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Propagating subduction initiation of the Caroline Plate at the Mussau Trench

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 University Laboratory of Marine Mineral resources Laoshan Laboratory Key Lab of Marine geology and Environment Institute of Oceanology Chinese Academy of Sciences Key Lab of Ocean and Marginal Sea geology South China Sea Institute of Oceanology Chinese Academy of Sciences Science & Technology on Integrated Information System Lab Institute of Software Chinese Academy of Sciences

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 plate. The 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 boundary. The 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 development. Highly contrasting trench deformation and sedimentary accretion between two parallel seismic sections support an evident migration of underthrusting or significant longitudinal heterogeneity along the trench. The swift transition from underthrusting to non-thrusting can be explained by a counter-clockwise rotation of the Caroline Plate. That miniature accretionary wedges develop even before the subduction initiates imply strong compression and uplifting before the underthrusting can kick-start. Rotation 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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Grounded-source short offset transient electromagnetic method:Theory and applications in deep mineral exploration

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Science China Earth Sciences 2025年

作者： Guoqiang XUE xin WU Weiying CHEN Nannan ZHOU 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

Abstract The Transient Electromagnetic (TEM) method is a critical geophysical technique for subsurface exploration of metal ore bodies, primarily utilizing either loop or grounded transmitters. The Long Offset Transient Electromagnetic(LOTEM) method employs a grounded-source transmitter, relying on a far-source observation mode and plane wave approximation for detection. However, 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 exploration. This study explores the theoretical framework, instrumentation, data processing, and field applications of SOTEM. Based on a point charge element model, SOTEM accurately computes surface wave effects in EM field calculations,optimized for near-source observation. High-power, high-resolution, wide-bandwidth exploration equipment and an advanced three-dimensional hybrid inversion technique were also developed to enhance the method’s effectiveness. Application 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 depth. These 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.

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Molecular dynamics simulation:The key to reveal the enrichment mechanisms of helium

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Science China Earth Sciences 2025年

作者： Wenhui LIU Department of geology Northwest University Petroleum Exploration and Production Research institute SINOPEC

In recent years,helium and its enrichment mechanisms have been the frontier and attractive research in the field of geological resources (Liu et al.,2024).In the earliest geosciences,noble gases and their isotopes,including helium,were used as tracers for geochronology and geological processes due to their chemical inertness and *** attention has been paid to the isotope composition in geological ***,as an important resource,the research on the source,migration and accumulation of helium is critically important.

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Spatiotemporal evolution of Ediacaran-Cambrian(ca. 551–523 Ma)sponges in South China and their simulated contributions to marine oxygenation

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Science China Earth Sciences 2025年

作者： Yan YE Lei ZHANG Can CHEN Shan CHANG Yuhao YI Qinglai FENG State Key Laboratory of Geological Processes and Mineral resources China University of Geosciences(Wuhan) School of Earth Science China University of Geosciences(Wuhan) Department of geology Lund University institute of Sedimentary geology Chengdu University of Technology Key Laboratory of Deep-time Geography and Environment Reconstruction and Applications of Ministry of Natural resources Chengdu University of Technology Second Geological Brigade of Hubei Geological Bureau College of Urban and Environmental Sciences Hubei Normal University Exploration and Development Research institute SINOPEC Jianghan Oilfield Company

The origin and evolution of sponges have attracted interest, not only because they are among the most basal metazoans, but also because they act as important ecological engineers in the ocean. Previous research suggested that sponge groups diversified quickly during the Cambrian Series 2, while Terreneuvian sponge fossils are conspicuously rare and poorly substantiated. Yet, an increasing number of sponge spicules have been reported from the Ediacaran-Cambrian(E-C, ca.551–523 Ma) transitional carbonates/cherts worldwide, particularly in South China, which calls for updated discussions. Ocean oxygenation has been widely proposed to play a critical role in organismal evolution, but its relationship with sponges is unclear and falls into a “chicken-egg” dilemma. In this study, we summarize reported sponge spicule distributions from five E-C sections in South China to investigate the early evolutionary pattern of siliceous sponges. According to current stratigraphic correlation,monaxons first appear in the late Ediacaran in the intrashelf basin-slope area, and then potentially expand to the continental shelf and deep basin in the lower Cambrian. In these sections, the abundance, size, and diversity of monaxons increase upwards,followed by the appearance of diaxons, triaxons and then polyactines. Despite the uncertain affinity of the sponge fossils, it is possible that siliceous hexactinellids evolved later than siliceous demosponges, given that the earliest spicule assemblages are exclusively composed of monaxons, which commonly form bundles comparable to modern demosponges. New geochemical data from the Sifangjing section, Guizhou Province and the Yanziqiao section, Hunan Province, South China show that the appearance of sponges usually corresponds to anoxic environment. In addition, we applied the recently proposed Biological Pump, Oxygen and Phosphorus(BPOP) model to trace the evolution of oceanic oxygen concentrations with the radiation of sponges. The results indic

