检索结果-南通市图书馆

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

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

来源：

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

The Camborygma Ichnofacies in a high-resolution sequence-stratigraphic framework for the Eocene palustrine-alluvial depositional interval of the Kutch Basin,India

引用

Journal of Palaeogeography 2025年第1期14卷 141-156页

作者： Mohuli Das Sudipta Dasgupta Seema Singh Marcos Ant?nio Klunk Renzo D'souza Bombay Ichnos Research Group Department of Earth Sciences Indian Institute of Technology Bombay (IIT Bombay) department of Petroleum Engineering and Earth Sciences Indian Institute of Petroleum and Energy (IIPE) department of geology Panjab University department of geology Universidade do Vale do Rio dos Sinos (UNISINOS)

The non-marine strata of the Ypresian Naredi Formation have been deposited and intermittently pedogenized after the culmination of the Early Eocene Climatic Optimum(EECO). This continental interval comprises intercalation of laterite and palaeosol horizons developed by cyclic episodes of erosion, subaerial exposure, and deposition. The palaeopedological analyses investigate the morphological and micromorphological features evidencing repeated subaerial exposure and consequently moderate to well-developed palaeosol horizons. The topmost laterite bed records an intensely bioturbated ichnofabric(consisting of the root traces and the composite ichnotaxa of lungfish aestivation burrows, Macanopsis(possible arachnid burrows), and Skolithos. The pedogenized shale horizons contain the paucispecific Camborygma-root trace ichnofabric with highly localized patchy preservation of Camborygma symplokonomos, Camborygma eumekenomos, and rhizoturbation. The ichnospecies variation of Camborygma along with the ichnofabric analyses led to the demarcation of stratigraphic horizons and evaluation of the palaeowater-table fluctuations vis-a-vis the low-order allocyclicity, the ethology of producers, and the depositional setting. The paucispecific suite of trace fossils refers to the Camborygma Ichnofacies, where the substrate is intermittently pedogenized and lateritized with upward increasing thickness of beds and intensity of pedogenesis, lateritization, ichnodiversity, and ***, as an expression of high-frequency(interpreted as 5th-order) stratigraphic fluctuations within an early Falling Stage Systems Tract(FSST), a hot palaeoclimate with seasonality varying between humid inundated to dry desiccated conditions is interpreted with the palaeowater table being the base-level control. It culminates with the driest condition at the top with the thickest laterite development associated with the RAeMaS *** the onset of early transgression as documented in the ove

关键词： Camborygma Lungfish aestivation burrow Macanopsis Skolithos Palaeosol-laterite profile Naredi formation

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Seismotectonics of the Kuhbanan fault zone analyzed through spatial distribution of fractal dimensions

引用

Journal of Mountain Science 2025年第2期22卷 436-450页

作者： Abolfazl MOKHTARI Seyed Davoud MOHAMMADI Saeed ZAREI department of geology Faculty of ScienceBu-Ali Sina UniversityHamedan ***Iran department of Geophysics Faculty of Nano and Bio Science and TechnologyPersian Gulf UniversityBushehr 75169Iran

Fractal geometry quantitatively analyzes the irregular distribution of geological features,highlighting the dynamic aspects of tectonics,seismic heterogeneity,and geological *** study analyzed the active fault data along the Kuhbanan fault zone in southeastern Iran by applying the boxcounting method and observing the changes in Coulomb stress and tried to find the potential triggering *** entire region was divided into 16subzones with the box-counting method,and then the fractal dimension(D)in each zone was *** analysis of the fractal dimension for active faults and earthquake epicenters along with the seismicity parameter(b)and their ratio in the Kuhbanan region indicates an imbalance between seismic fractals and *** finding suggests that the area may have the potential for future earthquakes or hidden *** conjunction with b-value and changes in Coulomb stress change,D-value analysis reveals intense tectonic activity and stress accumulation,particularly within the Ravar,Zarand,and Kianshahr *** may be considered a potential location for future *** changes in Coulomb stress resulting from the 2005Dahuieh earthquake have also placed this region within the stress accumulation zone,potentially triggering the mentioned *** integrative approach,backed by historical earthquake data,highlights the impact of fault geometry and stress dynamics,offering an enhanced framework for earthquake forecasting and seismic risk mitigation applicable to other tectonically active areas within the Iranian plateau.

