Over 90%of Earth’s carbon is stored in the mantle and core.The deep carbon cycle plays a critical role in regulating surface carbon fluxes,global climate,and the habitability of Earth.Carbon mainly residing within th...Over 90%of Earth’s carbon is stored in the mantle and core.The deep carbon cycle plays a critical role in regulating surface carbon fluxes,global climate,and the habitability of Earth.Carbon mainly residing within the sediments,altered oceanic crust,and mantle peridotite as carbonate minerals and organic carbon is transported to the deep Earth via plate subduction.A series of reactions(e.g.,metamorphism,dissolution,and melting)occurring in the subducting slab drive the carbon removal.Some of the car-bon is recycled to the surface via arc volcanism,while the rest is carried into the deeper Earth.More than two-thirds of the global subduction carbon input comes from sedimen-tary carbon,whose fate during subduction directly affects the flux in the global carbon cycle.Over the past two dec-ades,the sedimentary carbon cycle in subduction zones has been extensively studied by experiments and computational approaches.Here,we provide a comprehensive review of the sources,species,decarbonation reactions,carbon cycle trac-ing,and fluxes of sedimentary carbon in subduction zones,and the role of sedimentary carbon subduction in climate evolution and mantle chemistry.Further research is required for our understanding of deep carbon cycle processes and their role in Earth’s climate.展开更多
Subduction zones,linking the surface and deep carbon reservoirs,significantly affect the Earth’s long-term climate change and habitability.The subducting slabs undergo decarbonation with increasing pressure and tempe...Subduction zones,linking the surface and deep carbon reservoirs,significantly affect the Earth’s long-term climate change and habitability.The subducting slabs undergo decarbonation with increasing pressure and temperature,during which partial carbon mobilizes out of the slab and returns to the surface by arc volcanism or degassing,while the residual carbon continues to descend to greater depths in the mantle.The estimated carbon influx at subduction zones depends strongly on the calculation model,with contributions from sediments ranging from 15 to 60 Mt C/yr,altered ocean basalts from 18 to 61 Mt C/yr,and serpentinized perdotites from 1.3 to 36 Mt C/yr.The carbon influx varies in space and time.Carbon removal from subducting slab occurs through metamorphic reactions,carbonate dissolution,diapirism,hydrocarbon formation and melting.Among these decarbonation mechanisms,diapirism and slab meting play a decisive role in dictating the depth at which surface carbonates can subduct.Specifically,diapirism may restrict sedimentary carbonates at shallow depths(<200 km),while slab melting exhausts all carbonates from the altered ocean crust near transition zones(410–660 km).Consequently,a mechanism enabling surface carbonates to reach the lower mantle,i.e.,ultra-deep carbon cycle,is required to be in accordance with observations by natural samples.展开更多
Carbonates are viewed as the principal oxidized carbon carriers during subduction,and thus the stability of subducted carbonates has significant implications for the deep carbon cycle.Here we investigate the high pres...Carbonates are viewed as the principal oxidized carbon carriers during subduction,and thus the stability of subducted carbonates has significant implications for the deep carbon cycle.Here we investigate the high pressure-temperature behaviors of rhodochrosite in the presence of iron up to∼34 GPa by in-situ X-ray diffraction and ex-situ Raman spectroscopy.At relatively low temperature below∼1500 K,MnCO_(3)breaks down into MnO and CO_(2).Upon heating to∼1800 K,however,the MnCO_(3)-Fe^(0)reactions occur with the formation of Mn_(3)O_(4),Fe^(O)and reduced carbon.A'three-stage'reaction mechanism is proposed to understand the kinetics of the carbon-iron-manganese redox coupling.The results suggest that Fe^(0)can serve as a reductant to greatly affect the stability of rhodochrosite,which implies that the effect of Fe-metal should be seriously considered for the high pressure-temperature behaviors of other predominant carbonates at Earth's mantle conditions,particularly at depths greater than∼250 km.展开更多
This work was undertaken to investigate the microstructural evolution, mechanical properties and fracture behavior of sand-cast Mg-6 Gd-3 Y-0.5 Zr(GW63) alloy subject to thermal cycling treatment. In order to simulate...This work was undertaken to investigate the microstructural evolution, mechanical properties and fracture behavior of sand-cast Mg-6 Gd-3 Y-0.5 Zr(GW63) alloy subject to thermal cycling treatment. In order to simulate the thermal cycling under extreme service conditions(space or moon environments), the sand-cast and T6 treated GW63 alloys were subjected to thermal cycling treatment which consists of deep cryogenic-elevated temperature cycling treatment(DCET) and deep cryogenic cycling treatment(DCT). Results indicate that there are significant gains in yield strength(YS) and