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Trace fossil evidences of an Early Miocene paleoseismic event and depositional regime change from the Kutch(Kachchh) Basin

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Journal of Palaeogeography 2024年第1期13卷 165-180页

作者： Ayush Srivastava Sudipta Dasgupta Krishanu Chatterjee Mohuli Das Bombay Ichnos Research group Department of Earth SciencesIndian Institute of Technology Bombay(lIT Bombay)PowaiMumbaiMaharashtra400076India

Unconsolidated siliciclastic sediments can undergo post-burial deformation, which leads to the formation of distinctive sedimentary structures, known as soft-sediment deformation structures(SSDS). The presence of a series of sand volcanoes confined to a particular lithostratigraphic horizon can represent a paleoseismic activity and, thereby, exemplifies the concept of “seismite”. The Kutch Basin has been a tectonically active region since the initiation of eastern Gondwana rifting followed by a tectonic inversion during the Cenozoic due to the collision of the Indian and Eurasian plates. A stratum-bound series of sand volcanoes belonging to the Khari Nadi Formation(KNF) is exposed along the banks of Khari River. They separate the shallow marine deposits below and non-marine deposits above with their characteristic marine and paleosol trace fossil suites, respectively. Although a seismogenic origin has been much debated for the SSDS,the ichnofabric analysis of the sand-volcano-bearing stratum unequivocally points toward such an origin under a shallow seafloor condition. In addition to the sedimentary regime change from an open shallow-marine setting to a continental depositional environment concomitant with basinal uplift, the behavior of the burrowing crustaceans testifies to a syn-depositional development of a fault network associated with the fluidization, sand volcanism, and the resilience of the trace-producers in surviving those processes until the sedimentary regime change in the overlying strata. Although the ichno-sedimentological evidence apparently differs from the previous works that proposed a continuous base-level rise from the beginning of deposition of the Khari Nadi Formation up to the middle part of the overlying Chhasra Formation, the paleoseismic activity,its ichnologic signature, and the depositional regime change refer to a higher-resolution(i.e., lower-order)sequence-stratigraphic change causing a short-duration regression within a longer-durat

关键词： Sand volcano Seismite Ichnology Khari Nadi Formation Kutch Basin Kachchh Basin

Geochronology,petrogenesis,and geological significance of the quartz vein-type copper deposits in Longwei area,north-west Dayaoshan,Guangxi

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Frontiers of earth Science 2024年第1期18卷 68-82页

作者： Song FU Shehong LI Changxing LV Longqing SHI Xuhan HU Jinming WU Zhuolin XIE College of earth Sciences&Engineering Shandong University of Science and TechnologyQingdao 266590China School of earth Sciences Guilin University of TechnologyGuilin 541006China Xinwen Mining group Co. Ltd.Huafeng Coal MineTai’an 271409China

Quartz-vein-type copper deposits were discovered in SN-trend ore-bearing structures in north-west Dayaoshan,*** of reports on the precise metallogenic age of these deposit has become a bottleneck in metallogenic research in this *** this study,the quartz vein-type copper mine in Longwei area of Jinxiu was selected as the research *** illite samples in the fault gouges and ore samples were collected for testing and *** on the Re-Os isotope dating study,the age of pyrite isochron,belonging to the Caledonian period,was determined to be 417±25 Ma,whereas that of chalcopyrite isochron belonging to the Indosinian period,was found to be 243±18 *** crystallized considerably earlier than *** obtained EPMA data were combined with rock mineralogical analysis data,Metasomatous mineral pyrite and metasomatic mineral chalcopyrite were identified to have originated from different hydrothermal *** the Indosinian period,copper deposits in the Longwei area underwent pyrite crystallization,pyrite fragmentation,copper-bearing hydrothermal filling,and metasomatism,consolidating and forming *** study determined the mineralisation time and ore sources of copper deposits in the Longwei *** study provides evidence for the existence of Indosinian hydrothermal activities in the north-western Dayaoshan area.

关键词： Re-Os dating electron probe micro-analyser quartz-vein copper deposit Dayaoshan area

Improvements in properties of NdFeB magnets obtained via magnetron sputtering and thermal diffusion

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Journal of Rare earths 2024年第9期42卷 1710-1716页

作者： Jin Tang Weichao Huang Dan Li School of Electronic Engineering Guangxi University of Science and Technology China Rare earth (Guangxi) Jinyuan Rare earth New Materials Co. Ltd China Rare earth group Co. Ltd. Center of Experimental Teaching for Common Courses Panzhihua University

The grain boundary diffusion process（GBDP） of Dy and DyAl on sintered NdFeB magnets was conducted via magnetron-sputtering deposition of Dy and DyAl films to enhance coercivity(Hcj),The magnetic properties,microstructure and anti-corrosion properties of Dy-surface-alloying NdFeB magnets obtained via magnetron sputtering and thermal diffusion were *** Hcjof the Dy95Al5-NdFeB magnet increases by 32.68%,while the remanence declines ***,X-ray diffraction and microstructural analysis confirm the formation of Dy-rich shells,the higher-magnetic-anisotropy field of hard(NdxDy1-x)2（FeAl）14B magnetic phases and an optimised grain boundary structu re,contributing to the Hcjenhancement of the *** elemental distribution and diffusion mechanism of the magnets are also ***,the corrosion resistance of the Dy95Al5-NdFeB magnet is substantially improved by enhancing the electrochemical stability and optimising the distribution and morphology of the intergranular *** findings of this study are of substantial importance in the development of low-heavy rare-earth sintered NdFeB magnets.