关键词： Tectonic Dynamics Fractal Analysis Seismic Hazard Assessment Active Faults

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Evolution of the elastic properties of lacustrine organic shales under different thermal maturity conditions

引用

Science China Earth Sciences 2025年第3期68卷 781-802页

作者： Zhenjia CAI Luanxiao ZHAO Jiqiang MA Fengshou ZHANG Jianhua GENG State Key Laboratory of Marine geology Tongji University School of Ocean and Earth Science Tongji University department of Geotechnical Engineering College of Civil Engineering Tongji University

Research on the elastic responses of organic-rich shales during thermal evolution has predominantly focused on North American marine shales. However, the rock physics properties of lacustrine(continental) organic-rich shales with varying maturities, particularly under the unique geological conditions in China, have not yet been comprehensively explored. Therefore,characterizing the elastic properties of lacustrine organic-rich shales across various maturity stages is crucial for understanding their seismic rock physics responses and for enabling the identification of sweet spots in continental shale reservoirs using logging and seismic data, as well as facilitating geophysical monitoring of the in-situ conversion of oil shales. In this study,hydrous pyrolysis experiments were conducted on immature shales from the Chang 7 member of the Yanchang Formation in the Ordos Basin and the Jijuntun Formation in the Fushun Basin. Compressional and shear wave velocities, along with elastic anisotropy, were measured at various stages of thermal maturity to observe the evolution of the elastic properties. For the Chang7 shale(compacted shale), both P-and S-wave velocities perpendicular to the bedding decreased significantly during the oil and gas generation stages, with the S-wave velocity perpendicular to the bedding decreasing by over 40%. Meanwhile, the elastic anisotropy increased significantly, likely because of microcracks formed by hydrocarbon expulsion from the bedding-parallel organic matter. In contrast, the Jijuntun Formation shale(cemented shale) exhibited an increase in both P-and S-wave velocities during the oil generation stage. This trend could be attributed to early-stage cementation, which suppressed microcrack formation, while the increase in the elastic modulus of the organic matter became dominant. However, during the gas generation stage, both velocities decreased, while the anisotropy increased owing to the growth of organic pores and microcracks, which out

关键词： Lacustrine shales Thermal pyrolysis Elastic wave velocity Anisotropy In-situ conversion

来源：

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Geochemistry and mineral chemistry of granitic rocks from west Wadi El Gemal area,southern Eastern Desert of Egypt:Indicators for highly fractionated syn-to post-collisional Neoproterozoic felsic magmatism

引用

Acta Geochimica 2025年第1期44卷 163-188页

作者： Hesham Mokhtar Adel A.Surour Mokhles K.Azer Minghua Ren Amir Said department of geology Faculty of ScienceCairo UniversityGiza 12613Egypt department of Geological Sciences Faculty of ScienceGalala UniversityNew Galala City 43511Egypt department of Geological Sciences National Research CentreDokkiGiza 12622Egypt department of Geoscience University of Nevada Las VegasLas VegasNV 89154-4010USA

Leucogranite,pegmatite,and aplite from selected areas in the Wadi El Gemal area in the southern Eastern Desert of Egypt were investigated geochemically for their *** rocks represent a significant episode of felsic magmatism during the late stage of the Pan-African orogeny in the evolution of the Arabian–Nubian Shield(ANS)during the Late *** a petrographic basis,the leucogranite is sometimes garnetiferous and can be distinguished into monzogranite,syenogranite,and alkali feldspar *** analyses of muscovite,biotite,garnet,and apatite reveal the magmatic nature of the studied *** investigated leucogranite,pegmatite,and aplite are alkali-calcic,calc-alkaline,and *** peraluminous nature of these rocks is evidenced by using the chemical analyses of *** studied rocks show a slight enrichment in light rare-earth elements(LREEs)and large-ion lithophile elements(LILE,especially Rb and Th),with an insignificant depletion of heavy rareearth elements(HREEs).On a geochemical basis,the leucogranite,pegmatite,and aplite in the study area crystallized from multiple-sourced melts that include mafic,metagraywake,and *** were derived from melts generated at crystallization temperatures around 568-900℃ for leucogranite,553-781℃ for pegmatite,and 639-779℃ for aplite based on the Zr saturation geothermometers,and at a pressure around 0.39-0.48 GPa,*** depth *** studied felsic rocks have strong negative Eu anomalies,which are very consistent with an upper crust composition,indicating fractionation of feldspar ***,they show a moderate La/Sm ratio indicating combined magmatic processes represented by partial melting and fractional *** of whole-rock chemical composition and mineral microanalysis suggests that felsic magmatism in the west Wadi El Gemal area produced voluminous masses of syn-to post-collisional granite,pegmatite,and *** evolutionary three-

关键词： Leucogranite Pegmatite Aplite Wadi El Gemal Petrogenesis Syn-collisional Post-collisional

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Disentangling the contributing components of stream water by using environmental tracers

