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Geochemistry of island arc assemblage in the Eastern Desert of Egypt and the role of Pan-African magmatism in crustal growth of the Arabian–Nubian Shield:A review

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Acta Geochimica 2024年第3期43卷 588-622页

作者： Abdel-Aal MAbdel-Karim Mohamed MHamdy Adel A.Surour Geology department Faculty of ScienceZagazig UniversityZagazig 44519Egypt Geology department Faculty of ScienceTanta UniversityTanta 31527Egypt department of geological Sciences Faculty of ScienceNew Galala City 43511Egypt Geology department Faculty of ScienceCairo UniversityGiza 12613Egypt

Neoproterozoic island arc assemblage of the Arabian–Nubian Shield(ANS)in the Eastern Desert(ED)of Egypt comprises juvenile suites of metavolcanics(MV),large amounts of meta-sedimentary rocks(MS),and voluminous metagabbros-diorites(MGD)and syn-tectonic intrusions of older granitoids(OG).We report here the updates of these four rock units in terms of classification,distribution,chemical characteristics,geodynamic evolution,metamorphism,and *** addition,we discuss these integrated data to elucidate a reasonable and reliable model for crustal evolution in the *** main features of these rock units indicate their relation to each other and the geodynamic environment dominated by early immature oceanic island arcs to primitive continental *** information of the island arc metavolcanic and plutonic rocks(gabbros,diorites,tonalites,and granodiorites)furnish evidence of the genetic *** include proximity and a coeval nature in the field;all protolith magmas are subalkaline in nature following calc-alkaline series with minor tholeiitic affinities;common geochemical signature of the arc rocks and subduction-related magmatism;their similar enrichment in LREEs;and similar major element compositions with mafic melts derived from metasomatized mantle *** volcano-sedimentary and the OG rocks underwent multiphase deformation events whereas the MGD complexes deformed *** on the magmatic,sedimentological,and metamorphic evolutions constrained by geochronological data as well as the progressive evolutionary trend from extensional to compressional regimes,a possible gradual decrease in the subducted slab dip angle is the most infl uential in any geodynamic model for arc assemblage in the ED of Egypt.

关键词： Island arc assemblage Magmatism Crustal growth Neoproterozoic Arabian–Nubian Shield Eastern Desert Egypt

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geological reservoir and resource potential(10^(13)m^(3))of gas hydrates in the South China Sea

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China Geology 2024年第3期7卷 422-444页

作者： Pi-bo Su Wei Wei Yun-bao Sun Yao-yao Lü Huai Cheng Wei-feng Han Wei Zhang Jin-qiang Liang National Engineering Research Center for Gas Hydrate Exploration and Development Guangzhou 511458China Sanya Institute of South China Sea Geology Guangzhou Marine Geological SurveySanya 572025China Central Laboratory of geological Sciences Research Institute of Petroleum Exploration and DevelopmentLangfang 065007China Qingdao Institute of Marine Geology Qingdao 266237China Laboratory for Marine Mineral Resources Qingdao Marine Science and Technology CenterQingdao 266237China

A detailed understanding of the distribution and potential of natural gas hydrate(NGHs)resources is crucial to fostering the industrialization of those resources in the South China Sea,where NGHs are *** this study,this study analyzed the applicability of resource evaluation methods,including the volumetric,genesis,and analogy methods,and estimated NGHs resource potential in the South China Sea by using scientific resource evaluation methods based on the factors controlling the geological accumulation and the reservoir characteristics of ***,this study compared the evaluation results of NGHs resource evaluations in representative worldwise sea areas via rational *** results of this study are as follows:(1)The gas hydrate accumulation in the South China Sea is characterized by multiple sources of gas supply,multi-channel migration,and extensive accumulation,which are significantly different from those of oil and gas and other unconventional resources.(2)The evaluation of gas hydrate resources in the South China Sea is a highly targeted,stratified,and multidisciplinary evaluation of geological resources under the framework of a multi-type gas hydrate resource evaluation system and focuses on the comprehensive utilization of multi-source heterogeneous data.(3)Global NGHs resources is n×10^(15)m^(3),while the NGHs resources in the South China Sea are estimated to be 10^(13)m^(3),which is comparable to the abundance of typical marine NGHs deposits in other parts of the *** the South China Sea,the NGHs resources have a broad prospect and provide a substantial resource base for production tests and industrialization of NGHs.

