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Grounded-source short offset transient electromagnetic method:Theory and applications in deep mineral exploration

Science China Earth Sciences 2025年第2期68卷 626-638页

作者： Guoqiang XUE Xin WU Weiying CHEN Nannan ZHOU Key Laboratory of mineral resources Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of Chinese Academy of SciencesBeijing 100049China

The Transient Electromagnetic(TEM)method is a critical geophysical technique for subsurface exploration of metal ore bodies,primarily utilizing either loop or grounded *** Long Offset Transient Electromagnetic(LOTEM)method employs a grounded-source transmitter,relying on a far-source observation mode and plane wave approximation for ***,LOTEM's far-source configuration weakens signal strength,and the plane wave approximation reduces precision,limiting effective detection depth to approximately 1000 m with a comprehensive error of about 15%.Recently,we have developed the grounded-source Short Offset Transient Electromagnetic(SOTEM)method,achieving greater detection depth and accuracy within the 500–2000 m depth range,a crucial interval for mineral resource *** study explores the theoretical framework,instrumentation,data processing,and field applications of *** on a point charge element model,SOTEM accurately computes surface wave effects in EM field calculations,optimized for near-source ***-power,high-resolution,wide-bandwidth exploration equipment and an advanced three-dimensional hybrid inversion technique were also developed to enhance the method's *** of SOTEM to the deep exploration of the Zhou'an Ni-Cu-PGE deposit in Henan Province yielded high-resolution imaging of conductivity structures to about 2.5 km *** results,consistent with existing drill data,delineated mineralized ore bodies from surrounding formations,identified zones of mineralization potential,and suggested extensive resource prospects in the region.

关键词： Far-source observation Plane wave model approximation Grounded-source short-offset transient electromagnetic method Wide-bandwidth exploration equipment Three-dimensional hybrid inversion

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Nujiang Canyon ophiolites(eastern Tibetan Plateau): Records of early Jurassic subduction initiation at passive continental margin of the Lhasa block?

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Science China Earth Sciences 2025年第3期68卷 730-749页

作者： Qing QIAN Baolu SUN Feiyu DONG State Key Laboratory of Lithospheric and Environmental Coevolution Institute of Geology and Geophysics Chinese Academy of Sciences Key Laboratory of mineral resources Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences

The formation ages and genesis of the Nujiang Canyon ophiolites in the eastern Tibetan Plateau are still unclear, and it has been debated whether they belong to the Neo-Tethyan or Paleo-Tethyan suture zones. This study exhibits that the Diba and Youba ophiolites in Zogang formed at 190–185 Ma and are of supra-subduction zone(SSZ) type, and belong to the Neo-Tethyan Bangong-Nujiang suture zone. The parental magmas of cumulates in the ophiolites were likely boninitic, and the mantle sources had been metasomatized by subduction fluids and melts derived from subducted sediments with components of ancient continental crust. It is further proposed that subduction initiation in the Bangong-Nujiang oceanic basin developed during the early Jurassic(195–184 Ma) at the northern passive continental margin of the Lhasa block. The inception of subduction beneath the Lhasa block occurred simultaneously along >2000 km length, resulting in synchronous arc granitoids on its northern margin. The early Jurassic ophiolites in the Bangong-Nujiang suture zone represent the fragments of forearc oceanic lithosphere during subduction initiation, which was probably induced by abrupt global plate reorganization during the Pangea breakup.

关键词： Nujiang Canyon ophiolites Early Jurassic Subduction initiation Supercontinent breakup Global plate reorganization

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A new exceptionally preserved corystosperm wood from the Jurassic of East Asia

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Science China Earth Sciences 2025年第3期68卷 803-810页

作者： Zikun JIANG Ning TIAN Yongdong WANG Fangyu LI Junling PEI Dieter UHL Ya LI Hao WU Zhenguo NING Ruiying HAO Chinese Academy of Geological Sciences College of Palaeontology Shenyang Normal University nanjing institute of geology and Palaeontology Chinese Academy of Sciences College of resources and Environmental Engineering Guizhou University East China University of Technology Senckenberg Research institute and Natural History Museum Frankfurt Zhejiang Museum of Natural History Department of Natural resources of Shandong Province

Corystosperms, an extinct group of “seed ferns” that lived from the late Permian to the Cretaceous or Eocene, are significant for seed plant phylogeny for their unique roles in partially resolving the long-standing question of angiosperm origins.A new fossil wood taxon, Fengweioxylon sinense gen. et sp. nov. is reported here based on exceptionally preserved wood material from the Jurassic in western Liaoning, China, whose peculiar wood structure enables it to be recognized as the first unequivocal fossil wood record of a corystosperm plant in Laurasia. The anatomical structures of this corystosperm wood show gymnospermous characters. The discovery of the new specimen will provide more anatomical evidence for understanding the systematic and affinity of this seed plants.

