Since the beginning of the 21st century,advances in big data and artificial intelligence have driven a paradigm shift in the geosciences,moving the field from qualitative descriptions toward quantitative analysis,from...Since the beginning of the 21st century,advances in big data and artificial intelligence have driven a paradigm shift in the geosciences,moving the field from qualitative descriptions toward quantitative analysis,from observing phenomena to uncovering underlying mechanisms,from regional-scale investigations to global perspectives,and from experience-based inference toward data-and model-enabled intelligent prediction.AlphaEarth Foundations(AEF)is a next-generation geospatial intelligence platform that addresses these changes by introducing a unified 64-dimensional shared embedding space,enabling-for the first time-standardized representation and seamless integration of 12 distinct types of Earth observation data,including optical,radar,and lidar.This framework significantly improves data assimilation efficiency and resolves the persistent problem of“data silos”in geoscience research.AEF is helping redefine research methodologies and fostering breakthroughs,particularly in quantitative Earth system science.This paper systematically examines how AEF’s innovative architecture-featuring multi-source data fusion,high-dimensional feature representation learning,and a scalable computational framework-facilitates intelligent,precise,and realtime data-driven geoscientific research.Using case studies from resource and environmental applications,we demonstrate AEF’s broad potential and identify emerging innovation needs.Our findings show that AEF not only enhances the efficiency of solving traditional geoscientific problems but also stimulates novel research directions and methodological approaches.展开更多
How the subduction direction of the Paleo-Pacific plate beneath the Eurasian plate changes in the Early Cretaceous remains highly controversial due to the disappearance of the subducted oceanic plate.Intraplate deform...How the subduction direction of the Paleo-Pacific plate beneath the Eurasian plate changes in the Early Cretaceous remains highly controversial due to the disappearance of the subducted oceanic plate.Intraplate deformation structures in the east Asian continent,however,provide excellent opportunities for reconstructing paleostress fields in continental interior in relation to the Paleo-Pacific/Eurasian plate interaction.Anisotropy of magnetic susceptibility(AMS),geological,and geochronological analyses of post-kinematic mafic dykes intruding the detachment fault zone of the Wulian metamorphic core complex(WL MCC)in Jiaodong Peninsula exemplify emplacement of mantle-sourced dykes in a WNW-ESE(301°-121°)oriented tectonic extensional setting at ca.120 Ma.In combination with the results from our previous kinematic analysis of the MCC,a ca.21°clockwise change in the direction of intraplate extension is obtained for early(135-122 Ma)extensional exhumation of the MCC to late(122-108 Ma)emplacement of the dykes.Such a change is suggested to be related to the variation in subduction direction of the Paleo-Pacific plate beneath the Eurasian plate,from westward(pre-122 Ma)to west-northwestward(post-122 Ma).展开更多
0 INTRODUCTION The Yichun Li-Cs-Ta deposit in SE China has received significant attention for several decades,and it represents one of the most typical granitic examples that resemble typical LCT-type mineralization i...0 INTRODUCTION The Yichun Li-Cs-Ta deposit in SE China has received significant attention for several decades,and it represents one of the most typical granitic examples that resemble typical LCT-type mineralization in peraluminous pegmatites.展开更多
0 INTRODUCTION Serpentinite has high contents of water(up to~12 wt.%)and other volatiles(Pettke and Bretscher,2022).Dehydration of subducted serpentinite transfers massive water into the sub-arc mantle wedge and induc...0 INTRODUCTION Serpentinite has high contents of water(up to~12 wt.%)and other volatiles(Pettke and Bretscher,2022).Dehydration of subducted serpentinite transfers massive water into the sub-arc mantle wedge and induces fluxmelting to generate arc magmas.However,characterizing the role of serpentinite-derived fluids in arc magmatism is not easy,as serpentinite is depleted in incompatible elements compared to other subducted components(e.g.,altered oceanic crust(AOC)and sediments).展开更多
Zircon crystals,which form directly from igneous melts,are invaluable for probing the deep crustal basement and provide crucial insights into its composition and evolution.Supercontinent cycles,including the formation...Zircon crystals,which form directly from igneous melts,are invaluable for probing the deep crustal basement and provide crucial insights into its composition and evolution.Supercontinent cycles,including the formation and breakup of Columbia,Rodinia,and Gondwana,play a pivotal role in shaping global magmatic and metamorphic records,and deciphering magmatic patterns is critical for unraveling the complex interplay between tectonics and magmatism.This study investigates U-Pb geochronology and trace/rare earth element(REE)compositions of zircons from the Early Cretaceous Tethyan Himalaya Igneous Province,revealing critical insights into Precambrian-Paleozoic magmatic and tectonic evolution.Dominant Paleoproterozoic(2498 Ma,1912 Ma)and Neoproterozoic(826-762 Ma)zircon populations confirm the existence of the Precambrian basement.Neoproterozoic magmatism shows decoupling between light and heavy REE(LREE/HREE)and europium anomalies(Eu/Eu^(*)=Eu_(N)/(Sm_(N)×Gd_(N))^(1/2))during the 826-762 Ma and 725-702 Ma intervals,indicating that the Rodinia margin evolved from Andean-style subduction to continental collision.Early Paleozoic magmatism correlates with Pan-African orogenesis and subsequent Proto-Tethyan Ocean subduction beneath the Indian Craton.Neo-Tethyan initiation(ca.273 Ma)is evidenced by 200-300 Ma zircons which exhibit(1)absence of LREE/HREE-Eu/Eu^(*)crustal thickness correlations,and(2)a thermal peak at 273 Ma.展开更多
The water adsorption performance of shale gas reservoirs is a very important factor affecting their gas in place(GIP)contents,but the water-holding capacity and mechanism of over-mature shale,especially organic pores,...The water adsorption performance of shale gas reservoirs is a very important factor affecting their gas in place(GIP)contents,but the water-holding capacity and mechanism of over-mature shale,especially organic pores,are still not fully understood.In this study,systematic water vapor adsorption(WVA)experiments were carried out on the Lower Cambrian over-mature shale and its kerogen from the Sichuan Basin,China to characterize their WVA behaviors,and combined with the low-pressure gas(N_(2) and CO_(2))adsorption experiments,the main influencing factors of WVA capacity of the shale and the absorbed-water distribution in its organic and inorganic nanopores were investigated.The results show that the WVA isotherms of shale and kerogen are all typeⅡ,with an obvious hysteresis loop in the multilayer adsorption range,and that the positive relationship of the shale TOC content with the WVA capacity(including total adsorption capacity,primary adsorption capacity and secondary adsorption capacity)and WVA hysteresis index(AHIW),and the greater adsorption capacity and AHIW of kerogen than the shale,all indicate that the hydrophilicity of organic matter(OM)in the over-mature shale was underestimated in previous research.Although both the shale OM and clay minerals have a significant positive effect on the WVA,the former has a stronger adsorption ability than the latter.The WVA capacity of the studied Lower Cambrian shale is significantly greater than that of the Longmaxi shale reported in literatures,which was believed to be mainly attributed to its higher maturity,with a significant graphitization of OM.The shale micropores and non-micropores play an important role in WVA,especially OM pores.There are primary and secondary adsorption for water vapor in both the micropores and non-micropores of OM,while these adsorptions of minerals mainly occur in their non-micropores.These results have important guides for understanding the gas storage mechanism and exploration and development potential of marine over-mature shale in southern China,especially the Lower Cambrian shale.展开更多
Quartz trace elements are extensively employed in studying magmatic evolution,fluid evolution,and metal enrichment.The Bianjiadayuan Ag-Pb-Zn-Sn deposit is a typical magmatichydrothermal system in northeastern China,h...Quartz trace elements are extensively employed in studying magmatic evolution,fluid evolution,and metal enrichment.The Bianjiadayuan Ag-Pb-Zn-Sn deposit is a typical magmatichydrothermal system in northeastern China,however,studies on its complex magmatic-hydrothermal evolution are limited.This study investigates the quartz from the Bianjiadayuan deposit to gain insight into the physicochemical evolution of mineralization using cathodoluminescence(CL)textures and laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS)of quartz.Five types quartz(Q1 to Q5)were identified.From Q1 in quartz porphyry to Q5 in Ag-Pb-Zn veins,the CL intensity and Ti content gradually decreases,and Ge,Ge/Ti,and Al/Ti ratios increase,indicating a temperature decline from magmatic to hydrothermal stages.The Sb content shows an opposite trend to Ti content,correlating positively with Ge content in quartz,suggesting that Sb content could also be temperature-dependent.These trace elements in quartz indicate cooling is critical for Ag mineralization.Furthermore,quartz phenocryst(Q1)from the quartz porphyry shows low Al/Ti(mostly<4)and Ge/Ti ratios(<0.04),suggesting a low degree of magmatic evolution.The Sb content in Q5 from Ag-Pb-Zn-quartz veins(>1 ppm,mostly tens of ppm)is notably higher compared to quartz in other lithologies including Sn-bearing quartz veins(<1 ppm),suggesting that Sb contents can serve as an effective indicator of Ag mineralization.展开更多
