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Spatiotemporal evolution of wildfire activity during the Paleocene-Eocene Thermal Maximum in China

Science China Earth Sciences 2025年第2期68卷 509-522页

作者： Xue-Ting WANG Zuoling CHEN Linlin CUI Xu WANG State Key Laboratory of Lithospheric and Environmental Coevolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences College of Earth and Planetary SciencesBeijing 100049China institute of geology and geophysics Chinese Academy of SciencesBeijing 100029China

The Paleocene-Eocene Thermal Maximum(PETM)was the most prominent warming event in the Cenozoic and serves as a geological analog for the current global warming driven by anthropogenic CO_(2)emissions from burning fossil *** a primary disruptor of Earth's ecosystems,wildfire activity affects the balance of ecosystems,the global carbon cycle,and climate ***,studying the evolution and driving mechanisms of wildfires during the PETM is essential for predicting wildfire activity under global warming scenarios and for understanding the carbon cycle in the context of wildfire *** research on wildfires during the PETM has mainly focused on the Northern Hemisphere,particularly Europe and North America,whereas studies on Chinese mainland remain *** this study,we analyzed black carbon(BC)concentration and carbon isotope(δ13C)in the Beigou section of the Nanyang Basin and the Xilutian section of the Fushun Basin to reconstruct the spatiotemporal evolution of wildfires in arid/semi-arid and humid *** integrated these findings with those of previous studies on the paleoclimate of the research area to elucidate the driving mechanisms behind wildfire *** results indicate that wildfire activity weakened at the onset of the PETM,with the negative carbon isotope period characterized by low wildfire activity,except for a brief resurgence in the Nanyang *** the recovery phase of the PETM,wildfire activity gradually increased,returning to the pre-PETM *** prolonged low wildfire state was likely caused by extremely high temperatures and precipitation as well as the resulting vegetation *** the PETM recovery phase,increased wildfire activity transformed“short-term carbon sinks”of the biological-atmospheric carbon cycle into“long-term carbon sinks”through the burial of *** process of carbon sink conversion may have acted as a negative feedback mechanism,contributing to carbon sequestration and the e

关键词： PETM Wildfire Carbon cycle Nanyang Basin Fushun Basin

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Late Paleozoic to early Mesozoic volcanic-sedimentary history of the southeastern margin of the Central Asian Orogenic Belt:Timing of uplift of the Inner Mongolia paleo-uplift

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Science China Earth Sciences 2025年第1期68卷 297-309页

作者： Wenxing HAO Jin-Hui YANG Guang ZHU State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China School of Resource and Environmental Engineering Hefei University of TechnologyHefei230009China

The Kulun region is located in the eastern Bainaimiao arc belt on the southeastern margin of the Central Asian Orogenic Belt(CAOB),adjacent to the North China Craton(NCC)to the *** region records the closure of the PaleoAsian Ocean during the Paleozoic to early Mesozoic and is key to study the tectonic evolution of the northern margin of the *** conducted zircon U-Pb geochronology and Hf isotope analysis of volcanic-sedimentary and intrusive rocks in the Kulun *** volcanic-sedimentary rocks were previously assigned an early Carboniferous age,but include volcanic rocks with ages of 267–266 Ma and sedimentary rocks with youngest detrital zircon age peaks of 265–244 Ma,which were intruded by a granite with an age of 242 *** indicates that these rocks are actually middle Permian to Middle Triassic in age(267–242Ma)and correspond to the Qingfengshan and Liujiagou ***,two volcanic rock samples have highεHf(t)values(+1.6 to+16.1)and relatively young two-stage Hf model ages(1095–327 Ma),indicating their sources associated with the *** age spectra and Hf isotopic characteristics of detrital zircons from the sedimentary rocks suggest that,during the middle Permian to Middle Triassic,the sedimentary provenance in the Kulun region was mainly the ***,by the Early Jurassic,the provenance changed to the NCC(i.e.,the Inner Mongolia Paleo-uplift,IMPU).This result,combined with the development of a series of conglomerates on the northern margin of the NCC in the Late Triassic(i.e.,Xingshikou,Xiaoyingzi,and Xiaohekou formations),indicates the Kulun region experienced an abrupt change in paleogeography during the Late Triassic,with the IMPU undergoing significant uplift and thus becoming the main sediment source in the Kulun *** on the Late Triassic alkaline igneous belt(235–215 Ma)in the IMPU,we speculate that this uplift was caused by detachment of the southward-subducting Paleo-Asian oceanic plate,which occurred in a post-o

