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Two thin middle-crust low-velocity zones imaged in the Chuan-Dian region of southeastern Tibetan Plateau and their tectonic implications

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science China earth sciences 2024年第5期67卷 1675-1686页

作者： Long LI Xin WANG Guangbing HOU Yuan LING Yinshuang AI Key Laboratory of earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China Innovation academy for earth science Chinese Academy of SciencesBeijing 100029China

Intracrustal low-velocity zones(LVZs)indicate a mechanically weak crust and are widely observed in the southeast margin of the Tibetan ***,their spatial distributions and formation mechanisms remain *** investigate their distribution and detailed morphology of the LVZs in the southeastern Tibetan Plateau,here we used teleseismic events and continuous waveform data recorded by 40 broadband seismic stations newly deployed in the sichuan-Yunnan region from December 2018 to October 2020.A total of 12,924 high-quality P-wave receiver functions and 5–40 s fundamental Rayleigh surface wave phase velocity dispersion curves from ambient noise cross-correlation functions were *** swave velocity model at a depth interval of 0–100 km in the study area was inverted by using the trans-dimensional Markov chain Monte Carlo strategy to jointly invert the complementary data of the receiver function waveform and Rayleigh surface wave phase velocity *** results show that there are two separate LVZs(~3.5 km/s)surrounding the rigid Daliangshan subblock at crustal depths of approximately 30–40 km,providing new constraints on the geometry of the LVZs in our study *** two LVZs obtained in this study may represent the middle crustal flow channels,through which the material in the center of the Tibetan Plateau extrudes to its southeast *** by the rigid sichuan Basin and the spindle-like Daliangshan subblock,the material continues to flow southward through the mechanically weak middle crustal channels surrounding the Daliangshan *** addition,the existence of thin LVZs in the middle crust plays an important role in understanding the decoupling between the upper and lower crust in the study *** also provides new constraint on the complex tectonic deformation process of the southeastern margin of the Tibetan Plateau caused by the collision and compression of the Indian and the Eurasian plates.

关键词： southeastern Tibetan Plateau Joint inversion Intracrustal low-velocity zone Mid-crustal channel flow

Characteristics and geological significance of the stress state of the lithosphere in the Qinghai-Tibetan Plateau and its neighboring areas

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science China earth sciences 2024年第6期67卷 1836-1855页

作者： Qianwen ZHANG Ya XU Wei CHU shupeng LU Key Lab of Petroleum Resource Research Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of earth and Planetary sciences University of Chinese Academy of SciencesBeijing 100049China

The present-day lithospheric stress state of the Qinghai-Tibetan Plateau and neighboring areas is controlled by both the lithosphere itself and the underlying *** other words,the stress is affected by the gravitational potential energy(GPE)difference caused by the change in the density distribution within the lithosphere and the drag force on the base of the lithosphere caused by mantle *** study of the lithospheric stress state plays an important role in further understanding the dynamic background and mechanism for the evolution of the Qinghai-Tibetan *** this study,the crust1.0 crustal density model combined with the s40RTs mantle shear wave velocity variation model was used to calculate the *** EGM2008gravity field model was used to calculate the drag force from mantle convection at the base of the *** lithospheric and joint stress fields of the two sources were obtained by solving the force balance under the thin sheet *** way,we could comprehensively analyze the characteristics of the stress state within the *** regions were classified according to the GPE stress field,mantle drag force stress field,the relative magnitude of the two stress fields,and correlation between the two stress fields and surface *** lithospheric stress fields of the Tarim Basin and other stable blocks are mainly controlled by the GPE *** lithospheric stress field in the collision zone between the Indian Plate and the QinghaiTibetan Plateau is predominantly controlled by the deep mantle drag *** lithospheric stress field in the interior of the Plateau is controlled by both GPE and mantle *** correlation between the lithospheric stress field and surface deformation at the southeast margin of the Qinghai-Tibetan Plateau is *** is hypothesized that the presence of lower crustal flow with lower effective viscosity leads to crust-mantle decoupling,and the mantle drag force has a weaker influe

