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Microbes in mass extinction: an accomplice or a savior?

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National Science Review 2024年第1期11卷 12-15页

作者： Genming Luo Deng Liu Hao Yang State Key laboratory of Geobiology and Environmental geology China University of Geosciences (Wuhan)

Microbes include various types of organisms that are invisible to the naked eye,e.g. bacteria, archaea and microeukaryotes. Although the precise number remains largely unknown, microbes are recognized as the unseen majority of our biosphere [1]. As a group of organisms classified by body size, microbes cover a considerable spectrum of metabolisms,

关键词： AFTERMATH

Mass extinctions, their causes and consequences: an interview with Douglas H.Erwin and Shuzhong Shen

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National Science Review 2024年第1期11卷 66-70页

作者： Shucheng Xie State Key laboratory of Biogeology and Environmental geology China University of Geosciences at Wuhan

‘Mass extinctions’ have been a hot topic for several decades. What triggers a mass extinction? How does a mass extinction impact the evolution of life? How does our ecosystem recover after a mass extinction? These questions attracted the interest of both scientists and the public alike.NSR spoke to two renowned researchers in the field of mass extinctions: Prof. Douglas H. Erwin from the National Museum of Natural History of the USA, and Prof. Shuzhong Shen from Nanjing University, China.

关键词： Stratigraphy

Rapid growth in a large Cambrian apex predator

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National Science Review 2024年第3期11卷 128-136页

作者：吴雨 Stephen Pates Daniel Pauly 张兴亮傅东静 State Key laboratory of Continental Dynamics and Shaanxi Key laboratory of Early Life and Environment Department of Geology Northwest University Department of Zoology University of Cambridge Institute for the Oceans and Fisheries University of British Columbia Nanjing Institute of geology and Palaeontology Chinese Academy of Sciences

Despite the importance of ontogenetic data on early diverging euarthropods to our understanding of the ecology and evolution of past life, the data are distinctly lacking, as reconstructing life histories of fossil animals is often challenging. Here we report the growth trajectory of frontal appendages of the apex predator Amplectobelua symbrachiata, one of the most common radiodont arthropods from the early Cambrian Chengjiang biota(c. 520 Ma) of China. Analysis of 432 specimens(9.1–137.1 mm length; 1.3–25.6 mm height) reveals that appendages grew isometrically, with an estimated maximum size of the whole animal of c. 90 cm. Individuals grew rapidly compared to extant arthropods, as assessed using the electronic length-frequency analysis(ELEFAN) approach. Therefore, we show that the Cambrian apex predator A. symbrachiata was an extremely fast-growing arthropod, with an unusual life history strategy that formed as part of the escalatory ‘arms race’ that shaped the Cambrian explosion over 500 Ma.

关键词： stem-group Euarthropoda Radiodonta post-embryonic development growth dynamics Cambrian Explosion

Responses of Nutrients to the Precipitation Variation and Land Use in Subtropical Monsoonal Small Mountainous Rivers:A Case Study of Baixi Watershed

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Journal of Ocean University of China 2024年第2期23卷 383-391页

作者： TIAN Yuan GAO Fei CAO Ke LV Shenghua DUAN Xiaoyong YIN Ping Qingdao Institute of Marine geology China Geological SurveyMinistry of Natural ResourcesQingdao 266237China laboratory for Marine geology Laoshan LaboratoryQingdao 266237China