关键词： Central Asian Orogenic Belt the North China Craton Zircon geochronology Hf isotopes Inner Mongolia Paleo-uplift

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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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Upper mantle discontinuity structure beneath the Hindu Kush:Insights into dynamics of the Indian slab

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Science China Earth Sciences 2025年第3期68卷 720-729页

作者： Qinghui CUI Yuanze ZHOU Yuan GAO Lijun LIU Key Laboratory of Earthquake Prediction Institute of Earthquake ForecastingChina Earthquake Administration College of Earth and Planetary Sciences University of Chinese Academy of Sciences institute of geology and geophysics Chinese Academy of Sciences Department of geology University of Illinois at Urbana-Champaign

Upper mantle discontinuities play an important role in slab dynamics and mantle responses in the subduction *** increasing numbers of seismological observations in the Hindu Kush, fine structures of mantle discontinuities still remain less explored, highlighting less understood interactions of the Indian slab and discontinuities. Here we collected a large dataset of several dense seismic networks/arrays, extracted near-source SdP waves in P-wave codas using the N-th root slant stackings, and then systematically imaged upper mantle discontinuities around the Indian slab beneath Hindu Kush. In comparison with the IASP91 model, we confirmed an abrupt topographic transition of the 410-km discontinuity(410) from uplifts of up to 41 km to depressions of less than 20 km near the slab edge and a slightly depressed 660-km discontinuity(660) with depths of 660 to 668 km below the slab front, as well as a fluctuating 300-km discontinuity(300) with depths of 264 to 337 km. We suggest that the 410 is elevated by the Indian slab due to the interior coldness, and deepened near the slab edge by the hot upwelling slab-entrained mantle that escapes below the slab bottom. Based on a depressed 410 inside the Indian slab and a 660with slight depressions below the slab, we infer that the subducted Indian slab currently stretches into the upper MTZ. Moreover,we interpret the fluctuant 300 as the coesite to stishovite phase transition in the subduction-zone mantle enriched in the *** considered alongside other studies, our results can provide more insights into the dynamics of the Indian slab and mantle responses.

关键词： Hindu Kush subduction zone Upper mantle discontinuities Indian slab Hot slab-entrained mantle N-th root slant stacking

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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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Evaluating the hydrocarbon generation potential of the Paleocene–Eocene carbonaceous rocks in the Barmer and Bikaner-Nagaur Basins, western Rajasthan, India

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China geology 2025年第1期8卷 77-91页

作者： Alok Kumar Khairul Azlan Mustapha Alok K.Singh Mohammed Hail Hakimi Ali Y.Kahal Waqas Naseem Hijaz Kamal Hasnan Department of geology Faculty of ScienceUniversiti MalayaKuala Lumpur 50603Malaysia Department of geology Institute of ScienceBanaras Hindu UniversityVaranasi 221005India Department of Petroleum Engineering and GeoEngineering Rajiv Gandhi Institute of Petroleum TechnologyJais 229304India institute of geology and Petroleum Technologies Kazan Federal UniversityKazan 420008Russia geology and geophysics Department King Saud UniversityRiyadh 11451Saudi Arabia Department of geology University of PoonchRawalakot 12350Pakistan

