The Prydz Bay-Prince Charles Mountains region in East Antarctica constitutes an exceptional geological transect for investigating continental evolution from the Archean to the Phanerozoic and its relationship with sup...The Prydz Bay-Prince Charles Mountains region in East Antarctica constitutes an exceptional geological transect for investigating continental evolution from the Archean to the Phanerozoic and its relationship with supercontinent cycles.This region preserves a complex record of magmatism,metamorphism,and tectonic reworking.Studies by the Chinese National Antarctic Research Expeditions in this region have yielded critical insights into the geological evolution of Antarctica.Key advances over the past decades encompass the elucidation of the Pan-African and Grenvillian tectono-metamorphic history,the delineation of the continent’s crustal and lithospheric architecture,and the identification of extensive ultrahigh-temperature metamorphism and rare mineral assemblages.Despite these advances,many fundamental questions remain unresolved.The spatial and temporal extents of ancient orogenesis are poorly constrained across different crustal blocks,and the tectonic drivers of extreme metamorphism continue to be debated.The role of deep lithospheric architecture in controlling both past orogenic processes and present-day glacial isostatic adjustment remains underexplored.Furthermore,the origins of ancient cratonic nuclei and their constraints on early Earth geodynamics warrant further investigation.Future research should prioritize integrated,multi-disciplinary approaches that combine geological and geophysical analyses.Key objectives include delineating the architecture and evolution of subglacial basement,reconstructing the Phanerozoic uplift and erosion history of the orogens,and evaluating feedback mechanisms among lithospheric evolution,ice-sheet dynamics,and long-term climate.Holistic cross-disciplinary investigations will be essential to unravel the connections between deep Earth processes and surface systems in one of the planet’s most enigmatic and geologically significant regions.展开更多
The Solonker Suture records the termination of the Central Asian Orogenic Belt(CAOB),but its eastward extension beneath the Songliao Basin has not been clear.The Yaduwula ophiolite is one of the significant fragments ...The Solonker Suture records the termination of the Central Asian Orogenic Belt(CAOB),but its eastward extension beneath the Songliao Basin has not been clear.The Yaduwula ophiolite is one of the significant fragments within the Solonker Suture.LA–ICP–MS U–Pb dating of zircon grains from metamorphic basalts yield ages of 263±4 Ma and 274±3 Ma,constraining the Yaduwula ophiolite in the late Cisuralian and Guadalupian age.This might indicate that the subduction of Paleo-Asian Ocean continued until at least the Guadalupian(middle Permian).Geochemical analysis of the metamorphic basalts revealed enrichment in large ion lithophile elements(LILEs)and depletion in high field strength elements(HFSEs)and show the characteristics of a supra-subduction zone.The results provide the evidence for the closure time of the Paleo-Asian Ocean after the middle Permian and also suggest that the Yaduwula ophiolite may be considered the eastern extension of Solonker Suture.Our study provides further insights on the evolution of the southeastern Central Asian Orogenic Belt.展开更多
The Mailong gold deposit is located in the eastern section of the East Kunlun orogenic belt and is one of the recently discovered important gold polymetallic deposits in the Qinhai Gouli region.The primary host rocks ...The Mailong gold deposit is located in the eastern section of the East Kunlun orogenic belt and is one of the recently discovered important gold polymetallic deposits in the Qinhai Gouli region.The primary host rocks of the Mailong gold deposit consist of intermediate-acid intrusive rocks from the Varisian and Indosinian periods,as well as the Precambrian Jinshuikou Group,with mineralization controlled by northeast and northwest faults.The alteration of the host rocks is mainly characterized by silicification,sericitization,chloritization,and carbonatization.Based on the cross-cutting relationships of the veins,the hydrothermal mineralization of the gold deposit can be categorized into three stages:the quartz-pyrite stage,the quartzpolymetallic sulfide stage,and the quartz-carbonate stage.Microthermometry of fluid inclusions indicates that the Mailong gold deposit belongs to a low-density(0.73–0.86 g/cm3),medium-temperature(240–340℃),and medium-salinity(4.01–10.74 wt%NaCl)NaCl-CO2-H2O fluid system.The C-H-O isotopic analysis suggests that the mineralizing fluids is derived from magmatic water,with later contributions from atmospheric precipitation.In-situ S isotopic results indicate that the mineralizing materials mainly derive from igneous rocks.A comprehensive analysis concludes that the Mailong gold deposit is a mesothermal hydrothermal vein-type gold deposit controlled by structural factors.展开更多
Dabie-type porphyry Mo deposits were proposed as a new type of porphyry Mo deposits,and had unique geological characteristics.It is still poorly understood about the magmatic processes that led to the Dabie-type Mo mi...Dabie-type porphyry Mo deposits were proposed as a new type of porphyry Mo deposits,and had unique geological characteristics.It is still poorly understood about the magmatic processes that led to the Dabie-type Mo mineralization.Here,we present zircon U-Pb and Lu-Hf isotopic,whole-rock and biotite elemental,and whole-rock Sr-Nd isotopic analyses on the Lingshan granitic batholith in the Dabie Orogen.It consists of three units(ⅠtoⅢ)that were emplaced before,genetically accompanied with,and after the Mo mineralization.LA-ICP-MS zircon U-Pb dating yielded crystallization ages of 128.2±1.0 Ma(MSWD=1.14)for UnitⅠand ages of 127.8±1.2 Ma(MSWD=0.28)and 126.6±1.8 Ma(MSWD=1.6)for UnitⅡ,indicating that they were emplaced during 130 to 125 Ma.The granites have high SiO_(2)contents(75.84 wt.%to 78.94 wt.%)and low MgO contents(0.07 wt.%to 0.10 wt.%),and are classified as fractionatedⅠ-type granite.UnitsⅠandⅡhave similar Sr-Nd isotopic ratios(ε_(Nd)(t)=-16.2 to-17.2,(^(87)Sr/^(86)Sr)_(i)=0.70540 to 0.70692)and zirconε_(Hf)(t)values(-17.4 to-20.4),indicating they were derived from partial melting of the ancient Yangtze lower crust.Mo mineralized granite from UnitⅡis characterized by the lower oxygen fugacity,fluorine enrichment and high fractionation.Magmas of unitsⅠandⅡhave experienced fractional crystallization,with the assimilation of supracrustal materials that account for the increased TiO_(2),F and Mo contents,and the decreased fO_(2).We proposed that the assimilation in upper-crustal magmatic processes plays key factors for magmatic systems that led to the Dabie-type porphyry Mo deposits.展开更多
In the western segment of the East Kunlun Orogen(WEKO),muscovite granite and garnet granite from the Hureguole intrusion exhibit zircon U-Pb ages of 435-442 Ma.Geochemically,these rocks contain high concentrations of ...In the western segment of the East Kunlun Orogen(WEKO),muscovite granite and garnet granite from the Hureguole intrusion exhibit zircon U-Pb ages of 435-442 Ma.Geochemically,these rocks contain high concentrations of SiO_(2),K_(2)O and Al_(2)O_(3),with low concentrations of TiO_(2)and MgO,indicating a peraluminous high-K calc-alkaline affinity.They are enriched in Rb,Th,U and LREE,depleted in Eu,Ba,Sr and Ti,being classified as S-type granites.Negative whole-rockε_(Nd)(t)values(-9.8 to-9.1)and zirconε_(Hf)(t)values(-11.6 to-8.2)for those granites indicate that they were derived from partial melting of pelitic rocks in the Paleoproterozoic Baishahe Formation of the Jinshuikou Group.Based on the collected zircon ages,Cambrian-Devonian magmatic activity in the WEKO was divided into three stages:early(446-520 Ma),middle(427-441 Ma)and late(372-424 Ma)stages.Statistically,whole-rock Nd and zircon Hf isotope data(ε_(Nd)(t)/T_(DM)^(Nd),ε_(Hf)(t)/T_(DMC)^(Hf))from Paleozoic igneous rocks in the WEKO reveal a magma source that was initially dominated by depleted mantle components in the northward subduction stage of the Proto-Tethy an Ocean plate(446-520 Ma),shifting to predominantly crustal sources during the closure period of the North Qimantagh back-arc basin(427-441 Ma),then to crust-mantle mixed sources in the post-collision stage(372-424 Ma).展开更多