Small mountainous rivers are characterized by large instantaneous fluxes and susceptible to extreme weather events,which can rapidly transport materials into the sea and have a significant impact on the ecological environment of estuaries and bays.In order to investigate the seasonal characteristics of nutrients in small mountainous rivers in the subtropical monsoon region and the output pattern to the sea during heavy precipitation,surveys on the mountainous rivers were carried out in Baixi watershed in August 2020(wet season),March 2021(dry season)and June 2021(Meiyu period).The results showed that the dissolved inorganic nitrogen(DIN)of the rivers has an average concentration of 752μg L^(−1)in the wet season and 1472μg L^(−1)in the dry season.The concentrations of dissolved inorganic phosphorus(DIP)in wet season and dry season were 63μg L^(−1)and 51μg L^(−1),respectively.Influenced by the changes of land use in sub-watersheds,DIN concentrations in the mainstream increased from 701μg L^(−1)in the upper reaches to 1284μg L^(−1)in the middle reaches.Two rainstorms during the Meiyu period in the watershed caused the pulse runoff in the river.The maximum daily runoff reached 70 times that before rains.The maximum daily fluxes of DIN and DIP were 109 and 247 times that before rains,respectively.In view that the watershed experienced several rainstorms in the wet season,the river,with pulse runoff,carries a large amount of nutrients into the sea in a short time,which will have a significant impact on the environment of Sanmen bay and its adjacent sea.

关键词： small mountainous river uneven precipitation rainstorm pulse runoff nitrogen and phosphorus

Earthquake potential across the North–South seismic belt of China

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Science Bulletin 2024年第2期69卷 179-182页

作者： Yanchuan Li Xinjian Shan Chunyan Qu Guohong Zhang Xiaogang Song State Key laboratory of Earthquake Dynamics Institute of GeologyChina Earthquake AdministrationBeijing 100029China

The elastic rebound theory,which frames our understanding of earthquakes,suggests that the accumulated elastic strain on faults will ultimately be released through earthquakes[1].As such,identifying the location,rate,and accumulation of slip deficit on faults constitutes a basis for seismic potential assessment[2].Interseismic coupling(ISC)refers to the ratio of the slip deficit rate on a fault to the far-field loading rate,where full and no coupling correspond to 100%and 0%slip deficits,respectively.

关键词： seismic belt fault

Structural geology and Chronology of Shear Zones along the Shangdan Suture in Qinling Orogenic Belt,China:Implications for Late Mesozoic Intra-Continental Deformation of East Asia

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Journal of Earth Science 2024年第2期35卷 376-393页

作者： Falak Sheir Wei Li Le Zhang Basil Alabowsh Liuqing Jiang Li Liang Sainan Gao Shair Baz Umar Ashraf State Key laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi’an710069China Institute of geology University of PunjabLahore45590Pakistan

The Shangdan suture zone(SDZ)in the Qinling orogenic belt(QOB)is a key to understanding the East Asia tectonic evolution.The SDZ gives information about convergent processes between the North China Block(NCB)and South China Block(SCB).In the Late Mesozoic,several shear zones evolved along the SDZ boundary that helps us comprehend the collisional deformation between the NCB and SCB,which was neglected in previous studies.These shear zones play an essential role in the tectonic evolution of the East Asia continents.This study focuses on the deformation and geochronology of two shear zones distributed along the SDZ,identified in the Shaliangzi and Maanqiao areas.The shear sense indicators and kinematic vorticity numbers(0.54–0.90)suggest these shear zones have sinistral shear and sub-simple shear deformation kinematics.The quartz’s dynamic recrystallization and c-axis fabric analysis in the Maanqiao shear zone(MSZ)revealed that the MSZ experienced deformation under green-schist facies conditions at∼400–500℃.The Shaliangzi shear zone deformed under amphibolite facies at∼500–700℃.The^(40)Ar/^(39)Ar(muscovite-biotite)dating of samples provided a plateau age of 121–123 Ma.Together with previously published data,our results concluded that QOB was dominated by compressional tectonics during the Late Early Cretaceous.Moreover,we suggested that the Siberian Block moved back to the south and Lhasa-Qiantang-Indochina Block to the north,which promoted intra-continental compressional tectonics.