关键词： Qinghai-Tibetan Plateau Gravitational potential energy Mantle convection Lithospheric deviatoric stress field GPs strain rate field

A lunar time scale from the perspective of the Moon’s dynamic evolution

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science China earth sciences 2024年第1期67卷 234-251页

作者： Dijun GUO Jianzhong LIU James WHEAD Fuqin ZHANG Zongcheng LING shengbo CHEN Jianping CHEN Xiaozhong DING Jinzhu JI Ziyuan OUYANG state Key Laboratory of space Weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Center for Lunar and Planetary sciences Institute of GeochemistryChinese Academy of SciencesGuiyang 550081China Department of earth Environmental and Planetary SciencesBrown UniversityProvidence RI 02912USA institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China shandong Provincial Key Laboratory of Optical Astronomy and solar-Terrestrial Environment Institute of Space SciencesShandong UniversityWeihai 264209China College of Geoexploration science and Technology Jilin UniversityChangchun 130026China school of earth sciences and Resources China University of GeosciencesBeijing 100083China institute of Geology Chinese Academy of Geological SciencesBeijing 100037China school of Resources and Environmental Engineering Inner Mongolia University of TechnologyHohhot 010051China Center for Excellence in Comparative Planetology Chinese Academy of SciencesHefei 230026China

A geologic time scale is a chronological system that separates the geological strata of a planetary body into different units in temporal sequence and shows its progressive *** time scale of the Moon was established a half-century ago during the telescopic-early Apollo exploration era,using data with limited spatial coverage and *** past decades have seen a wide array of studies,which have significantly extended our understanding of global lunar geologic *** on a comprehensive review of lunar evolution with respect to the dynamical changes,we propose two major updates to the current lunar time scale paradigm to include the evolution of both endogenic and exogenic dynamic forces now known to have influenced early lunar ***,based on the temporal interplay of exogenic and endogenic processes in altering the Moon,we defined three Eon/Eonothem-level units to represent three dynamical evolutionary ***,the pre-Nectarian system is redefined and divided as the magma ocean-era Magma-oceanian system and the following Aitkenian system beginning with the south Pole-Aitken *** ejecta of this basin,Das Formation,was deposited on the primordial lunar crust as the oldest stratum produced from exogenic *** updated lunar time scale,facilitated by the post-Apollo exploration and research advances,provides an integrated framework to depict the evolution of the Moon and has important implications for the geologic study of other terrestrial planets.

关键词： The Moon Geologic time scale Evolution history Endogenic process Exogenic process

Return to the Moon:New perspectives on lunar exploration

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science Bulletin 2024年第13期69卷 2136-2148页

作者： Yangting Lin Wei Yang Hui Zhang Hejiu Hui sen Hu Long Xiao Jianzhong Liu Zhiyong Xiao Zongyu Yue Jinhai Zhang Yang Liu Jing Yang Honglei Lin Aicheng Zhang Dijun Guo sheng Gou Lin Xu Yuyang He Xianguo Zhang Liping Qin Zongcheng Ling Xiongyao Li Aimin Du Huaiyu He Peng Zhang Jinbin Cao Xianhua Li Key Laboratory of earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China state Key Laboratory for Mineral Deposits Research and school of earth sciences and Engineering Nanjing UniversityNanjing 210023China state Key Laboratory of Geological Processes and Mineral Resources School of Earth SciencesChina University of GeosciencesWuhan 430074China institute of Geochemistry Chinese Academy of SciencesGuiyang 550002China Planetary Environmental and Astrobiological Research Laboratory School of Atmospheric SciencesSun Yat-sen UniversityZhuhai 519082China National space science Center Chinese Academy of SciencesBeijing 100190China Deep space Exploration Laboratory/CAs Key Laboratory of crust-Mantle Materials and Environments University of Science and Technology of ChinaHefei 230026China shandong Key Laboratory of Optical Astronomy and solar-Terrestrial Environment Institute of Space SciencesShandong UniversityWeihai 264209China Technology and Engineering Center for space Utilization Chinese Academy of SciencesBeijing 100094China school of space and Environment Beihang UniversityBeijing 100191China