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Opening of an early Paleozoic limited oceanic basin in the northern Altyn area: Constraints from plagiogranites in the Hongliugou-Lapeiquan ophiolitic mélange

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Science China Earth Sciences 2011年第12期54卷 1871-1879页

作者： GAO xiaoFeng xiAO Peixi GUO Lei DONG ZengChan xi RenGang xi＇an institute of geology and Mineral resources Xi＇an 710054 China

This paper reports petrological and geochemical features and zircon U-Pb age of plagiogranite from the Hongliugou-Lapeiquan ophiolitic melange belt in the northern Altyn Tagh. The zircon U-Pb dating results yield a mean ^238U/^206pb age of 512.1 ± 1.5 Ma, representing an emplacement time of the plagiogranites in the Middle Cambrian. The plagiogranites are interpreted to have derived from anatexis of hydrated amphibolites by ductile shearing during transports of the oceanic crust. Thus it is believed that the formation age of such type of plagiogranite was coeval to or slightly younger than the spreading of the Hongliugou-Lapeiquan limited oceanic basin. The new results from the plagiogranites suggest that an oceanic basin existed in the northern Altyn area during the Middle Cambrian.

关键词： plagiogranite limited oceanic basin early Paleozoic northern Altyn area

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Underground laboratories · Deep underground observation ·Scientific questions—Insights from observations of multi-physic fields in deep underground labs

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Science China Earth Sciences 2025年

作者： Huiqi REN Yun WANG Chang CHEN Guangyu FU Longqing QIU Lianghui GUO Chengliang xiE Yongsheng HE Heping SUN Jiwen TENG institute of Defense Engineering Academy of Military Sciences State Kay Laboratory of Geological Processes and Mineral resources Key Laboratory of Intraplate Volcanoes and Earthquakes Ministry of Education China University of Geosciences (Beijing) Shanghai institute of Microsystem and Information Technology Chinese Academy of Sciences Innovation Academy for Precision Measurement Science and Technology Chinese Academy of Sciences institute of geology and Geophysics Chinese Academy of Sciences

This paper presents a comprehensive review on recent development and research conducted in domestic and international underground laboratories. We first introduce the differences in three environments—surface, mountain tunnel cavities and underground coal mine tunnels—by examining cosmic ray background, ambient noises related to gravity and seismic measurement, and electromagnetic noises in magnetic and magnetotelluric measurements. We highlight potential misuse of the term Underground Lab or Deep Underground Lab when describing observations in different physical fields. We introduce unique features of underground coal mine tunnels in China, such as large spaces, ultra-quiet conditions, and ultra-clean environments. When comparing with mountain tunnel cavities and borehole observations, coal mine tunnel observations have superior long-term stability and high precision. Through observations and comparisons of multi-physic fields at surface and the deep underground, we find that the higher SNR seismic observations conducted in deep underground tunnels in coal mines are beneficial to improve velocity tomography of the solid earth. The gravity observation with a Superconducting Quantum Interference Device(SQUID) makes it possibly to capture slow earthquake, which has not been observed previously in the Chinese mainland. SQUID magnetic observations can detect fluctuations as weak as femto-Tesla(fT), enabling us to explore the attenuation of Schumann Resonance down to the solid Earth. This opens opportunities to investigate the connections between the Earth's magnetic field and the interactions within the human brain and heart. To improve the precision of quantum measurement,we should consider the possible effects of weak magnetic disturbances in deep underground environments. Finally, we discuss the importance of deep underground laboratories, observing facilities and techniques deployed in these laboratories, and their possible connection with respect to “deep space” an

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Coseismic surface ruptures of MW7.8 and MW7.5 earthquakes occurred on February 6, 2023, and seismic hazard assessment of the East Anatolian Fault Zone, Southeastern Türkiye

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Science China Earth Sciences 2025年

作者： Peng LIANG Yueren XU xiaocheng ZHOU Ying LI Qinjian TIAN Huiping ZHANG Zhikun REN Jingxing YU Chuanyou LI Zheng GONG Shiguang WANG Aixia DOU Zifa MA Junjie LI Key Laboratory of Earthquake Prediction Institute of Earthquake ForecastingChina Earthquake Administration China Earthquake Disaster Prevention Center State Key Laboratory of Earthquake Dynamics Institute of GeologyChina Earthquake Administration institute of Geophysics China Earthquake Administration