关键词： Magnetron sputtering NdFeB Rare earths Microstructure Magnetic property Corrosion resistance

Three-stage niobium mineralization at Bayan Obo, China

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National Science Review 2024年第4期11卷 102-110页

作者： Yan Yu Yang Li Yu Liu Xiao-Xiao Ling Li-Guang Wu Li Yang Lan Yang Bo Yang Yong-Gang Zhao Xian-Hua Li State Key Laboratory of Lithospheric Evolution Institute of Geology and Geophysics Chinese Academy of Sciences College of earth and Planetary Science University of Chinese Academy of Sciences Ministry of Education Key Laboratory of Orogenic Belts and Crustal Evolution School of Earth and Space SciencesPeking University Mining Research Institute Baotou Iron and Steel(Group) Co.LTD State Key Laboratory of Baiyunobo Rare earth Resource Research and Comprehensive Utilization

The Chinese Bayan Obo deposit is a world-class rare earth element(REE) deposit with considerable niobium(Nb) and iron(Fe) resources. A complete genetic understanding on all metals is fundamental for establishing genetic models at Bayan Obo. With extensive research being focused on REE enrichment, the timing and controls of Nb enrichment remain unresolved at Bayan Obo, which is mainly due to the challenges in dating, i.e. multistage thermal events, fine-grained minerals with complex textures and the rare occurrence of uranium-enriched minerals with mature dating methods. Based on robust geological and petrographic frameworks, here we conducted ion probe uranium-lead(U-Pb) dating of ferrocolumbite to unravel the timing, hence the genesis of Nb mineralization. Three types of hydrothermal ferrocolumbites—key Nb-bearing minerals—are identified based on their textures and mineral assemblages. They yield U-Pb ages of 1312 ± 47 Ma(n = 99), 438 ± 7 Ma(n = 93), and 268 ± 5 Ma(n = 19), respectively. In line with deposit geology, we tentatively link the first, second and third stage Nb mineralization to Mesoproterozoic carbonatite magmatism, ubiquitous early Paleozoic hydrothermal activity, and Permian granitic magmatism, respectively. While quantifying the contribution of metal endowment from each stage requires further investigation, our new dates highlight that multi-stage mineralization is critical for Nb enrichment at Bayan Obo, which may also have implications for the enrichment mechanism of Nb in REE deposits in general.

关键词： niobium mineralization U-Pb dating ferrocolumbite Bayan Obo

A novel Ce_(0.485)Zr_(0.485)Y_(0.03)O_(2) composite oxide with surface doping of Y and its application in Pd-only three-way catalyst

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Rare Metals 2024年第2期43卷 749-757页

作者： Zheng Zhao Wei-Xin Zhao Yong-Qi Zhang Mei-Sheng Cui Yong-Ke Hou Dong-Ming Chen Juan-Yu Yang Zong-Yu Feng Xiao-Wei Huang National Engineering Research Center for Rare earth Grirem Advanced Materials Co.Ltd.GRINM Group Corporation LimitedBeijing100088China Griem Hi-Tech Co.Ltd. Langfang065000China Rare earth Functional Materials(Xiong’an)Innovation Venter Co.Ltd. Baoding071700China

The ceria-zirconia compound oxide-supported noble metal Pd(Pd@CZ)is widely used in three-way ***,the surface structure of CZ plays an important role in catalytic activity of ***,how to regulate the surface structure of CZ and clarify the structure–activity relationship is still a *** this paper,a strategy is proposed to develop high activity Pd@CZ nanocatalysts by tuning Y doping sites in *** precipitate-deposition method is developed to prepare the novel Ce_(0.485)Zr_(0.485)Y_(0.03)O_(2) composite with surface doping of Y(CZ-Y-S).In addition,the Pd@CZ-Y-S(Pd supported on CZ-Y-S)exhibits superior catalytic activity for HC,CO,and NO oxide,wherein,for CO and C_(3)H_(6) oxidation,the low-temperature activity of Pd@CZ-Y-S is still 20%higher than that of Pd@CZ-Y-B(Y bulk doping)and commercial Pd@CZ after 1000℃/4 h *** effect mechanism is further studied by density functional theory(DFT)*** with Pd@CZ-Y-B,Pd@CZ-Y-S shows the lower CO oxide reaction energy barriers due to the weaker adsorption strength of *** Y surface doping strategy could provide valuable insights for the development of highly efficient Pd@CZ catalyst with extensive applications.