Lunar exploration is deemed crucial for uncovering the origins of the earth-Moon system and is the first step for advancing humanity’s exploration of deep *** the past decade,the Chinese Lunar Exploration Program(CLEP),also known as the Chang’e(CE)Project,has achieved remarkable *** has successfully developed and demonstrated the engineering capability required to reach and return from the lunar ***,the CE Project has made historic firsts with the landing and on-site exploration of the far side of the Moon,along with the collection of the youngest volcanic samples from the Procellarum KREEP *** achievements have significantly enhanced our understanding of lunar *** on this success,China has proposed an ambitious crewed lunar exploration strategy,aiming to return to the Moon for scientific exploration and *** plan encompasses two primary phases:the first crewed lunar landing and exploration,followed by a thousand-kilometer scale scientific expedition to construct a geological cross-section across the lunar *** the limitations of current lunar exploration efforts and China’s engineering and technical capabilities,this paper explores the benefits of crewed lunar exploration while leveraging synergies with robotic *** study refines fundamental lunar scientific questions that could lead to significant breakthroughs,considering the respective engineering and technological *** research lays a crucial foundation for defining the objectives of future lunar exploration,emphasizing the importance of crewed missions and offering insights into potential advancements in lunar science.

关键词： Crewed lunar exploration Water and volatiles Composition and structure of lunar interior Volcanic activity and evolution of lunar mantle space weathering and radiation environments Exploration technology

Microstructures, Fabrics, and seismic Properties of Mylonitic Amphibolites: Implications for strain Localization in a Thickening Anisotropic Middle crust of the North China Craton

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Journal of earth science 2024年第3期35卷 769-785页

作者： siqi Liu Bo Zhang Jinjiang Zhang Jian Zhang Lei Guo Tao Wang Baoyou Hang Xiaorong Li Key Laboratory of Orogenic Belts and crustal Evolution School of Earth and Space SciencesPeking UniversityBeijing 100871China Department of earth sciences The University of Hong KongHong KongChina institute of Geology Chinese Academy of Geological SciencesBeijing 100037China

strain localization processes in the continental crust generate faults and ductile shear zones over a broad range of scales affecting the long-term lithosphere deformation and the mechanical response of faults during the seismic *** anisotropy originated within the continental crust can be applied to deduce the kinematics and structures within orogens and is widely attributed to regionally aligned minerals,e.g.,***,naturally deformed rocks commonly show various structural layers(e.g.,strain localization layers).It is necessary to reveal how both varying amphibole contents and fabrics in the structural layers of strain localization impact seismic property and its interpretations in terms of *** present microstructures,petrofabrics,and calculate seismic properties of deformed amphibolite with the microstructures ranging from mylonite to *** transition from mylonite to ultramylonite is accompanied by a slight decrease of amphibole grain size,a disintegration of amphibole and plagioclase aggregates,and amphibole aspect ratio increase(from 1.68 to 2.23),concomitant with the precipitation of feldspar and/or quartz between amphibole *** intensities of amphibole crystallographic preferred orientations(CPOs)show a progressively increasing trend from mylonitic layers to homogeneous ultramylonitic layers,as indicated by the JAm index increasing from 1.9–4.0 for the mylonitic layers and 4.0–4.8 for the transition layer,to 5.1–6.9 for the ultramylonitic *** CPO patterns are nearly random for plagioclase and *** amphibole aggregates in the amphibolitic mylonite deform by diffusion,mechanical rotation,and weak dislocation creep,and develop CPOs *** polymineralic matrix(such as quartz and plagioclase)of the mylonite and the ultramylonite deform dominantly by dissolution-precipitation,combined with weak dislocation *** mean P and s wave velocities are estimated to be 6.3 and 3.5 km/

关键词： amphibolitic mylonite microstructures petrofabrics seismic property middle crust rheology tectonics.

