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地球科学学刊（英文版）
地球科学学刊（英文版）

王亨君

双月刊

1674-487X

ejournal@cug.edu.cn

027-67885075 67885076

430074

武汉市洪山区鲁磨路388号

地球科学学刊（英文版）/Journal Journal of Earth ScienceCSCDCSTPCD北大核心SCI
查看更多>>本刊是教育部主管、中国地质大学主办的综合性地球科学学术理论刊物，是中国自然科学核心期刊，以反映我国地球科学领域最新的高水平的基础地质、应用地质、资源与环境地质及地学工程技术科研成果为主要任务，以促进国内外地学学术交流，繁荣我国地质教育、地质科技与地质找矿事业，为我国社会主义现代化建设服务为目的。读者对象为从事地质教育和科研工作的研究者以及大学生和研究生。
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    Foraminiferal Extinction and Size Reduction during the Permian-Triassic Transition in Southern Tibet

    Lirong YangXu DaiXiaokang LiuYan Feng...
    1799-1809页
    查看更多>>摘要：The miniaturization of organisms during the Permian-Triassic mass extinction,as an eco-logical strategy in response to environmental devastation,has been widely recognized in diverse marine invertebrates.Previous studies on the extinction process and miniaturization of foraminifers in the Permian-Triassic interval have relied on the fossil record of the low-latitude Paleotethys or a global da-tabase,although data and materials from the high-latitude Neotethys region are still rare.To reveal the evolutionary patterns and spatial variability of foraminifers at different latitudes and paleogeographic contexts,here we investigated the fossil distribution and size variation of foraminifers in the Selong Sec-tion of southern Tibet,located in the mid-latitude Neotethys of the Southern Hemisphere during the Permian-Triassic transition.The results show that the foraminifer of the Selong Section experienced a two-pulsed extinction(total species extinction rate of 71％),consistent with the time in South China but with a lower magnitude of extinction.Meanwhile,the data show that foraminiferal test volume was sig-nificantly miniaturized following the first pulse of extinction event:the mean size of post-extinction for-aminifer was only 15％of that in the pre-extinction,mainly reflected by the disappearance of large forms as well as occurrences of smaller survivors and originators.Combined with the South China re-cord,size data from southern Tibet indicate that the miniaturization of foraminifera is synchronous in the Paleotethys and Neotethys but smaller in magnitude in the Neotethys.We propose that ocean anox-ia and acidification may be the environmental pressures leading to local and global foraminiferal min-iaturizations,along with global warming,which might play a dominant role.
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    A potentially New Early Ediacaran Glaciation

    Zhongwu LanMagdalena H.HuyskensRong RenQing-Zhu Yin...
    1810-1819页
    查看更多>>摘要：Multiple episodes of Neoproterozoic glaciation,namely the Beiyixi,Altungol,Tereeken and Hankalchough glaciations,are recorded in the Kuruktag area of northeastern Tarim Craton,NW China.The Tereeken glaciation was previously correlated with the global Marinoan glaciation based on sedimentary and chemostratigraphic features recorded in the cap dolostone immediately overlying the glaciogenic diamictite,as well as less precise radiometric age constraints.In this study,we obtained chemical-abrasion isotope dilution isotope ratio mass spectrometry(CA-ID-IRMS)U-Pb age of 624.03±0.10 Ma from zircons extracted from a tuff lava interbeded within the diamictite of the Tereeken Forma-tion,which suggests an Early Ediacaran age for the Tereeken glaciation.Such newly discovered Early Ediacaran glaciation in the Tarim region could have induced the negative δ13Ccarb excursions of 625-605 Ma by providing oxygen and other oxidants to invoke remineralization of a deep ocean dissolved organic carbon(DOC)reservoir.
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    Discovery of the Middle Jurassic Small Theropod Footprints in Eastern Tibet,China