ultimate tensile strength(UTS) of the sand-cast GW63 alloy after DCET, whereas the T6 state alloy undergoes a different variation in mechanical properties. However, no appreciable influence is revealed on the mechanical properties of the tested GW63 alloys after DCT. Meanwhile, the DCT and DCET have no obvious effects on the fracture morphology. The DCT enhances the precipitation kinetics via providing favorable nucleation sites for the precipitation of second phases. The elevated temperature process of DCET plays a crucial role in improving the aging-hardening responses and releasing the stress concentration brought by DCT to a great extent, leading to overcome the obstacle of essential phase transformation. The changes in mechanical properties are primarily attributed to the phase transformation of the studied alloys during DCET.展开更多
It has been suggested that the carbonated mantle reflected by Mg-Zn isotopic anomalies of Cenozoic intraplate basalts from East Asia coincides with the stagnant West Pacific slab in the mantle transition zone.However,...It has been suggested that the carbonated mantle reflected by Mg-Zn isotopic anomalies of Cenozoic intraplate basalts from East Asia coincides with the stagnant West Pacific slab in the mantle transition zone.However,the northern boundary of such carbonated domain beneath East Asia is uncertain.Late Mesozoic-Cenozoic intraplate basalts are widespread in far eastern Russia and thus provide an opportunity to examine this issue.Here we report major-trace element contents and Sr-NdMg-Zn isotopic compositions for 9 Late Mesozoic-Cenozoic basaltic samples from the Khanka Block and Sikhote-Alin accretionary complex.They are characterized by large variations in SiO_(2)contents(41 wt.%to 50 wt.%)and CaO/Al_(2)O_(3)(0.50 to 0.97),enrichments of large-ion lithophile elements(LILE),positive Nb-Ta anomalies and strongly negative K,Pb,Zr,Hf,Ti,Y anomalies in primitive mantle-normalized trace element spider diagram.Furthermore,the rocks show good correlations of Ti/Ti^(*)with Hf/Hf^(*),La/Yb,Fe/Mn and trace element contents(e.g.,Nb).In addition,they have lighter Mg and heavier Zn isotope compositions than the BSE estimates,coupled with depleted Sr-Nd isotope compositions.These elemental and isotopic characteristics cannot be explained by alteration,magma differentiation or diffusion,but are consistent with the partial melting of carbonated peridotite.By and large,the Late Mesozoic-Cenozoic basalts from far eastern Russia bear very similar geochemical characteristics as those Na-series Cenozoic basalts from eastern China.The extended region of Mg-Zn isotopic anomalies is roughly coincident with the stagnant West Pacific slab beneath East Asia,and all of these alkali basalts can be generated from mantle sources hybridized by recycled Mg-carbonates from the Pacific slab stagnant in the mantle transition zone.We infer that(1)the carbonated big mantle wedge extends to the NE edge of the West Pacific slab and may have also appeared in the Late Mesozoic due to the effect of the Paleo-Pacific slab beneath this region,and(2)decarbonation of stagnant slabs in the mantle transition zone is a key mechanism for carbon outgassing from deep mantle to surface via intraplate alkali melts.展开更多
The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe^0 system at 70-150 GPa and 800-2600 Kin a laser-heated diamond anvil cell.Using in situ...The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe^0 system at 70-150 GPa and 800-2600 Kin a laser-heated diamond anvil cell.Using in situ synchrotro n X-ray diffraction and ex situ transmission electron microscopy we show that the reduction of Mg-carbonate can be exemplified by:6 MgCO3+19 Fe=8 FeO+10(Mg0.6Fe^0.4)O+Fe7 C3+3 C.The presented results suggest that the interaction of carbonates with Fe^0 or Fe^0-bearing rocks can produce Fe-carbide and diamond,which can accumulate in the D"region,depending on its carbon to Fe ratio.Due to the sluggish kinetics of the transformation,diamond can remain metastable at the core-mantle boundary(CMB)unless it is in a direct contact with Fe-metal.In addition,it can be remobilized by redox melting accompanying the generation of mantle plumes.展开更多
The geologic production of abiotic organic compounds has been the subject of increasing scientific attention due to their use in the global carbon flux balance,by chemosynthetic biological communities,and for energy r...The geologic production of abiotic organic compounds has been the subject of increasing scientific attention due to their use in the global carbon flux balance,by chemosynthetic biological communities,and for energy resources.Extensive analysis of methane(CH_(4))and other organics in diverse geologic settings,combined with thermodynamic modelings and laboratory simulations,have yielded insights into the distribution of specific abiotic organic molecules on Earth and the favorable conditions and pathways under which they form.This updated and comprehensive review summarizes published results of petrological,thermodynamic,and experimental investigations of possible pathways for the