Microstructures,Deformation Mechanisms and seismic Properties of synkinematic Migmatite from southeastern Tibet:Insights from the Migmatitic Core of the Ailao shan-Red River shear Zone,Western Yunnan,China

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Journal of earth science 2024年第4期35卷 1149-1169页

作者： Weiwei Ma Bo Zhang Fulong Cai Baoyou Huang Lei Zhang Key Laboratory of Orogenic Belts and crustal Evolution School of Earth and Space SciencesPeking UniversityBeijing100871China institute of Tibetan Plateau Research Chinese Academy of SciencesBeijing100085China

seismic anisotropy originating within the continental crust is commonly used to determine the deformation and kinematic flow within active orogens and is attributed to regionally oriented mica or hornblende ***,naturally deformed rocks usually contain compositional layers(e.g.,parallel compositional banding).It is necessary to understand how both varying mineral contents and differing intensities of compositional layering influence the seismic properties of the deep *** this study,we analyzed the seismic response of migmatitic amphibolite with compositional banding *** present the microstructures,fabrics,calculated seismic velocities,and seismic anisotropies of mylonitic amphibolite from a horizontal shear layer preserved within the Ailao shan-Red River shear zone,southwestern Yunnan,*** investigated sample is characterized by pronounced centimeter-scale compositional *** microstructures and fabrics suggest that migmatitic amphibolite rocks within deep crust may delineate regions of deformation-assisted,channelized,reactive,porous melt *** origin of compositional banding in the studied migmatitic amphibolite is attributed primarily to partial melting together with some horizontal shearing *** microfabrics and structures investigated in this study are considered to be typical for the base of active horizontal shear layers in the deep crust of southeastern *** responses are modeled by using crystal preferred orientations for minerals of the migmatitic amphibolite by applying the Voigt-Reuss-Hill homogenization *** P-wave and s-wave velocities are largely consistent in the various layers of the ***,seismic anisotropies of P-wave(AV_(p))and s-wave(AVs)are higher in the melanosomes(AV_(p)=5.6%,AV_(s)=6.83%)than those in the leucosomes and the whole rock(AV_(p)=4.2%–4.6%,AV_(s)=3.1%–3.2%).In addition,there is pronounced,s-wave splitting oblique to the foliation plane in the migm

关键词： deformation-assisted melt flow seismic anisotropy microstructure compositional banding migmatite deep crust southeastern Tibet

Present-day Upper-crustal strain Rate Field in southeastern Tibet and its Geodynamic Implications:Constraints from GPs Measurements with ABIC Method

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Acta Geologica sinica(English Edition) 2024年第1期98卷 265-275页

作者： YANG shaohua PAN Jiawei LI Haibing sHI Yaolin Key Laboratory of Continental Dynamics of Ministry of Natural Resources Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China Jiangsu Donghai Continental Deep Hole crustal Activity National Observation and Research station DonghaiJiangsu 222300China Key Laboratory of Computational Geodynamics College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China