The Early Paleozoic porphyry-epithermal Au system of the Songshunangou District sits in the central segment of the North Qilian orogenic belt(NQOB).The porphyry Au mineralization is centered on the quartz diorite porp...The Early Paleozoic porphyry-epithermal Au system of the Songshunangou District sits in the central segment of the North Qilian orogenic belt(NQOB).The porphyry Au mineralization is centered on the quartz diorite porphyry(QDP),which is constrained to the Late Ordovician period.However,the geochemical signatures,the origin,and the tectonic setting of the QDP are not yet known and understood and are thus in the focus here.The QDP is a high-K calc-alkaline metaluminous rocks(K_(2)O+Na_(2)O:6.90-8.13;Al_(2)O_(3)/(CaO+Na_(2)O+K_(2)O):0.69-0.90)characterized by high(^(87)Sr/^(86)Sr)_(t)values(0.7093-0.7101)and lowε_(Nd)(t)values(-2.9 to-2.7)with corresponding T_(DM2)(Nd)ages of 1408 to 1430 Ma.Zirconε_(Hf)(t)values are low(-1.51 to+2.76)with corresponding T_(DM2)(Hf)ages of 1262 to 1533 Ma.The lead isotope values are 17.695-18.476 for(^(206)Pb/^(204)Pb)_(t),15.585-15.629 for(^(207)Pb/^(204)Pb)_(t),and 37.214-37.948 for(^(208)Pb/^(204)Pb)_(t).These data indicate that the QDP formed by the mixing of mantle-derived magmas(50%-70%)with lower crustal melts.The QDP is enriched in LREEs and LILE(Rb,Th,K)and is depleted in HFSE(Nb,Ta,Ti),expressing a clear volcanic arc affinity.High La and Th contents,and Zr/Y and Hf/Yb values suggest that the QDP formed in an Andean-type continental margin arc setting related to the northward subduction of the North Qilian oceanic slab.The Early Paleozoic subduction-related intermediate-acidic intrusions in NQOB have arc magma affinity,indicating that these rocks bear a great potential to discover further fertile porphyry deposits.展开更多
Jiuhua Mountain,situated in the eastern segment of the Jiangnan Orogenic Belt,is characterized by extensive granite masses,providing an ideal setting for investigating the exhumation history of the region.This study p...Jiuhua Mountain,situated in the eastern segment of the Jiangnan Orogenic Belt,is characterized by extensive granite masses,providing an ideal setting for investigating the exhumation history of the region.This study presents the first zircon(U-Th)/He thermochronological investigation utilizing an age-elevation approach for Jiuhua Mountain.Zircon(U-Th)/He analyses of six bedrock samples yielded consistent ages ranging from 89 to 74 Ma.This finding aligns with the results of thermal history simulations(90-70 Ma),indicating significant exhumation in the Jiuhua Mountain region during the late Cretaceous.Comparative analysis with adjacent orogenic belts(e.g.,the Mufu and Dabie Mountains)reveals a consistent pattern:low-temperature thermochronological ages are younger than the U-Pb zircon ages.This indicates a widespread tectonic exhumation and erosion phase affecting multiple regions within the northern part of the South China Block.The rapid exhumation observed during the late Cretaceous is primarily attributed to extensional tectonics,driven by the rollback of the Paleo-Pacific slab and accompanied by thermal upwelling of the asthenosphere beneath the South China Block.These findings establish crucial temporal constraints for the exhumation history of the eastern Jiangnan Orogenic Belt,significantly enhancing our understanding of its poorly constrained Cretaceous tectonic evolution.展开更多
The Indosinian and Yanshanian orogenic movements are both important Mesozoic orogenies in eastern China.The resulted tectonic belts are neither products of the third stage of crustal evolution,as proposed by Chen Guod...The Indosinian and Yanshanian orogenic movements are both important Mesozoic orogenies in eastern China.The resulted tectonic belts are neither products of the third stage of crustal evolution,as proposed by Chen Guoda,nor intra-continental(or intraplate)orogenic belts generated by intraplate dynamics,as argued by some scholars-rather,they are superposed orogenic belts formed on the pre-existing continental crust in eastern China due to Mesozoic Paleo-Pacific dynamic system.In the past,these orogenic belts were called the marginal Pacific epicontinental activation belts of eastern China.In the Mesozoic,under the effect of Paleo-Pacific dynamic system,the East Asia margin orogenic system formed along Northeast Russia-Sikhote Alin(Russia)-Japan-Ryukyu-Taiwan(China)-Palawan(Philippines)regions,while simultaneously the Mesozoic superposed orogenic system formed in the pre-existing continental crust in eastern China adjacent to the East Asia continental margin.The two orogenic systems,both driven by Mesozoic Paleo-Pacific dynamic system,developed synchronously to form the giant Mesozoic orogenic system in the Pacific tectonic domain in eastern Asia,radically changing the pre-Indosian tectonic framework of the area.展开更多
0 INTRODUCTION Orogenic belts are commonly built by multiple-stage processes involving oceanic subduction and continental collisions that result in the generation of magma with distinct geochemical compositions,as exe...0 INTRODUCTION Orogenic belts are commonly built by multiple-stage processes involving oceanic subduction and continental collisions that result in the generation of magma with distinct geochemical compositions,as exemplified by Central Asian Orogenic Belts(e.g.,Wang et al.,2024;Yin et al.,2024;Xiao et al.,2005)and the Tethyan tectonic domains(e.g.,Chen et al.,2024;Li et al.,2024;Tao et al.,2024a;Gehrels et al.,2011;Yin and Harrison,2000).展开更多
The Ediacaran-Cambrian Petermann Orogen is a dextral transpressional orogen exposed in central Australia,which facilitated the exhumation of a high-pressure core and the deformation of the Neoproterozoic-Palaeozoic Am...The Ediacaran-Cambrian Petermann Orogen is a dextral transpressional orogen exposed in central Australia,which facilitated the exhumation of a high-pressure core and the deformation of the Neoproterozoic-Palaeozoic Amadeus Basin.Several studies have investigated the metamorphic and deformational evolution of the Petermann Orogen;however,the spatiotemporal variation of the deformation and cooling history is yet to be fully understood.In situ muscovite and biotite Rb-Sr geochronology,in combination with Ti-in-quartz thermometry is applied to map the spatiotemporal deformation and cooling patterns of the northern part of the Petermann Orogen.Interpreted muscovite Rb-Sr growth ages obtained from samples in the Petermann Nappe Complex(PNC),range between c.598 Ma and 565 Ma,which correlate with the timing of deformation during the 600-520 Ma Petermann Orogeny.Interpreted muscovite and biotite cooling ages are younger in the east of the PNC(c.556-541 Ma)and broadly correlate with the regional pattern of crustal heat production,suggesting that the geothermal gradient had a significant control on the timing and duration of cooling.Biotite Rb-Sr cooling ages between c.555 Ma and 497 Ma for the orogenic core show no correlation with high heat production areas,however,differences in exhumed crustal levels across the Petermann Orogen are observed:high-P granulite facies rocks in the orogenic core vs middle-upper crustal rocks in the PNC,indicating that at least part of the spatiotemporal variation of cooling ages can be attributed to differential exhumation during the Petermann Orogeny.Hence,crustal heat production and differential exhumation were likely the main controlling factors on the duration and variation of cooling rates in the Petermann Orogen.展开更多
Understanding the formation of lithium-rich pegmatites is critical for meeting global lithium demand.The 509 Daobanxi Li pegmatite deposit,located in the West Kunlun orogenic belt of northwestern China,represents a si...Understanding the formation of lithium-rich pegmatites is critical for meeting global lithium demand.The 509 Daobanxi Li pegmatite deposit,located in the West Kunlun orogenic belt of northwestern China,represents a significant example of an LCT-type(Li-Cs-Ta)pegmatite system.This study investigates the paragenetic sequence of lithium(Li)minerals and the factors controlling their crystallization,providing new insights into the magmatic-hydrothermal evolution of rare-element pegmatites.Pegmatite dikes exhibit distinct zonation,comprising a wall rock zone,a border zone(aplitic layer),and a core zone(pegmatitic layer),with Li mineralization concentrated in the pegmatitic and aplitic layers.The primary Li minerals include spodumene(Spd),montebrasite(Mbs),eucryptite(Ecr),elbaite(Elb),and lepidolite(Lpd),which crystallize in the order of spodumene→montebrasite→elbaite→lepidolite.Spodumene,the dominant Li-bearing mineral,crystallizes from a Li-saturated melt during the magmatic stage.Montebrasite,a Li-phosphate mineral,forms in P-rich environments,coexisting with spodumene and columbite-group minerals(CGM).During the