The Bikaner-Nagaur and Barmer Basins(Rajasthan)are the most important petroliferous sedimentary basins in *** over a decade,the exploration and extraction of hydrocarbons in these ***-Eocene age rocks bear organic-rich sediments in these basins,including lignite and carbonaceous shale *** present research investigates the source rock properties,petroleum potential and thermal maturity of the carbonaceous shale partings from the lignite mines of Gurha(Bikaner-Nagaur Basin)and Kapurdi(Barmer Basin)using petrographical and geochemical *** carbonaceous shales have high organic matter(OM),with considerable total organic carbon(TOC)contents ranging from 13%to 39%.Furthermore,they contain hydrogen-rich kerogen,including types II and II/III,as evidenced by the Rock-Eval and elemental analysis *** existence of these kerogen types indicates the abundance of reactive(vitrinite and liptinite)***,the carbonaceous shales from the Bikaner–Nagaur Basin have oil generation potentials,with a high hydrogen index(up to 516 mg HC/g TOC)and a H/C ratio(up to 1.5)along with a significant presence of oil-prone liptinitic *** from the geochemical and petrological results,the studied shales have low huminite reflectance(0.31%–0.48%),maximum temperature(S_(2) peak;Tmax)between 419℃ and 429℃,and low production index values(PI:0.01–0.03).These results indicate that these carbonaceous shales contain immature OM,and thereby,they cannot yet release commercial amount of *** immaturity level in the studied outcrop section is due to the shallow burial *** proxies further indicate the presence of both oil and gas-prone source rocks.

关键词： Carbonaceous shale Petroliferous Bikaner-Nagaur Basin Barmer Basin High hydrogen index Hydrogen-rich kerogen Western Rajasthan Geochemistry Petrology

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Petrogenesis of rodingites along the northern margin of the North China Craton: Constraints from zirconology and whole-rock geochemistry

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Science China Earth Sciences 2025年第3期68卷 750-767页

作者： Jing RAN Hao WANG Jinhui YANG Yaoqi YAN Yusheng ZHU Baoquan ZHOU State Key Laboratory of Lithospheric and Environmental Coevolution Institute of Geology and Geophysics Chinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences

Rodingite is a metasomatic product formed from various rock types by aqueous fluids, providing a direct record of lithosphere-hydrosphere interactions and serving as a key carrier of surface water into Earth's deep interior（water content >1.5wt.%）. Determining the properties of metasomatic fluids is crucial for understanding the petrogenesis of rodingites. In this study,we conducted a detailed study of mineral inclusions, U-Pb ages, trace elements, and Hf-O isotopes of zircon, as well as wholerock geochemical and Sr-Nd-Hf isotopic data on rodingites and associated felsic alkaline veins/dikes along the northern margin of the North China Craton（NMNCC）, with aims to elucidate their formation ages, petrogenesis, and geodynamic settings. The results show that zircons from syenite and albite syenite veins/dikes exhibit clear oscillatory zoning, a wide range of Th/U ratios（0.0001–4.073）, low concentrations of rare-earth elements（REEs）, and low crystallization temperatures（<600°C）. These characteristics suggest that the zircons crystallized from fluids separated from late-stage melts during magma evolution. Consequently, the zircon U-Pb ages obtained through Secondary Ion Mass Spectrometry（SIMS） and Laser Ablation Inductively Coupled Plasma Mass Spectrometry（LA-ICPMS） analyses（389.1±3.5 to 390.2±1.6 Ma） record the timing of hydrothermal fluid activity. Zircons within the rodingites contain grandite, hematite, and aqueous fluid inclusions, indicating their formation during rodingitization, with an oxidizing, water-rich fluid acting as the metasomatic agent. SIMS and LA-ICPMS analyses of these zircons yielded U-Pb ages of 388.1±3.9 and 388.6±4.6 Ma, which register the formation ages of the rodingites. Both the syenite and albite syenite samples display high total alkali contents（9.9–13.9 wt.%）, consistent initial Sr isotopic ratios（0.7047–0.7051）,negative εNd（t）(-10.1 to-8.5) and εHf（t）(-13.9 to-13.7) values, and slightly elevated zircon δ18O values（6.20‰±0.18‰）compared to ma

关键词： North China Craton Rodingite Syenite Inclusions Zircon U-Pb age Sr-Nd-Hf-O isotopes