引用

Journal of Mountain Science 2025年第1期22卷 260-277页

作者： Abul Amir KHAN Naresh Chandra PANT Amity Centre for Air Pollution Control(ACAPC)&Amity Centre for Ocean Atmospheric Science and Technology(ACOAST) Amity University Haryana(AUH)Gurugram-122413India department of geology University of DelhiNorth CampusDelhi-11007India

Identifying the various components contributing to river discharge can be *** study relies on stable isotopes and electrical conductivity(EC)of water as tracers to distinguish the different components contributing to total river ***,we have made an effort to comprehend the processes that may influence glacier ice melt as well as the limits of oxygen-based hydrograph *** distinct geographic domains in terms of climates and topographies were *** first study site represents the upper Ganga catchment(central Himalaya),while the second site is located in the Chandra sub-basin in western *** in estimating the proportion of glacier melt in isotope mixing model are likely if end-member isotopic compositions,are not well defined,particularly for *** separation results indicate that snowmelt is the largest contributor to total river flow in both *** contribution of snowmelt to the total runoff of the upper Ganga ranged from~60%to 70%.The estimated contributions of glacier melt varied from 36%to 63%in upper Ganga headwater to 6%to 15%at Devprayag and~8%at *** the Hamtah River,glacier and snowmelt contributions,quantified using a two-component mixing model,ranged from 10%to 14%during the pre-and postmonsoon seasons of *** significant spatial and temporal variability,coupled with overlapping isotopic signatures,suggests complex glacio-fluvial interactions in these *** slow-moving air masses with whirling motion closer to the study area irrespective of the direction,and air parcels coming through Bay of Bengal branch are characterized by depleted isotopic rainfall compared to air masses originating from the Arabian Sea.

关键词： Snowmelt Glacier melt Oxygen isotopes Bhagirathi River Alaknanda River Hamtah

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A complementary approach to quantify the basic GSI chart considering scale effect on rock structure

引用

Journal of Rock Mechanics and Geotechnical Engineering 2025年第1期17卷 154-167页

作者： Harun Sonmez Gulseren Dagdelenler Yilmaz Ozcelik Murat Ercanoglu Applied geology Division Geological Engineering DepartmentFaculty of EngineeringHacettepe UniversityBeytepeAnkara06800Türkiye Mining Engineering department Faculty of EngineeringHacettepe UniversityBeytepeAnkara06800Türkiye

Geological strength index(GSI)has been widely used as an input parameter in predicting the strength and deformation properties of rock *** study derived a series of equations to satisfy the original GSI lines on the basic GSI *** axes ranging from 0 to 100 were employed for surface conditions of the discontinuities and the structure of rock mass,which are independent of the input *** derived equations can analyze GSI values ranging from 0 to 100 within±5%*** engineering dimensions(EDs)such as the slope height,tunnel width,and foundation width were used together with representative elementary volume(REV)in jointed rock mass to define scale factor(sf)from 0.2 to 1 in evaluating the rock mass structure including joint *** transformation of GSI into a scaledependent parameter based on engineering scale addresses a crucial requirement in various engineering *** improvements proposed in this study were applied to a real slope which was close to the time of *** results of stability assessments show that the new proposals have sufficient capability to define rock mass quality considering EDs.

关键词： Basic GSI chart Engineering dimension(ED) Hoek and Brown failure criterion Quantification of GSI Quantitative GSI chart Scale effect

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

Petrogenesis of late Cretaceous high Ba-Sr granodiorites,SE Lhasa block,China:implications for the reworking of juvenile crust and continental growth

引用

Acta Geochimica 2025年第1期44卷 86-111页

作者： Li-Hang Lin Ren-Zhi Zhu Shao-Cong Lai Jiang-Feng Qin Yu Zhu Shao-Wei Zhao Min Liu State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi’an 710069China Ministry of Education Key Laboratory of Western China’s Mineral Resources and Geological Engineering School of Earth Science and ResourcesChang’an UniversityXi’an 710054China