magmatic-hydrothermal transition,elbaite crystallizes from a B-rich melt,exhibiting skeletal and patchy zoning due to undercooling and disequilibrium crystallization.Hydrothermal alteration leads to the breakdown of spodumene and the formation of secondary minerals such as eucryptite and lepidolite,with lepidolite being the final Li-bearing phase,enriched in fluorine.The coupled dissolution-precipitation processes during the magmatic-hydrothermal transition play a critical role in the remobilization and enrichment of rare elements such as Li,Nb,Ta,and Sn.This deposit,characterized by spodumene crystallization in the Spd+Quartz stability field(≥300 MPa,≤725℃)and subsequent alteration to Ecr+quartz assemblages(<270℃,<160 MPa),exhibits broader temperature-pressure conditions exceeding typical global pegmatites like Tanco,with no petalite formation observed due to its persistent exclusion from petalite stability fields throughout mineralization.The shear zone controls the pegmatite emplacement and lithium enrichment in the 509 Daobanxi lithium deposit,and its deformation-fluid coupling mechanism provides new insights for the exploration of LCT pegmatite deposits.The present study highlights the importance of understanding both magmatic and hydrothermal processes in the formation of LCT-type pegmatites and provides valuable insights for the exploration of critical metal resources in similar geological settings.展开更多
The Ordovician-Silurian transition was marked by extensive volcanic activity globally.In South China,intensive volcanism was documented by abundant ash layers in strata,but the origins and tectonic settings of these a...The Ordovician-Silurian transition was marked by extensive volcanic activity globally.In South China,intensive volcanism was documented by abundant ash layers in strata,but the origins and tectonic settings of these ashes remain controversial.This study presents the stratigraphic distribution of volcanic ash layers,zircon trace element and Hf isotope data from the Wanhe Section in the southwestern Yangtze Shelf,providing insights into the tectonic setting and the origin of the parent magmas.The results suggest that volcanic ashes in the southwestern Yangtze Shelf primarily originated from arc magmatism in the Wuyi-Yunkai Orogen,with a mixed source from mantle and crust.The findings corroborate the hypothesis that the Late Ordovician–Silurian Wuyi-Yunkai Orogen in South China represents a collisional orogenic belt.展开更多
A cluster of serpentinite bodies has been recognized tectonically emplaced within the greenschist-amphibolite-facies metamorphic terrane in Hong'an,western Dabie orogen,central China.Two types of serpentinites are...A cluster of serpentinite bodies has been recognized tectonically emplaced within the greenschist-amphibolite-facies metamorphic terrane in Hong'an,western Dabie orogen,central China.Two types of serpentinites are identified on the basis of integrated petrographic,mineralogical and geochemical study.The first type,represented by Yinshanzhai serpentinite complex(Group 1)comprises heterogeneous lithology as a massive serpentinite matrix“intruded”by antigoriteenriched serpentinite lenses.They are both pseudomorphic textured with different mineral assemblages indicating an increasing temperature-pressure condition.Serpentinite matrix(Group 1a)is chemically characterized by high MgO/SiO_(2)and low Al_(2)O_(3)/SiO_(2),Ti and Ca contents,suggesting a depleted mantle wedge origin.The coexistence of compositionally-heterogeneous chromite with highCr^(#)(0.78-0.96)and intermediate-Cr^(#)(0.59-0.70)pristine cores indicates extensive mantle melting.Meanwhile,extremely high Fo olivine relicts(96-97)with considerably higher MnO and lower NiO contents than mantle olivine indicate that they are metamorphic products from serpentine decomposition.Accordingly,we propose that Yinshanzhai serpentinite complex experienced two distinct episodes of hydration.The serpentinite lenses(Group 1b)show higher SiO_(2)and lower MgO concentrations.Nevertheless,the trace elements of groups 1a and 1b are consistent:U-shaped REE patterns,positive Eu anomalies and enrichment of LILE(i.e.,Cs,U)are all identified as forearc properties.They are affected by reducing slab-derived fluids in forearc mantle,with f_(O2)of 1 to 2 logarithmic units below f_(O2)of fayalite-magnetite-quartz buffer(FMQ-2~FMQ-1).The second type is antigorite-serpentinites(Group2)represented by Ximaoshan and Wangchunwan blocks.They are non-pseudomorphic,with no primary framework silicate surviving.Fertile compositions(i.e.,higher Al_(2)O_(3)and Al_(2)O_(3)/SiO_(2),nearly flat REE patterns)and conjoint enrichment of LILE with HFSE suggest melt/rock interaction.Negative Ce,Eu anomalies,and enriched U relative to alkaline elements demonstrate interactions with more oxidized seawater or seafloor fluids(FMQ~FMQ-1).Remarkable Sr negative anomalies may be attributed to Sr release during lizardite/antigorite transition in subduction zone,indicating interaction with low-Sr slab fluids.We propose that Group 2 serpentinites originate either from mantle wedge or abyssal peridotites,refertilized by mantle melts,then hydrated in seafloor or shallow forearc and entrapped into subduction channel.Combined with geochronology and tectonic constraints of associated eclogites in Hong'an terrane,the two types of serpentinites may correlate with subduction of different oceanic basins during the late Paleozoic and/or Proterozoic eras.It raises possibility of defining an ophiolitic setting in Hong'an Orogen for which further evidence is required.展开更多
A set of ultramafic-mafic-felsic rock assemblages was discovered in the Long-shenggeng area of the eastern part of the East Kunlun orogenic belt.Petrography,chronology and whole-rock geochemistry were conducted on thi...A set of ultramafic-mafic-felsic rock assemblages was discovered in the Long-shenggeng area of the eastern part of the East Kunlun orogenic belt.Petrography,chronology and whole-rock geochemistry were conducted on this set of intrusive rock assemblages.U-Pb dating of apatite shows that the lherzolite formed at 492±5 Ma,the granite at 473±6 Ma,and the diabase at 260±14 Ma,respectively.The lherzolites belong to a supra-subduction zone type(SSZ-type)ophiolite component above a subduction zone;the granites formed in an ocean-continent subduction setting;and the diabases represent products of partial melting of an asthenospheric mantle at shallow depth.The East Kunlun orogenic belt features the East Kunzhong and Buqingshan-Animaqing ophiolitic mélange belts,with the latter representing remnants of the Proto-Tethys Ocean.The Late Cambrian lherzolites and granites in the Longshenggeng area were magmatic products of the back-arc ocean basin and island arc formed during the northward subduction of the Proto-Tethys Ocean.Subsequently,extensive island arc magmatism occurred from the Late Permian to Middle Triassic,driven by the northward subduction of the Paleo-Tethys Ocean beneath the East Kunlun Block.The diabase may have formed during the transition from subduction to post-collisional extension.展开更多
Subducting slabs transport carbon to deep mantle depths and release it into the overlying mantle wedge and lithospheric mantle through multiple mechanisms,including mechanical removal via diapirism,metamorphic decarbo...Subducting slabs transport carbon to deep mantle depths and release it into the overlying mantle wedge and lithospheric mantle through multiple mechanisms,including mechanical removal via diapirism,metamorphic decarbonization,carbonate dissolution and parting melting.Identifying the dominant carbon recycling mechanism responsible for carbonation of subcontinental lithospheric mantle(SCLM)remains challenging,yet it is critical for understanding the genesis of post-collisional carbonatites and associated rare earth element deposits.To address this issue,we investigate the Li isotopic systematics of typical post-collisional carbonatite-alkalic complexes from Mianning-Dechang(MD),Southeast Xizang.Our results show that the less-evolved magmas(lamprophyres)have mantle-like or slightly lowerδ^(7)Li values(0.3‰–3.6‰)with limited variability,contrasting sharply with the widerδ^(7)Li range observed in associated carbonatites and syenites.We interpret this dichotomy as reflecting distinct processes:while the variable and anomalousδ^(7)Li values in differentiated rocks(carbonatites and syenites)were caused by late-stage magmatic-hydrothermal processes(including biotite fractionation,fluid exsolution and hydrothermal alteration),the lamprophyres retain the primary Li isotopic signature of their mantle source.Together with their arc-like trace element and EM1-EM2-type Sr-Nd-Pb isotopic signatures,such mantle-like or slightly lowerδ^(7)Li values of the lamprophyres preclude carbon derivation from high-δ^(7)Li reservoirs(altered oceanic crust,serpentinites)and recycling of sedimentary carbon through metamorphic decarbonization or dissolution.Instead,these features indicate that the carbon was predominantly transported into the mantle source via partial melting of subducted carbonate-bearing sediments.This study demonstrates that Li isotopes can serve as a tracer for identifying the mechanism of carbon recycling in collision zones.展开更多