关键词： Reservoir characteristics Natural gas hydrates Gas migration Resource potential Resource evaluation methods Hierarchical evaluation system Volumetric method South China Sea Clean energy exploration engineering

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Optimization of modelling strategies for regional landslide susceptibility assessment based on machine learning methods -A viewpoint from the modelling dataset design and partition

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Journal of Earth Science 2024年

作者： Yuhang Zhu Kunlong Yin Shuhao Liu Zhenyi Liu Taorui Zeng Institute of geological survey， China University of Geosciences Wuhan Faculty of Engineering， China University of Geosciences Institute of Future Civil Engineering Science and Technology， Chongqing Jiaotong University Institute of Frontier Interdisciplinary Technology， Chongqing Jiaotong University

The inappropriatemodelling strategies can lead to unsatisfactory prediction results for landslide susceptibility assessment (LSA). The objectivesof this study are to reveal the impact of dataset design value (ratio of negative to positive samples) and partition (ratio of training to testing dataset) on the accuracy of LSA based on different machine learning models. The Yunyang County of the Three Gorges Reservoir area (China) was taken as the study area and 15 conditioning factors were determined. Ten modelling datasets design values (0.125， 0.25， 0.5， 1， 2， 5， 8， 10， 12 and 15) were determined for the ratio of non-landslide and landslide samples， and each modelling dataset was divided into five partitions ((50:50) %， (60:40) %， (70:30) %， (80:20) % and (90:10) %) for the ratio of training and testing datasets. Each scenario was then applied on four machine learning models (Classification and Regression tree (CART)， Bayes Network (BN)， Logistic Regression (LR) and Multilayer Perceptron (MLP)). The optimal parameters of the modelling dataset were obtained by comparing 200 sets of the AUC under different combined scenarios. The results showed that different sampling strategies significantly affect the accuracy of LSA. With increasing of the design values， the AUC of the CART and MLP models first increased and then decreased， peaking at 1 (AUC=0.85 and 0.83)， while the AUC of the BN and LR models remained stable， vary from 0.755 to 0.796. Comparatively， different partitions had less impact on the AUC of various models， AUC vary by around 0.04. The highest prediction accuracy was obtained when the design value was 1 and the partition was (80:20) %. The outcome can provide a guideline for researchers to choose an optimal modelling strategy for LSA in the future.

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First-Arrival Picking Method for Active Source Data with Ocean Bottom Seismometers Based on Spatial Waveform Variation Characteristics

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Journal of Ocean University of China 2024年第4期23卷 970-980页

作者： LIU Hongwei XING Lei ZHU Henghua ZHANG Jin ZHANG Jing LIU Huaishan Key Laboratory of Submarine Geosciences and Prospecting Techniques Ministry of EducationCollege of Marine GeosciencesOcean University of ChinaQingdao 266100China Laboratory for Marine Mineral Resources Qingdao Marine Science and Technology CenterQingdao 266071China College of Underwater Acoustic Engineering Harbin Engineering UniversityHarbin 150001China Shandong Institute of geological survey Jinan 250014China

The precision and reliability of first-arrival picking are crucial for determining the accuracy of geological structure inversion using active source ocean bottom seismometer(OBS)refraction *** methods for first-arrival picking based on sample points are characterized by theoretical errors,especially in low-sampling-frequency OBS data because the travel time of seismic waves is not an integer multiple of the sampling *** this paper,a first-arrival picking method that utilizes the spatial waveform variation characteristics of active source OBS data is ***,the distribution law of theoretical error is examined;adjacent traces exhibit variation characteristics in their ***,a label cross-correlation superposition method for extracting highfrequency signals is presented to enhance the first-arrival picking *** from synthetic and field data verify that the proposed approach is robust,successfully overcomes the limitations of low sampling frequency,and achieves precise outcomes that are comparable with those of high-sampling-frequency data.

