development within the West Proto-Tethys Ocean.Integrating our new data with published work,we reconstruct the late Ediacaran–early Paleozoic tectonic evolution of the northern Gondwana.During the late Ediacaran–early Cambrian,the rollback of the West Proto-Tethys oceanic plate triggered the separation of the Wechsel-Silvretta-Gleinalpe continental arc from the northern Gondwana.This process led to the formation of the Speik back-arc oceanic basin,a southwestern branch of the West Proto-Tethys Ocean.In the latest Cambrian–Early Ordovician,subduction initiation occurred in the Speik Ocean,which subsequently developed into an intra-oceanic arc system.During the Early Devonian,the Speik Ocean closed and the Wechsel-Silvretta-Gleinalpe continental arc reattached to the Gondwana,as evidenced by the metamorphic event at ca.400 Ma.
基金financially supported by projects from the National Natural Science Foundation of China(No.42321001)the Qinghai Provincial Department of Science and Technology Key R&D Project(No.2025-SF-141)+1 种基金the Qinghai“Kunlun Talent”Program(Qing RC Talent Zi(2024)No.1)the Academician Zhao Pengda Innovation Center in Qinghai Geological Bureau of Nuclear Industry。
文摘0 INTRODUCTION The Haidewula uranium deposit is located in the Haidewula volcanic basin,which hosts a suite of basic,intermediate to felsic volcanic and subvolcanic rocks,including basalt,trachyte,trachyandesite.Previous geochronological studies of the intrusions within this volcanic basin suggest that they primarily formed during the Silurian and Triassic periods(Dai et al.,2025;Sun et al.,2024;Wang et al.,2024;Zhu et al.,2022;Lei et al.,2021).
基金funded by the Science and Technology Department of Yunnan Province(202303AA080006)the National Natural Science Foundation of China(41972312 and 41672329).
文摘A systematic study of early Paleozoic S-type granites in Pinghe enhances our understanding of the tectonic evolution of proto-Tethys and provides a foundation for exploring rare metal deposits in the region.The Pinghe granites consist of monzogranite and leucogranite.Zircon U-Pb dating shows that the emplacement ages of the monzogranite and leucogranite are 502.0 Ma and 500.9 Ma,respectively.All samples have high SiO_(2) content and a weakly to strongly peraluminous character(A/CNK=1.08-1.23),consistent with S-type granites.The monzogranite has relatively high CaO,Sr,Ba,and CaO/Na_(2)O ratios but lower Rb.In contrast,the leucogranite has lower CaO,Sr,Ba,and CaO/Na_(2)O ratios but higher Rb.The similar ε_(Nd)(t)values(−9.3 to−8.4)and Pb isotopic compositions((^(206)Pb/^(204)Pb)t=18.03-19.36,(^(207)Pb/^(204)Pb)t=15.66-15.76,(^(208)Pb/^(204)Pb)t=37.97-38.55)suggest that the monzogranite formed through partial melting of crustal greywacke,while the leucogranite originated from partial melting of crustal pelite.Regional geological studies suggest that these S-type granites in Pinghe were emplaced in an active continental margin setting,associated with the westward subduction of the proto-Tethys oceanic slab.The geochemical characteristics of leucogranite are consistent with those of tungsten-tin-related granites,indicating significant metallogenic potential for W and Sn deposits.
基金Supported by the Sichuan Province Regional Innovation Cooperation Project(21QYCX0048)Sinopec Science and Technology Department Project(P21048-3)。
文摘According to the complex differential accumulation history of deep marine oil and gas in superimposed basins,the Lower Paleozoic petroleum system in Tahe Oilfield of Tarim Basin is selected as a typical case,and the process of hydrocarbon generation and expulsion,migration and accumulation,adjustment and transformation of deep oil and gas is restored by means of reservoine-forming dynamics simulation.The thermal evolution history of the Lower Cambrian source rocks in Tahe Oilfield reflects the obvious differences in hydrocarbon generation and expulsion process and intensity in different tectonic zones,which is the main reason controlling the differences in deep oil and gas phases.The complex transport system composed of strike-slip fault and unconformity,etc.controlled early migration and accumulation and late adjustment of deep oil and gas,while the Middle Cambrian gypsum-salt rock in inner carbonate platform prevented vertical migration and accumulation of deep oil and gas,resulting in an obvious"fault-controlled"feature of deep oil and gas,in which the low potential area superimposed by the NE-strike-slip fault zone and deep oil and gas migration was conducive to accumulation,and it is mainly beaded along the strike-slip fault zone in the northeast direction.The dynamic simulation of reservoir formation reveals that the spatio-temporal configuration of"source-fault-fracture-gypsum-preservation"controls the differential accumulation of deep oil and gas in Tahe Oilfield.The Ordovician has experienced the accumulation history of multiple periods of charging,vertical migration and accumulation,and lateral adjustment and transformation,and deep oil and gas have always been in the dynamic equilibrium of migration,accumulation and escape.The statistics of residual oil and gas show that the deep stratum of Tahe Oilfield still has exploration and development potential in the Ordovician Yingshan Formation and Penglaiba Formation,and the Middle and Upper Cambrian ultra-deep stratum has a certain oil and gas resource prospect.This study provides a reference for the dynamic quantitative evaluation of deep oil and gas in the Tarim Basin,and also provides a reference for the study of reservoir formation and evolution in carbonate reservoir of paleo-craton basin.