The Cretaceous gold deposits along the margins of the North China Craton(NCC),which formed in a craton destruction setting,display geological characteristics similar to traditional orogenic gold deposits typically ass...The Cretaceous gold deposits along the margins of the North China Craton(NCC),which formed in a craton destruction setting,display geological characteristics similar to traditional orogenic gold deposits typically associated with accretionary orogeny.These deposits,known as Jiaodong-type gold deposits,have attracted considerable attention.However,the lithospheric controls and formation mechanisms of these deposits remain unclear,as they cannot be fully explained by the supracrustal metamorphic genetic model commonly applied to classic orogenic gold deposits.In this study,the compiled S-Hg-Pb isotope ratios of gold deposits on different NCC margins display compatible variations to the Sr-Nd-Hg isotope ratios of mafic dikes spatial-temporally associated with the deposits.This implies that mantle lithosphere,metasomatized by variable proportions of oceanic and continental crust,was the source for both gold deposits and mafic dikes.Increase of oxygen fugacity and zirconεHf(t)from pre-to syn-gold granites suggests continuous basic magma underplating,which could induce concentrations of Au-rich sulfides and contribute additional Au to auriferous CO_(2)-rich fluids derived from metasomatized mantle lithosphere and basic magma.Localization of gold deposits was controlled by craton-margin sinistral shearing induced by clockwise rotation of the craton coincident with distal emplacement of metamorphic core complexes.Thus,the Cretaceous Jiaodong-type orogenic gold deposits were derived from fertilized mantle lithosphere through such crust-mantle processes within a lithosphere thinning background.展开更多
The timings and geodynamic controls of Mo,Au,and Au-Mo deposits in the Xiaoqinling Orogen(>630 t Au and 115,000 t Mo),a rare Au-Mo province globally,are addressed by a combination of mineral par-ageneses,crystallin...The timings and geodynamic controls of Mo,Au,and Au-Mo deposits in the Xiaoqinling Orogen(>630 t Au and 115,000 t Mo),a rare Au-Mo province globally,are addressed by a combination of mineral par-ageneses,crystalline mineralogy,geochemistry,and Re-Os and U-Pb geochronology in the Dahu,Qinnan,and Yangzhaiyu deposits.The Xiaoqinling Orogen comprises an E-W-trending fold and thrust system with repeated structural reactivation and the Mo or Au orebodies in these deposits are dominantly controlled by E-W-trending and NW-SE-trending shear zones.Molybdenum mineralization related to K-feldspar alteration comprises early molybdenite,pyrite,rutile,and monazite within gray quartz veins plus late molybdenite and pyrite within white quartz veins in the Dahu and Qinnan Au-Mo deposits.Early and late Au mineralization events have similar mineral assemblages of pyrite,native gold±Au-Ag-Te minerals,rutile,and monazite associated with quartz-sericite alteration at Yangzhaiyu.The early dissem-inated molybdenite is characterized by rhombohedral polytype and oscillatory Re zoning,in contrast to the late molybdenite with a coexistence of rhombohedral and hexagonal polytypes and irregularly distributed Re.The early molybdenite has a Re-Os isochron age of 222.5±1.3 Ma,compatible with a monazite U-Pb age of 224±6.1 Ma,whereas late molybdenite provides a Re-Os isochron age of 185.0±12 Ma,with the implication that the 3R-polytype molybdenite with oscillatory Re zoning is more suitable for high-precision dating.The early and late Au mineralization have a pyrite Re-Os age of 202.0±5.9 Ma and U-Pb age of 124.0±1.3 Ma,respectively.In accordance with its complex geodynamic setting,geological and geochronological studies record a complicated 100-million-year mineralization history with multiple magmatic-hydrothermal Mo and orogenic Au mineralization events that formed within a structural framework of multiply reactivated shear zones.展开更多
Backscatter electron analysis from scanning electron microscopes(BSE-SEM)produces high-resolution image data of both rock samples and thin-sections,showing detailed structural and geochemical(mineralogical)information...Backscatter electron analysis from scanning electron microscopes(BSE-SEM)produces high-resolution image data of both rock samples and thin-sections,showing detailed structural and geochemical(mineralogical)information.This allows an in-depth exploration of the rock microstructures and the coupled chemical characteristics in the BSE-SEM image to be made using image processing techniques.Although image processing is a powerful tool for revealing the more subtle data“hidden”in a picture,it is not a commonly employed method in geoscientific microstructural analysis.Here,we briefly introduce the general principles of image processing,and further discuss its application in studying rock microstructures using BSE-SEM image data.展开更多
The Lower Cambrian shale gas in the western Hubei area,South China has a great resource prospect,but the gas-in-place(GIP)content in different sedimentary facies varies widely,and the relevant mechanism has been not w...The Lower Cambrian shale gas in the western Hubei area,South China has a great resource prospect,but the gas-in-place(GIP)content in different sedimentary facies varies widely,and the relevant mechanism has been not well understood.In the present study,two sets of the Lower Cambrian shale samples from the Wells YD4 and YD5 in the western Hubei area,representing the deep-water shelf facies and shallowwater platform facies,respectively,were investigated on the differences of pore types,pore structure and methane adsorption capacity between them,and the main controlling factor and mechanism of their methane adsorption capacities and GIP contents were discussed.The results show that the organic matter(OM)pores in the YD4 shale samples are dominant,while the inorganic mineral(IM)pores in the YD5 shale samples are primary,with underdeveloped OM pores.The pore specific surface area(SSA)and pore volume(PV)of the YD4 shale samples are mainly from micropores and mesopores,respectively,while those of the YD5 shale samples are mainly from micropores and macropores,respectively.The methane adsorption capacity of the YD4 shale samples is significantly higher than that of the YD5 shale samples,with a maximum absolute adsorption capacity of 3.13 cm^(3)/g and 1.31 cm^(3)/g in average,respectively.Compared with the shallow-water platform shale,the deep-water shelf shale has a higher TOC content,a better kerogen type and more developed OM pores,which is the main mechanism for its higher adsorption capacity.The GIP content models based on two samples with a similar TOC content selected respectively from the Wells YD4 and YD5 further indicate that the GIP content of the deep-water shelf shale is mainly 34 m^(3)/t within a depth range of 1000—4000 m,with shale gas exploration and development potential,while the shallow-water platform shale has normally a GIP content of<1 m^(3)/t,with little shale gas potential.Considering the geological and geochemical conditions of shale gas formation and preservation,the deep-water shelf facies is the most favorable target for the Lower Cambrian shale gas exploration and development in the western Hubei area,South China.展开更多
The Ailaoshan Orogen in the southeastern Tibet Plateau,situated between the Yangtze and Simao blocks,underwent a complex structural,magmatic,and metamorphic evolution resulting in different tectonic subzones with vary...The Ailaoshan Orogen in the southeastern Tibet Plateau,situated between the Yangtze and Simao blocks,underwent a complex structural,magmatic,and metamorphic evolution resulting in different tectonic subzones with varying structural lineaments and elemental concentrations.These elements can conceal or reduce anomalies due to the mutual effect between different anomaly areas.Dividing the whole zone into subzones based on tectonic settings,ore cluster areas,or sample catchment basins(Scb),geochemical and structural anomalies associated with gold(Au)mineralization have been identified utilizing mean plus twice standard deviations(Mean+2STD),factor analysis(FA),concentration-area(CA)modeling of stream sediment geochemical data,and lineament density in both the Ailaoshan Orogen and the individual subzones.The FA in the divided 98 Scbs with 6 Scbs containing Au deposits can roughly ascertain unknown rock types,identify specific element associations of known rocks and discern the porphyry or skarn-type Au mineralization.Compared with methods of Mean+2STD and C-A model of data in the whole orogen,which mistake the anomalies as background or act the background as anomalies,the combined methods of FA and C-A in the separate subzones or Scbs works well in regional metallogenic potential analysis.Mapping of lineament densities with a 10-km circle diameter is not suitable to locate Au deposits because of the delineated large areas of medium-high lineament density.In contrast,the use of circle diameters of 1.3 km or 1.7 km in the ore cluster scale delineates areas with a higher concentration of lineament density,consistent with the locations of known Au deposits.By analyzing the map of faults and Au anomalies,two potential prospecting targets,Scbs 1 and 63 with a sandstone as a potential host rock for Au,have been identified in the Ailaoshan Orogen.The use of combined methods in the divided subzones proved to be more effective in improving geological understanding and identifying mineralization anomalies associated with Au,rather than analyzing the entire large area.展开更多