    Yangui LiHuazhou YaoAsma TahirJunaid Khan...
    1820-1831页
    查看更多>>摘要：Jurassic continental strata are widely distributed in the Changdu area of eastern Tibet,but very few dinosaur footprints have been reported.Abundant sauropod,ornithopod and theropod foot-prints preserved in the Wenda site have been found during the recent geological surveys.This is a novel assemblage of the Middle Jurassic dinosaur footprints.These footprint fossils provide a key insight into the members of dinosaur faunas,and the behavior of the trackmakers.Here,the newly discovery small theropod footprints,which are identified as Wildeichnus isp.,are discussed.The analysis of two track-ways suggest that these two trackmakers(with a hip height of approx.35 cm,and a body length of ap-prox.1 m)were moving slowly,with an estimated speed of 0.82 and 0.57 m/s,respectively.It is unusual for small theropods to move so slowly,and the present study supports the view that Wildeichnus had a global distribution,but the trackmaker of Wildeichnus is not interpreted as a juvenile Grallator.
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    Zircon SHRIMP U-Pb Ages,Geochemical,and Sr-Nd Isotopic Constraints on the Petrogenesis of the Middle Eocene Calc-Alkaline Andesitic Rocks:Implications for Continental Arc Magmatism and Slab Break-off in NE Iran

    Soheila SakiAmir Ali Tabbakh ShabaniMingguo ZhaiYuruo Shi...
    1832-1848页
    查看更多>>摘要：The Torbat-e-Heydariyeh andesitic rocks(THA)are part of the Cenozoic continental arc magmatic system of the northern branch of the Neotethys Ocean(NE Iran).Columnar jointing is the most significant feature of these rocks and they also show porphyritic,vitrophyric,and vitroglomero-porphyric textures.Plagioclase,clinopyroxene,±orthopyroxene are the major mineral phases.The SHRIMP U-Pb zircon dating yielded an age of 41.00±0.69 Ma for the rocks(Middle Eocene,Bartoni-an).Geochemically,they are of medium-to high-K calc-alkaline affinity.Primitive mantle-normalized diagrams exhibit enrichment in large ion lithophile elements(LILE),such as Cs and Rb,and also deplet-ed in high field strength elements(HFSE)and heavy rare earth elements(HREE),with prominent nega-tive anomalies of Ti,Nb,Y,and Yb,suggesting a tectonic setting of an active continental margin.The chondrite-normalized REE diagram displays enrichment of light rare earth elements(LREE;LaN/YbN=5.37-6.66)and small negative Eu anomalies(Eu/Eu*of 0.69-0.78).Thorium enrichment implies the re-action between the mantle wedge and the melt of subducting oceanic slab,and/or subducting sediment.The role of subducted sediments along with subducted oceanic lithosphere is evident in these magmatic rocks using Ba/La versus Th/Nd and Ba/Th versus LaN/SmN diagrams.The εNd(t)and(87Sr/86Sr)i,values vary between-0.1 to+0.2 and 0.704 89 to 0.705 01,respectively,and are compatible with parental melts from subduction of the lithospheric mantle.We suggest that the THA rocks were produced by the par-tial melting of the metasomatized lithospheric mantle,which corresponds to slab break-off of the north-ward subducted Neotethys oceanic slab in an extensional setting.The hot asthenospheric mantle upwell-ing triggered by the Neotethys slab break-off would severely heat the physically mixed mantle wedge pe-ridotite and therefore caused partial melting to produce the Middle Eocene volcanic rocks in NE Iran.
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    Electrical Conductivity of Multiphase Garnet under High-Temperature and High-Pressure Conditions

    Kui HanXinzhuan GuoHanyong LiuFengbao Ji...
    1849-1859页
    查看更多>>摘要：Mineral mixing,a fundamental process during mantle convection,alters the chemical com-position of mantle minerals.However,the impact of this process on the electrical conductivity of mineral assemblages remains poorly understood.We measured the electrical conductivity of three single-phase garnets and their corresponding mixtures at 1.5 GPa and varying temperatures using the impedance spectroscopy within frequency from 10-1 to 106 Hz.The electrical conductivity of dehydrated garnets is primarily controlled by their iron content,exhibiting an activation energy about 1.0 eV,indicative of small polaron conduction.The garnet mixture displays lower electrical conductivities and higher activa-tion energies compared to their single-phase counterparts.This discrepancy of conductivity can be half order of magnitude at high temperatures(＞1 073 K),suggesting formation of resistive grain boundaries during the mixing process.In the mantle transition zones,grain boundary conductivity could exert a lim-ited impact on the bulk conductivity of the interface between the stagnant slab and ambient mantle.
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    Imaging the Western Boundary of the Sichuan Craton from Multiple Geophysical Observations