formation of particular species of abiotic simple hydrocarbon molecules such as CH_(4),and of complex hydrocarbon systems,e.g.,long-chain hydrocarbons and even solid carbonaceous matters,in various geologic processes,distinguished into three classes:(1)pre-to early planetary processes;(2)mantle and magmatic processes;and(3)the gas/water-rock reaction processes in low-pressure ultramafic rock and high-pressure subduction zone systems.We not only emphasize how organics are abiotically synthesized but also explore the role or changes of organics in evolutionary geological environments after synthesis,such as phase transitions or organic-mineral interactions.Correspondingly,there is an urgent need to explore the diversity of abiotic organic compounds prevailing on Earth.展开更多
δ-(Al,Fe)OOH is considered to be one of the most important hydrous phases on Earth,remaining stable under the extreme conditions throughout the mantle.The behavior ofδ-(Al,Fe)OOH at high pressure is essential to und...δ-(Al,Fe)OOH is considered to be one of the most important hydrous phases on Earth,remaining stable under the extreme conditions throughout the mantle.The behavior ofδ-(Al,Fe)OOH at high pressure is essential to understanding the deep water cycle.δ-(Al_(0.956)Fe_(0.044))OOH crystals synthesized at 21 GPa and 1473 K were investigated by high-pressure Brillouin light scattering spectroscopy and synchrotron X-ray diffraction up to 135.4 GPa in diamond anvil cells.The incorporation of 5 mol%FeOOH increases the unit-cell volume ofδ-AlOOH by~1%and decreases the shear-wave velocity(VS)by~5%at 20–135 GPa.In particular,the compressional(V_(P))and shear(VS)wave velocities ofδ-(Al_(0.956)Fe_(0.044))OOH are 7%–16%and 10%–24%greater than all the major minerals in the mantle transition zone including wadsleyite,ringwoodite,and majorite.The distinctly high sound velocities ofδ-(Al_(0.956)Fe_(0.044))OOH at 20–25 GPa may contribute to the seismic anomalies observed at~560–680 km depths in the cold and stagnant slab beneath Izu-Bonin and/or Korea.Furthermore,the VS ofδ-(Al_(0.956)Fe_(0.044))OOH is about 10%and 4%–12%lower than iron-bearing bridgmanite Mg_(0.96)Fe_(0.05)Si_(0.99O3)and ferropericlase(Mg_(0.92)Fe_(0.08))O,respectively,under the lowermost mantle conditions,which might partially contribute to the large low-shear-velocity provinces and ultralow velocity zones at the bottom of the lower mantle.展开更多
Carbonates are considered to be important hosts of oxidized carbon during subduction processes.Here we investigate the redox interactions between dolomite and metallic iron in laser-heated diamond anvil cells up to~20...Carbonates are considered to be important hosts of oxidized carbon during subduction processes.Here we investigate the redox interactions between dolomite and metallic iron in laser-heated diamond anvil cells up to~20 GPa.The identification of recovered samples via in-situ synchrotron X-ray diffraction and ex-situ Raman spectroscopy shows that the reaction occurs with the formation of ferropericlase,graphite and hexagonal diamond,while CaCO_(3) remains stable.The experimental results indicate dolomite and metallic iron phases cannot coexist and demonstrate a possible formation mechanism of ultradeep diamonds via redox reaction between dolomite and iron under the mantle transition zone conditions.The results are significant for understanding carbon transportation during subduction processes and have further implications to the processes in the more complex systems regarding to carbonate-silicate-metal phase relations.展开更多
The high-pressure behavior of deep carbonate dictates the state and dynamics of oxidized carbon in the Earth's mantle,playing a vital role in the global carbon cycle and potentially influencing long-term climate c...The high-pressure behavior of deep carbonate dictates the state and dynamics of oxidized carbon in the Earth's mantle,playing a vital role in the global carbon cycle and potentially influencing long-term climate change.Optical absorption and Raman spectroscopic measurements were carried out on two natural carbonate samples in diamond-anvil cells up to 60 GPa.Mg-substitution in high-spin siderite FeCO_(3)increases the crystal field absorption band position by approximately 1000 cm^(-1),but such an effect is marginal at>40 GPa when entering the low-spin state.The crystal field absorption band of dolomite cannot be recognized upon compression to 45.8 GPa at room temperature but,in contrast,the high-pressure polymorph of dolomite exhibits a strong absorption band at frequencies higher than(Mg,Fe)CO_(3)in the lowspin state by 2000–2500 cm^(-1).Additionally,these carbonate minerals show more complicated features for the absorption edge,decreasing with pressure and undergoing a dramatic change through the spin crossover.The optical and vibrational properties of carbonate minerals are highly correlated with iron content and spin transition,indicating that iron is preferentially partitioned into low-spin carbonates.These results shed new light on how carbonate minerals evolve in the mantle,which is crucial to decode the deep carbon cycle.展开更多