关键词： first-arrival picking spatial waveform variation label cross-correlation superposition method

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Mantle Driven Early Eocene Magmatic Flare-up of the Gangdese Arc, Tibet: A Case Study on the Nymo Intrusive Complex

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Acta Geologica Sinica(English Edition) 2024年第4期98卷 878-903页

作者： MA Xuxuan Joseph GMEERT CAO Wenrong TIAN Zuolin LIU Dongliang XIONG Fahui LI Haibing Key Laboratory of Continental Tectonics and Dynamics of Ministry of Natural Resources Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China Jiangsu Donghai Continental Deep Borehole Crustal Activity National Observation and Research Station DonghaiJiangsu 222300China department of geological Sciences Neil Opdyke Paleomagnetic LaboratoryUniversity of Florida241 Williamson HallGainesvilleFL 32611USA department of geological Sciences and Engineering University of NevadaRenoMS-1721664 N.Virginia St.RenoNV 89557USA

Magmatic periodicity is recognized in continental arcs worldwide, but the mechanism responsible for punctuated arc magmatism is controversial. Continental arcs in the Trans-Himalayan orogenic system display episodic magmatism and the most voluminous flare-up in this system was in early Eocene during the transition from subduction to collision. The close association of the flare-up with collision is intriguing. Our study employs zircon Lu-Hf and bulk rock Sr-Nd isotopes, along with mineral geochemistry, to track the melt sources of the Nymo intrusive complex and the role of mantle magma during the early Eocene flare-up of the Gangdese arc, Tibet. The Nymo intrusive complex is composed of gabbronorite, diorite, quartz diorite, and granodiorite which define an arc-related calc-alkaline suite. Zircon U-Pb ages reveal that the complex was emplaced between ~50–47 Ma. Zircon Hf isotopes yield εHf(t) values of 8.2–13.1, while whole-rock Sr and Nd isotopes yield εNd(t) values of 2.7–6.5 indicative of magmatism dominated by melting of a juvenile mantle source with only minor crustal assimilation(~15%–25%) as indicated by assimilation and fractional crystallization modeling. Together with published data, the early Eocene magmatic flare-up was likely triggered by slab breakoff of subducted oceanic lithosphere at depths shallower than the overriding plate. The early Eocene magmatic flare-up may have contributed to crustal thickening of the Gangdese arc. This study provides important insights into the magmatic flare-up and its significant role in the generation of large batholiths during the transition from subduction to collision.

关键词： mantle magmatic flare-up subduction–collision transition Nymo intrusive complex Gangdese Tibet

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Zircon Hf Isotope Mapping for Understanding Crustal Architecture and Its Controls on Mineralization during Early Cretaceous in the Southern Great Xing'an Range,NE China

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Journal of Earth Science 2024年第1期35卷 41-50页

作者： Feng Yuan Huanan Liu Shengjin Zhao Mingjing Fan State Key Laboratory of geological Processes and Mineral Resources Collaborative Innovation Center for Exploration of Strategic Mineral ResourcesSchool of Earth ResourcesChina University of GeosciencesWuhan 430074China State Key Laboratory of geological Processes and Mineral Resources School of Earth Sciences and ResourcesChina University of GeosciencesBeijing100083China No.10 Institute of geological Exploration Inner Mongolia Bureau of Geology and Mineral ResourcesChifeng 024000China Key Laboratory of Metallogeny and Mineral Assessment Institute of Mineral ResourcesChinese Academy of Geological SciencesBeijing 100037China

Voluminous Early Cretaceous granitoids and associated large-scale ore deposits are distributed within the southern Great Xing'an Range(SGXR),NE *** on previously published geochronology and zircon Hf-isotope data,Hf isotope mapping is undertaken to improve our understanding of crustal architecture and its controls on ore *** ore-related Early Cretaceous granitoids were sourced predominantly from juvenile crust,with the involvement of variable proportions of ancient crustal *** crustal architecture,as inferred from Hf isotopic contour maps,indicates two distinct Hf isotopic domains in SGXR,including(1)a higher-ε_(Hf)(+7 to+11)juvenile crust containing minor ancient crustal material,and(2)a lower-ε_(Hf)(+2 to+6)juvenile crust containing a greater proportion of ancient crustal *** Hf isotopic maps identify links between crustal architecture and regional *** deposits and other deposits with significant Cu production are restricted mainly to the higher-ε_(Hf)juvenile crustal regions in the northern and eastern *** dominated by other metals(e.g.,Mo,Sn,W,Pb,Zn,and Ag)occur mainly in the lower-ε_(Hf)juvenile crustal regions in the southern and western *** between juvenile crust-derived melts and ancient crustal components played an important role on the distribution of various ore metals.