The ocean crust remnants of the Proto-Tethys were preserved as the Kudi ophiolites in the West Kunlun Orogenic Belt(WKOB),and its evolutionary history was mainly constructed by research on igneous or metamorphic rocks...The ocean crust remnants of the Proto-Tethys were preserved as the Kudi ophiolites in the West Kunlun Orogenic Belt(WKOB),and its evolutionary history was mainly constructed by research on igneous or metamorphic rocks in the WKOB.Sedimentary rocks in the WKOB received little attention in the past;however,they could provide important constraints on the evolution of the oceanic lithosphere.Here,a series of shales and greywackes found in the Kudi area of WKOB were studied to constrain their deposition ages and explore their significance in the evolution of the ProtoTethys oceanic crust.The U-Pb dating and europium anomaly(Eu/Eu^(*))were analyzed for detrital zircons from greywackes interlayers,while bulk rare earth elements and yttrium(REY)of the shales were measured.Detrital zircons U-Pb ages yield a maximum deposition age of 436 Ma for the greywackes and black shales,while the REY distribution patterns of the black shales are similar to those of the Tarim Ordovician Saergan shales.Accordingly,the studied WKOB black shales were deposited in the Proto-Tethys Ocean during the Late Ordovician-Early Silurian period.The maximum deposition age at 436 Ma may represent a minimum closure time of the Proto-Tethys Ocean,which is also supported by the absence of increases in Eu/Eu^(*)values during the Late Ordovician-Early Silurian.Besides,our Eu/Eu^(*)values in detrital zircons indicate diminished orogenesis during the Archean to Meso-Proterozoic,subduction-related accretion at the margins of the supercontinent Rodinia during the Neoproterozoic.展开更多
As a highly coupled aggregate of tectonism,magmatism,and metamorphism,a gneiss dome is usually taken as a vital window for understanding the crustal internal structure and the exchange of material and energy during or...As a highly coupled aggregate of tectonism,magmatism,and metamorphism,a gneiss dome is usually taken as a vital window for understanding the crustal internal structure and the exchange of material and energy during orogenic exhumation.The Qinghe gneiss dome located in the eastern Chinese Altai orogen,lies in Qinghe County,Xinjiang,records important information of late accretionary orogeny associated with continental uplift and crustal growth.According to the field investigation,the dome shows core-mantle-margin domains,in which the core is composed of migmatized granite and gneiss,the mantle consists of banded gneiss,schist,and leptynite,and the margin has rock assemblages of phyllite,schist,and meta-sandstone.From the margin to the core,the dome can be divided into chlorite-sericite,andalusite-staurolite,sillimanite-biotite,and sillimanite-garnet metamorphic zones,recording progressive metamorphism.Detailed structural analyses in the Qinghe gneiss dome indicate progressive deformation from the margin to the core.Internal and external detachment faults are clarified,with the former characterized by inflow and outward migration of crustal material and the latter marked by brittle-ductile deformation with a lineation indicating lateral slip of the upper wall when the dome uplifted.Based on these faults,upper,middle,lower structural layers are observed from the outer to inner domains of the dome.Considering the general geological background and new data,the Qinghe gneiss dome probably predominantly underwent early ductile shear deformation and late heat-flow diapirism in the early Permian,closely related to upwelling of asthenosphere mantle that resulted from slab break-off in the extensional tectonic setting.展开更多
We report new SHRIMP zircon U-Pb ages,zircon Lu-Hf isotopic and whole rock geochemical data from Permian granitoids located in the Alxa area of Inner Mongolia,China.In combination with published geochronological and g...We report new SHRIMP zircon U-Pb ages,zircon Lu-Hf isotopic and whole rock geochemical data from Permian granitoids located in the Alxa area of Inner Mongolia,China.In combination with published geochronological and geochemical data,the granitoids in the region can be divided into two age groups:ca.285 Ma and ca.269 Ma.The granitoids of the first group are mainly composed of calc-alkaline to high-K calc-alkaline,weakly peraluminous Ⅰ-type granodiorites with ε_(Hf)(t)values of-19.6 to-4.3,which demonstrates evidence of crustal reworking;the granitoids of the second group,however,mainly consist of A-type granites that are high-K calc-alkaline to shoshonite,metaluminous to weakly peraluminous,and have high 10,000×Ga/Al ratios(2.59-3.12)and ε_(Hf)(t)values ranging from-11.3 to-2.7,all of which demonstrates a mixed crust-mantle source.We interpret the granitoids of the first group to have formed during the subduction of Central Asian oceanic crust and the second group to have formed by the asthenospheric upwelling caused by the formation of slab windows during late ocean ridge subduction.展开更多
To explore the high heat flow anomalies from the Dabie orogenic belt,We have set up 15 Magnetotelluric(MT)stations.The stations have an average spacing of~2 km.Firstly,the phase tensor method is used to analyze MT dat...To explore the high heat flow anomalies from the Dabie orogenic belt,We have set up 15 Magnetotelluric(MT)stations.The stations have an average spacing of~2 km.Firstly,the phase tensor method is used to analyze MT data to estimate the dimensional characteristics of the underground resistivity structure.Then,based on the results of dimensional characteristics analysis,three-dimensional(3D)inversion was performed using ModEM,and a 3D resistivity structure from the surface to a depth of 30 km was obtained.It shows:that there are extensive low resistivity anomalies in the lower crust of the northern margin of the Dabie orogenic belt,which may be partial melting or water-bearing fluid.The high heat flow anomaly in the northern margin of the Dabie orogenic belt may be due to the increase of the background heat flow value caused by the orogenic belt delamination during post-collision,the thinning of the lithosphere and the upwelling of the asthenosphere.展开更多
The subduction and closure history of the Paleo-Tethyan Ocean is of significant importance to the formation of the Alpine-Himalayan orogenic belt.However,in West Qinling,China,the evolution of the subducted Paleo-Teth...The subduction and closure history of the Paleo-Tethyan Ocean is of significant importance to the formation of the Alpine-Himalayan orogenic belt.However,in West Qinling,China,the evolution of the subducted Paleo-Tethyan oceanic slab in the mantle remains unclear.In this work,we determine high-resolution P-wave azimuthal anisotropic tomography of the crust and upper mantle beneath west Qinling by inverting newly collected local and teleseismic data.The local earthquakes are relocated by jointly using permanent and portable stations and weighted by their hypocentral errors during the inversion.Our model reveals a slab-like high P-wave velocity(V_(p))anomaly below 300 km depth and significant depth variations of anisotropy in the upper mantle beneath the West Qinling orogen.By comparing with previous geophysical results and integrating with geological and geochemical findings,we interpret that this high-V_(p)anomaly is most likely the subducted Mianlue oceanic slab preserved in the upper mantle and the mantle transition zone since the early Mesozoic.Beneath the Songpan-Ganzi block and the Longzhong basin,low-V anomalies with weak azimuthal anisotropy suggest a vertical mantle upwelling at a depth of 120 to 200 km,providing positive buoyancy to the subducted oceanic slab and extends its stagnation duration in the upper mantle.展开更多
基金financially supported by the National Natural Science Foundation of China(Grant nos.U2444210,42172068)the Fundamental Research Funds of the Chinese Academy of Geological Sciences(CAGS)(Grant no.JKYZD202321)geological survey program(Grant no.DD20221810).