The high Ba-Sr rocks can provide significant clues about the evolution of the continent lithosphere,but their petrogenesis remains *** the Late Cretaceous high Ba–Sr granodiorites in the SE Lhasa Block could potentially provide valuable insights into the continent evolution of the Qinghai-Tibet *** U–Pb ages suggest that the granodiorites were emplaced at 87.32±0.43 ***,the high Ba–Sr granodiorites are characterized by elevated K_(2)O+Na_(2)O contents(8.18-8.73 wt%)and K_(2)O/Na_(2)O ratios(0.99-1.25,mostly>1),and belong to high-K calc-alkaline to shoshonitic *** Yonglaga granodiorites show notably high Sr(653-783 ppm)and Ba(1346-1531 ppm)contents,plus high Sr/Y(30.92-38.18)and(La/Yb)_(N)(27.7-34.7)ratios,but low Y(20.0-22.8 ppm)and Yb(1.92-2.19 ppm)contents with absence of negative Eu anomalies(δEu=0.83-0.88),all similar to typical high Ba–Sr *** variable zirconεHf(t)values of-4.58 to+12.97,elevated initial^(87)Sr/^(86)Sr isotopic ratios of 0.707254 to 0.707322 and lowεNd(t)values of-2.8 to-3.6 with decoupling from the Hf system suggest that a metasomatized mantle source included significant recycled ancient *** occurrence of such high Ba–Sr intrusions indicates previous contributions of metasomatized mantle-derived juvenile material to the continents,which imply the growth of continental crust during the Late Cretaceous in the SE *** with regional data,we infer that the underplated mafic magma provides a significant amount of heat,which leads to partial melting of the juvenile *** melting of the metasomatized mantle could produce a juvenile mafic lower crust,from which the high Ba–Sr granitoids were derived from reworking of previous mafic crust during the Late Cretaceous(ca.100-80 Ma)in the SE Lhasa.

关键词： Late Cretaceous High Ba-Sr granodiorites SE Lhasa Growth of continental crust Juvenile crust

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

A new exceptionally preserved corystosperm wood from the Jurassic of East Asia

引用

Science China Earth Sciences 2025年第3期68卷 803-810页

作者： Zikun JIANG Ning TIAN Yongdong WANG Fangyu LI Junling PEI Dieter UHL Ya LI Hao WU Zhenguo NING Ruiying HAO Chinese Academy of Geological Sciences College of Palaeontology Shenyang Normal University Nanjing Institute of geology and Palaeontology Chinese Academy of Sciences College of Resources and Environmental Engineering Guizhou University East China university of Technology Senckenberg Research Institute and Natural History Museum Frankfurt Zhejiang Museum of Natural History department of Natural Resources of Shandong Province

Corystosperms, an extinct group of “seed ferns” that lived from the late Permian to the Cretaceous or Eocene, are significant for seed plant phylogeny for their unique roles in partially resolving the long-standing question of angiosperm origins.A new fossil wood taxon, Fengweioxylon sinense gen. et sp. nov. is reported here based on exceptionally preserved wood material from the Jurassic in western Liaoning, China, whose peculiar wood structure enables it to be recognized as the first unequivocal fossil wood record of a corystosperm plant in Laurasia. The anatomical structures of this corystosperm wood show gymnospermous characters. The discovery of the new specimen will provide more anatomical evidence for understanding the systematic and affinity of this seed plants.

关键词： Corystosperms Fossil wood Laurasia Jurassic

来源：

同方期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Metallogenic model of sandstone-hosted copper deposits:a case study from the Paleogene in Jiashi area,northwestern China

引用

Journal of Palaeogeography 2025年第01期14卷 105-125页

作者： Long-Qing Shi Xing-Yue Qu Carlos Zavala Yang Li College of Earth Science and Engineering Shandong University of Science and Technology geology department Universidad Nacional del Sur Geología de Cuencas Sedimentarias (GCS) Argentina Institute of Energy Peking University Ordos Research Institute of Energy Peking University Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals Shandong University of Science and Technology

Sandstone-hosted copper deposits,a type of Sediment-Hosted Stratiform Copper (SSC) deposits,are widely distributed *** economically viable deposits of SSC are relatively scarce,they account for approximately 30%of the world's total discovered copper ***,there is still a lack of comprehensive and in-depth research into the depositional and metallogenic models of these *** Jiashi area of the Tarim Basin in northwestern China,known for its economically significant Paleogene SSC deposit,lacks in-depth studies on metallogenic *** address this,field profile observations were conducted to analyze the sedimentary evolution,sequence stratigraphy,and tectonism of the Paleogene strata in the Jiashi *** with elemental geochemical analysis of samples,the provenance of sediment,and the source of metallogenic materials,a robust metallogenic model was *** results reveal the influence of provenance for the origin of Paleogene copper-rich *** evolution played a crucial role in controlling the distribution of copper and sulfur elements,as well as the spatial arrangement of metallogenic ***,nappe movement potentially generated faults,allowing upward movement of basin fluids,which played a crucial role in the formation of copper deposits within sandstone-hosted ***,this study offers a comprehensive analysis of the metallogenic processes involved in sandstone-hosted copper deposits,thereby contributing significant insights to the broader research on SSC deposits worldwide.

关键词： Tarim Basin Paleogene Sandstone-hosted copper deposits Metallogenic material source Metallogenic model

来源：

同方期刊数据库评论

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：