The earth’s surface kinematics and deformation are fundamental to understanding crustal *** effective research approach is to estimate regional motion field and deformation fields based on modern geodetic *** the discrete observed velocity field is obtained,the velocity related fields,such as dilatation rate and maximum shear strain rate,can be estimated by applying varied mathematical *** study applied Akaike's Bayesian Information Criterion(ABIC)method to calculate strain rate fields constrained by GPs observations in the southeast Tibetan *** with results derived from other three methods revealed that our ABIC-derived strain rate fields were more *** maximum shear strain rate highlighted the Xianshuihe–Xiaojiang fault system as the main boundary for the outward migration of material in southeastern Tibet,indicating rotation of eastern Tibet material around the eastern Himalaya rather than whole extrusion along a fixed ***,distinct dilatation rate patterns in the northeast and southwest regions of the fault system were *** northeast region,represented by the Longmenshan area,exhibited negative dilatational anomalies;while the southwest region,represented by the Jinsha River area north of 29°N,displayed positive dilatational *** indicates compression in the former and extension in the *** with deep geophysical observations,we believe that the upper and lower crusts of the Jinsha River area north of 29°N are in an entire expanding state,probably caused by the escape-drag effect of *** presence of a large,low-viscosity region south of 29°N may not enable the entire escape of the crust,but instead result in a differential escape of the lower crust faster than the upper crust.

关键词： strain rate differential escape ABIC GPs southeastern Tibet

Molybdenum isotope composition of the upper mantle and its origin:insight from mid-ocean ridge basalt

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Journal of Oceanology and Limnology 2024年第3期42卷 705-708页

作者： shuo CHEN Key Laboratory of Marine Geology and Environment Institute of OceanologyChinese Academy of SciencesQingdao 266071China

The molybdenum(Mo)isotope system is pivotal in reconstructing marine redox changes throughout earth’s history and has emerged as a promising tracer for igneous and metamorphic *** its composition and variation across major geochemical reservoirs is essential for its application in investigating high-temperature ***,there is debate regarding theδ^(98/95)Mo value of the earth’s mantle,with estimates ranging from sub-chondritic to super-chondritic *** analyses of global mid-ocean ridge basalt(MORB)glasses revealed significantδ^(98/95)Mo variations attributed to mantle heterogeneity,proposing a two-component mixing model to explain the observed *** studies confirmed the sub-chondriticδ^(98/95)Mo of the depleted upper mantle,suggesting remixing of subduction-modified oceanic crust as a plausible *** findings underscore the role of Mo isotopes as effective tracers for understanding dynamic processes associated with mantle-crustal recycling.

关键词： molybdenum(Mo)isotope mantle crustal recycling mid-ocean ridge basalt(MORB)

The 2023 Turkey earthquake doublet: earthquake relocation, seismic tomography, and stress field inversion

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earth and Planetary Physics 2024年第3期8卷 535-548页

作者： HuiLi Zhan Ling Bai Bagus Adi Wibowo ChaoYa Liu Kazuo Oike Yuzo Ishikawa state Key Laboratory of Tibetan Plateau earth system Environment and Resources(TPESER)Institute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China University of Chinese academy of sciences Beijing 100049China Center of earthquake and Tsunami Agency of MeteorologyClimatology and GeophysicsJakarta 10610Indonesia University of shizuoka Shizuoka 422-8526Japan shizuoka University Shizuoka 422-8529Japan

On February 6,2023,two earthquakes with magnitudes of M_(W) 7.8 and M_(W) 7.5 struck southeastern Turkey,causing significant casualties and economic *** seismic events occurred along the East Anatolian Fault Zone,a convergent boundary between the Arabian Plate and the Anatolian *** this study,we analyze the M_(W) 7.8 and M_(W) 7.5 earthquakes by comparing their aftershock relocations,tomographic images,and stress field *** earthquakes were localized in the upper crust and exhibited steep dip ***,the aftershocks occurred either close to the boundaries of low and high P-wave velocity anomaly zones or within the low P-wave velocity anomaly *** East Anatolia Fault,associated with the M_(W) 7.8 earthquake,and the sürgüFault,related to the M_(W) 7.5 earthquake,predominantly experienced shear ***,their western sections experienced a combination of strike-slip and tensile stresses in addition to shear *** ruptures of the M_(W) 7.8 and M_(W) 7.5 earthquakes appear to have bridged a seismic gap that had seen sparse seismicity over the past 200 years prior to the 2023 Turkey earthquake sequence.

关键词： Turkey earthquake doublet earthquake relocation seismic tomography stress field seismicity