Precambrian cratons are archives of several precious metallic deposits that significantly contribute to our planet’s resources and habitability and also provide key information on plate tectonics on Earth. The North ...Precambrian cratons are archives of several precious metallic deposits that significantly contribute to our planet’s resources and habitability and also provide key information on plate tectonics on Earth. The North China Craton (NCC) preserves important records of Neoarchean to Paleoproterozoic tectonic processes and associated episodes of metallogenic pulses that generated five major types of mineral deposits including banded iron formations (BIFs), volcanogenic massive sulfide (VMS) Cu–Pb–Zn deposits, orogenic Au deposits, magmatic sulfide Cu-Ni deposits and porphyry Cu deposits. These deposits are distributed in Neoarchean granite-greenstone belts and Paleoproterozoic orogenic belts, and show dominant mineralization ages of 2.6–2.5 Ga and two subordinate age groups of 2.7–2.6 Ga and 2.3–1.95 Ga. The Neoarchean metallogenic events generated BIFs, VMSs, Au and magmatic sulfide Cu-Ni deposits and the tectonic framework correlates with the microblock amalgamation and plate subduction possibly also aided by mantle plumes. The BIFs representing the dominant mineral deposits in Neoarchean are mainly Algoma-type with few examples of Superior-type. Meta-basaltic rocks associated with the Algoma-type BIF deposits in the granite-greenstone belts of the NCC display highly variable trace element compositions and LREE-depleted and LREE-enriched. The REE distribution patterns and high field-strength element characteristics of meta-basaltic rocks suggest the formation of BIF and VMS deposits in mid-ocean ridge, island arc and back-arc settings. The formation of VMS, Au and magmatic Cu-Ni deposits correspond to plate subduction and collision in a convergent continental margin setting during the late Neoarchean. The Paleoproterozoic deposits are represented by BIFs and porphyry Cu deposits. The Paleoproterozoic BIFs and meta-basaltic rocks correspond to magmatic-hydrothermal activities in passive continental margin or island arc settings, whereas the porphyry Cu deposits were formed in an extensional environment, corresponding to the Paleoproterozoic subduction-rifting events in the Trans-North China Orogen. The variation of δ^(56)Fe, Ce anomalies and Y/Ho ratios in BIFs from Neoarchean to Paleoproterozoic indicate the initial increase of oxygen in late Neoarchean and the change of ambient marine environment from anoxic to oxic during the Great Oxidation Event. The multi-stage Neoarchean to Paleoproterozoic metallogenic systems of the NCC were intrinsically linked to the plate subduction along with arc-plume interaction and rifting-subduction-collision activities. The contemporaneous increasing in weathering of exposed continental crust due to plate subduction potentially controlled the atmosphere-hydrosphere oxidation state and formation of BIF deposits in the NCC.展开更多
Low-salinity fracturing fluids tend to induce ion migration,alter wettability,and cause fluctuations in gas desorption efficiency when penetrating deep coal seams.Taking the No.8 coal from the Daning-Jixian area in th...Low-salinity fracturing fluids tend to induce ion migration,alter wettability,and cause fluctuations in gas desorption efficiency when penetrating deep coal seams.Taking the No.8 coal from the Daning-Jixian area in the Ordos Basin,NW China,as a representative example,this study employs physical simulation experiments to reveal the coupled control mechanism of salinity gradient on the ion-coal matrix-gas/water interfacial system and its key role in the imbibition-desorption process.The increasing ionic concentration improves the hydrophobicity of coal,with multivalent ions exhibiting particularly significant effects.The imbibition and ion diffusion occur in opposite directions,with imbibition equilibrium being achieved earlier than ionic equilibrium.Water-coal interactions induce both mineral dissolution and secondary precipitation.When a low-salinity fracturing fluid is injected into a high-salinity reservoir,the osmotic-pressure difference drives imbibition,promotes CH4 desorption,but results in higher fluid loss.Conversely,injecting high-salinity fracturing fluid into a low-salinity reservoir creates a reverse osmotic gradient that suppresses leak-off while improving flowback efficiency.Based on these findings,a high-low salinity sequential injection strategy is proposed for deep coal seams:high-salinity fluid is first injected to form stable fracture networks,followed by low-salinity fluid to enlarge the imbibition zone and enhance CH4 desorption and diffusion.Moderate well soaking is recommended to increase the imbibition volume,thereby achieving multiple positive effects such as maintaining reservoir pressure,preserving formation energy,and promoting imbibition-driven displacement.展开更多
Continental collision zones undergo a series of deep processes,including subduction of oceanic lithosphere,slab rollback,slab breakoff,continental subduction,lithospheric thickening,and lithospheric delamination.How t...Continental collision zones undergo a series of deep processes,including subduction of oceanic lithosphere,slab rollback,slab breakoff,continental subduction,lithospheric thickening,and lithospheric delamination.How these deep processes influence the magma generation and the compositional maturation of continental crust in collision zones remain poorly understood.Based on the consensus that plate motion during the Phanerozoic is primarily driven by the pull force of the subducting oceanic slab,this paper divides the evolution of continental collision zones into four stages,including pre-collision(oceanic subduction),syn-collision,transition,and post-collision,separated,respectively,by initial collision,oceanic slab breakoff,and initial extension occurring at the passive continental margin.Intermediate-felsic magma generated during pre-collision primarily originates from the fractional crystallization of mantle-derived mafic magmas under water-rich conditions,producing a large amount of compositionally complementary hornblende-rich mafic-ultramafic cumulates,whereas intermediate-felsic magma formed during syn-and post-collision is generated primarily by the partial melting of pre-existing hornblende-rich maficultramafic rocks,leaving a large number of eclogitized melting residues.The two-stage process of accumulation and remelting in the collision zone-defined herein as accumelting in this paper-involving the formation of voluminous hornblende-rich cumulates during pre-collision and their remelting during late subduction,syn-collision,and post-collision,has led to the compositional maturation of the continental crust in collision zones.Similar trends in magma compositional changes and deep processes are observed in other collision zones,suggesting that accumelting may be an effective process leading to the generation and compositional maturation of the continental crust.Future research directions should focus on(1)the scarcity of arc magmas and the genesis of intermediate-felsic rocks in continental collision zones,(2)whether eclogitized melting residues or cumulates experienced large-scale delamination or were transferred across the Moho into the seismically-defined upper mantle during syncollision,(3)whether the extensive I-type K-rich intermediate-felsic rocks(including I-type granitic rocks and extrusive equivalents)in the upper plate of collision zones primarily come from the partial melting of pre-existing K-rich mafic-ultramafic meta-igneous rocks(protoliths include cumulates and basaltic rocks)in the lower crust,and(4)whether the lower crust of magmatic arcs containing hornblende-rich cumulates is an important reservoir for volatiles.展开更多