Efficient plating/stripping of Na metal is critical to stable operation of any rechargeable Na metal battery.However,it is often overlooked or misunderstood in electrochemical measurements using thick Na electrodes wi...Efficient plating/stripping of Na metal is critical to stable operation of any rechargeable Na metal battery.However,it is often overlooked or misunderstood in electrochemical measurements using thick Na electrodes with large excess of Na reserves.Herein,we report two crucial aspects,which have generally been ignored in previous studies,in the development of more practical capacity-controlled Na metal electrodes that can be efficiently cycled at 100%depth.We find that common carbonate electrolytes induce severe side reaction and highly irreversible Na plating/stripping,whereas ether electrolytes without any additive support thick Na metal electrodes operating at a high average Coulombic efficiency of 99.6%for over 300 cycles.We further show that to realize such high efficiency in thin Na metal electrodes,it is necessary to ensure strong adhesion between the thin Na layer and the Cu current collector,which we solve by introducing an Au interlayer.The resulting transferable thin Na metal electrodes enable high-energy-density,high-efficiency and reasonably stable-cycling Na||Na3V2(PO4)3 batteries.展开更多
The effect of deep cryogenic cycle treatment(DCT)on Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5)(Vit-1)bulk metallic glass(BMG)prepared from high-purity raw materials was investigated.After DCT,no obvious rejuvenation ...The effect of deep cryogenic cycle treatment(DCT)on Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5)(Vit-1)bulk metallic glass(BMG)prepared from high-purity raw materials was investigated.After DCT,no obvious rejuvenation of the samples was detected.With an increasing number of cryogenic cycles,the hardness of the samples first decreased and then increased,the room-temperature compression plasticity first increased and then generally remained unchanged,and the impact toughness underwent almost no obvious change.The absence of rejuvenation was attributed to the high fragility index(47-50)and high glass forming ability(GFA)of the material.As lower purity of the raw materials is expected in practical applications,DCT of Vit-1 BMG prepared from low-purity raw materials was also performed.After DCT,the samples prepared with the lower-purity raw materials were clearly rejuvenated,and the room-temperature mechanical properties improved significantly.Both the compression plasticity and impact toughness reached peak values after 5 cryogenic cycles.The initial impurities(including Y and O)had a complex and comprehensive effect on the deformation mechanism of the BMG during DCT.Our findings indicate that the structural heterogeneity,fragility index,and GFA of the BMG alter the effect of DCT.展开更多
The deep carbon cycle,which plays a critical role in mantle evolution and Earth habitability,is closely linked to the recycling of carbonate-bearing rocks through subduction.Marine carbonates are subducted to differen...The deep carbon cycle,which plays a critical role in mantle evolution and Earth habitability,is closely linked to the recycling of carbonate-bearing rocks through subduction.Marine carbonates are subducted to different depths during the closure of oceanic basins,thus carry important signatures of the disappeared oceanic basins.Petrological and geochemical features of the Hannuoba carbonatites in the northern North China Craton indicate that they were formed by melting of limestone subducted to mantle depths.Here,we show that detrital zircons carried by these carbonatites have a broad spectrum of U-Pb ages from Precambrian to Phanerozoic.Precambrian age peaks are at~2.5 Ga,2.1–2.3 Ga,1.8–2.0 Ga,~1.65 Ga,1.3–1.4 Ga,~1.1 Ga,0.91–0.94 Ga,0.74–0.81 Ga,and 0.62–0.63 Ga,respectively.The recorded age peaks are different from those in the northern North China Craton and thus preclude an origin of crustal contamination.Nevertheless,the Precambrian age spectra are compatible with those of the Xingmeng Orogen in the southeastern Central Asian Orogenic Belt.Furthermore,the significantly positiveεHf(t)values of 7.7–13.5 for the 300–373 Ma zircons are similar to those in the Xingmeng Orogen but different from those in the northern North China Craton.All these features suggest that the limestone precursor for the Hannuoba carbonatites was originated from the Paleo-Asian Ocean,and its deposition time was not earlier than 300 Ma.This indicates that the PaleoAsian Ocean still existed in the late Carboniferous to early Permian.The widespread distribution of metamorphic carbonates in the Central Asian Orogenic Belt indicates that there may have been widespread sedimentary carbonates in the Paleo-Asian Ocean.A large amount of sedimentary carbonates was probably carried into mantle during subduction of the Paleo-Asian oceanic slab,which significantly modified the chemical and physical properties of the lithospheric mantle.展开更多
基金supported by the National Natural Science Foundation of China(No.42274137).