关键词： Qinling orogenic belt Shangdan suture zone shear zone Late Mesozoic intra-continental deformation East Asia tectonics

Geochronological and geochemical constraints on the petrogenesis and geodynamic process of Hemler,Vlinder,and Il'ichev seamount lavas in NW Pacific

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Science China Earth Sciences 2024年第6期67卷 1856-1871页

作者： Xun WEI Yan ZHANG Xuefa SHI Hui ZHANG Key laboratory of Marine geology and Metallogeny First Institute of OceanographyMinistry of Natural ResourcesQingdao 266061China laboratory for Marine geology Qingdao Marine Science and Technology CenterQingdao 266237China Shandong Key laboratory of Deep Sea Mineral Resources Development(Preparatory) Qingdao 266061China

Oceanic intraplate volcanoes with linear age progressions are usually accepted to be derived from melting of an upwelling mantle plume.Several seamount groups in NW Pacific,however,show complex age-distance relationships that are difficult to explain using the classic“mantle plume hypothesis”,and thus their origins are controversial.In this study,we present ^(40)Ar-^(39)Ar age,geochemical,and Sr-Nd-Pb-Hf isotopic data of lavas from Hemler,Vlinder,and Il’ichev seamounts in NW Pacific,to elucidate their petrogenesis and geodynamic process.The lavas from Hemler,Vlinder,and Il’ichev seamounts are classified as alkali basalt,basanite/nephelinite,and trachyte.Lavas with Mg O>8 wt.%exhibit high contents of CaO,FeO^(T),and TiO_(2),similar to the composition of melts formed from reaction between carbonated eclogite-derived melts and fertile peridotite.These lavas have elevated Zr/Hf ratios(40.6-45.2)and negative Zr and Hf anomalies,indicating the presence of a carbonate component in the mantle source.They are enriched in incompatible trace elements and have enriched mantle 1(EM1)-like SrNd-Pb-Hf isotopic compositions.The isotopic compositions of Vlinder,Il’ichev basanite,and Hemler lavas in this study are similar to the Rarotonga hotspot.Although occurring at the same seamount,the Il’ichev alkali basalts display more depleted SrNd-Hf isotopic compositions compared to Il’ichev basanite.According to plate tectonic reconstruction results,the ages of Hemler(100.1 Ma),Vlinder pre-(100.2 Ma)and post-shield(87.5 Ma),and Il’ichev(56.4 Ma)lavas clearly deviate from the Macdonald,Arago,Rarotonga,and Samoa hotspot tracks,indicating that they cannot directly originate from mantle plumes.We propose that in the mid-Cretaceous,when the Pacific plate passed over Rarotonga hotspot,melting of Rarotonga plume formed the Vlinder(main-shield stage),Pako,and Ioah seamounts.The Rarotonga(and possibly Samoa)plume materials would have been dispersed into the surrounding asthenosphere by mantle convection.These diffuse plume materials would underg

关键词： Mantle plume Magellan seamount trail Carbonated mantle component Hotspot Lithosphere extension

Riverine sulfate sources and behaviors in arid environment,Northwest China:Constraints from sulfur and oxygen isotopes

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Journal of Environmental Sciences 2024年第3期137卷 716-731页

作者： Yifu Xu Wenjing Liu Bing Xu Zhifang Xu Key laboratory of Cenozoic geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