文摘The Prydz Bay-Prince Charles Mountains region in East Antarctica constitutes an exceptional geological transect for investigating continental evolution from the Archean to the Phanerozoic and its relationship with supercontinent cycles.This region preserves a complex record of magmatism,metamorphism,and tectonic reworking.Studies by the Chinese National Antarctic Research Expeditions in this region have yielded critical insights into the geological evolution of Antarctica.Key advances over the past decades encompass the elucidation of the Pan-African and Grenvillian tectono-metamorphic history,the delineation of the continent’s crustal and lithospheric architecture,and the identification of extensive ultrahigh-temperature metamorphism and rare mineral assemblages.Despite these advances,many fundamental questions remain unresolved.The spatial and temporal extents of ancient orogenesis are poorly constrained across different crustal blocks,and the tectonic drivers of extreme metamorphism continue to be debated.The role of deep lithospheric architecture in controlling both past orogenic processes and present-day glacial isostatic adjustment remains underexplored.Furthermore,the origins of ancient cratonic nuclei and their constraints on early Earth geodynamics warrant further investigation.Future research should prioritize integrated,multi-disciplinary approaches that combine geological and geophysical analyses.Key objectives include delineating the architecture and evolution of subglacial basement,reconstructing the Phanerozoic uplift and erosion history of the orogens,and evaluating feedback mechanisms among lithospheric evolution,ice-sheet dynamics,and long-term climate.Holistic cross-disciplinary investigations will be essential to unravel the connections between deep Earth processes and surface systems in one of the planet’s most enigmatic and geologically significant regions.
基金Supported by Projects of National Natural Science Foundation of China(Nos.42230303,42430305,42402219 and 42302236).
文摘The Solonker Suture records the termination of the Central Asian Orogenic Belt(CAOB),but its eastward extension beneath the Songliao Basin has not been clear.The Yaduwula ophiolite is one of the significant fragments within the Solonker Suture.LA–ICP–MS U–Pb dating of zircon grains from metamorphic basalts yield ages of 263±4 Ma and 274±3 Ma,constraining the Yaduwula ophiolite in the late Cisuralian and Guadalupian age.This might indicate that the subduction of Paleo-Asian Ocean continued until at least the Guadalupian(middle Permian).Geochemical analysis of the metamorphic basalts revealed enrichment in large ion lithophile elements(LILEs)and depletion in high field strength elements(HFSEs)and show the characteristics of a supra-subduction zone.The results provide the evidence for the closure time of the Paleo-Asian Ocean after the middle Permian and also suggest that the Yaduwula ophiolite may be considered the eastern extension of Solonker Suture.Our study provides further insights on the evolution of the southeastern Central Asian Orogenic Belt.
基金Supported by Qinghai Provincial Geological Exploration Special Fund Project(No.2023085029KY004).
文摘The Mailong gold deposit is located in the eastern section of the East Kunlun orogenic belt and is one of the recently discovered important gold polymetallic deposits in the Qinhai Gouli region.The primary host rocks of the Mailong gold deposit consist of intermediate-acid intrusive rocks from the Varisian and Indosinian periods,as well as the Precambrian Jinshuikou Group,with mineralization controlled by northeast and northwest faults.The alteration of the host rocks is mainly characterized by silicification,sericitization,chloritization,and carbonatization.Based on the cross-cutting relationships of the veins,the hydrothermal mineralization of the gold deposit can be categorized into three stages:the quartz-pyrite stage,the quartzpolymetallic sulfide stage,and the quartz-carbonate stage.Microthermometry of fluid inclusions indicates that the Mailong gold deposit belongs to a low-density(0.73–0.86 g/cm3),medium-temperature(240–340℃),and medium-salinity(4.01–10.74 wt%NaCl)NaCl-CO2-H2O fluid system.The C-H-O isotopic analysis suggests that the mineralizing fluids is derived from magmatic water,with later contributions from atmospheric precipitation.In-situ S isotopic results indicate that the mineralizing materials mainly derive from igneous rocks.A comprehensive analysis concludes that the Mailong gold deposit is a mesothermal hydrothermal vein-type gold deposit controlled by structural factors.
基金supported by the National Science and Technology Major Project(No.2024ZD1001005)the National Natural Science Foundation of China(No.42172103)+2 种基金the Natural Science Foundation of Hubei Province(Nos.2023AFD206,2024AFD401,2025AFD439,2025AFD452)the Research Fund Program of Hubei Key Laboratory of Resources and Eco-Environment Geology(Nos.HBREGKFJJ-202302,HBREGKFJJ-202402)the State Key Laboratory of Geological Processes and Mineral Resources(No.GPMR202424)。
文摘Dabie-type porphyry Mo deposits were proposed as a new type of porphyry Mo deposits,and had unique geological characteristics.It is still poorly understood about the magmatic processes that led to the Dabie-type Mo mineralization.Here,we present zircon U-Pb and Lu-Hf isotopic,whole-rock and biotite elemental,and whole-rock Sr-Nd isotopic analyses on the Lingshan granitic batholith in the Dabie Orogen.It consists of three units(ⅠtoⅢ)that were emplaced before,genetically accompanied with,and after the Mo mineralization.LA-ICP-MS zircon U-Pb dating yielded crystallization ages of 128.2±1.0 Ma(MSWD=1.14)for UnitⅠand ages of 127.8±1.2 Ma(MSWD=0.28)and 126.6±1.8 Ma(MSWD=1.6)for UnitⅡ,indicating that they were emplaced during 130 to 125 Ma.The granites have high SiO_(2)contents(75.84 wt.%to 78.94 wt.%)and low MgO contents(0.07 wt.%to 0.10 wt.%),and are classified as fractionatedⅠ-type granite.UnitsⅠandⅡhave similar Sr-Nd isotopic ratios(ε_(Nd)(t)=-16.2 to-17.2,(^(87)Sr/^(86)Sr)_(i)=0.70540 to 0.70692)and zirconε_(Hf)(t)values(-17.4 to-20.4),indicating they were derived from partial melting of the ancient Yangtze lower crust.Mo mineralized granite from UnitⅡis characterized by the lower oxygen fugacity,fluorine enrichment and high fractionation.Magmas of unitsⅠandⅡhave experienced fractional crystallization,with the assimilation of supracrustal materials that account for the increased TiO_(2),F and Mo contents,and the decreased fO_(2).We proposed that the assimilation in upper-crustal magmatic processes plays key factors for magmatic systems that led to the Dabie-type porphyry Mo deposits.
基金funded by the China Postdoctoral Science Foundation(Grant No.2019M663959XB)the Geological Survey and Development Bureau of Qinghai Province 2019 Geological Survey Project(2019[45])the Key Laboratory of Deep Dynamics of the Ministry of Natural Resources,Open Research Project 2019。
文摘In the western segment of the East Kunlun Orogen(WEKO),muscovite granite and garnet granite from the Hureguole intrusion exhibit zircon U-Pb ages of 435-442 Ma.Geochemically,these rocks contain high concentrations of SiO_(2),K_(2)O and Al_(2)O_(3),with low concentrations of TiO_(2)and MgO,indicating a peraluminous high-K calc-alkaline affinity.They are enriched in Rb,Th,U and LREE,depleted in Eu,Ba,Sr and Ti,being classified as S-type granites.Negative whole-rockε_(Nd)(t)values(-9.8 to-9.1)and zirconε_(Hf)(t)values(-11.6 to-8.2)for those granites indicate that they were derived from partial melting of pelitic rocks in the Paleoproterozoic Baishahe Formation of the Jinshuikou Group.Based on the collected zircon ages,Cambrian-Devonian magmatic activity in the WEKO was divided into three stages:early(446-520 Ma),middle(427-441 Ma)and late(372-424 Ma)stages.Statistically,whole-rock Nd and zircon Hf isotope data(ε_(Nd)(t)/T_(DM)^(Nd),ε_(Hf)(t)/T_(DMC)^(Hf))from Paleozoic igneous rocks in the WEKO reveal a magma source that was initially dominated by depleted mantle components in the northward subduction stage of the Proto-Tethy an Ocean plate(446-520 Ma),shifting to predominantly crustal sources during the closure period of the North Qimantagh back-arc basin(427-441 Ma),then to crust-mantle mixed sources in the post-collision stage(372-424 Ma).