关键词： Corystosperms Fossil wood Laurasia Jurassic

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Distribution, characteristics, metallogenic processes and prospecting potential of terrestrial brine-type lithium deposits in the world and lithium demand situation

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China geology 2025年第1期8卷 1-25页

作者： Dian-he Liu Cheng-lin Liu Chun-lian Wang Xiao-can Yu MNR Key Laboratory of Metallogeny and mineral Assessment Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing 100037China Peking University School of Earth and Space SciencesBeijing 100871China School of Earth resources China University of Geosciences(Wuhan)Wuhan 430074China institute of geology Chinese Academy of Geological SciencesBeijing 100037China

In response to the rise of the energy storage industries such as new energy vehicles and the wide application of lithium in various fields worldwide,the global demand for lithium resources has been in explosive *** order to further comprehensively understand the global supply and demand pattern,development and utilization status,genesis of ore deposits and other characteristics of lithium resources,based on the achievements of many researchers at home and abroad,this paper systematically summarized the lithium supply and demand situation,resource endowment,deposit classification and distribution,typical geological characteristics,metallogenic factors and metallogenic regularity of terrestrial brine-type lithium deposits which are the main types of development and utilization all over the *** review shows that brine-type lithium resource and(or)reserves in the plateau salt lakes are huge and play an important *** addition,the mineralization potential of the underground brine-type lithium deposit is broad *** potential resources of underground brines are enormous,and the geothermal spring water type is also worthy of *** lithium deposits are mainly controlled by the subduction and collision of regional plate tectonics,arid climate and provenance *** of the scientific research on underground brines in the future is expected to provide another significant support for the global demand for lithium resources.

关键词： Brine in plateau salt lake Underground brine Geothermal spring brine Terrestrial brine classification Lithium migration mechanism Brine genesis mineral exploration engineering Lithium enrich mechanism

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Facilitation of microbialite development by continental weathering in the Cambrian Zhangxia Formation,southern North China Block

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Journal of Palaeogeography 2025年第1期14卷 172-185页

作者： Wen-Tao Yang Jia-Qi Zhu Min Wang Chao Liu Yong-An Qi School of resources and Environment Henan Polytechnic University Key Laboratory of Biogenic Traces and Sedimentary minerals of Henan Province Henan Polytechnic University State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of Sciences

We report geochemical data for carbonate rocks from the Cambrian Zhangxia Formation,southern North China Block,including trace-element contents and C,O,and Sr isotopic compositions,to determine the controls on the development of microbialites in this *** sedimentary environment of the Zhangxia Formation evolved from carbonate-slope through platform-margin-reef to ooid-shoal,and then to open-platform settings,corresponding to the development of micrites,microbialites,and oolitic *** data show that δ13C values decrease upwards through the Zhangxia Formation,from 0.99‰to-1.59‰,whereas δ18O values increase from-9.91‰to-7.10‰.Total rare earth element （REE）contents decrease upwards through the stratigraphy,and the contents of Th and Sc show a similar trend.87Sr/86Sr ratios reach a maximum of 0.710544 in the horizons of microbialite development,Member 2 of the Zhangxia Formation,above which the ratios are uniform,with a mean value of *** these geochemical data with the inferred sedimentary evolution,the Zhangxia Formation is interpreted to have formed in a depositional environment that changed from transgression to *** weathering played a crucial role in promoting the input of terrigenous materials,which in turn favored the development of microbialites during the early stage of deposition of the Zhangxia Formation.

关键词： Carbonate rocks Trace elements C and Sr isotopes Microbialites Cambrian

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Propagating subduction initiation of the Caroline Plate at the Mussau Trench

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Science China Earth Sciences 2025年第1期68卷 253-269页

作者： Chun-Feng LI Yongkang DENG Tao WU Dongdong DONG Guoliang ZHANG Jiazheng ZHANG Yutao LIU Yaqing LI Fugui TANG Lulu ZHANG Department of Marine Sciences Zhejiang UniversityZhoushan316021China Laboratory of Marine mineral resources Laoshan LaboratoryQingdao266237China Key Lab of Marine geology and Environment Institute of OceanologyChinese Academy of SciencesQingdao266071China Key Lab of Ocean and Marginal Sea geology South China Sea Institute of OceanologyChinese Academy of SciencesGuangzhou510301China Science&Technology on Integrated Information System Lab Institute of SoftwareChinese Academy of SciencesBeijing100190China