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Solar cycles during the seventeenth century revealed by equatorial aurora records

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Earth and Planetary Physics 2025年第1期9卷 182-187页

作者： Yong Wei LiMei Yan 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

Solar cycles are fundamental to astrophysics,space exploration,technological infrastructure,and Earth's climate.A better understanding of these cycles and their history can aid in risk mitigation on Earth,while also deepening our knowledge of stellar physics and solar system *** the solar cycles between 1600 and 1700-especially the post-1645 Maunder Minimum,characterized by significantly reduced solar activity-poses challenges to existing solar activity *** study utilizes a new red equatorial auroral catalog from ancient Korean texts to establish solar cycle patterns from 1623 to ***,a further reevaluation of the solar cycles between 1610 and 1755 identified a total of 13 cycles,diverging from the widely accepted record of 12 cycles during that *** research enhances our understanding of historical solar activity,and underscores the importance of integrating diverse historical sources into modern analyses.

关键词： solar cycle Maunder Minimum solar activity red equatorial aurora West Pacific geomagnetic anomaly

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Recent progress in studying orbital forcing of late Amazonian climate changes on Mars from Polar Layered Deposits

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Earth and Planetary Physics 2025年第02期 435-443页

作者： Xiang Li Xu Wang XiaoGuang Qin State Key Laboratory of Lithospheric and Environmental Coevolution Institute of Geology and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences

The polar layered deposits(PLD) of Mars can provide deep insight into paleoclimate changes over the planet's last several million years. Since the 1960s, researchers have studied almost all aspects of Martian PLD properties, searching for patterns that might reveal periodic characteristics of the planet's climate history. Although much progress has been made in our understanding of orbital periodicities reflected in the PLD, questions remain regarding how Martian orbital changes have affected the formation of the PLD and regarding the extent of climate information that is recorded in the PLD. Future studies of PLD should be carried out via integrated research that targets multi-profiles throughout the entire Martian polar regions that would clarify their general features at the hemisphere scale. Numerical modeling, coupled with modern observations of dust and water vapor transportation, should greatly advance our understanding of planetary climate evolution. Furthermore, future landing missions may help to clarify the paleoclimatic characteristics reflected in the PLD by drilling into these layered deposits and measuring mineralogical and geochemical compositions of the drilled samples.

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MITM: A new Mars Ionosphere-Thermosphere Model

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Earth and Planetary Physics 2025年第02期 337-345页

作者： ZhiPeng Ren YunBo Liu WeiXing Wan Yong Wei XinAn Yue Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Beijing National Observatory of Space Environment Institute of Geology and Geophysics Chinese Academy of Sciences Innovation Academy for Earth Science Chinese Academy of Sciences College of Earth and Planetary Sciences University of the Chinese Academy of Sciences

In this study, we present an innovative Mars Ionosphere-Thermosphere Model（MITM）, which is a time-dependent, threedimensional（3-D） model that comprehensively represents the self-consistently coupled thermosphere and ionosphere of Mars within the altitude range of 70-300 km. The model incorporates an extensive range of parameters, including neutral number densities of CO2, CO,O, O2, N2, NO, N（2D）, N（4S）, Ar, and He; ion number densities of CO2+, CO+, O+, O2+, N2+, NO+, N+ions, and electrons; neutral temperature;and neutral wind fields. The MITM code employs a high-resolution grid system in a spherical geographical coordinate system, with a horizontal resolution of 5° latitude by 7.5° longitude. This altitude-resolved grid system enables accurate depiction of spatial variations in the Martian thermosphere and ionosphere. To showcase the capabilities of the MITM, we present two simulation cases: one during the equinox and another during the solstice. Both simulations reproduce key features of the Martian thermosphere and ionosphere including the characteristics of horizontal circulation, diurnal variations in chemical composition, and distribution of electron density. The MITM offers a robust framework for understanding the intricate interactions and processes that shape the Mars thermosphere and ionosphere,which are crucial for enhancing our understanding of Martian upper atmosphere and ionosphere.

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