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Sedimentary Expressions of the Early Jurassic Jenkyns Event in an Inland Lacustrine System in the Yin'gen–Ejinaqi Basin, North China

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Acta Geologica Sinica(English Edition) 2024年第5期98卷 1359-1375页

作者： YANG Bing XU Guozhen HUI Guangji WEI Yi ZHANG Xinzhi YI Jinjun SUN Siyuan ZHANG Sujiang Cores and Samples Center of Natural Resources Nanjing institute of geology and Palaeontology Chinese Academy of Sciences North China institute of Science and Technology

The Jenkyns Event, more widely known as the Toarcian Oceanic Anoxic Event(T-OAE), is marked by globally distributed negative carbon-isotope excursions, widespread oxygen depletion, and large-scale organic carbon burial, which indicate major climate/environmental perturbations in Earth's surface systems during the Early Jurassic. Although extensive research has been conducted in European continental settings, particularly in the western peri-Tethys regions, the impacts of this event beyond Europe remains largely unexplored. Here, a multiapproach study including investigations into the sporepollen assemblages, pyrite framboids, clay minerals, total organic carbon(TOC) levels, and organic carbon isotope(δ13Corg) levels in a lacustrine borehole section(MED1) from the Yin'gen–Ejinaqi Basin, North China, provides evidence of the occurrence of the Jenkyns Event and its extensive sedimentary responses in the eastern Tethys terrestrial systems. Two distinct spore-pollen assemblages have been identified in MED1(drilling depth: 982.4 m to 12.7.5 m), with the Cycadopites–Protopinus–Osmundacidites assemblage in the lower part(12.7.5 m to 1132.9 m) indicating a middle Early Jurassic age and the Classopollis assemblage in the upper part(1132.9 m to 985.7 m) suggesting a Toarcian age. Framboidal pyrite data suggest more anoxic conditions during the deposition of black mudstone and shale intercalations in the lower part of the Classopollis assemblage(1132.9 m to 1066.9 m), which combined with organic carbon enrichment and negative δ13Corg excursions, are considered the paleoenvironmental response to the Jenkyns Event in the study area. Furthermore, the evolution of vegetation groups changed from plant groups characterized by bisaccate and cycad pollen, as well as fern spores, to vegetation groups represented by Cheirolepidiaceae pollen across the Jenkyns Event, as evidenced by sporepollen data, together with the clay mineral assemblage change characterized by a notable increase in i

关键词： clay minerals Jenkyns event organic carbon isotope pyrite framboids spore-pollen assemblages

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Spatial distribution characteristics and influence factor analysis of landslides——case study of the Hanwang area in Qinba Mountains

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Earthquake Research Advances 2024年第3期4卷 55-65页

作者： Jikai Zhang Yanbo Cao Wen Fan Wenbo Zheng Zequan Wang Chengcheng He Hongquan Teng School of Geological Engineering and Geomatics Chang’an UniversityXi'an710054China Mine Geological Disasters Mechanism and Prevention Key Laboratory Xi'an710054China China DK Comprehensive Investigate and Design Research institute Co. Ltd.Xi'an710054China Shaanxi Engineering Technology Research Center for Urban geology and Underground Space Xi'an710068China Shaanxi Hydrogeology Engineering Geology and Environment Geology Survey CenterXi'an710068China Chang'an University Xi'anShaanxiChina

The geological hazards of landslides in Hanwang Town, Ziyang County, Ankang City, Shaanxi Province, have emerged. Yet, the current understanding of the spatial distribution characteristics and influencing factors of landslides in this area remains unclear. Combining the results of remote sensing interpretation and field investigation, seven influencing factors, namely, elevation, slope direction, slope gradient, distance from rivers, distance from faults, engineering geologic lithology, and distance from roads, are selected for the study. The distribution characteristics of landslides in each influencing factor and the influence of the resolution of the Digital Elevation Model(DEM) on the results are statistically and analytically analyzed. Furthermore, two highrisk landslides within the study area were subjected to comprehensive analysis, integrating the findings from drilling and other field investigations in order to examine their deformation mechanisms. Based on this analysis,the following conclusions were derived:(1) 34 landslides in the study area, mainly small earth landslides, with a distribution density of 0.42.km~2. threatening 414 people and property of about 55.87 million Yuan.(2.The landslides in the study area easily occur in the 2.0 m), the landslide-prone strata are mainly the softer and weaker metamorphic rocks, and the landslides are mainly around roads.(3) The resolution of the DEM should be selected based on the specific conditions of the study area, the requirements of the investigation, and the scale of the landslide. Opting for an appropriate DEM resolution is advantageous for understanding the patterns of landslides and conducting risk assessments in the region.(4) The Zhengjiabian landslide is a trac