The fate of riverine sulfate ion (SO_(4)^(2-)) and its environmental effects in arid environment are difficult to evaluate due to its complicated sources and strongly coupled behaviors with water cycle which is significantly modified by humans.To understand the sulfur cycle in aquatic systems in arid environment,the chemical and sulfur and oxygen isotopic compositions (δ^(34)S_(SO4)and δ^(18)O_(SO4)) of major rivers around the Badain Jaran Desert,northwestern China,were investigated.These rivers had averaged SO_(4)^(2-)content at 1336μmol/L,over 10times higher than the global average.The δ^(34)S_(SO4)and δ^(18)O_(SO4)values ranged from-5.3‰to+11.8‰and+1.6‰to+12.8‰,respectively.The end-member analysis and the inverse model showed that riverine sulfate was mainly derived from evaporites dissolution (0-87%),sulfide oxidation (13%-100%) and precipitation (0-33%),indicating heterogeneity in sulfur sources and behaviors along the river drainage with the lithology variations and climate gradients.Multiple isotopic tools combining with hydro-chemistry compositions could be applied to reveal sulfur cycle in arid environment.Based on the calculation,sulfide oxidation plays the primary role in the headwater and upstream in the Qilian-Mountains area,where sulfide is widely exposed.While the proportion of evaporites dissolution contributing to riverine sulfate is much higher in downstream in a drier environment.Besides,less precipitation and higher temperature can lead to more intensive evaporation,affecting the process of sulfide oxidation and enhancing the rates of evaporites dissolution and sulfate precipitation in the basin.

关键词： Sulfur and oxygen isotopes Source apportionment Inverse model Arid environment Inland rivers Northwestern China

The influence of silica on reaction rates and molecular hydrogen(H_(2))generation during olivine hydrothermal alteration

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Science China Earth Sciences 2024年第1期67卷 222-233页

作者： Ruifang HUANG Weidong SUN Xing DING Yusheng ZHAO Yibing LI Xiuqi SHANG CAS Key laboratory of Ocean and Marginal Sea geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou 510301China SUSTech Academy for Advanced Interdisciplinary Studies Southern University of Science and TechnologyShenzhen 518055China Center of Deep Sea Research Institute of OceanologyChinese Academy of SciencesQingdao 266071China State Key laboratory of isotope Geochemistry Guangzhou Institute of GeochemistryChinese Academy of SciencesGuangzhou 510640China Institue of geology Chinese Academy of Geological SciencesBeijing 100037China

Hydrothermal alteration of olivine greatly influences geodynamics and the recycling of volatiles(such as water and carbon)in subduction zones.Silica is an important component of geological fluids,and its influence on the hydrothermal alteration of olivine remains poorly constrained.In this study,we performed experiments at 300–515℃ and 3.0 kbar(1 bar=10^(5)Pa)by reacting well homogenized mixtures of olivine and silica powders with saline solutions(0.5 mol L^(−1)NaCl).Silica greatly influences the reaction pathways,reaction rates,and molecular hydrogen(H_(2))formation during olivine hydrothermal alteration.In experiments at 300℃ and 3.0 kbar with mixtures of olivine and 10 wt%silica,olivine was replaced by serpentine and talc.The proportions of serpentine and talc were determined according to standard curves based on infrared spectroscopy analyses.Around 6.5%serpentine and 12%talc were produced after an experimental duration of 7 days,which had no change after a longer period(14 days).Compared to the kinetics in silica-free systems,the rates of olivine hydrothermal alteration in experiments with 10 wt%silica are much lower.The overall reaction is:4.5Forsterite+5.5SiO_(2),aq+4H_(2)O=Serpentine+2Talc.With the addition of more silica(20 wt%and 40 wt%),olivine was transformed into talc.The rates of reaction were much faster,e.g.,for experiments with olivine and 20 wt%silica,43%of talc was produced after 14 days,which increased to 77%for experiments with 40 wt%silica over the same period.The overall reaction is:3Forsterite+5SiO_(2),aq+2H_(2)O=2Talc.In experiments at 400–505℃ and 3.0 kbar,the promoting effect of silica on olivine hydrothermal alteration was also observed,which is closely associated with a decrease in Gibbs free energies of olivine hydrothermal alteration.At 300℃ and 3.0 kbar,silica decreased H_(2)formed during olivine hydrothermal alteration by around an order of magnitude,resulting in an increase in oxygen fugacity.Based on measured H_(2),we calibrated oxygen fugacities,ranging from 0.96 to 3.41 log un

关键词： Olivine hydrothermal alteration Silica Serpentinization Hydrogen Serpentine