Magmatic hydrothermal deposits are important sources of many bulk,precious,and rare metals,and have attracted interest from both academic and industrial communities.However,it is still unclear if the major enrichment ...Magmatic hydrothermal deposits are important sources of many bulk,precious,and rare metals,and have attracted interest from both academic and industrial communities.However,it is still unclear if the major enrichment of the ore-forming metals occurs in the parental magma source region,during the magma evolution,or after the fluid exsolution.Fluid inclusions trapped in hydrothermal minerals crystallized in the early,high-temperature stage before metal precipitation record information close to that of the initially exsolved magmatic fluids,which are helpful in revealing whether the metals have been already significantly enriched prior to the hydrothermal stage.In this study,available compositional data of such early-stage fluid inclusions from magmatic hydrothermal systems globally have been compiled.The results indicate that the concentrations of Cu,Sn,and W respectively from the Cu-,Sn-,and W-mineralized fluids are significantly higher than the hydrothermal systems that do not produce ores with the corresponding metals.This suggests that Cu,Sn,and W could have already been enriched in the magma source and/or magma evolution stage.The Mo concentrations show no difference between Mo-mineralized and Mobarren fluid systems,indicating no significant pre-enrichment in the source region or during the magma evolution.This also implies that an efficient collection of Mo from a large volume of magmas is required to account for the formation of a large Mo deposit.Almost all the hydrothermal fluids contain high concentrations of Fe and Zn-Pb,but only a few of them eventually form Fe or Zn-Pb deposits,reflecting an important role of the hydrothermal evolution process on the selective metal mineralization.The above results indicate that different metals are enriched in different stages of a magmatic hydrothermal system,and that the major roles played in the formation of a deposit vary with the metal types.In addition to the metal concentrations in the orerelated magmas and fluids,other factors(including but not limited to the intrusion shapes,emplacement depths,structural pathways,and wallrock properties)are also critical in determining the fertility and mineralization diversity of a magmatic hydrothermal system.展开更多
The NE-striking Longmen Shan thrust belt(LSTB)in the eastern margin of the Tibetan Plateau is located at the junction of the Songpan-Ganze Terrane and the Yangtze block.This belt experienced the Late Triassic Qinling-...The NE-striking Longmen Shan thrust belt(LSTB)in the eastern margin of the Tibetan Plateau is located at the junction of the Songpan-Ganze Terrane and the Yangtze block.This belt experienced the Late Triassic Qinling-Dabie and Songpan-Ganze orogenesis and the Cenozoic eastern propagation of the Tibetan Plateau.A series of klippes were produced along the foreland thrust belt of the LSTB.Traditional research proposed that the klippes are the front zone of the modern NE-trending Longmen Shan foreland thrust belt,while recent studies suggested that the klippes might be the result of Mesozoic thrusting of the LSTB.Nonetheless,there still remains a lack of crucial constraints regarding the emplacement time and formation mechanism of the klippes.In this study,we conducted systematic structural measurements on the Tangbazi klippe and Woniuping klippe,and performed petrographic analysis for the brecciated limestone.The results confirm a typical structural breccia with top-to-the-SSE kinematics of thrusting at the bottom of the klippes.Structural kinematics reveals the ultimate emplacement of the klippes was under NNE to SSW gliding,and the tail-like brecciated limestone in the southeast edge of the Tangbazi klippe was produced by the Pliocene gravitational collapse.Systematical samples were collected from both the hanging wall and footwall of the klippes and apatite and zircon were separated for(U-Th)/He dating.The(U-Th)/He ages of apatite from the Woniuping klippe are dated at 66.8–72.3 Ma,corresponding to the rapid uplift of the LSTB during the Late Cretaceous;the(UTh)/He ages of apatite from the footwall of the klippe are dated at 33.2–25.2 Ma,corresponding to the rapid uplift and denudation of the LSTB during the Oligocene.Integrated structural analysis and geochronological constraints,the northern segment of the LSTB,including the Tangwangzhai and Longwangmiao thrust complexes,might be produced by in-sequence thrusting during the Late Triassic to Early Jurassic.The northern segment of the LSTB and the northern Sichuan region experienced rapid uplift during the Late Cretaceous.During the Late Eocene to Early Miocene,gravity-driving klippes gliding from the Tangwangzhai and Longwangmiao thrust complexes toward the Sichuan basin occurred along the Silurian mudstone or phyllite and formed gravitational collapse.展开更多
Due to tidal locking in the Earth-Moon system,the Moon’s farside remained enigmatic until Luna 3 captured its first image,unveiling a rugged landscape largely devoid of extensive dark regions(i.e.,maria),which,by con...Due to tidal locking in the Earth-Moon system,the Moon’s farside remained enigmatic until Luna 3 captured its first image,unveiling a rugged landscape largely devoid of extensive dark regions(i.e.,maria),which,by contrast,cover a substantial fraction on the Earth-facing nearside.Subsequent orbital missions further revealed remarkable hemispherical differences:the nearside exhibits more intense volcanic activity.展开更多
Geologic time is an essential dimension in geological research,acting as a pivotal attribute that integrates data across various subdisciplines.The Geologic Time Scale(GTS)provides a formal framework for interpreting ...Geologic time is an essential dimension in geological research,acting as a pivotal attribute that integrates data across various subdisciplines.The Geologic Time Scale(GTS)provides a formal framework for interpreting and communicating geologic time within the field of geological studies,such as macro-geological evolution and regional geologic surveys.展开更多
Carbonate weathering is crucial for regulating global C cycle and short-term climate change.Calcium(Ca)is one of the major elements involved in carbonate weathering,and studying complex carbonate weathering processes ...Carbonate weathering is crucial for regulating global C cycle and short-term climate change.Calcium(Ca)is one of the major elements involved in carbonate weathering,and studying complex carbonate weathering processes can be helped by Ca isotopes in river system.Here,elemental and Ca isotopic(δ^(44/40)Ca)data for dissolved loads and suspended sediments from the Lancang River(Southeastern Tibetan Plateau)were determined.Dissolvedδ^(44/40)Ca values in river water(0.64‰–1.05‰)decreased downstream,and most values are close to 0.88‰in the mainstream.Relatively,suspended sediments are enriched in light Ca isotopes(0.46‰–0.75‰),which is controlled by mineralogy(clay vs.carbonate)based on the Ca/Al mass ratios and Ca-Zn isotopes evidence.According to the forward model,carbonate and evaporite weathering contribute>90%dissolved Ca to river water,while silicate weathering contributes only a minor fraction(2%–8%).Dissolvedδ^(44/40)Ca values are positively related to Sr/Ca,Mg/Ca ratios,and calcite saturation index,revealing the precipitation of secondary carbonate as a possible mechanism causing heavier Ca isotopes in river water.However,such an effect is not observed in the lowland tributaries,where river water with highδ^(44/40)Ca andδ7Li values indicates the influence of secondary clay formation.After comparing Ca fluxes and dissolvedδ^(44/40)Ca values in large world rivers,we propose that riverine dissolvedδ^(44/40)Ca values are dominated by carbonate weathering and secondary carbonate precipitation.Riverine Ca isotopes could serve as a potential indicator to understand and model secondary processes during carbonate weathering in the surficial environment of Earth.展开更多
基金National Natural Science Foundation of China Key Project(No.42050103)Higher Education Disciplinary Innovation Program(No.B25052)+2 种基金the Guangdong Pearl River Talent Program Innovative and Entrepreneurial Team Project(No.2021ZT09H399)the Ministry of Education’s Frontiers Science Center for Deep-Time Digital Earth(DDE)(No.2652023001)Geological Survey Project of China Geological Survey(DD20240206201)。
文摘Since the beginning of the 21st century,advances in big data and artificial intelligence have driven a paradigm shift in the geosciences,moving the field from qualitative descriptions toward quantitative analysis,from observing phenomena to uncovering underlying mechanisms,from regional-scale investigations to global perspectives,and from experience-based inference toward data-and model-enabled intelligent prediction.AlphaEarth Foundations(AEF)is a next-generation geospatial intelligence platform that addresses these changes by introducing a unified 64-dimensional shared embedding space,enabling-for the first time-standardized representation and seamless integration of 12 distinct types of Earth observation data,including optical,radar,and lidar.This framework significantly improves data assimilation efficiency and resolves the persistent problem of“data silos”in geoscience research.AEF is helping redefine research methodologies and fostering breakthroughs,particularly in quantitative Earth system science.This paper systematically examines how AEF’s innovative architecture-featuring multi-source data fusion,high-dimensional feature representation learning,and a scalable computational framework-facilitates intelligent,precise,and realtime data-driven geoscientific research.Using case studies from resource and environmental applications,we demonstrate AEF’s broad potential and identify emerging innovation needs.Our findings show that AEF not only enhances the efficiency of solving traditional geoscientific problems but also stimulates novel research directions and methodological approaches.