New seismic imaging from the Mussau Trench confirms that,under horizontal compression on an oceanic plate boundary,it is within the young and weak oceanic plate that a trench will develop,and it is the young plate,not so long after its birth,that starts to subduct toward the old *** Mesozoic Pacific Plate cannot easily bend,under the joint horizontal compression and vertical gravity pull,even with a pre-existing weak zone in place and with a large age offset across the plate *** bending of the Caroline Plate near the northern end of the Mussau Trench started only after a long-time span of trench migration,and/or after a prolonged transition from initial compression to trench *** contrasting trench deformation and sedimentary accretion between two parallel seismic sections support an evident migration of underthrusting or significant longitudinal heterogeneity along the *** swift transition from underthrusting to non-thrusting can be explained by a counter-clockwise rotation of the Caroline *** miniature accretionary wedges develop even before the subduction initiates imply strong compression and uplifting before the underthrusting can *** of the Caroline Plate have been halted as the Mussau Trench is seismically rather quiet and the Lyra Trough to the east shows relaxational extension.

关键词： Mussau Trench Subduction initiation Seismic reflection Caroline Plate

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New progresses of fine-grained sediment gravity-flow deposits and their importance for unconventional shale oil and gas plays

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Petroleum Science 2025年第1期22卷 1-15页

作者： Tian Yang Ying-Lin Liu State Key Laboratory of Oil and Gas Reservoir geology and Exploitation (Chengdu University of Technology) Institute of Sedimentary Geology Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural resources Chengdu University of Technology

Fine-grained sediments are widely distributed and constitute the most abundant component in sedimentary systems, thus the research on their genesis and distribution is of great significance. In recent years, fine-grained sediment gravity-flows(FGSGF) have been recognized as an important transportation and depositional mechanism for accumulating thick successions of fine-grained sediments. Through a comprehensive review and synthesis of global research on FGSGF deposition, the characteristics,depositional mechanisms, and distribution patterns of fine-grained sediment gravity-flow deposits(FGSGFD) are discussed, and future research prospects are clarified. In addition to the traditionally recognized low-density turbidity current and muddy debris flow, wave-enhanced gravity flow, lowdensity muddy hyperpycnal flow, and hypopycnal plumes can all form widely distributed FGSGFD. At the same time, the evolution of FGSGF during transportation can result in transitional and hybrid gravityflow deposits. The combination of multiple triggering mechanisms promotes the widespread development of FGSGFD, without temporal and spatial limitations. Different types and concentrations of clay minerals, organic matters, and organo-clay complexes are the keys to controlling the flow transformation of FGSGF from low-concentration turbidity currents to high-concentration muddy debris flows. Further study is needed on the interaction mechanism of FGSGF caused by different initiations, the evolution of FGSGF with the effect of organic-inorganic synergy, and the controlling factors of the distribution patterns of FGSGFD. The study of FGSGFD can shed some new light on the formation of widely developed thin-bedded siltstones within shales. At the same time, these insights may broaden the exploration scope of shale oil and gas, which have important geological significances for unconventional shale oil and gas.

关键词： Fine-grained sediment gravity-flow Depositional mechanism Transportation and evolution Distribution pattern Shale oil and gas

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Spatio-temporal patterns and climatic drivers of spring phenology in eight forest communities across the north-south transitional zone of China

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Journal of Geographical Sciences 2025年第1期35卷 17-38页

作者： ZHU Wenbin LU Yu institute of Geographic Sciences and Natural resources Research CASBeijing100101China School of Geographical Science Nanjing University of Information Science&TechnologyNanjing210044China

The Qinba Mountains are climatically and ecologically recognized as the north-south transitional zone of *** of its phenology is critical for comprehending the response of vegetation to climatic *** retrieved the start of spring phenology(SOS)of eight forest communities from the MODIS products and adopted it as an indicator for spring *** analysis,partial correlation analysis,and GeoDetector were employed to reveal the spatio-temporal patterns and climatic drivers of *** results indicated that the SOS presented an advance trend from 2001 to 2020,with a mean rate of−0.473 d yr^(−1).The SOS of most forests correlated negatively with air temperature(TEMP)and positively with precipitation(PRE),suggesting that rising TEMP and increasing PRE in spring would forward and delay SOS,*** dominant factors influencing the sensitivity of SOS to climatic variables were altitude,forest type,and latitude,while the effects of slope and aspect were relatively *** response of SOS to climatic factors varied significantly in space and among forest communities,partly due to the influence of altitude,slope,and aspect.