    Qihang YinXi XuXiaodong YangXuhua Shi...
    1860-1877页
    查看更多>>摘要：The boundary between cratonic and orogenic lithospheres is a significant seismogenic zones marked by intense lithospheric deformation.The Sichuan Craton(SCC),as a key tectonic block bordering eastern Tibetan Plateau,resists the eastward escape of plateau's crustal materials,resulting in the uplift of the Songpan-Ganzi Block(SGB)and crustal deformation of the Longmenshan tectonic belt(LMTB).To elucidate the compressional structures and deformational modes of the LMTB and SCC,it is essential to accurately determine the location and geometry of the SCC'western boundary.To investigate this issue,the lithospheric properties of the obducted SGB,underthrusting SCC,and LMTB were analyzed using various geophysical data,including seismic reflection profiles,magnetotel-lurics,aeromagnetics,gravity,and seismic tomography.The SGB crust is characterized by low magne-tism,seismic velocity,resistivity and Bouguer gravity,whereas the SCC crust exhibits non-uniform high magnetism,seismic velocity,resistivity and Bouguer gravity.The LMTB,as the boundary between the SGB and SCC,exhibits geophysical characteristics similar to those of the SCC in the southern and central segments.The integration of these geophysical observations indicate that the SCC's western boundary is situated west of the Wenchuan-Maoxian fault zone in the southern and central segments,exhibiting distinct westward wedging and underthrusting.However,this boundary aligns with the Yingxiu-Beichuan fault in the northern segment,without significant underthrusting.The irregular ge-ometry of the SCC's western boundary further elucidates the variation in structural deformation along the LMTB.By comparing crustal thickness and lithospheric strength between the SGB and SCC,this study posits that the differing crustal strength between tectonic blocks may control the irregular geometry of the SCC's western boundary.
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    Lithium Isotope Analytical Methods and Implications for Rare-Metal Mineralization in Granite-Pegmatite Systems:An Overview

    Xiangying YeBin LiDongbo TanKecheng Liu...
    1878-1894页
    查看更多>>摘要：The origin of highly-fractionated granite-pegmatite systems and their associated rare met-al mineralization has been widely studied,but there is still ongoing debate.Prevailing hypotheses sug-gest that pegmatite formation and the associated rare metal mineralization are closely related to aque-ous fluid processes.Lithium(Li)isotope analysis has been widely applied to trace granite-pegmatite evo-lution.This is because lithium is widely present in various minerals(e.g.,mica,tourmaline)that record the melt and fluid compositions,and lithium isotopes are sensitive to magmatic-hydrothermal processes.We briefly review the methodology of Li isotope analyses,the mechanisms of Li isotopic fractionation,and,in particular,Li isotope fractionation in granite-pegmatite system based on Li isotope data we have collected and the latest developments in Li isotope geochemistry.With the development of analytical technology,high-precision measurement of the Li content and isotopic compositions have facilitated a series of scientific breakthroughs in understanding the magmatic-hydrothermal evolution of rare-element ore deposits.Li isotope analyses on bulk mineral separates have demonstrated their ability to trace various hydrothermal processes.In situ Li isotope analysis methods has been enhanced by the de-velopment of new,homogeneous mineral reference materials.In situ SIMS and LA-MC-ICP-MS Li iso-tope measurements on minerals(e.g.,tourmaline)will likely become more important in studying the fluid-rock interactions in magmatic,metamorphic,and hydrothermal processes,as well as on pegmatite petrogenesis and rare-metal mineralization.
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    Lithium Isotopic Fractionation in Minerals from Pegmatites:Perspective of Crystal Chemistry