基金jointly funded by the National Natural Science Foundation of China(Nos.42230813,41972084)the National Key R&D Program of China(No.2022YFC2905000)the Everest Scientific Research Program of the Chengdu University of Technology(No.2020ZF11407)。
文摘The Early Paleozoic porphyry-epithermal Au system of the Songshunangou District sits in the central segment of the North Qilian orogenic belt(NQOB).The porphyry Au mineralization is centered on the quartz diorite porphyry(QDP),which is constrained to the Late Ordovician period.However,the geochemical signatures,the origin,and the tectonic setting of the QDP are not yet known and understood and are thus in the focus here.The QDP is a high-K calc-alkaline metaluminous rocks(K_(2)O+Na_(2)O:6.90-8.13;Al_(2)O_(3)/(CaO+Na_(2)O+K_(2)O):0.69-0.90)characterized by high(^(87)Sr/^(86)Sr)_(t)values(0.7093-0.7101)and lowε_(Nd)(t)values(-2.9 to-2.7)with corresponding T_(DM2)(Nd)ages of 1408 to 1430 Ma.Zirconε_(Hf)(t)values are low(-1.51 to+2.76)with corresponding T_(DM2)(Hf)ages of 1262 to 1533 Ma.The lead isotope values are 17.695-18.476 for(^(206)Pb/^(204)Pb)_(t),15.585-15.629 for(^(207)Pb/^(204)Pb)_(t),and 37.214-37.948 for(^(208)Pb/^(204)Pb)_(t).These data indicate that the QDP formed by the mixing of mantle-derived magmas(50%-70%)with lower crustal melts.The QDP is enriched in LREEs and LILE(Rb,Th,K)and is depleted in HFSE(Nb,Ta,Ti),expressing a clear volcanic arc affinity.High La and Th contents,and Zr/Y and Hf/Yb values suggest that the QDP formed in an Andean-type continental margin arc setting related to the northward subduction of the North Qilian oceanic slab.The Early Paleozoic subduction-related intermediate-acidic intrusions in NQOB have arc magma affinity,indicating that these rocks bear a great potential to discover further fertile porphyry deposits.
基金National Natural Science Foundation of China for its support of this study(grant numbers 41972212,42030305,and W2411033).
文摘Jiuhua Mountain,situated in the eastern segment of the Jiangnan Orogenic Belt,is characterized by extensive granite masses,providing an ideal setting for investigating the exhumation history of the region.This study presents the first zircon(U-Th)/He thermochronological investigation utilizing an age-elevation approach for Jiuhua Mountain.Zircon(U-Th)/He analyses of six bedrock samples yielded consistent ages ranging from 89 to 74 Ma.This finding aligns with the results of thermal history simulations(90-70 Ma),indicating significant exhumation in the Jiuhua Mountain region during the late Cretaceous.Comparative analysis with adjacent orogenic belts(e.g.,the Mufu and Dabie Mountains)reveals a consistent pattern:low-temperature thermochronological ages are younger than the U-Pb zircon ages.This indicates a widespread tectonic exhumation and erosion phase affecting multiple regions within the northern part of the South China Block.The rapid exhumation observed during the late Cretaceous is primarily attributed to extensional tectonics,driven by the rollback of the Paleo-Pacific slab and accompanied by thermal upwelling of the asthenosphere beneath the South China Block.These findings establish crucial temporal constraints for the exhumation history of the eastern Jiangnan Orogenic Belt,significantly enhancing our understanding of its poorly constrained Cretaceous tectonic evolution.
基金funded by the Regional Geological Survey Project of the China Geological Survey(DD20221646)the National Natural Science Foundation of China(42172218).
文摘The Indosinian and Yanshanian orogenic movements are both important Mesozoic orogenies in eastern China.The resulted tectonic belts are neither products of the third stage of crustal evolution,as proposed by Chen Guoda,nor intra-continental(or intraplate)orogenic belts generated by intraplate dynamics,as argued by some scholars-rather,they are superposed orogenic belts formed on the pre-existing continental crust in eastern China due to Mesozoic Paleo-Pacific dynamic system.In the past,these orogenic belts were called the marginal Pacific epicontinental activation belts of eastern China.In the Mesozoic,under the effect of Paleo-Pacific dynamic system,the East Asia margin orogenic system formed along Northeast Russia-Sikhote Alin(Russia)-Japan-Ryukyu-Taiwan(China)-Palawan(Philippines)regions,while simultaneously the Mesozoic superposed orogenic system formed in the pre-existing continental crust in eastern China adjacent to the East Asia continental margin.The two orogenic systems,both driven by Mesozoic Paleo-Pacific dynamic system,developed synchronously to form the giant Mesozoic orogenic system in the Pacific tectonic domain in eastern Asia,radically changing the pre-Indosian tectonic framework of the area.
基金supported by the National Key Research and Development Project(No.2022YFC2903302)the Second Tibet Plateau Scientific Expedition and Research Program(STEP),(No.2019QZKK0802)+2 种基金the National Natural Science Foundation of China(No.42361144841)the Chinese Academy of Geological Sciences Basal Research Fund(No.JKYZD202402)the Scientific Research Fund Project of BGRIMM Technology Group(No.JTKY202427822)。
文摘0 INTRODUCTION Orogenic belts are commonly built by multiple-stage processes involving oceanic subduction and continental collisions that result in the generation of magma with distinct geochemical compositions,as exemplified by Central Asian Orogenic Belts(e.g.,Wang et al.,2024;Yin et al.,2024;Xiao et al.,2005)and the Tethyan tectonic domains(e.g.,Chen et al.,2024;Li et al.,2024;Tao et al.,2024a;Gehrels et al.,2011;Yin and Harrison,2000).
基金supported by the Mineral Exploration Cooperative Research Centre whose activities are funded by the Australian Government’s Cooperative Research Centre Program.This is MinEx CRC Document 2025/06.
文摘The Ediacaran-Cambrian Petermann Orogen is a dextral transpressional orogen exposed in central Australia,which facilitated the exhumation of a high-pressure core and the deformation of the Neoproterozoic-Palaeozoic Amadeus Basin.Several studies have investigated the metamorphic and deformational evolution of the Petermann Orogen;however,the spatiotemporal variation of the deformation and cooling history is yet to be fully understood.In situ muscovite and biotite Rb-Sr geochronology,in combination with Ti-in-quartz thermometry is applied to map the spatiotemporal deformation and cooling patterns of the northern part of the Petermann Orogen.Interpreted muscovite Rb-Sr growth ages obtained from samples in the Petermann Nappe Complex(PNC),range between c.598 Ma and 565 Ma,which correlate with the timing of deformation during the 600-520 Ma Petermann Orogeny.Interpreted muscovite and biotite cooling ages are younger in the east of the PNC(c.556-541 Ma)and broadly correlate with the regional pattern of crustal heat production,suggesting that the geothermal gradient had a significant control on the timing and duration of cooling.Biotite Rb-Sr cooling ages between c.555 Ma and 497 Ma for the orogenic core show no correlation with high heat production areas,however,differences in exhumed crustal levels across the Petermann Orogen are observed:high-P granulite facies rocks in the orogenic core vs middle-upper crustal rocks in the PNC,indicating that at least part of the spatiotemporal variation of cooling ages can be attributed to differential exhumation during the Petermann Orogeny.Hence,crustal heat production and differential exhumation were likely the main controlling factors on the duration and variation of cooling rates in the Petermann Orogen.
基金supported by the National Natural Science Foundation of China(Nos.42250202,92162323,42272075)the Fundamental Research Funds for the Central Universities,Sun Yat-sen University(No.24lgqb01).