基金supported by the National Natural Science Foundation of China(Grant Nos:42130801,41430211,90814006,and 42072226)the“Deep-time Digital Earth”Science and Technology Leading Talents Team Funds for the Central Universities for the Frontiers Science Center for Deep-time Digital Earth,CUGB(Fundamental Research Funds for the Central UniversitiesGrant No:2652023001).
文摘How the subduction direction of the Paleo-Pacific plate beneath the Eurasian plate changes in the Early Cretaceous remains highly controversial due to the disappearance of the subducted oceanic plate.Intraplate deformation structures in the east Asian continent,however,provide excellent opportunities for reconstructing paleostress fields in continental interior in relation to the Paleo-Pacific/Eurasian plate interaction.Anisotropy of magnetic susceptibility(AMS),geological,and geochronological analyses of post-kinematic mafic dykes intruding the detachment fault zone of the Wulian metamorphic core complex(WL MCC)in Jiaodong Peninsula exemplify emplacement of mantle-sourced dykes in a WNW-ESE(301°-121°)oriented tectonic extensional setting at ca.120 Ma.In combination with the results from our previous kinematic analysis of the MCC,a ca.21°clockwise change in the direction of intraplate extension is obtained for early(135-122 Ma)extensional exhumation of the MCC to late(122-108 Ma)emplacement of the dykes.Such a change is suggested to be related to the variation in subduction direction of the Paleo-Pacific plate beneath the Eurasian plate,from westward(pre-122 Ma)to west-northwestward(post-122 Ma).
基金funded by the National Natural Science Foundation of China(Nos.42403065 and 92462302)the Frontiers Science Center for Deep-time Digital Earth(No.2652023001)the Open Research Project from the State Key Laboratory of Critical Earth Material Cycling and Mineral Deposits,Nanjing University(No.2025-K16).
文摘0 INTRODUCTION The Yichun Li-Cs-Ta deposit in SE China has received significant attention for several decades,and it represents one of the most typical granitic examples that resemble typical LCT-type mineralization in peraluminous pegmatites.
基金supported by the National Natural Science Foundation of China(Nos.42122019 and 42288201)the Fundamental Research Funds for the Central Universities(No.2652023001)the State Key Laboratory of Geological Processes and Mineral Resources,China。
文摘0 INTRODUCTION Serpentinite has high contents of water(up to~12 wt.%)and other volatiles(Pettke and Bretscher,2022).Dehydration of subducted serpentinite transfers massive water into the sub-arc mantle wedge and induces fluxmelting to generate arc magmas.However,characterizing the role of serpentinite-derived fluids in arc magmatism is not easy,as serpentinite is depleted in incompatible elements compared to other subducted components(e.g.,altered oceanic crust(AOC)and sediments).
基金funded by the National Natural Science Foundation of China(42172055)。
文摘Zircon crystals,which form directly from igneous melts,are invaluable for probing the deep crustal basement and provide crucial insights into its composition and evolution.Supercontinent cycles,including the formation and breakup of Columbia,Rodinia,and Gondwana,play a pivotal role in shaping global magmatic and metamorphic records,and deciphering magmatic patterns is critical for unraveling the complex interplay between tectonics and magmatism.This study investigates U-Pb geochronology and trace/rare earth element(REE)compositions of zircons from the Early Cretaceous Tethyan Himalaya Igneous Province,revealing critical insights into Precambrian-Paleozoic magmatic and tectonic evolution.Dominant Paleoproterozoic(2498 Ma,1912 Ma)and Neoproterozoic(826-762 Ma)zircon populations confirm the existence of the Precambrian basement.Neoproterozoic magmatism shows decoupling between light and heavy REE(LREE/HREE)and europium anomalies(Eu/Eu^(*)=Eu_(N)/(Sm_(N)×Gd_(N))^(1/2))during the 826-762 Ma and 725-702 Ma intervals,indicating that the Rodinia margin evolved from Andean-style subduction to continental collision.Early Paleozoic magmatism correlates with Pan-African orogenesis and subsequent Proto-Tethyan Ocean subduction beneath the Indian Craton.Neo-Tethyan initiation(ca.273 Ma)is evidenced by 200-300 Ma zircons which exhibit(1)absence of LREE/HREE-Eu/Eu^(*)crustal thickness correlations,and(2)a thermal peak at 273 Ma.
基金supported by the National Natural Science Foundation of China(42030804,42330811)the“Deep-time Digital Earth”Science and Technology Leading Talents Team Funds for the Central Universities for the Frontiers Science Center for Deep-time Digital Earth,China University of Geosciences(Fundamental Research Funds for the Central Universities,grant number:2652023001).
文摘The water adsorption performance of shale gas reservoirs is a very important factor affecting their gas in place(GIP)contents,but the water-holding capacity and mechanism of over-mature shale,especially organic pores,are still not fully understood.In this study,systematic water vapor adsorption(WVA)experiments were carried out on the Lower Cambrian over-mature shale and its kerogen from the Sichuan Basin,China to characterize their WVA behaviors,and combined with the low-pressure gas(N_(2) and CO_(2))adsorption experiments,the main influencing factors of WVA capacity of the shale and the absorbed-water distribution in its organic and inorganic nanopores were investigated.The results show that the WVA isotherms of shale and kerogen are all typeⅡ,with an obvious hysteresis loop in the multilayer adsorption range,and that the positive relationship of the shale TOC content with the WVA capacity(including total adsorption capacity,primary adsorption capacity and secondary adsorption capacity)and WVA hysteresis index(AHIW),and the greater adsorption capacity and AHIW of kerogen than the shale,all indicate that the hydrophilicity of organic matter(OM)in the over-mature shale was underestimated in previous research.Although both the shale OM and clay minerals have a significant positive effect on the WVA,the former has a stronger adsorption ability than the latter.The WVA capacity of the studied Lower Cambrian shale is significantly greater than that of the Longmaxi shale reported in literatures,which was believed to be mainly attributed to its higher maturity,with a significant graphitization of OM.The shale micropores and non-micropores play an important role in WVA,especially OM pores.There are primary and secondary adsorption for water vapor in both the micropores and non-micropores of OM,while these adsorptions of minerals mainly occur in their non-micropores.These results have important guides for understanding the gas storage mechanism and exploration and development potential of marine over-mature shale in southern China,especially the Lower Cambrian shale.