关键词： Landslide Spatial distribution Influence factor Landslide density Deformation mechanism DEM

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Characteristics and genesis of groundwater salinization in coastal areas of the Lower Reaches of Oujiang Basin

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Journal of Groundwater Science and Engineering 2024年第2期12卷 190-204页

作者： Mei-hui Zhang Shi-yang Zhou Dan-dan Liu Ying Zhang Yu-xi Zhang Xi Chen Hui-wei Wang Bei Li Wei Kang Bing Yi Wan-peng Shi institute of Hydrogeology and Environmental geology Chinese Academy of Geological SciencesShijiazhuang 050061China Fujian Provincial Key Laboratory of Water Cycling and Eco–Geological Processes Xiamen 361021FujianChina China University of Geosciences(Beijing) Beijing 100083China Changsha Center of Natural Resources Comprehensive survey China Geological SurveyChangsha 410600China Hydrogeological Environmental Geological survey Center of China Geological survey Tianjin 071501China China University of Geosciences Wuhan 430074China

The coastal areas of the lower reaches of Oujiang River Basin are rich in groundwater ***,the unsustainable exploitation and utilization of groundwater have led to significant changes in the groundwater *** the characteristics and genesis of groundwater salinization is crucial for preventing its deterioration and ensuring sustainable *** this study,a comprehensive approach combining the ion ratio method,mineral saturation index method and multivariate statistical analysis was employed to investigate the hydrochemical characteristics and main controlling factors in the study *** findings reveal that:(1)Groundwater samples in study area exhibit a neutral to slightly alkaline *** predominant chemical types of unconfined water are HCO_(3)-Ca·Na,HCO_(3)·Cl-Na·Ca and HCO_(3)·SO_(4)-Ca·Na,while confined water mainly exhibits Cl·HCO_(3)-Na and Cl-Na types.(2.Salinity coefficients indicate an increase in salinity from unconfined to confined ***,Na^(+)and Cl^(–)concentrations show an increasing trend from mountainous to coastal areas in unconfined water,while confined water displays variability in TDS,Na^(+)and Cl^(–)concentrations.(3)Groundwater salinity is mainly influenced by water-rock interactions,including the dissolution of halite and gypsum,cation exchange,and seawater intrusion ***,human activities and carbonate dissolution contribute to salinity in unconfined *** intrusion is identified as the primary factor leading to higher salinity in confined water compared to unconfined water,with increasing cation exchange and seawater interaction observed from unconfined to confined water.

关键词： Hydrochemical Multivariate statistical analysis Seawater intrusion

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Late Mesoproterozoic to Early Neoproterozoic Tectonic Evolution of the SW Yangtze Block, South China: Evidence from U-Pb Geochronology and Lu-Hf Isotopes of Detrital Zircons from Sedimentary Rocks

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Journal of Earth Science 2024年第3期35卷 812-827页

作者： Peiwen Liu Xiaozhong Ding Yanxue Liu Jibiao Zhang institute of geology Chinese Academy of Geological SciencesBeijing 100037China School of Civil and Hydraulic Engineering Xichang UniversityXichang 615000China

In situ zircon U-Pb geochronological and Lu-Hf isotope studies of detrital zircons from Late Mesoproterozoic to Early Neoproterozoic sedimentary units on the southwestern margin of the Yangtze Block have important implications for the tectonic evolution of the Yangtze *** Huili Group contains zircons whose ages are mainly Late Archean to Mesoproterozoic(2.50-2.50,2.00-1800,and 1350-1150 Ma).The Dengxiangying Group has one major age population of 1900-1600 Ma,and two subordinate age populations of 1350-1100 and 2.00-2.00 *** Group sedimentary rocks have a zircon age population mainly in the range of 970-850 Ma,contemporaneous with the ages of widespread arc-related magmatism in the western Yangtze *** these results with previous work,the Huili and Dengxiangying groups were most likely deposited during ca.1160 to 1000 Ma in an intra-continental rift basin setting,while the Yanbian Group accumulated during>92. to 782.Ma in a back-arc basin setting at the southwestern margin of the Yangtze *** addition,all these results further suggest a tectonic transition from a continental rift basin to a convergent environment at the southwestern margin of the Yangtze Block at 1000-970 Ma.

