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Convex-up Style of Deformation within Grabens in Regions of Incomplete Crossing Conjugate Normal Faults: A Numerical Simulation Investigation and Case Study

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Journal of earth Science 2024年第3期35卷 839-849页

作者： Zheng Li Kai Wang Xiong Xiong Bing Zhou School of Geophysics and Geomatics China University of GeosciencesWuhan 430074China State Key Laboratory of Geodesy and earth’s Dynamics Innovation Academy for Precision Measurement Science and TechnologyChinese Academy of SciencesWuhan 430077China department of earth Sicences Khalifa UniversityAbu DhabiUnited Arab Emirates

Crossing conjugate normal faults(CCNFs)are extensively developed in many hydrocarbon-producing basins,generally existing in the form of incomplete ***,the effect of the non-conjugate zone of the CCNFs on the conjugate relay zone post late tectonic action has not been previously *** use 3D elastic-plastic modeling to investigate the influence of incomplete(i.e.,partially intersecting)CCNFs on the pattern of deformation of strata in the intersection region.A series of model simulations were performed to examine the effects of horizontal tectonic extension,fault size,and fault depth on the deformation of conjugate relay zones of incomplete *** analyses yielded the following results.(1)The model of incomplete conjugation predicts a convex-up style of deformation in the conjugate graben region superimposed on overall subsidence under applied horizontal tectonic extension.(2)The degree of convex-up deformation of the conjugate graben depends on the influence of the non-conjugate zone on the conjugate relay zone,which varies with the amount of horizontal tectonic extension,fault size,and fault burial depth.(3)Our results indicate that incomplete CCNFs can form convex-up deformation,similar to that in the Nanpu Sag area and provide a sound understanding of hydrocarbon migration and accumulation.

关键词： incomplete conjugate normal fault conjugate graben convex-up deformation hydrocarbons Nanpu Sag tectonics.

An Overview on the Composition and Age of Upper Crust of Proto-Tethyan Lajishan Intra-oceanic Arc,NE Tibet Plateau

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Acta Geologica Sinica(English Edition) 2024年第2期98卷 285-302页

作者： FU Changlei HE Xiaohu YAN Zhen Jonathan CAITCHISON XIAO Wenjiao WANG Bingzhang LI Wufu LI Yusen SinoProbe Laboratory Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China Key Laboratory of the Northern Qinghai–Tibet Plateau Geological Processes and Mineral Resources Qinghai Geological Survey InstituteXining 810012China department of Geology School of Earth SciencesYunnan UniversityKunming 650091China School of earth and Environmental sciences University of QueenslandBrisbane 4072Australia Xinjiang Institute of Ecology and Geography Chinese Academy of SciencesUrumqi 830011China State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China School of earth Science and Resources China University of GeosciencesBeijing 100083China

Identification and anatomy of oceanic arcs within ancient orogenic belt are significant for better understanding the tectonic framework and closure process of paleo-ocean *** article summarizes the geological,geochemical,and geochronological characteristics of upper crust of Proto-Tethyan Lajishan intra-oceanic arc and provides new data to constrain the subduction evolution of the South Qilian *** intra-oceanic arc volcanic rocks,including intermediate-mafic lava,breccia,tuff,and minor felsic rocks,are distributed along southern part of the Lajishan ophiolite *** and isotopic compositions indicate that the intermediate-mafic lava were originated from depleted mantle contaminated by sediment melts or hydrous fluids,whereas the felsic rocks were likely generated by partial melting of juvenile mafic crust in intra-oceanic arc *** from felsic rocks yield consistent and concordant ages ranging from 506 to 523 Ma,suggesting these volcanic rocks represent the relicts of upper crust of the Cambrian intra-oceanic *** with the Cambrian forearc ophiolite and accretionary complex,we suggest that the Cambrian intra-oceanic arc in the Lajishan ophiolite belt is belonging to the intra-oceanic arc system which was generated by south-directed subduction in the South Qilian Ocean at a relatively short interval between approximately 530 and 480 Ma.