基金supported by the National Natural Science Foundation of China(No.42222205)the National Key Research and Development Program of China(No.2017YFC0602403)the Fundamental Research Funds for the Central Universities,CHD(No.300102273301)。
文摘Quartz trace elements are extensively employed in studying magmatic evolution,fluid evolution,and metal enrichment.The Bianjiadayuan Ag-Pb-Zn-Sn deposit is a typical magmatichydrothermal system in northeastern China,however,studies on its complex magmatic-hydrothermal evolution are limited.This study investigates the quartz from the Bianjiadayuan deposit to gain insight into the physicochemical evolution of mineralization using cathodoluminescence(CL)textures and laser ablation-inductively coupled plasma-mass spectrometry(LA-ICP-MS)of quartz.Five types quartz(Q1 to Q5)were identified.From Q1 in quartz porphyry to Q5 in Ag-Pb-Zn veins,the CL intensity and Ti content gradually decreases,and Ge,Ge/Ti,and Al/Ti ratios increase,indicating a temperature decline from magmatic to hydrothermal stages.The Sb content shows an opposite trend to Ti content,correlating positively with Ge content in quartz,suggesting that Sb content could also be temperature-dependent.These trace elements in quartz indicate cooling is critical for Ag mineralization.Furthermore,quartz phenocryst(Q1)from the quartz porphyry shows low Al/Ti(mostly<4)and Ge/Ti ratios(<0.04),suggesting a low degree of magmatic evolution.The Sb content in Q5 from Ag-Pb-Zn-quartz veins(>1 ppm,mostly tens of ppm)is notably higher compared to quartz in other lithologies including Sn-bearing quartz veins(<1 ppm),suggesting that Sb contents can serve as an effective indicator of Ag mineralization.
基金funded by the National Natural Science Foundation of China(42125203,42330809)the 111 project of the Ministry of Science and Technology(BP0719021).
文摘The Cretaceous gold deposits along the margins of the North China Craton(NCC),which formed in a craton destruction setting,display geological characteristics similar to traditional orogenic gold deposits typically associated with accretionary orogeny.These deposits,known as Jiaodong-type gold deposits,have attracted considerable attention.However,the lithospheric controls and formation mechanisms of these deposits remain unclear,as they cannot be fully explained by the supracrustal metamorphic genetic model commonly applied to classic orogenic gold deposits.In this study,the compiled S-Hg-Pb isotope ratios of gold deposits on different NCC margins display compatible variations to the Sr-Nd-Hg isotope ratios of mafic dikes spatial-temporally associated with the deposits.This implies that mantle lithosphere,metasomatized by variable proportions of oceanic and continental crust,was the source for both gold deposits and mafic dikes.Increase of oxygen fugacity and zirconεHf(t)from pre-to syn-gold granites suggests continuous basic magma underplating,which could induce concentrations of Au-rich sulfides and contribute additional Au to auriferous CO_(2)-rich fluids derived from metasomatized mantle lithosphere and basic magma.Localization of gold deposits was controlled by craton-margin sinistral shearing induced by clockwise rotation of the craton coincident with distal emplacement of metamorphic core complexes.Thus,the Cretaceous Jiaodong-type orogenic gold deposits were derived from fertilized mantle lithosphere through such crust-mantle processes within a lithosphere thinning background.
基金supported by the National Key Research and Development Project of China(2020YFA0714802)the National Natural Science Foundation of China(42330809)the 111 Project of the Ministry of Science and Technology(BP0719021).
文摘The timings and geodynamic controls of Mo,Au,and Au-Mo deposits in the Xiaoqinling Orogen(>630 t Au and 115,000 t Mo),a rare Au-Mo province globally,are addressed by a combination of mineral par-ageneses,crystalline mineralogy,geochemistry,and Re-Os and U-Pb geochronology in the Dahu,Qinnan,and Yangzhaiyu deposits.The Xiaoqinling Orogen comprises an E-W-trending fold and thrust system with repeated structural reactivation and the Mo or Au orebodies in these deposits are dominantly controlled by E-W-trending and NW-SE-trending shear zones.Molybdenum mineralization related to K-feldspar alteration comprises early molybdenite,pyrite,rutile,and monazite within gray quartz veins plus late molybdenite and pyrite within white quartz veins in the Dahu and Qinnan Au-Mo deposits.Early and late Au mineralization events have similar mineral assemblages of pyrite,native gold±Au-Ag-Te minerals,rutile,and monazite associated with quartz-sericite alteration at Yangzhaiyu.The early dissem-inated molybdenite is characterized by rhombohedral polytype and oscillatory Re zoning,in contrast to the late molybdenite with a coexistence of rhombohedral and hexagonal polytypes and irregularly distributed Re.The early molybdenite has a Re-Os isochron age of 222.5±1.3 Ma,compatible with a monazite U-Pb age of 224±6.1 Ma,whereas late molybdenite provides a Re-Os isochron age of 185.0±12 Ma,with the implication that the 3R-polytype molybdenite with oscillatory Re zoning is more suitable for high-precision dating.The early and late Au mineralization have a pyrite Re-Os age of 202.0±5.9 Ma and U-Pb age of 124.0±1.3 Ma,respectively.In accordance with its complex geodynamic setting,geological and geochronological studies record a complicated 100-million-year mineralization history with multiple magmatic-hydrothermal Mo and orogenic Au mineralization events that formed within a structural framework of multiply reactivated shear zones.
基金funded by the National Natural Science Foundation(No.42261134535)the National Key Research and Development Program(No.2023YFE0125000)+2 种基金the Frontiers Science Center for Deep-time Digital Earth(No.2652023001)the 111 Project of the Ministry of Science and Technology(No.BP0719021)supported by the department of Geology,University of Vienna(No.FA536901)。
文摘Backscatter electron analysis from scanning electron microscopes(BSE-SEM)produces high-resolution image data of both rock samples and thin-sections,showing detailed structural and geochemical(mineralogical)information.This allows an in-depth exploration of the rock microstructures and the coupled chemical characteristics in the BSE-SEM image to be made using image processing techniques.Although image processing is a powerful tool for revealing the more subtle data“hidden”in a picture,it is not a commonly employed method in geoscientific microstructural analysis.Here,we briefly introduce the general principles of image processing,and further discuss its application in studying rock microstructures using BSE-SEM image data.
基金financially supported by the National Natural Science Foundation of China(Grant Nos.42030804 and 42330811)the“Deep-time Digital Earth”Science and Technology Leading Talents Team Funds for the Central Universities for the Frontiers Science Center for Deep-time Digital Earth,China University of Geosciences(Beijing)(Fundamental Research Funds for the Central UniversitiesGrant No.2652023001)。
文摘The Lower Cambrian shale gas in the western Hubei area,South China has a great resource prospect,but the gas-in-place(GIP)content in different sedimentary facies varies widely,and the relevant mechanism has been not well understood.In the present study,two sets of the Lower Cambrian shale samples from the Wells YD4 and YD5 in the western Hubei area,representing the deep-water shelf facies and shallowwater platform facies,respectively,were investigated on the differences of pore types,pore structure and methane adsorption capacity between them,and the main controlling factor and mechanism of their methane adsorption capacities and GIP contents were discussed.The results show that the organic matter(OM)pores in the YD4 shale samples are dominant,while the inorganic mineral(IM)pores in the YD5 shale samples are primary,with underdeveloped OM pores.The pore specific surface area(SSA)and pore volume(PV)of the YD4 shale samples are mainly from micropores and mesopores,respectively,while those of the YD5 shale samples are mainly from micropores and macropores,respectively.The methane adsorption capacity of the YD4 shale samples is significantly higher than that of the YD5 shale samples,with a maximum absolute adsorption capacity of 3.13 cm^(3)/g and 1.31 cm^(3)/g in average,respectively.Compared with the shallow-water platform shale,the deep-water shelf shale has a higher TOC content,a better kerogen type and more developed OM pores,which is the main mechanism for its higher adsorption capacity.The GIP content models based on two samples with a similar TOC content selected respectively from the Wells YD4 and YD5 further indicate that the GIP content of the deep-water shelf shale is mainly 34 m^(3)/t within a depth range of 1000—4000 m,with shale gas exploration and development potential,while the shallow-water platform shale has normally a GIP content of<1 m^(3)/t,with little shale gas potential.Considering the geological and geochemical conditions of shale gas formation and preservation,the deep-water shelf facies is the most favorable target for the Lower Cambrian shale gas exploration and development in the western Hubei area,South China.
基金supported by the National Natural Science Foundation of China(Grant Nos.42125203 and 42102107)the National Key Research and Development Project of China(Grant No.2020YFA0714802)+1 种基金the“Deep-time Digital Earth”Science and Technology Leading Talents Team Funds from the Central Universities for the Frontiers Science Center for Deep-time Digital Earth,China University of Geosciences(Beijing)(Grant No.2652023001)the 111 Project of the Ministry of Science and Technology(Grant No.BP0719021).