关键词： spring phenology climatic drivers altitude forest communities lag effect Qinba Mountains

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Spatial Characteristics of the Plasma Spark Source Wavelet

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Journal of Ocean University of China 2025年第1期24卷 103-112页

作者： WEI Jia HAO Xiaozhu FENG Jing YANG Rui XING Lei LIU Huaishan WANG Wei WU Zhiqiang ZHANG Dong LI Linwei Qingdao institute of Marine geology CGSQingdao 266071China Key Laboratory of Marine mineral resources Ministry of Natural ResourcesGuangzhou Marine Geological SurveyGuangzhou 511458China College of Marine Geosciences Ocean University of ChinaQingdao 266100China Center for Biomedical Materials and Interfaces Shenzhen Institutes of Advanced TechnologyChinese Academy of SciencesShenzhen 518055China

Plasma spark sources are widely used in high-resolution seismic ***,research on the excitation mechanism and propagation characteristics of plasma spark sources is very *** this study,we elaborated on the excitation process of corona discharge plasma spark source based on indoor experimental *** electrode spacing has a direct impact on the movement of *** the spacing between bubbles decreases,they collapsed and fused,thereby suppressing the secondary pulse *** on the premise of linear arrangement and equal energy synchronous excitation,the motion equation of multiple bubbles under these conditions was derived,and a calculation method for the near-field wavelet model of plasma spark source was *** simulated the source signals received in different directions and constructed a spatial wavelet face *** with traditional far-field wavelets,the spatial wavelet facial feature representation method provides a more comprehensive display of the variation characteristics and propagation properties of source wavelets in three-dimensional *** spatial wavelet variation process of the plasma spark source was analyzed,and the source depth and the virtual reflection path are the main factors affecting the *** high-frequency properties of plasma electric spark source wavelets lead to their sensitivity to factors such as wave fluctuations,position changes,and environmental *** changes in collection parameters may result in significant changes in the recorded waveform and final data ***,the facial feature method provides more effective technical support for wavelet evaluation.

关键词： plasma spark source seismic wavelet spatial characteristics facial features

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First SHRIMP Zircon U-Pb Dating Constraints for the Ediacaran Wenghui Biota

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Journal of Earth Science 2025年第1期36卷 102-112页

作者： Mingsheng Zhao Feng Tang Giovanni Mussini Yulan Li Heng Zhang Jianshu Chen Linzhi Gao College of Paleontology Shenyang Normal UniversityShenyang 110034China State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of SciencesNanjing 210008China institute of geology Chinese Academy of Geological SciencesBeijing 100037China Department of Earth Sciences University of CambridgeCambridge CB23EQUnited Kingdom 111 Geological Brigade Guizhou Bureau of Geology and Mineral ResourcesGuiyang 550081China Guizhou Geological Survey Guiyang 550018China

The Ediacaran Period records a significant turning point in the evolution of life on Earth,witnessing the rise to ecological dominance of macroscopic tissue-grade *** Wenghui biota from the Doushantuo Formation of South China hosts abundant multicellular algal macrofossils and problematica,some of which might be closely related to taxa from classic Late Ediacaran assemblages from South Australia and the White Sea biota of ***,a lack of well-resolved isotopic age estimates has hampered efforts to constrain the timing of appearance of the Wenghui biota,obfuscating its significance to our understanding of Ediacaran macroevolution in the aftermath of the Snowball Earth ***,we present the first SHRIMP zircon U-Pb dating results for samples obtained from a laminated tuff ash layer at the base of the Wenghui biota in the Doushantuo Formation,Jiangkou County,Tongren City,Guizhou Province,*** analyses yield an age of 595.4±5.3 Ma for the first appearance of Wenghui biota,suggesting that its appearance postdated that of the Lantian and Weng'an biotas,but preceded that of the Miaohe *** newly obtained age proxies offer an independent test of previous isotopic estimates for the age of the Wenghui biota,providing new chronostratigraphic evidence to map the succession of Ediacaran fossil assemblages on the Yangtze Platform during the Doushantuo *** data suggest that the Lantian,Weng'an,Wenghui,and Miaohe biotas may record a sequence of biotic assemblages attesting to successive phases in the radiation of Ediacaran macroscopic organisms,particularly macroalgae.

关键词： zircon SHRIMP U-Pb dating Wenghui biota Doushantuo Formation Ediacaran system southern China

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