关键词： Late Mesoproterozoic Early Neoproterozoic zircon U-Pb age Lu-Hf isotope southwestern Yangtze Block geochronology

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Petrogenesis and tectonic implications of the Silurian adakitic granitoids in the eastern segment of the Qilian Orogenic Belt,Northwest China

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Acta Geochimica 2024年第1期43卷 72-86页

作者： Jiao-Long Zhao Xiao-Jun Huang Pei-Qing Hu Zhen-Xi Yang Ying Fan Er-Teng Wang Fu-Bo Yang Jing-Yu Zhang School of Earth Sciences Key Laboratory of Mineral Resources in Western China(Gansu Province)Lanzhou UniversityLanzhou 730000China Nuclear Industry 2.7 Brigade Tianjin North China Geological Survey BureauTianjin 301800China Fourth institute of Geological and Mineral Exploration of Gansu Provincial Bureau of geology and Mineral Resources Jiuquan 735000China

Geodynamic mechanism responsible for the generation of Silurian granitoids and the tectonic evolution of the Qilian orogenic belt remains controversial. In this study, we report the results of zircon U–Pb age, and systematic whole-rock geochemical data for the Haoquangou and Liujiaxia granitoids within the North Qilian orogenic belt and the Qilian Block, respectively, to constrain their petrogenesis, and the Silurian tectonic evolution of the Qilian orogenic belt. Zircon U–Pb ages indicate that the Haoquangou and Liujiaxia intrusions were emplaced at42. ± 3 Ma and 432.± 4 Ma, respectively. The Haoquangou granodiorites are calc-alkaline, while the Liujiaxia granites belong to the high-K calc-alkaline *** are peraluminous in composition and have relatively depleted Nd isotopic [ε_(Nd)(t) =(-3.9 – + 0.6)] characteristics compared with regional basement rocks, implying their derivation from a juvenile lower crust. They show adakitic geochemical characteristics and were generated by partial melting of thickened lower continental crust. Postcollisional extensional regime related to lithospheric delamination was the most likely geodynamic mechanism for the generation of the Haoquangou granodiorite, while the Liujiaxia granites were generated in a compressive setting during continental collision between the Qaidam and Qilian blocks.

关键词： Silurian adakitic granitoids Petrogenesis Tectonic setting Qilian Orogenic Belt

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Geological characteristics of unconventional tight oil reservoir (10^(9) t): A case study of Upper Cretaceous Qingshankou Formation, northern Songliao Basin, NE China

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China geology 2024年第1期7卷 51-62页

作者： Li-zhi Shi Zhuo-zhuo Wang Zhan-tao Xing Shan Meng Shuai Guo Si-miao Wu Li-yan Luo Chinese Academy of Geological Sciences Beijing 100037China Beijing institute of Engineering geology Beijing 100048China

The Daqing exploration area in the northern Songliao Basin has great potential for unconventional oil and gas resources,among which the total resources of tight oil alone exceed 109 t and is regarded as an important resource base of Daqing *** years of exploration in the Qijia area,Songliao Basin,NE China,tight oil has been found in the Upper Cretaceous Qingshankou *** work out tight oil’s geological characteristics,taking tight oil in Gaotaizi oil layers of the Upper Cretaceous Qingshankou Formation in northern Songliao Basin as an example,this paper systematically analyzed the geological characteristics of unconventional tight oil in Gao3 and Gao4 layers of the Qijia area,based on the data of the geological survey,well drilling journey,well logging,and *** is that three sets of hydrocarbon source rocks(K2.n1,K2.n2.3,and K2.1)develop in the examined area,and exhibit excellent type I and II kerogens,high organic matter abundance,and moderate *** reservoir is generally composed of thin-bedded mudstone,siltstone,and sandstone,and presents poor porosity(average 8.5 vol.%)and air permeability(average 4 mD).The main reservoir space primarily includes intergranular pores,secondary soluble pores,and intergranular soluble *** types of orifice throats were identified,namely fine throat,extra-fine throat,and micro-fine *** siltstone is generally oil-bearing,the reservoirs with slime and calcium become worse oil-bearing,and the mudstone has no obvious oil-bearing *** brittleness indices of the sandstone in the tight oil reservoir range from 40%to 60%,and those of the mudstone range from 40%to 45%,indicating a better brittleness of the tight oil *** on the study of typical core hole data,this paper gives a comprehensive evaluation of the properties of the tight oil and establishes a tight oil single well composite bar chart as well as the initial evaluation system with the core of properties in the tigh

关键词： Unconventional oil and gas Tight oil Thin-bedded mudstone-siltstone-sandstone reservoir Qijia area Qingshankou Formation Oil and gas exploration engineering Songliao Basin Daqing oilfield

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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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Characteristics of the Deep Crustal Structure of the Greenland–Iceland–Faroe Ridge in the North Atlantic