文摘Understanding the formation of lithium-rich pegmatites is critical for meeting global lithium demand.The 509 Daobanxi Li pegmatite deposit,located in the West Kunlun orogenic belt of northwestern China,represents a significant example of an LCT-type(Li-Cs-Ta)pegmatite system.This study investigates the paragenetic sequence of lithium(Li)minerals and the factors controlling their crystallization,providing new insights into the magmatic-hydrothermal evolution of rare-element pegmatites.Pegmatite dikes exhibit distinct zonation,comprising a wall rock zone,a border zone(aplitic layer),and a core zone(pegmatitic layer),with Li mineralization concentrated in the pegmatitic and aplitic layers.The primary Li minerals include spodumene(Spd),montebrasite(Mbs),eucryptite(Ecr),elbaite(Elb),and lepidolite(Lpd),which crystallize in the order of spodumene→montebrasite→elbaite→lepidolite.Spodumene,the dominant Li-bearing mineral,crystallizes from a Li-saturated melt during the magmatic stage.Montebrasite,a Li-phosphate mineral,forms in P-rich environments,coexisting with spodumene and columbite-group minerals(CGM).During the magmatic-hydrothermal transition,elbaite crystallizes from a B-rich melt,exhibiting skeletal and patchy zoning due to undercooling and disequilibrium crystallization.Hydrothermal alteration leads to the breakdown of spodumene and the formation of secondary minerals such as eucryptite and lepidolite,with lepidolite being the final Li-bearing phase,enriched in fluorine.The coupled dissolution-precipitation processes during the magmatic-hydrothermal transition play a critical role in the remobilization and enrichment of rare elements such as Li,Nb,Ta,and Sn.This deposit,characterized by spodumene crystallization in the Spd+Quartz stability field(≥300 MPa,≤725℃)and subsequent alteration to Ecr+quartz assemblages(<270℃,<160 MPa),exhibits broader temperature-pressure conditions exceeding typical global pegmatites like Tanco,with no petalite formation observed due to its persistent exclusion from petalite stability fields throughout mineralization.The shear zone controls the pegmatite emplacement and lithium enrichment in the 509 Daobanxi lithium deposit,and its deformation-fluid coupling mechanism provides new insights for the exploration of LCT pegmatite deposits.The present study highlights the importance of understanding both magmatic and hydrothermal processes in the formation of LCT-type pegmatites and provides valuable insights for the exploration of critical metal resources in similar geological settings.
基金funded by the National Natural Science Foundation of China(Nos.42222209 and 42488201)the State Scholarship Fund.
文摘The Ordovician-Silurian transition was marked by extensive volcanic activity globally.In South China,intensive volcanism was documented by abundant ash layers in strata,but the origins and tectonic settings of these ashes remain controversial.This study presents the stratigraphic distribution of volcanic ash layers,zircon trace element and Hf isotope data from the Wanhe Section in the southwestern Yangtze Shelf,providing insights into the tectonic setting and the origin of the parent magmas.The results suggest that volcanic ashes in the southwestern Yangtze Shelf primarily originated from arc magmatism in the Wuyi-Yunkai Orogen,with a mixed source from mantle and crust.The findings corroborate the hypothesis that the Late Ordovician–Silurian Wuyi-Yunkai Orogen in South China represents a collisional orogenic belt.
基金funded by the National Natural Science Foundation of China(No.42130309)China Geological Survey(Nos.DD20160030,DD20190050)。
文摘A cluster of serpentinite bodies has been recognized tectonically emplaced within the greenschist-amphibolite-facies metamorphic terrane in Hong'an,western Dabie orogen,central China.Two types of serpentinites are identified on the basis of integrated petrographic,mineralogical and geochemical study.The first type,represented by Yinshanzhai serpentinite complex(Group 1)comprises heterogeneous lithology as a massive serpentinite matrix“intruded”by antigoriteenriched serpentinite lenses.They are both pseudomorphic textured with different mineral assemblages indicating an increasing temperature-pressure condition.Serpentinite matrix(Group 1a)is chemically characterized by high MgO/SiO_(2)and low Al_(2)O_(3)/SiO_(2),Ti and Ca contents,suggesting a depleted mantle wedge origin.The coexistence of compositionally-heterogeneous chromite with highCr^(#)(0.78-0.96)and intermediate-Cr^(#)(0.59-0.70)pristine cores indicates extensive mantle melting.Meanwhile,extremely high Fo olivine relicts(96-97)with considerably higher MnO and lower NiO contents than mantle olivine indicate that they are metamorphic products from serpentine decomposition.Accordingly,we propose that Yinshanzhai serpentinite complex experienced two distinct episodes of hydration.The serpentinite lenses(Group 1b)show higher SiO_(2)and lower MgO concentrations.Nevertheless,the trace elements of groups 1a and 1b are consistent:U-shaped REE patterns,positive Eu anomalies and enrichment of LILE(i.e.,Cs,U)are all identified as forearc properties.They are affected by reducing slab-derived fluids in forearc mantle,with f_(O2)of 1 to 2 logarithmic units below f_(O2)of fayalite-magnetite-quartz buffer(FMQ-2~FMQ-1).The second type is antigorite-serpentinites(Group2)represented by Ximaoshan and Wangchunwan blocks.They are non-pseudomorphic,with no primary framework silicate surviving.Fertile compositions(i.e.,higher Al_(2)O_(3)and Al_(2)O_(3)/SiO_(2),nearly flat REE patterns)and conjoint enrichment of LILE with HFSE suggest melt/rock interaction.Negative Ce,Eu anomalies,and enriched U relative to alkaline elements demonstrate interactions with more oxidized seawater or seafloor fluids(FMQ~FMQ-1).Remarkable Sr negative anomalies may be attributed to Sr release during lizardite/antigorite transition in subduction zone,indicating interaction with low-Sr slab fluids.We propose that Group 2 serpentinites originate either from mantle wedge or abyssal peridotites,refertilized by mantle melts,then hydrated in seafloor or shallow forearc and entrapped into subduction channel.Combined with geochronology and tectonic constraints of associated eclogites in Hong'an terrane,the two types of serpentinites may correlate with subduction of different oceanic basins during the late Paleozoic and/or Proterozoic eras.It raises possibility of defining an ophiolitic setting in Hong'an Orogen for which further evidence is required.
基金supported by the Qinghai Provincial Special Fund for Geological Exploration-Deep Mineral Exploration Breakthrough Demonstration Project in Key Ore Concentration Areas of Qinghai Province(No.2023085029ky004)New Round of National Strategic Action for Mineral Exploration Breakthrough-Research and Demonstration of Air-Ground Collaborative Efficient Technologies for Copper-Nickel Sulfide Deposits in the East Kunlun Plateau Desert Region(No.ZKKJ202416)+1 种基金National Key R&D Program of China-Novel Geochemical Exploration Technologies for Desert Gobi and Alpine Grassland Shallow Overburden Terrains(No.2024ZD1002403)Kunlun Talent Program of Qinghai Province jointly support。
文摘A set of ultramafic-mafic-felsic rock assemblages was discovered in the Long-shenggeng area of the eastern part of the East Kunlun orogenic belt.Petrography,chronology and whole-rock geochemistry were conducted on this set of intrusive rock assemblages.U-Pb dating of apatite shows that the lherzolite formed at 492±5 Ma,the granite at 473±6 Ma,and the diabase at 260±14 Ma,respectively.The lherzolites belong to a supra-subduction zone type(SSZ-type)ophiolite component above a subduction zone;the granites formed in an ocean-continent subduction setting;and the diabases represent products of partial melting of an asthenospheric mantle at shallow depth.The East Kunlun orogenic belt features the East Kunzhong and Buqingshan-Animaqing ophiolitic mélange belts,with the latter representing remnants of the Proto-Tethys Ocean.The Late Cambrian lherzolites and granites in the Longshenggeng area were magmatic products of the back-arc ocean basin and island arc formed during the northward subduction of the Proto-Tethys Ocean.Subsequently,extensive island arc magmatism occurred from the Late Permian to Middle Triassic,driven by the northward subduction of the Paleo-Tethys Ocean beneath the East Kunlun Block.The diabase may have formed during the transition from subduction to post-collisional extension.
基金funded by the National Natural Science Foundation of China(42263006)Open Fund from the Jiangxi Province,China(Grant No.20224ACB203011 and 2020101003)East China University of Technology(DHYC-202401 and 1410000874).