On February 6, 2023, southeastern Türkiye experienced a devastating earthquake doublet along the East Anatolian Fault（EAF）, with moment magnitude（MW） values of 7.8 and 7.5. These strong earthquakes resulted in at least 50,000 deaths and severe economic losses. Systematic research on coseismic surface ruptures induced by these events is vital for assessing the cascade rupture behaviors of plate boundary faults and future seismic hazards in the region. Interpretation of high-resolution post-earthquake satellite images and field investigations yielded the following results:（1） the two strong earthquakes had separate rupture zones. The first earthquake generated an approximately 280 km coseismic surface rupture along the southwestern segment of the main EAF, with 241 left-lateral displacements reaching up to 6.8±0.68 m, particularly 40 km northeast of the epicenter. The second earthquake produced a roughly 110 km surface rupture on an east-west branch of the EAF, with maximum displacements of 7.2±0.72 m.（2） The MW7.8 earthquake resulted in a cascading rupture across multiple segments of the southwestern section of the main EAF, with significantly variable displacements. The northeastern and southwestern parts of the main EAF and Malatya Fault remain at risk of strong earthquakes in the future.（3） The EAF rupture zone is densely populated, and due to the site amplification effect of loose sediments on foreland alluvial fans, foundation failures of buildings in the populated areas are common. Therefore, it is crucial to enhance the future seismic fortification capabilities in urban and rural areas along the EAF.

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Evaluation of ecological risk and primary empirical research on heavy metals in polluted soil over xiaoqinling gold mining region,Shaanxi,China

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Transactions of Nonferrous Metals Society of China 2010年第4期20卷 688-694页

作者：吴耀国徐友宁张江华胡思海 Department of Applied Chemistry Northwestern Polytechnical University xi'an institute of geology and Mineral resources

Soil,crop and residents'hair over xiaoqinling gold mining region,China,which was selected as a case study,were sampled and analyzed for Hg,Cd,Pb,Cu,Cr,As and Zn *** concentrations of heavy metals in soil or crop and hair samples were used to assess their potential ecological risks,or to find the responses to these metals as evidences to prove the potential risk was coming down to observed harm,*** results showed that,these metals in soil were ranked by severity of ecological risk as Hg>Cd>Pb>Cu>Cr>As>Zn,based on their single-element *** the view of the potential ecological risk indexes,of all soil samples,about half had significantly high or high potential ecological risk,which covered more than 74%of the studied *** of the risks were 97.41%from Hg,Pb and Cd,especially,84.37%from *** the single-element and potential ecological risk indexes indicated that,the ecological risk grades had a special spatial characteristic,and increased from northwest to southeast *** was agreed with the spatial distribution of the strength in gold mining activities over the studied *** concentrations of Hg and Pb were higher than their relative backgrounds in the corps,and were even 9.48 and 25.09 times higher than their relative backgrounds in residents'hair,*** these showed that the heavy metals in the soil had a high potential ecological risk,especially,had been affecting these crops'growing and yield,and even the residents'health through food ***,these metals'potential ecological harm had been coming down to observed harm to the ecology.

关键词： gold mining activity soil pollution heavy metal potential ecological risk

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Discovery and significance of microfossils from Qinbaikouian Dazhuang Formation in Luonan, Shaanxi Province

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Chinese Science Bulletin 1997年第3期42卷 243-245页

作者： Chen, Z Hua, H Jian, WC Hu, YX Department of geology Northwest University Xi’an China xi’an institute of geology and Mineral resources Chinese Academy of Geological Sciences Xi’an China

THE microfossils were obtained by using 5%—7% HF acid from Qingbaikouian Dazhuang Formation in Luonan County, Shaanxi Province, with an age of 800—1000 Ma. The fossils may be one type of the oldest skeletal mierofos... 详细信息

关键词： microfossil Qinbaikouian Dazhuang Formation Shaanxi Province.

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Oxygen and hydrogen isotope exchange of geopressured thermal water in the central Guanzhong basin

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Mining Science and Technology 2009年第1期19卷 115-119页

作者： YU Juan MA Zhi-yuan WANG Zhao-wei LI Wei-liang SU Yan Environmental Science and Engineering institute Chang ＇an University Xi＇an Shaanxi 710054 China xi＇an institute of geology and minerals resources Xi＇an Shaanxi 710054 China xi ＇an institute of Thermal Power Research Xi＇an Shaanxi 710032 China

Geothermal water of xi＇an and xianyang in the central Guanzhong basin is typically geopressured thermal water in China. 5180 and 5D data of geopressured thermal water＇in xi＇an and xianyang, combined with data from the perimeter of the basin, are analyzed to study features of hydrogen and oxygen shifts. The results show that ^18O exchange of geothermal water at the perimeter of the basin and in the non-geopressured thermal water in the center of the basin is not evident, while in most of the geopressured thermal water in the central basin, in cities such as xi＇an and xianyang, significant oxygen exchange had taken place as well as hydrogen exchange, suggesting that isotope exchanges would slowly move the geothermal water system towards equilibrium. Thermal water reservoirs in the central basin have passed through significant water-rock reactions. Moreover, the geothermal reservoir of xianyang city is relatively much more enclosed than that of xi＇an city. It has been observed that the more enclosed the geological environment of geothermal water is, the more obvious the oxygen shifts are. With the increasing of the depth, residence time, total amounts of dissolute solids and temperatures of geothermal waters, the oxygen exchange accelerates.

关键词： Guanzhong basin geopressured thermal water.^18O shifts

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