文摘Over 90%of Earth’s carbon is stored in the mantle and core.The deep carbon cycle plays a critical role in regulating surface carbon fluxes,global climate,and the habitability of Earth.Carbon mainly residing within the sediments,altered oceanic crust,and mantle peridotite as carbonate minerals and organic carbon is transported to the deep Earth via plate subduction.A series of reactions(e.g.,metamorphism,dissolution,and melting)occurring in the subducting slab drive the carbon removal.Some of the car-bon is recycled to the surface via arc volcanism,while the rest is carried into the deeper Earth.More than two-thirds of the global subduction carbon input comes from sedimen-tary carbon,whose fate during subduction directly affects the flux in the global carbon cycle.Over the past two dec-ades,the sedimentary carbon cycle in subduction zones has been extensively studied by experiments and computational approaches.Here,we provide a comprehensive review of the sources,species,decarbonation reactions,carbon cycle trac-ing,and fluxes of sedimentary carbon in subduction zones,and the role of sedimentary carbon subduction in climate evolution and mantle chemistry.Further research is required for our understanding of deep carbon cycle processes and their role in Earth’s climate.
基金supported by the Marine S&T Fund of Shandong Province for Pilot National Laboratory for Marine Science and Technology(Qingdao)(No.2022QNLM050201-3)the National Key R&D Program of China(No.2022YFF0801000)the National Natural Science Foundation of China(Nos.92158206,42003049).
文摘Subduction zones,linking the surface and deep carbon reservoirs,significantly affect the Earth’s long-term climate change and habitability.The subducting slabs undergo decarbonation with increasing pressure and temperature,during which partial carbon mobilizes out of the slab and returns to the surface by arc volcanism or degassing,while the residual carbon continues to descend to greater depths in the mantle.The estimated carbon influx at subduction zones depends strongly on the calculation model,with contributions from sediments ranging from 15 to 60 Mt C/yr,altered ocean basalts from 18 to 61 Mt C/yr,and serpentinized perdotites from 1.3 to 36 Mt C/yr.The carbon influx varies in space and time.Carbon removal from subducting slab occurs through metamorphic reactions,carbonate dissolution,diapirism,hydrocarbon formation and melting.Among these decarbonation mechanisms,diapirism and slab meting play a decisive role in dictating the depth at which surface carbonates can subduct.Specifically,diapirism may restrict sedimentary carbonates at shallow depths(<200 km),while slab melting exhausts all carbonates from the altered ocean crust near transition zones(410–660 km).Consequently,a mechanism enabling surface carbonates to reach the lower mantle,i.e.,ultra-deep carbon cycle,is required to be in accordance with observations by natural samples.
基金supported by National Natural Science Foundation of China(Nos.42072047,41772034).
文摘Carbonates are viewed as the principal oxidized carbon carriers during subduction,and thus the stability of subducted carbonates has significant implications for the deep carbon cycle.Here we investigate the high pressure-temperature behaviors of rhodochrosite in the presence of iron up to∼34 GPa by in-situ X-ray diffraction and ex-situ Raman spectroscopy.At relatively low temperature below∼1500 K,MnCO_(3)breaks down into MnO and CO_(2).Upon heating to∼1800 K,however,the MnCO_(3)-Fe^(0)reactions occur with the formation of Mn_(3)O_(4),Fe^(O)and reduced carbon.A'three-stage'reaction mechanism is proposed to understand the kinetics of the carbon-iron-manganese redox coupling.The results suggest that Fe^(0)can serve as a reductant to greatly affect the stability of rhodochrosite,which implies that the effect of Fe-metal should be seriously considered for the high pressure-temperature behaviors of other predominant carbonates at Earth's mantle conditions,particularly at depths greater than∼250 km.
基金supported by the National Natural Science Foundation of China(Nos.51771115 and 51775334)the National Science and Technology Major Project(No.2017ZX04006001)+1 种基金the Joint Fund for Space Science and Technology(Nos.6141B06310106 and 6141B06300401)the Research Program of Joint Research Center of Advanced Spaceflight Technologies(No.USCAST2016-18)。
文摘This work was undertaken to investigate the microstructural evolution, mechanical properties and fracture behavior of sand-cast Mg-6 Gd-3 Y-0.5 Zr(GW63) alloy subject to thermal cycling treatment. In order to simulate the thermal cycling under extreme service conditions(space or moon environments), the sand-cast and T6 treated GW63 alloys were subjected to thermal cycling treatment which consists of deep cryogenic-elevated temperature cycling treatment(DCET) and deep cryogenic cycling treatment(DCT). Results indicate that there are significant gains in yield strength(YS) and ultimate tensile strength(UTS) of the sand-cast GW63 alloy after DCET, whereas the T6 state alloy undergoes a different variation in mechanical properties. However, no appreciable influence is revealed on the mechanical properties of the tested GW63 alloys after DCT. Meanwhile, the DCT and DCET have no obvious effects on the fracture morphology. The DCT enhances the precipitation kinetics via providing favorable nucleation sites for the precipitation of second phases. The elevated temperature process of DCET plays a crucial role in improving the aging-hardening responses and releasing the stress concentration brought by DCT to a great extent, leading to overcome the obstacle of essential phase transformation. The changes in mechanical properties are primarily attributed to the phase transformation of the studied alloys during DCET.