文摘The Ailaoshan Orogen in the southeastern Tibet Plateau,situated between the Yangtze and Simao blocks,underwent a complex structural,magmatic,and metamorphic evolution resulting in different tectonic subzones with varying structural lineaments and elemental concentrations.These elements can conceal or reduce anomalies due to the mutual effect between different anomaly areas.Dividing the whole zone into subzones based on tectonic settings,ore cluster areas,or sample catchment basins(Scb),geochemical and structural anomalies associated with gold(Au)mineralization have been identified utilizing mean plus twice standard deviations(Mean+2STD),factor analysis(FA),concentration-area(CA)modeling of stream sediment geochemical data,and lineament density in both the Ailaoshan Orogen and the individual subzones.The FA in the divided 98 Scbs with 6 Scbs containing Au deposits can roughly ascertain unknown rock types,identify specific element associations of known rocks and discern the porphyry or skarn-type Au mineralization.Compared with methods of Mean+2STD and C-A model of data in the whole orogen,which mistake the anomalies as background or act the background as anomalies,the combined methods of FA and C-A in the separate subzones or Scbs works well in regional metallogenic potential analysis.Mapping of lineament densities with a 10-km circle diameter is not suitable to locate Au deposits because of the delineated large areas of medium-high lineament density.In contrast,the use of circle diameters of 1.3 km or 1.7 km in the ore cluster scale delineates areas with a higher concentration of lineament density,consistent with the locations of known Au deposits.By analyzing the map of faults and Au anomalies,two potential prospecting targets,Scbs 1 and 63 with a sandstone as a potential host rock for Au,have been identified in the Ailaoshan Orogen.The use of combined methods in the divided subzones proved to be more effective in improving geological understanding and identifying mineralization anomalies associated with Au,rather than analyzing the entire large area.
基金supported by the“Deep-time Digital Earth”Science and Technology Leading Talents Team Funds for the Central Universities(2652023001)Geological Survey project of China Geological Survey(DD20243265)Fundamental Research Funds for the Central Universities(590223001).
文摘Precambrian cratons are archives of several precious metallic deposits that significantly contribute to our planet’s resources and habitability and also provide key information on plate tectonics on Earth. The North China Craton (NCC) preserves important records of Neoarchean to Paleoproterozoic tectonic processes and associated episodes of metallogenic pulses that generated five major types of mineral deposits including banded iron formations (BIFs), volcanogenic massive sulfide (VMS) Cu–Pb–Zn deposits, orogenic Au deposits, magmatic sulfide Cu-Ni deposits and porphyry Cu deposits. These deposits are distributed in Neoarchean granite-greenstone belts and Paleoproterozoic orogenic belts, and show dominant mineralization ages of 2.6–2.5 Ga and two subordinate age groups of 2.7–2.6 Ga and 2.3–1.95 Ga. The Neoarchean metallogenic events generated BIFs, VMSs, Au and magmatic sulfide Cu-Ni deposits and the tectonic framework correlates with the microblock amalgamation and plate subduction possibly also aided by mantle plumes. The BIFs representing the dominant mineral deposits in Neoarchean are mainly Algoma-type with few examples of Superior-type. Meta-basaltic rocks associated with the Algoma-type BIF deposits in the granite-greenstone belts of the NCC display highly variable trace element compositions and LREE-depleted and LREE-enriched. The REE distribution patterns and high field-strength element characteristics of meta-basaltic rocks suggest the formation of BIF and VMS deposits in mid-ocean ridge, island arc and back-arc settings. The formation of VMS, Au and magmatic Cu-Ni deposits correspond to plate subduction and collision in a convergent continental margin setting during the late Neoarchean. The Paleoproterozoic deposits are represented by BIFs and porphyry Cu deposits. The Paleoproterozoic BIFs and meta-basaltic rocks correspond to magmatic-hydrothermal activities in passive continental margin or island arc settings, whereas the porphyry Cu deposits were formed in an extensional environment, corresponding to the Paleoproterozoic subduction-rifting events in the Trans-North China Orogen. The variation of δ^(56)Fe, Ce anomalies and Y/Ho ratios in BIFs from Neoarchean to Paleoproterozoic indicate the initial increase of oxygen in late Neoarchean and the change of ambient marine environment from anoxic to oxic during the Great Oxidation Event. The multi-stage Neoarchean to Paleoproterozoic metallogenic systems of the NCC were intrinsically linked to the plate subduction along with arc-plume interaction and rifting-subduction-collision activities. The contemporaneous increasing in weathering of exposed continental crust due to plate subduction potentially controlled the atmosphere-hydrosphere oxidation state and formation of BIF deposits in the NCC.
基金Supported by the National Natural Science Foundation of China(NSFC)-Enterprise Innovation and Development Joint Fund Key Project(U24B2018)the Distinguished Young Scholars Program of the National Natural Science Foundation of China(42125205).
文摘Low-salinity fracturing fluids tend to induce ion migration,alter wettability,and cause fluctuations in gas desorption efficiency when penetrating deep coal seams.Taking the No.8 coal from the Daning-Jixian area in the Ordos Basin,NW China,as a representative example,this study employs physical simulation experiments to reveal the coupled control mechanism of salinity gradient on the ion-coal matrix-gas/water interfacial system and its key role in the imbibition-desorption process.The increasing ionic concentration improves the hydrophobicity of coal,with multivalent ions exhibiting particularly significant effects.The imbibition and ion diffusion occur in opposite directions,with imbibition equilibrium being achieved earlier than ionic equilibrium.Water-coal interactions induce both mineral dissolution and secondary precipitation.When a low-salinity fracturing fluid is injected into a high-salinity reservoir,the osmotic-pressure difference drives imbibition,promotes CH4 desorption,but results in higher fluid loss.Conversely,injecting high-salinity fracturing fluid into a low-salinity reservoir creates a reverse osmotic gradient that suppresses leak-off while improving flowback efficiency.Based on these findings,a high-low salinity sequential injection strategy is proposed for deep coal seams:high-salinity fluid is first injected to form stable fracture networks,followed by low-salinity fluid to enlarge the imbibition zone and enhance CH4 desorption and diffusion.Moderate well soaking is recommended to increase the imbibition volume,thereby achieving multiple positive effects such as maintaining reservoir pressure,preserving formation energy,and promoting imbibition-driven displacement.
基金supported by the National Natural Science Foundation of China(Grant Nos.42121002,42330307,42372079,91755207)the 111 Project(Grant No.B18048)。
文摘Continental collision zones undergo a series of deep processes,including subduction of oceanic lithosphere,slab rollback,slab breakoff,continental subduction,lithospheric thickening,and lithospheric delamination.How these deep processes influence the magma generation and the compositional maturation of continental crust in collision zones remain poorly understood.Based on the consensus that plate motion during the Phanerozoic is primarily driven by the pull force of the subducting oceanic slab,this paper divides the evolution of continental collision zones into four stages,including pre-collision(oceanic subduction),syn-collision,transition,and post-collision,separated,respectively,by initial collision,oceanic slab breakoff,and initial extension occurring at the passive continental margin.Intermediate-felsic magma generated during pre-collision primarily originates from the fractional crystallization of mantle-derived mafic magmas under water-rich conditions,producing a large amount of compositionally complementary hornblende-rich mafic-ultramafic cumulates,whereas intermediate-felsic magma formed during syn-and post-collision is generated primarily by the partial melting of pre-existing hornblende-rich maficultramafic rocks,leaving a large number of eclogitized melting residues.The two-stage process of accumulation and remelting in the collision zone-defined herein as accumelting in this paper-involving the formation of voluminous hornblende-rich cumulates during pre-collision and their remelting during late subduction,syn-collision,and post-collision,has led to the compositional maturation of the continental crust in collision zones.Similar trends in magma compositional changes and deep processes are observed in other collision zones,suggesting that accumelting may be an effective process leading to the generation and compositional maturation of the continental crust.Future research directions should focus on(1)the scarcity of arc magmas and the genesis of intermediate-felsic rocks in continental collision zones,(2)whether eclogitized melting residues or cumulates experienced large-scale delamination or were transferred across the Moho into the seismically-defined upper mantle during syncollision,(3)whether the extensive I-type K-rich intermediate-felsic rocks(including I-type granitic rocks and extrusive equivalents)in the upper plate of collision zones primarily come from the partial melting of pre-existing K-rich mafic-ultramafic meta-igneous rocks(protoliths include cumulates and basaltic rocks)in the lower crust,and(4)whether the lower crust of magmatic arcs containing hornblende-rich cumulates is an important reservoir for volatiles.