文摘Subducting slabs transport carbon to deep mantle depths and release it into the overlying mantle wedge and lithospheric mantle through multiple mechanisms,including mechanical removal via diapirism,metamorphic decarbonization,carbonate dissolution and parting melting.Identifying the dominant carbon recycling mechanism responsible for carbonation of subcontinental lithospheric mantle(SCLM)remains challenging,yet it is critical for understanding the genesis of post-collisional carbonatites and associated rare earth element deposits.To address this issue,we investigate the Li isotopic systematics of typical post-collisional carbonatite-alkalic complexes from Mianning-Dechang(MD),Southeast Xizang.Our results show that the less-evolved magmas(lamprophyres)have mantle-like or slightly lowerδ^(7)Li values(0.3‰–3.6‰)with limited variability,contrasting sharply with the widerδ^(7)Li range observed in associated carbonatites and syenites.We interpret this dichotomy as reflecting distinct processes:while the variable and anomalousδ^(7)Li values in differentiated rocks(carbonatites and syenites)were caused by late-stage magmatic-hydrothermal processes(including biotite fractionation,fluid exsolution and hydrothermal alteration),the lamprophyres retain the primary Li isotopic signature of their mantle source.Together with their arc-like trace element and EM1-EM2-type Sr-Nd-Pb isotopic signatures,such mantle-like or slightly lowerδ^(7)Li values of the lamprophyres preclude carbon derivation from high-δ^(7)Li reservoirs(altered oceanic crust,serpentinites)and recycling of sedimentary carbon through metamorphic decarbonization or dissolution.Instead,these features indicate that the carbon was predominantly transported into the mantle source via partial melting of subducted carbonate-bearing sediments.This study demonstrates that Li isotopes can serve as a tracer for identifying the mechanism of carbon recycling in collision zones.
基金financially supported by the National Major Science and Technology Project of China(No.2016ZX05004-004)the State Scholarship Grant from the China Scholarship Council(CSC)to Yinggang Zhang。
文摘The ocean crust remnants of the Proto-Tethys were preserved as the Kudi ophiolites in the West Kunlun Orogenic Belt(WKOB),and its evolutionary history was mainly constructed by research on igneous or metamorphic rocks in the WKOB.Sedimentary rocks in the WKOB received little attention in the past;however,they could provide important constraints on the evolution of the oceanic lithosphere.Here,a series of shales and greywackes found in the Kudi area of WKOB were studied to constrain their deposition ages and explore their significance in the evolution of the ProtoTethys oceanic crust.The U-Pb dating and europium anomaly(Eu/Eu^(*))were analyzed for detrital zircons from greywackes interlayers,while bulk rare earth elements and yttrium(REY)of the shales were measured.Detrital zircons U-Pb ages yield a maximum deposition age of 436 Ma for the greywackes and black shales,while the REY distribution patterns of the black shales are similar to those of the Tarim Ordovician Saergan shales.Accordingly,the studied WKOB black shales were deposited in the Proto-Tethys Ocean during the Late Ordovician-Early Silurian period.The maximum deposition age at 436 Ma may represent a minimum closure time of the Proto-Tethys Ocean,which is also supported by the absence of increases in Eu/Eu^(*)values during the Late Ordovician-Early Silurian.Besides,our Eu/Eu^(*)values in detrital zircons indicate diminished orogenesis during the Archean to Meso-Proterozoic,subduction-related accretion at the margins of the supercontinent Rodinia during the Neoproterozoic.
基金financially supported by the National Key Research and Development Program(Grant No.2021YFC2901802)the Shaanxi Province Natural Science Foundation(Grant No.2020JM-310)+2 种基金the Hong Kong RGC Co-funding Mechanism on Joint Laboratories with the Chinese Academy of Science(JLFS/P-702/24)the National Key R&D Program of China(Grant Nos.2018YFC0604000,2017YFC0601205)the National Natural Science Foundation of China(Grant Nos.41730213,42072264,41902229,41972237).
文摘As a highly coupled aggregate of tectonism,magmatism,and metamorphism,a gneiss dome is usually taken as a vital window for understanding the crustal internal structure and the exchange of material and energy during orogenic exhumation.The Qinghe gneiss dome located in the eastern Chinese Altai orogen,lies in Qinghe County,Xinjiang,records important information of late accretionary orogeny associated with continental uplift and crustal growth.According to the field investigation,the dome shows core-mantle-margin domains,in which the core is composed of migmatized granite and gneiss,the mantle consists of banded gneiss,schist,and leptynite,and the margin has rock assemblages of phyllite,schist,and meta-sandstone.From the margin to the core,the dome can be divided into chlorite-sericite,andalusite-staurolite,sillimanite-biotite,and sillimanite-garnet metamorphic zones,recording progressive metamorphism.Detailed structural analyses in the Qinghe gneiss dome indicate progressive deformation from the margin to the core.Internal and external detachment faults are clarified,with the former characterized by inflow and outward migration of crustal material and the latter marked by brittle-ductile deformation with a lineation indicating lateral slip of the upper wall when the dome uplifted.Based on these faults,upper,middle,lower structural layers are observed from the outer to inner domains of the dome.Considering the general geological background and new data,the Qinghe gneiss dome probably predominantly underwent early ductile shear deformation and late heat-flow diapirism in the early Permian,closely related to upwelling of asthenosphere mantle that resulted from slab break-off in the extensional tectonic setting.
基金financially supported by the Geological Survey of China(Grant Nos.DD20240075,and DD20243516)the National Natural Science Foundation of China(Grant No.41872209)Basic Scientific Research Fund of the Institute of Geology,Chinese Academy of Geological Sciences(Grant No.J2314)。
文摘We report new SHRIMP zircon U-Pb ages,zircon Lu-Hf isotopic and whole rock geochemical data from Permian granitoids located in the Alxa area of Inner Mongolia,China.In combination with published geochronological and geochemical data,the granitoids in the region can be divided into two age groups:ca.285 Ma and ca.269 Ma.The granitoids of the first group are mainly composed of calc-alkaline to high-K calc-alkaline,weakly peraluminous Ⅰ-type granodiorites with ε_(Hf)(t)values of-19.6 to-4.3,which demonstrates evidence of crustal reworking;the granitoids of the second group,however,mainly consist of A-type granites that are high-K calc-alkaline to shoshonite,metaluminous to weakly peraluminous,and have high 10,000×Ga/Al ratios(2.59-3.12)and ε_(Hf)(t)values ranging from-11.3 to-2.7,all of which demonstrates a mixed crust-mantle source.We interpret the granitoids of the first group to have formed during the subduction of Central Asian oceanic crust and the second group to have formed by the asthenospheric upwelling caused by the formation of slab windows during late ocean ridge subduction.
基金supported by the National Key Research and Development Program of China(grant no.2023YFF0615101).
文摘To explore the high heat flow anomalies from the Dabie orogenic belt,We have set up 15 Magnetotelluric(MT)stations.The stations have an average spacing of~2 km.Firstly,the phase tensor method is used to analyze MT data to estimate the dimensional characteristics of the underground resistivity structure.Then,based on the results of dimensional characteristics analysis,three-dimensional(3D)inversion was performed using ModEM,and a 3D resistivity structure from the surface to a depth of 30 km was obtained.It shows:that there are extensive low resistivity anomalies in the lower crust of the northern margin of the Dabie orogenic belt,which may be partial melting or water-bearing fluid.The high heat flow anomaly in the northern margin of the Dabie orogenic belt may be due to the increase of the background heat flow value caused by the orogenic belt delamination during post-collision,the thinning of the lithosphere and the upwelling of the asthenosphere.
基金supported by the Geological Investigation Project(DD20250209005,DD20242873,and DD20221643)the National Natural Science Foundation of China(Nos.42074112,4171101169 and 42174117)Japan Society for the Promotion of Science(No.19H01996).
文摘The subduction and closure history of the Paleo-Tethyan Ocean is of significant importance to the formation of the Alpine-Himalayan orogenic belt.However,in West Qinling,China,the evolution of the subducted Paleo-Tethyan oceanic slab in the mantle remains unclear.In this work,we determine high-resolution P-wave azimuthal anisotropic tomography of the crust and upper mantle beneath west Qinling by inverting newly collected local and teleseismic data.The local earthquakes are relocated by jointly using permanent and portable stations and weighted by their hypocentral errors during the inversion.Our model reveals a slab-like high P-wave velocity(V_(p))anomaly below 300 km depth and significant depth variations of anisotropy in the upper mantle beneath the West Qinling orogen.By comparing with previous geophysical results and integrating with geological and geochemical findings,we interpret that this high-V_(p)anomaly is most likely the subducted Mianlue oceanic slab preserved in the upper mantle and the mantle transition zone since the early Mesozoic.Beneath the Songpan-Ganzi block and the Longzhong basin,low-V anomalies with weak azimuthal anisotropy suggest a vertical mantle upwelling at a depth of 120 to 200 km,providing positive buoyancy to the subducted oceanic slab and extends its stagnation duration in the upper mantle.