基金financially supported by the National Natural Science Foundation of China(Nos.41730214,41822301,and 41790451)the National Key R&D Program of China(Nos.2019YFA0708400,2020YFA0714800,and 2019YFC0605403)+4 种基金China“1000 Youth Talents Program”the“111”Project(No.B18048)the pre-research project on Civil Aerospace Technologies(No.D020202)from Chinese National Space AdministrationChinese Academy of Sciences President’s International Fellowship Initiative(PIFI)for Visiting Scientists in 2019(No.2017VCA0009)CUGB petro-geochemical contribution No.PGC-201572(RIG-No.11)。
文摘It has been suggested that the carbonated mantle reflected by Mg-Zn isotopic anomalies of Cenozoic intraplate basalts from East Asia coincides with the stagnant West Pacific slab in the mantle transition zone.However,the northern boundary of such carbonated domain beneath East Asia is uncertain.Late Mesozoic-Cenozoic intraplate basalts are widespread in far eastern Russia and thus provide an opportunity to examine this issue.Here we report major-trace element contents and Sr-NdMg-Zn isotopic compositions for 9 Late Mesozoic-Cenozoic basaltic samples from the Khanka Block and Sikhote-Alin accretionary complex.They are characterized by large variations in SiO_(2)contents(41 wt.%to 50 wt.%)and CaO/Al_(2)O_(3)(0.50 to 0.97),enrichments of large-ion lithophile elements(LILE),positive Nb-Ta anomalies and strongly negative K,Pb,Zr,Hf,Ti,Y anomalies in primitive mantle-normalized trace element spider diagram.Furthermore,the rocks show good correlations of Ti/Ti^(*)with Hf/Hf^(*),La/Yb,Fe/Mn and trace element contents(e.g.,Nb).In addition,they have lighter Mg and heavier Zn isotope compositions than the BSE estimates,coupled with depleted Sr-Nd isotope compositions.These elemental and isotopic characteristics cannot be explained by alteration,magma differentiation or diffusion,but are consistent with the partial melting of carbonated peridotite.By and large,the Late Mesozoic-Cenozoic basalts from far eastern Russia bear very similar geochemical characteristics as those Na-series Cenozoic basalts from eastern China.The extended region of Mg-Zn isotopic anomalies is roughly coincident with the stagnant West Pacific slab beneath East Asia,and all of these alkali basalts can be generated from mantle sources hybridized by recycled Mg-carbonates from the Pacific slab stagnant in the mantle transition zone.We infer that(1)the carbonated big mantle wedge extends to the NE edge of the West Pacific slab and may have also appeared in the Late Mesozoic due to the effect of the Paleo-Pacific slab beneath this region,and(2)decarbonation of stagnant slabs in the mantle transition zone is a key mechanism for carbon outgassing from deep mantle to surface via intraplate alkali melts.
基金supported byRussian Science Foundation,project No 17-17-01177.AGsupport of the Deep Carbon Observatory through the Alfred P.Sloan Foundation
文摘The fate of subducted carbonates in the lower mantle and at the core-mantle boundary was modelled via experiments in the MgCO3-Fe^0 system at 70-150 GPa and 800-2600 Kin a laser-heated diamond anvil cell.Using in situ synchrotro n X-ray diffraction and ex situ transmission electron microscopy we show that the reduction of Mg-carbonate can be exemplified by:6 MgCO3+19 Fe=8 FeO+10(Mg0.6Fe^0.4)O+Fe7 C3+3 C.The presented results suggest that the interaction of carbonates with Fe^0 or Fe^0-bearing rocks can produce Fe-carbide and diamond,which can accumulate in the D"region,depending on its carbon to Fe ratio.Due to the sluggish kinetics of the transformation,diamond can remain metastable at the core-mantle boundary(CMB)unless it is in a direct contact with Fe-metal.In addition,it can be remobilized by redox melting accompanying the generation of mantle plumes.
基金financially supported by the National Key Research and Development Program of China(Grant No.2019YFA0708501)the NSFC Major Research Plan on West-Pacific Earth System Multispheric Interactions(Grant No.92158206)。
文摘The geologic production of abiotic organic compounds has been the subject of increasing scientific attention due to their use in the global carbon flux balance,by chemosynthetic biological communities,and for energy resources.Extensive analysis of methane(CH_(4))and other organics in diverse geologic settings,combined with thermodynamic modelings and laboratory simulations,have yielded insights into the distribution of specific abiotic organic molecules on Earth and the favorable conditions and pathways under which they form.This updated and comprehensive review summarizes published results of petrological,thermodynamic,and experimental investigations of possible pathways for the formation of particular species of abiotic simple hydrocarbon molecules such as CH_(4),and of complex hydrocarbon systems,e.g.,long-chain hydrocarbons and even solid carbonaceous matters,in various geologic processes,distinguished into three classes:(1)pre-to early planetary processes;(2)mantle and magmatic processes;and(3)the gas/water-rock reaction processes in low-pressure ultramafic rock and high-pressure subduction zone systems.We not only emphasize how organics are abiotically synthesized but also explore the role or changes of organics in evolutionary geological environments after synthesis,such as phase transitions or organic-mineral interactions.Correspondingly,there is an urgent need to explore the diversity of abiotic organic compounds prevailing on Earth.