    Shan-Ke LiuBen-Xun Su
    1895-1901页
    查看更多>>摘要：Lack of information regarding lithium(Li)crystal chemistry in numerous minerals,espe-cially those containing trace amounts of Li(ranging from a few to tens of ppm),limits our understand-ing of Li isotopic fractionation in pegmatites.In this study,we examined the Li isotopic composition and Li content in various Li-poor(e.g.,quartz or feldspar)together with Li-rich(sopdumene or lepidolite)mineral phases within granitic pegmatites.We compiled a comprehensive dataset,encompassing a broad spectrum of Li contents(ranging from a few to tens of thousands of ppm)and Li isotopic values(-8‰ to 41‰).The minerals exhibit distinct Li isotopic signatures.Specifically,elbaite and beryl show the highest values,while biotite displays a negative average.Compared to individual minerals,whole rocks demonstrate lower Li isotopic values,with pegmatites exhibiting the highest and non-granitic peg-matite wall rocks showing the lowest.Our study also uncovers a clear"V"shape relationship between Li isotopic values and logarithm of Li contents,with different mineral groups occupying specific regions within this shape.Furthermore,a significant correlation was observed between average Li isotopic val-ues and Li-O(OH,F)bond lengths in various minerals.These discoveries underscore the crucial role of crystal chemistry in shaping the Li isotopic behavior in pegmatites from a statistical perspective.
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    Linkage of Mineral Inclusions and Zoning of Magnetite with Fluid Evolution of Hydrothermal Systems:A Case Study of the Fenghuangshan Cu-Fe-Au Skarn Deposit,Eastern China

    Xiao-Wen HuangYiping YangMei-Fu ZhouYu-Miao Meng...
    1902-1917页
    查看更多>>摘要：Magnetite from hydrothermal deposits may show compositional zoning with various min-eral inclusions in response to the evolution of hydrothermal fluids.Magnetite from the Fenghuangshan Cu-Fe-Au skarn deposit(eastern China)is a common mineral formed in the earlier stage of skarniza-tion.Magnetite grains have dark gray and light gray zones and contain diverse mineral inclusions.Dark gray zones have higher Si,Ca,Al,and Mg contents than light gray zones.The magnetite matrix from dark gray zones shows superstructure along the[0-11]zone axis in fast Fourier transform pat-terns,different from magnetite in light gray zones with normal structure.Three types of mineral inclu-sions are identified within magnetite:nano-,micron-and submicron-nanometer inclusions.Nanoinclu-sions hosted in dark gray zones are actinolite,diopside,and trace element-rich magnetite,and these are likely formed by growth entrapment during magnetite crystallization at the skarn stage.The chain-width order-disorder intergrowths of diopside nanoinclusion likely indicate fluctuating fluid composi-tions in a lattice scale.Submicron to nanometer inclusions at the boundary between dark gray and light gray zones are quartz,titanite,and Ti-rich magnetite,which were formed via a dissolution and re-precipitation process at the quartz-sulfide stage.Micron-inclusions randomly distributed in both dark and light gray zones include calcite,ankerite,quartz,and chlorite,and these were formed via penetra-tion of fluids at the carbonate stage.Zoned magnetite was formed by fluid replacement,overgrowth,and fluid infilling.Our study highlights the importance of mineral inclusion assemblages,and textural and chemical zonation of magnetite in constraining fluid evolution.
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    Quartz Cementation in the Lower Paleozoic Shales,Middle Yangtze Region,South China:Implications for Shale Reservoir Properties

    Tian DongJian GaoShuangjian LiChuan Wang...
    1918-1933页
    查看更多>>摘要：As one of the most important constitutes of shales/mudstones,quartz has received in-creasing interests in the last decades,because productive shale gas successions are generally rich in quartz content.This study critically documents quartz types,silica source for quartz cementation and effect of quartz cementation on reservoir quality in the Lower Paleozoic shales,Middle Yangtze region,South China,including the Lower Cambrian Niutitang Formation and the Upper Ordovician-Lower Silurian Wufeng-Longmaxi formations.Our results suggest that high-resolution scanning electron mi-croscopy combined with cathodoluminescene techniques are necessary for identifying quartz types in shales.Integrations of high-resolution imaging technique and detailed geochemical analysis are able to document silica source for quartz cementation and silica diagenetic processes.Six types of quartz can be identified in the Paleozoic shales,primarily including detrital quartz silt,siliceous skeletons,quartz overgrowth,microcrystalline quartz(matrix-dispersed microquartz and aggregated microquartz),sili-ca nanospheres and fracture-filling quartz veins.Dissolution of siliceous skeletons provides the princi-pal silica sources for authigenic quartz formation in the Paleozoic shales.Authigenic quartz has dual ef-fects on porosity development.Quartz overgrowth definitely occupies interparticle pores and possibly squeeze spaces,whereas aggregated microquartz can form rigid framework that is favorable for gener-ating and preserving intercrystalline pores and organic pores.
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