关键词： Rare earth Ceria-zirconia-supported Pd Surface doping Experiment and theory Catalytic application

Universal Hyperthermal Model for Mass Extinctions

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Journal of earth Science 2024年第2期35卷 704-707页

作者： Michael J.Benton Paleobiology Research group School of Earth SciencesUniversity of BristolLife Sciences BuildingTyndall AvenueBristolBS81TQUK

INTRODUCTION earth scientists have long sought universal features of past extinction *** can be argued that each past extinction event was a singularity,caused by combinations of circumstances that are unique in each case,and therefore that the search for common causes is ***,a key feature of the uniformitarian approach to geology is that past processes are the same as modern-day processes and,with that in mind,earth scientists are keen to use their knowledge to contribute some understanding to the study of the present and future climate crisis.

关键词： extinction singularity Extinction

Holocene Hydroclimatic Variations in the Asian Drylands:Current Understanding and Future Perspectives

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Journal of earth Science 2024年第1期35卷 292-295页

作者： Guoqiang Ding Shengqian Chen Yuanhao Sun Shuai Ma Jianhui Chen MOE Key Laboratory of West China's Environmental System College of Earth and Environmental SciencesLanzhou UniversityLanzhou 730000China Alpine Paleoecology and Human Adaptation group State Key Laboratory of Tibetan Plateau Earth SystemEnvironment and ResourcesInstitute of Tibetan Plateau ResearchChinese Academy of SciencesBeijing 100101China

0 *** intensification of global warming is generating increasing risks to human society and sustainable development,which are of growing concern to the international scientific community and policymakers(Sun,2023).The ecosystems of the Asian drylands are fragile and highly sensitive to global changes;moreover,while these drylands are the most important areas of oasis agriculture on earth,their water resources are being adversely impacted by ongoing climate change(Zhang et al.,2023).Hence,an improved understanding of the patterns of climate change in this region is important and attracting increasing research attention.

关键词： Asian Holocene climatic

Tungsten separation behavior on preparation of high-purity cerium by combined vacuum gravity sedimentation-directional solidification

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Journal of Rare earths 2024年第6期42卷 1182-1186,I0007页

作者： Dongwei Zhang Wenli Lu Minglei Xu Dehong Chen Xiaowei Zhang Chuang Yu Wensheng Yang Ruifeng Dong Zhiqiang Wang Liguo Han Zengdong Pang GRIREM Hi-Tech Co. Ltd.Langfang065201China National Engineering Research Center for Rare earth China GRINM Group Co.Ltd.Beijing100088China GRIREM Advanced Materials Co. Ltd.Beijing100088China

In light of the difficult removal of harmful impurity tungsten(W)in Ce metal,in this paper a combined vacuum gravity sedimentation-directional solidification method was innovatively designed and the W separation behavior was *** reducing the electron beam power instantly and gradually at reduction rates of 1,3 and 5 kW/min,it is found that W is enriched at the bottom of ingots as the melt *** enrichment effect is much better than that of single purification method and the enrichment degree increases as the beam reduction rate decreases,attributed to the k0(W)>1 andρ(W)>ρ(Ce).Overall,the minimum content of W impurity can decrease from 630 to 0.1 ppm at the top of the ingot,and the purity of Ce increases from 99.932 wt%to 99.995 wt%by this combined ***,this paper provides a new method for the removal of high density and low evaporation coefficient impurities in low vapor pressure rare earth metals.

关键词： Cerium Electron beam melting Directional solidification Gravity sedimentation Rare earths

Explainable artificial intelligence models for mineral prospectivity mapping

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Science China earth Sciences 2024年第9期67卷 2864-2875页

作者： Renguang ZUO Qiuming CHENG Ying XU Fanfan YANG Yihui XIONG Ziye WANG Oliver P.KREUZER State Key Laboratory of Geological Processes and Mineral Resources China University of Geosciences School of earth Sciences and Engineering Sun Yat-sen University Corporate Geoscience group (CGSG) Economic Geology Research Centre (EGRU) College of Science and EngineeringJames Cook University

Mineral prospectivity mapping(MPM) is designed to reduce the exploration search space by combining and analyzing geological prospecting big data. Such geological big data are too large and complex for humans to effectively handle and interpret. Artificial intelligence(AI) algorithms, which are powerful tools for mining nonlinear mineralization patterns in big data obtained from mineral exploration, have demonstrated excellent performance in MPM. However, AI-driven MPM faces several challenges, including difficult interpretability, poor generalizability, and physical inconsistencies. In this study, based on previous studies, we devised a novel workflow that aims to constructing more transparent and explainable artificial intelligence(XAI) models for MPM by embedding domain knowledge throughout the AI-driven MPM, from input data to model design and model output. This newly proposed approach provides strong geological and conceptual leads that guide the entire AI-driven MPM model training process, thereby improving model interpretability and performance. Overall, the development of XAI models for MPM is capable of embedding prior and expert knowledge throughout the modeling process, presenting a valuable and promising area for future research designed to improve MPM.

关键词： Artificial intelligence Mineral prospectivity mapping Geological prospecting big data Domain knowledge Interpretability

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