基金the National Key Research and Development Program of China(2019YFA0708502)the National Natural Science Foundation of China(Grant No.U1930401)+3 种基金BL14U1 of the Shanghai Synchrotron Radiation Facility for beamtime access based on proposal 2019-SSRF-PT-011035 and Geo-SoilEnviroCARS(Sector 13-BMC and 13-BMD)at the Advanced Photon Source,Argonne National Laboratory,USAthe National Science Foundation Earth Sciences(Grant No.EAR1128799)the Department of Energy-GeoSciences(Grant No.DEFG02-94ER14466)The Advanced Photon Source is a U.S.Department of Energy(DOE)Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under Contract No.DE-AC02-06CH11357.
文摘δ-(Al,Fe)OOH is considered to be one of the most important hydrous phases on Earth,remaining stable under the extreme conditions throughout the mantle.The behavior ofδ-(Al,Fe)OOH at high pressure is essential to understanding the deep water cycle.δ-(Al_(0.956)Fe_(0.044))OOH crystals synthesized at 21 GPa and 1473 K were investigated by high-pressure Brillouin light scattering spectroscopy and synchrotron X-ray diffraction up to 135.4 GPa in diamond anvil cells.The incorporation of 5 mol%FeOOH increases the unit-cell volume ofδ-AlOOH by~1%and decreases the shear-wave velocity(VS)by~5%at 20–135 GPa.In particular,the compressional(V_(P))and shear(VS)wave velocities ofδ-(Al_(0.956)Fe_(0.044))OOH are 7%–16%and 10%–24%greater than all the major minerals in the mantle transition zone including wadsleyite,ringwoodite,and majorite.The distinctly high sound velocities ofδ-(Al_(0.956)Fe_(0.044))OOH at 20–25 GPa may contribute to the seismic anomalies observed at~560–680 km depths in the cold and stagnant slab beneath Izu-Bonin and/or Korea.Furthermore,the VS ofδ-(Al_(0.956)Fe_(0.044))OOH is about 10%and 4%–12%lower than iron-bearing bridgmanite Mg_(0.96)Fe_(0.05)Si_(0.99O3)and ferropericlase(Mg_(0.92)Fe_(0.08))O,respectively,under the lowermost mantle conditions,which might partially contribute to the large low-shear-velocity provinces and ultralow velocity zones at the bottom of the lower mantle.
基金funded by the National Natural Science Foundation of China(No.41772034).
文摘Carbonates are considered to be important hosts of oxidized carbon during subduction processes.Here we investigate the redox interactions between dolomite and metallic iron in laser-heated diamond anvil cells up to~20 GPa.The identification of recovered samples via in-situ synchrotron X-ray diffraction and ex-situ Raman spectroscopy shows that the reaction occurs with the formation of ferropericlase,graphite and hexagonal diamond,while CaCO_(3) remains stable.The experimental results indicate dolomite and metallic iron phases cannot coexist and demonstrate a possible formation mechanism of ultradeep diamonds via redox reaction between dolomite and iron under the mantle transition zone conditions.The results are significant for understanding carbon transportation during subduction processes and have further implications to the processes in the more complex systems regarding to carbonate-silicate-metal phase relations.
基金supported by the National Key Research and Development Program of China(Grant No.2019YFA0708502)。
文摘The high-pressure behavior of deep carbonate dictates the state and dynamics of oxidized carbon in the Earth's mantle,playing a vital role in the global carbon cycle and potentially influencing long-term climate change.Optical absorption and Raman spectroscopic measurements were carried out on two natural carbonate samples in diamond-anvil cells up to 60 GPa.Mg-substitution in high-spin siderite FeCO_(3)increases the crystal field absorption band position by approximately 1000 cm^(-1),but such an effect is marginal at>40 GPa when entering the low-spin state.The crystal field absorption band of dolomite cannot be recognized upon compression to 45.8 GPa at room temperature but,in contrast,the high-pressure polymorph of dolomite exhibits a strong absorption band at frequencies higher than(Mg,Fe)CO_(3)in the lowspin state by 2000–2500 cm^(-1).Additionally,these carbonate minerals show more complicated features for the absorption edge,decreasing with pressure and undergoing a dramatic change through the spin crossover.The optical and vibrational properties of carbonate minerals are highly correlated with iron content and spin transition,indicating that iron is preferentially partitioned into low-spin carbonates.These results shed new light on how carbonate minerals evolve in the mantle,which is crucial to decode the deep carbon cycle.