基金supported by the National Key Research and Development Project of China(Grant No.2022YFF0800902)the National Natural Science Foundation of China(Grant No.42322206)+1 种基金the Frontiers Science Center for Deep-time Digital Earth(Grant No.2652023001)the Beijing Nova Program(Grant No.20220484089)。
文摘Magmatic hydrothermal deposits are important sources of many bulk,precious,and rare metals,and have attracted interest from both academic and industrial communities.However,it is still unclear if the major enrichment of the ore-forming metals occurs in the parental magma source region,during the magma evolution,or after the fluid exsolution.Fluid inclusions trapped in hydrothermal minerals crystallized in the early,high-temperature stage before metal precipitation record information close to that of the initially exsolved magmatic fluids,which are helpful in revealing whether the metals have been already significantly enriched prior to the hydrothermal stage.In this study,available compositional data of such early-stage fluid inclusions from magmatic hydrothermal systems globally have been compiled.The results indicate that the concentrations of Cu,Sn,and W respectively from the Cu-,Sn-,and W-mineralized fluids are significantly higher than the hydrothermal systems that do not produce ores with the corresponding metals.This suggests that Cu,Sn,and W could have already been enriched in the magma source and/or magma evolution stage.The Mo concentrations show no difference between Mo-mineralized and Mobarren fluid systems,indicating no significant pre-enrichment in the source region or during the magma evolution.This also implies that an efficient collection of Mo from a large volume of magmas is required to account for the formation of a large Mo deposit.Almost all the hydrothermal fluids contain high concentrations of Fe and Zn-Pb,but only a few of them eventually form Fe or Zn-Pb deposits,reflecting an important role of the hydrothermal evolution process on the selective metal mineralization.The above results indicate that different metals are enriched in different stages of a magmatic hydrothermal system,and that the major roles played in the formation of a deposit vary with the metal types.In addition to the metal concentrations in the orerelated magmas and fluids,other factors(including but not limited to the intrusion shapes,emplacement depths,structural pathways,and wallrock properties)are also critical in determining the fertility and mineralization diversity of a magmatic hydrothermal system.
基金supported by the National Natural Science Foundation of China(Grant Nos.42030306,42372263&41972206)the Center for Deep-Time Digital Earth Frontier Science(Grant No.2652023001)。
文摘The NE-striking Longmen Shan thrust belt(LSTB)in the eastern margin of the Tibetan Plateau is located at the junction of the Songpan-Ganze Terrane and the Yangtze block.This belt experienced the Late Triassic Qinling-Dabie and Songpan-Ganze orogenesis and the Cenozoic eastern propagation of the Tibetan Plateau.A series of klippes were produced along the foreland thrust belt of the LSTB.Traditional research proposed that the klippes are the front zone of the modern NE-trending Longmen Shan foreland thrust belt,while recent studies suggested that the klippes might be the result of Mesozoic thrusting of the LSTB.Nonetheless,there still remains a lack of crucial constraints regarding the emplacement time and formation mechanism of the klippes.In this study,we conducted systematic structural measurements on the Tangbazi klippe and Woniuping klippe,and performed petrographic analysis for the brecciated limestone.The results confirm a typical structural breccia with top-to-the-SSE kinematics of thrusting at the bottom of the klippes.Structural kinematics reveals the ultimate emplacement of the klippes was under NNE to SSW gliding,and the tail-like brecciated limestone in the southeast edge of the Tangbazi klippe was produced by the Pliocene gravitational collapse.Systematical samples were collected from both the hanging wall and footwall of the klippes and apatite and zircon were separated for(U-Th)/He dating.The(U-Th)/He ages of apatite from the Woniuping klippe are dated at 66.8–72.3 Ma,corresponding to the rapid uplift of the LSTB during the Late Cretaceous;the(UTh)/He ages of apatite from the footwall of the klippe are dated at 33.2–25.2 Ma,corresponding to the rapid uplift and denudation of the LSTB during the Oligocene.Integrated structural analysis and geochronological constraints,the northern segment of the LSTB,including the Tangwangzhai and Longwangmiao thrust complexes,might be produced by in-sequence thrusting during the Late Triassic to Early Jurassic.The northern segment of the LSTB and the northern Sichuan region experienced rapid uplift during the Late Cretaceous.During the Late Eocene to Early Miocene,gravity-driving klippes gliding from the Tangwangzhai and Longwangmiao thrust complexes toward the Sichuan basin occurred along the Silurian mudstone or phyllite and formed gravitational collapse.
基金supported by the National Natural Science Foundation of China(42122019)the Fundamental Research Funds for the Central Universities(2652023001 and 3-7-5-2019-07)the State Key Laboratory of Geological Processes and Mineral Resources。
文摘Due to tidal locking in the Earth-Moon system,the Moon’s farside remained enigmatic until Luna 3 captured its first image,unveiling a rugged landscape largely devoid of extensive dark regions(i.e.,maria),which,by contrast,cover a substantial fraction on the Earth-facing nearside.Subsequent orbital missions further revealed remarkable hemispherical differences:the nearside exhibits more intense volcanic activity.
基金supported by the Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project of China(Grant number:2024ZD1001105)National Natural Science Foundation of China(Grant number:42488201).
文摘Geologic time is an essential dimension in geological research,acting as a pivotal attribute that integrates data across various subdisciplines.The Geologic Time Scale(GTS)provides a formal framework for interpreting and communicating geologic time within the field of geological studies,such as macro-geological evolution and regional geologic surveys.
基金supported by the“Deep-time Digital Earth”Science and Technology Leading Talents Team Funds for the Central Universities for the Frontiers Science Center for Deep-time Digital Earth,China University of Geosciences(Beijing)(Grant No.2652023001)。
文摘Carbonate weathering is crucial for regulating global C cycle and short-term climate change.Calcium(Ca)is one of the major elements involved in carbonate weathering,and studying complex carbonate weathering processes can be helped by Ca isotopes in river system.Here,elemental and Ca isotopic(δ^(44/40)Ca)data for dissolved loads and suspended sediments from the Lancang River(Southeastern Tibetan Plateau)were determined.Dissolvedδ^(44/40)Ca values in river water(0.64‰–1.05‰)decreased downstream,and most values are close to 0.88‰in the mainstream.Relatively,suspended sediments are enriched in light Ca isotopes(0.46‰–0.75‰),which is controlled by mineralogy(clay vs.carbonate)based on the Ca/Al mass ratios and Ca-Zn isotopes evidence.According to the forward model,carbonate and evaporite weathering contribute>90%dissolved Ca to river water,while silicate weathering contributes only a minor fraction(2%–8%).Dissolvedδ^(44/40)Ca values are positively related to Sr/Ca,Mg/Ca ratios,and calcite saturation index,revealing the precipitation of secondary carbonate as a possible mechanism causing heavier Ca isotopes in river water.However,such an effect is not observed in the lowland tributaries,where river water with highδ^(44/40)Ca andδ7Li values indicates the influence of secondary clay formation.After comparing Ca fluxes and dissolvedδ^(44/40)Ca values in large world rivers,we propose that riverine dissolvedδ^(44/40)Ca values are dominated by carbonate weathering and secondary carbonate precipitation.Riverine Ca isotopes could serve as a potential indicator to understand and model secondary processes during carbonate weathering in the surficial environment of Earth.