关键词： Hf isotope mapping crustal architecture large-scale Early Cretaceous granitoids distribution of ore deposits southern Great Xing'an Range zircon

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Theory and classification of mass extinction causation

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National Science Review 2024年第1期11卷 16-36页

作者： Thomas J.Algeo Jun Shen State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences—Wuhan State Key Laboratory of geological Processes and Mineral Resources China University of Geosciences—Wuhan department of Geosciences University of Cincinnati

Theory regarding the causation of mass extinctions is in need of systematization, which is the focus of this contribution. Every mass extinction has both an ultimate cause, i.e. the trigger that leads to various climato-environmental changes, and one or more proximate cause(s), i.e. the specific climato-environmental changes that result in elevated biotic mortality. With regard to ultimate causes, strong cases can be made that bolide(i.e. meteor) impacts, large igneous province(LIP) eruptions and bioevolutionary events have each triggered one or more of the Phanerozoic Big Five mass extinctions, and that tectono-oceanic changes have triggered some second-order extinction events. Apart from bolide impacts, other astronomical triggers(*** flares, gamma bursts and supernova explosions) remain entirely in the realm of speculation. With regard to proximate mechanisms, most extinctions are related to either carbon-release or carbon-burial processes, the former being associated with climatic warming, ocean acidification, reduced marine productivity and lower carbonate δ13C values, and the latter with climatic cooling, increased marine productivity and higher carbonate δ13C values. Environmental parameters such as marine redox conditions and terrestrial weathering intensity do not show consistent relationships with carbon-cycle *** this context, mass extinction causation can be usefully classified using a matrix of ultimate and proximate factors. Among the Big Five mass extinctions, the end-Cretaceous biocrisis is an example of a bolide-triggered carbon-release event, the end-Permian and end-Triassic biocrises are examples of LIP-triggered carbon-release events, and the Late Ordovician and Late Devonian biocrises are examples of bioevolution-triggered carbon-burial events. Whereas the bolide-impact and LIP-eruption mechanisms appear to invariably cause carbon release, bioevolutionary triggers can result in variable carbon-cycle changes, e.g. carbon burial durin

关键词： biocrisis ultimate cause proximate cause bolide large igneous province bioevolutionary event

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Late Cenozoic uplift of the Liupan Mountains:Evidence from the Neogene loess deposits

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Science China Earth Sciences 2024年第5期67卷 1480-1488页

作者： Zhilin HE Yansong QIAO Zhengtang GUO Chaoqin CHEN Long CHEN Yang FU Ye YANG Yanxia LIANG Xinru LIN Guoqiao XIAO Tao ZHAN Key Laboratory of Cenozoic Geology and Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Institute of Geomechanics Chinese Academy of Geological SciencesBeijing 100081China CAS Center for Excellence in Life and Paleoenvironment Beijing 100044China University of Chinese Academy of Sciences Beijing 100049China Institute of Ecological Geology survey and Research of Heilongjiang Province Harbin 150030China School of Geography and Information Engineering China University of GeosciencesWuhan 430078China School of Earth Sciences China University of GeosciencesWuhan 430074China Natural Resources survey Institute of Heilongjiang Province Harbin 150036China

The Liupan Mountains,one of the important mountain ranges in western China,are located on the boundary between the northeastern Tibetan Plateau and the Ordos *** uplift history of the Liupan Mountains remains *** deposits are good tracers of regional tectonic and geomorphic changes,because loess is sensitive to erosion and the formation and preservation of loess requires relatively flat highlands and relatively stable tectonic *** investigated the distribution of Neogene loess deposits on the western piedmont of the Liupan Mountains and examined a near-continuous loess section(Nanping section)on the piedmont alluvial *** of magnetic susceptibility stratigraphy with the QA-ⅠMiocene loess sequence dates this 56-m section covering the interval from~8.1 to 6.2 *** lower boundary age of this section,together with previously reported Zhuanglang red clay(sand-gravel layers with intercalated loess during~9–8 Ma and near-continuous loess during~8–4.8 Ma)and Chaona red clay(~8.1–2.58 Ma),indicates that the Liupan Mountains were uplifted in the late Miocene(~9–8 Ma)and basically formed by~8 Ma,attesting to no intense mountain building since that *** addition,based on the information from the Zhuanglang core and the QA-Ⅰsection,we infer that sizable parts of the Liupan Mountains were uplifted during the late Oligocene–early Miocene and did not experience intense uplift during~22–9 Ma.