基金This work was supported by the U.S.National Science Foundation(CBET-1903342).
文摘Efficient plating/stripping of Na metal is critical to stable operation of any rechargeable Na metal battery.However,it is often overlooked or misunderstood in electrochemical measurements using thick Na electrodes with large excess of Na reserves.Herein,we report two crucial aspects,which have generally been ignored in previous studies,in the development of more practical capacity-controlled Na metal electrodes that can be efficiently cycled at 100%depth.We find that common carbonate electrolytes induce severe side reaction and highly irreversible Na plating/stripping,whereas ether electrolytes without any additive support thick Na metal electrodes operating at a high average Coulombic efficiency of 99.6%for over 300 cycles.We further show that to realize such high efficiency in thin Na metal electrodes,it is necessary to ensure strong adhesion between the thin Na layer and the Cu current collector,which we solve by introducing an Au interlayer.The resulting transferable thin Na metal electrodes enable high-energy-density,high-efficiency and reasonably stable-cycling Na||Na3V2(PO4)3 batteries.
基金financially supported by the National Science Foundation for Distinguished Young Scholars of China(Grant No.51725504)the open funding via State Key Laboratory of Materials Processing and Die&Mould Technology(Grant No.P2019-011)+1 种基金the Guangdong Provincial Natural Science Foundation of China(Grant No.2020A1515011524)the Fundamental Research Funds for the Central Universities,HUST(Grant No.2018KFYRCPT001).
文摘The effect of deep cryogenic cycle treatment(DCT)on Zr_(41.2)Ti_(13.8)Cu_(12.5)Ni_(10)Be_(22.5)(Vit-1)bulk metallic glass(BMG)prepared from high-purity raw materials was investigated.After DCT,no obvious rejuvenation of the samples was detected.With an increasing number of cryogenic cycles,the hardness of the samples first decreased and then increased,the room-temperature compression plasticity first increased and then generally remained unchanged,and the impact toughness underwent almost no obvious change.The absence of rejuvenation was attributed to the high fragility index(47-50)and high glass forming ability(GFA)of the material.As lower purity of the raw materials is expected in practical applications,DCT of Vit-1 BMG prepared from low-purity raw materials was also performed.After DCT,the samples prepared with the lower-purity raw materials were clearly rejuvenated,and the room-temperature mechanical properties improved significantly.Both the compression plasticity and impact toughness reached peak values after 5 cryogenic cycles.The initial impurities(including Y and O)had a complex and comprehensive effect on the deformation mechanism of the BMG during DCT.Our findings indicate that the structural heterogeneity,fragility index,and GFA of the BMG alter the effect of DCT.
基金supported by the Key R&D Program of China(Grant No.2019YFA0708400)the National Natural Science Foundation of China(Grant No.41530211)the Special Fund of the State Key Laboratory of Geological Processes and Mineral Resources(Grant No.MSFGPMR01)。
文摘The deep carbon cycle,which plays a critical role in mantle evolution and Earth habitability,is closely linked to the recycling of carbonate-bearing rocks through subduction.Marine carbonates are subducted to different depths during the closure of oceanic basins,thus carry important signatures of the disappeared oceanic basins.Petrological and geochemical features of the Hannuoba carbonatites in the northern North China Craton indicate that they were formed by melting of limestone subducted to mantle depths.Here,we show that detrital zircons carried by these carbonatites have a broad spectrum of U-Pb ages from Precambrian to Phanerozoic.Precambrian age peaks are at~2.5 Ga,2.1–2.3 Ga,1.8–2.0 Ga,~1.65 Ga,1.3–1.4 Ga,~1.1 Ga,0.91–0.94 Ga,0.74–0.81 Ga,and 0.62–0.63 Ga,respectively.The recorded age peaks are different from those in the northern North China Craton and thus preclude an origin of crustal contamination.Nevertheless,the Precambrian age spectra are compatible with those of the Xingmeng Orogen in the southeastern Central Asian Orogenic Belt.Furthermore,the significantly positiveεHf(t)values of 7.7–13.5 for the 300–373 Ma zircons are similar to those in the Xingmeng Orogen but different from those in the northern North China Craton.All these features suggest that the limestone precursor for the Hannuoba carbonatites was originated from the Paleo-Asian Ocean,and its deposition time was not earlier than 300 Ma.This indicates that the PaleoAsian Ocean still existed in the late Carboniferous to early Permian.The widespread distribution of metamorphic carbonates in the Central Asian Orogenic Belt indicates that there may have been widespread sedimentary carbonates in the Paleo-Asian Ocean.A large amount of sedimentary carbonates was probably carried into mantle during subduction of the Paleo-Asian oceanic slab,which significantly modified the chemical and physical properties of the lithospheric mantle.