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Acta Geologica Sinica(English Edition) 2024年第S1期 87-89页

作者： ZHANG Chunguan LI Fengyuan ZHANG Qiang ZHANG Guoli HU Hongchuan YIN Rui School of Earth Sciences and Engineering Xi'an Shiyou University Shaanxi Key Laboratory of Petroleum Accumulation geology Xi'an Shiyou University institute of Geophysical and Geochemical Exploration CAGS Tianjin Center China Geological Survey

The Greenland–Iceland–Faroe Ridge, located between the central eastern part of Greenland and the northwestern edge of Europe, spans across the North Atlantic. As the core component of the Greenland–Iceland–Faroe Ridge, the Iceland is an alkaline basalt area, which belongs to the periodic submarine magmatism and submarine volcano eruption resulting from mantle plume upwelling(Jiang et al., 2.2.). For the oceanic plateaus, the characteristics of the Iceland are closest to the continental crust, so the Iceland is considered the most suitable for simulating the earliest continental crust on the Earth(Reimink et al., 2.14).

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Phanerozoic Tectonic Evolution,Metallogenesis and Formation of Mineral Systems in China

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Acta Geologica Sinica(English Edition) 2024年第4期98卷 819-842页

作者： CHEN Xuanhua HAN Lele DING Weicui XU Shenglin TONG Ying ZHANG Yiping LI Bing ZHOU Qi WANG Ye SinoProbe Laboratory Chinese Academy of Geological SciencesBeijing 100037China institute of geology Chinese Academy of Geological SciencesBeijing 100037China

The continental Asia is mainly composed of three major tectonic regimes,the Tethys,Paleo Asian Ocean,and West *** underwent multi-stage plate convergences,ocean-continent transformations,and subductions,collisions and/or collages,and post collisional(orogenic)extensions in *** evolution of the Asia brings up a unique fault system and tectonic geomorphological features in the China's ***,it provides a geodynamic background for the formation and evolution of metallogeneses and mineral systems,resulting in nonuniform distribution of tectono-metallogenic systems and metallogenic *** spatiotemporal distribution of mineral deposits in China and adjacent areas exhibits periodic variation under controlling of the full life Wilson cycle and tectonic evolution,forming the plate convergence-related mineral system in East *** Cu deposits are mainly related to compressional systems in Paleozoic and early Mesozoic,and more closely related to post-collision extensional settings in late Mesozoic and *** Au deposits mainly formed in post-orogeny extensional *** rock related rare earth element deposits formed mainly at margins of the North China and Yangtze ***-pegmatite Li and other rare metal deposits formed mainly in early Mesozoic,related to Indosinian post-orogeny ***-metallogenic systems provide important basis for the prospecting of mineral resources.

关键词： tectonic evolution geodynamic system post-orogenic extension metallogenesis tectono-metallogenic system East Asia

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Flow variation and circulation process of saline springs in the Nangqen Basin， Tibetan Plateau

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Journal of Earth Science 2024年

作者： Jibin Han Jianping Wang Hongkui Ma Yongshou Li Zhao An Yong Xiao Wenhua Han Huaide Cheng Haizhou Ma Hongchen Jiang Key Laboratory of Green and High-end Utilization of Salt Lake Resources， Qinghai institute of Salt Lakes， Chinese Academy of Sciences Qinghai Provincial Key Laboratory of geology and Environment of Salt Lakes， Qinghai institute of Salt Lakes， Chinese Academy of Sciences Qinghai Geological survey Faculty of Geosciences and Engineering， Southwest Jiaotong University State Key Laboratory of Biogeology and Environmental geology， China University of Geosciences

There was limited knowledge about the flow fluctuations and cycling processes of saline springs in the Nangqen Basin in the Sanjiang tectonic zone. In this work， the flow variation of the saline springs during the wet and dry seasons were monitored using volumetric and cross-sectional methods， and the cycling process of the saline springs was quantitatively identified using the integrated hydrochemical and isotopic methods. The results show that most saline springs in the Nangqen Basin had significantly different flow rates， ion concentrations， and TDS concentrations. The ions mainly come from carbonate and sulfate minerals. There is no internal hydraulic connection between these saline springs， and the impact of seasonal changes on the flow is relatively small， indicating that the saline springs originate mainly from deep circulation. The recharge elevation of the saline springs ranges 3661–4990 m， with an average of 4100 m. The circulation depth of the saline springs ranges 2.0–570 m， with an average of 431 m. The recycle time ranges 1.15–30.86 years， with an average of 15.66 years. These results could provide a scientific basis for the development and utilization of saline spring resources in the Nangqen Basin.

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