关键词： Liupan Mountains Mountain building Neogene Loess Chinese Loess Plateau Late Miocene Late Oligocene–early Miocene

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Exploring mechanism of hidden,steep obliquely inclined bedding landslides using a 3DEC model:A case study of the Shanyang landslide in Shaanxi Province,China

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China Geology 2024年第2期7卷 303-314,I0001-I0003页

作者： Jia-yun Wang Zi-long Wu Xiao-ya Shi Long-wei Yang Rui-ping Liu Na Lu Xi’an Center of China geological survey/Northwest China Center for Geoscience Innovation Xi’an 710119China Xi’an University of Science and Technology Xi’an 710054China Wuhan Design&Research Institute Co. Ltd.of China Coal Technology&Engineering GroupWuhan 430064China

Catastrophic geological disasters frequently occur on slopes with obliquely inclined bedding structures(also referred to as obliquely inclined bedding slopes),where the apparent dip sliding is not readily *** phenomenon has become a focal point in landslide ***,there is a lack of studies on the failure modes and mechanisms of hidden,steep obliquely inclined bedding *** study investigated the Shanyang landslide in Shaanxi Province,*** field investigations,laboratory tests of geotechnical parameters,and the 3DEC software,this study developed a numerical model of the landslide to analyze the failure process of such *** findings indicate that the Shanyang landslide primarily crept along a weak interlayer under the action of *** landslide,initially following a dip angle with the support of a stable inclined rock mass,shifted direction under the influence of argillization in the weak interlayer,moving towards the apparent dip *** slide resistance effect of the karstic dissolution zone was increasingly significant during this process,with lateral friction being the primary resistance force.A reduction in the lateral friction due to karstic dissolution made the apparent dip sliding characteristics of the Shanyang landslide more ***,deformations such as bending and uplift at the slope’s foot suggest that the main slide resistance shifts from lateral friction within the karstic dissolution zone to the slope foot’s resistance force,leading to the eventual buckling failure of the *** study unveils a novel failure mode of apparent dip creep-buckling in the Shanyang landslide,highlighting the critical role of lateral friction from the karstic dissolution zone in its failure *** insights offer a valuable reference for mitigating risks and preventing disasters related to obliquely inclined bedding landslides.

关键词： Landslide Steep obliquely inclined bedding slope Failure mode Failure mechanism Apparent dip creep-buckling Lateral friction 3DEC model Landslide numerical model geological hazards survey engineering

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First Record of Cyclocarya from the Early Oligocene Qaidam Basin,North Tibet:Implications for the Paleogeography and Paleoecology

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Journal of Earth Science 2024年第1期35卷 201-211页

作者： Yafei Hou Bowen Song Xiangchuan Li Fang Han Xu Zhang Kexin Zhang Institute of geological survey China University of GeosciencesWuhan 430074China Faculty of Materials Science and Chemistry China University of GeosciencesWuhan 430074China State Key Laboratory of Biogeology and Environmental Geology China University of GeosciencesWuhan 430074China College of Earth Sciences and Resources&Key Laboratory of Western Mineral Resources and geological Engineering of the Ministry of Education Chang'an UniversityXi'an 710054China State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of SciencesNanjing 210008China School of Earth Sciences East China University of TechnologyNanchang 330013China

As the largest intermontane basin in the northeastern Tibetan Plateau(TP),the Qaidam Basin provides unique insight into paleoclimatic change and its relationship with global change and uplift on the *** this study,based on morphological comparison,fossil fruit of Cyclocarya from the Early Oligocene Shangganchaigou Formation in the Qaidam Basin is assigned as Cyclocarya *** discovery of Cyclocarya *** demonstrates the occurrence of Cyclocarya in the Oligocene sediment in Qaidam *** is the first record of Cyclocarya fossil of Early Oligocene Age in China and indicates that Cyclocarya has existed on the northeastern TP since at least the Early *** living analogues of the current fossil now lives in sub-tropical China,where the East Asian Monsoon is *** the new fossils and previously reported fossil remains of plants and fishes,it can be inferred that the Early Oligocene Qaidam Basin was primarily influenced by westerly circulation and had a relatively warm and humid climate,which was in sharp contrast to the present-day climate in Qaidam Basin.

关键词： biostratigraphy climate change winged-fruit fossil Qaidam Basin Early Oligocene paleoclimate paleogeography

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