基金supports from the International Continental Scientific Drilling Programfunded by the National Natural Science Foundation of China(Grant Nos.41790453,41472304,42102129,42102135 and 41972313)+2 种基金Natural Science Foundation of Jilin Province(Grant No.20170101001JC)the National Key Research&Development Program of China(Grant No.2019YFC0605402)China Geological Survey(Grant No.DD20189702)。
文摘The Songliao Basin(SLB)covers an area of approximately 260,000 km2in northeastern Asia and preserves a continuous and complete Cretaceous terrestrial record(Wang et al.,2021).The region is the most important petroliferous sedimentary basin in China because of its continual annual oil and gas equivalent production of tens of millions of tons(ca.220–440 million barrels per year)since 1959.The SLB was previously thought to have developed on Hercynian basement and accumulated continuous sedimentary deposits during the Late Jurassic and Cretaceous(Wan et al.,2013;Wang et al.,2016).
基金financially supported by grants from the Geological Survey Projects of China Geological Survey(grant nos.20242065,20230260)the Fundamental Research Fund of Chinese Academy of Geological Sciences(grant no.JKYQN202342)the National Natural Science Foundation of China(grant no.41772272)。
文摘Reconstructing the thermal evolution of the eastern Qaidam Basin is important for gaining a deeper understanding of its lithospheric geodynamics and for more accurate hydrocarbon evaluation and prediction.This article presents a set of new apatite and zircon(U-Th)/He thermochronological ages.Combined with 336 vitrinite reflectance(R_(o))data,the thermal history of the Ouanan Sag in the eastern Qaidam Basin has been reconstructed using inversion models.Three detrital samples from the Ounan Sag shows that the apatite(U-Th)/He ages are primarily concentrated in the range of 17.0 Ma to 76.5 Ma and that the zircon(U-Th)/He ages range from 200 Ma to 289.3 Ma.The time-temperature models demonstrate that the Ounan Sag experienced rapid subsidence and heating from the Carboniferous to late Permian,and exhumation/cooling events from the end of Permian to the Triassic.This thermal evolution was influenced by the widespread intrusion of plutons,and the collision and orogenesis caused by asthenosphere upwelling below the Qaidam arc,and slab rollback of the Southern Kunlun oceanic lithosphere,respectively.Additionally,our models depict the main exhumation/cooling stages since the Paleogene and a reheating event in the Miocene as a result of the intensifying growth of the Qinghai-Tibet Plateau and local sedimentary loading,followed by the initial India-Eurasia collision.Furthermore,the eastern Qaidam Basin experienced consistent heating during the late Paleozoic,reaching the maximum paleotemperature and geothermal gradient in the late Permian,with values of~230℃and~43-44℃/km,respectively.This study suggests that the source rocks in the most upper member of upper Carboniferous Keluke(C_(2)k)Formations in the Ounan Sag reached the gas generation stage in the late Permian.
基金The study was conducted within the framework of the state task(topic ID 0350-2019-0007)and supported by grant 20-55-44002-Mong_a of the Russian Foundation for Basic Research.
文摘The detailed description of two granite complexes in the Olkhon subterrane is given.The Early Paleozoic Sharanur complex was formed by granitization of gneisses of the Olkhon series.It includes migmatites,granite-gneisses,granites and pegmatites of normal alkalinity;they belong to the type of syncollisional granites.The Middle Paleozoic Aya granite complex includes mother Aya massif of amazonite-bearing granites and several types of rare-metal pegmatites.They have elevated alkalinity,low of Ba,Sr,and high LILE and HFSE elements contents.The Aya pegmatites lie in northwest cracks of stretching and associated with the rise of the territory under the influence of the North Asian plume.These cracks and pegmatites mark the beginning of a new intraplate geodynamic setting.Two geochemical types are distinguished among the pegmatites of this complex.These are amazonite pegmatites of Li-F type with Ta mineralization and complex type pegmatite with Be-Rb-Nb-Ta and Li-F mineralization(the Ilixin vein).The Tashkiney pegmatite vein is similar to Ilixin,but lies in the gneisses of the Olkhon series.It shows high concentrations of Be,Nb,Ta,as well as W,Sn,but lacks Li and F,due to a greater depth and higher temperature of the melt crystallization of this pegmatite.
基金financially supported by the SINOPEC Key Laboratory of Geology and Resources in Deep Stratum Foundation(No.33550000-22-ZC0613-0252)the National Natural Science Foundation(Nos.U19B6003,U20B6001 and 42002137)。
文摘As one of the most important constitutes of shales/mudstones,quartz has received increasing interests in the last decades,because productive shale gas successions are generally rich in quartz content.This study critically documents quartz types,silica source for quartz cementation and effect of quartz cementation on reservoir quality in the Lower Paleozoic shales,Middle Yangtze region,South China,including the Lower Cambrian Niutitang Formation and the Upper Ordovician-Lower Silurian Wufeng-Longmaxi formations.Our results suggest that high-resolution scanning electron microscopy combined with cathodoluminescene techniques are necessary for identifying quartz types in shales.Integrations of high-resolution imaging technique and detailed geochemical analysis are able to document silica source for quartz cementation and silica diagenetic processes.Six types of quartz can be identified in the Paleozoic shales,primarily including detrital quartz silt,siliceous skeletons,quartz overgrowth,microcrystalline quartz(matrix-dispersed microquartz and aggregated microquartz),silica nanospheres and fracture-filling quartz veins.Dissolution of siliceous skeletons provides the principal silica sources for authigenic quartz formation in the Paleozoic shales.Authigenic quartz has dual effects on porosity development.Quartz overgrowth definitely occupies interparticle pores and possibly squeeze spaces,whereas aggregated microquartz can form rigid framework that is favorable for generating and preserving intercrystalline pores and organic pores.