关键词： volcanic rocks intra-oceanic arc U-Pb age Lajishan ophiolite belt South Qilian Ocean Proto-Tethyan realm

New findings on the influence of El Nino events on tropical cyclone formation

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Science China earth sciences 2024年第3期67卷 892-893页

作者： Liguang WU department of Atmospheric and Oceanic sciences Institute of Atmospheric SciencesFudan UniversityShanghai 200438China

Tropical cyclones typically form over warm tropical and subtropical ocean surfaces, as their formation and intensification rely primarily on the energy provided by the ocean. Pioneering research by Gray (1968) revealed that the formation of tropical cyclones requires the sea surface temperature (SST) to be no less than 26.5℃. Consequently, SST is commonly recognized as a crucial parameter among the environmental factors influencing tropical cyclone formation(Gray, 1979;Emanuel and Nolan, 2004).

关键词： tropical cyclone ocean

Seasonal influence of freshwater discharge on spatio-temporal variations in primary productivity, sea surface temperature, and euphotic zone depth in the northern Bay of Bengal

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Acta Oceanologica Sinica 2024年第6期43卷 1-14页

作者： Hafez Ahmad Felix Jose Md.Simul Bhuyan Md.Nazrul Islam Padmanava Dash Geosystems Research Institute/department of Geosciences Mississippi State UniversityStarkville 39759USA department of Oceanography University of ChittagongChittagong 4331Bangladesh department of Marine&earth sciences Florida Gulf Coast UniversityFort Myers 33965USA Bangladesh Oceanographic Research Institute Cox’s Bazar 4730Bangladesh Faculty of Marine sciences&Fisheries Institute of Marine SciencesUniversity of ChittagongChittagong 4331Bangladesh department of Geography and Environment Jahangirnagar UniversityDhaka 1342Bangladesh department of Geosciences Mississippi State UniversityStarkville 39759USA

Ocean productivity is the foundation of marine food web,which continuously removes atmospheric carbon dioxide and supports life at sea and on ***-temporal variability of net primary productivity(NPP),sea surface temperature(SST),sea surface salinity(SSS),mixed layer depth(MLD),and euphotic zone depth(EZD) in the northern B ay of Bengal(BoB) during three monsoon seasons were examined in this study based on remote sensing data for the period 2005 to *** compare the NPP distribution between the coastal zones and open BoB,the study area was divided into five zones(Z1-Z5).Results suggest that most productive zones Z2 and Zl are located at the head bay area and are directly influenced by freshwater discharge together with riverine sediment and nutrient *** Z1-Z5,the NPP ranges from 5 315.38 mg/(m^(2)·d) to 346.7 mg/(m^(2)·d)(carbon,since then the same).The highest monthly average NPP of 5 315.38 mg/(m^(2)·d) in February and 5 039.36 mg/(m^(2)·d) in June were observed from Z2,while the lowest monthly average of 346.72 mg/(m^(2)·d) was observed in March from Z4,which is an oceanic *** values vary from 6-154 m for the study area,and it has an inverse correlation with NPP *** is deeper during the summer season and shallower during the wintertime,with a corresponding increase in *** the year,monthly SST shows slight fluctuation for the entire study area,and statistical analysis shows a significant correlation among NPP,and EZD,overall positive between NPP and MLD,whereas no significant correlation among SSS,and SST for the northern ***-term trends in SST and productivity were significantly po sitive in head bay zones but negatively productive in the open *** findings in this study on the distribution of NPP,SST,SSS,MLD,and EZD and their seasonal variability in five different zones of BoB can be used to further improve the management of marine resources and overall environmental condition in response to clim

关键词： chlorophyll a sea surface temperature euphotic zone depth primary productivity Ganges-Brahmaputra ocean color Bay of Bengal monsoon

On the Optimal Initial Inner-Core Size for Tropical Cyclone Intensification: An Idealized Numerical Study

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Advances in Atmospheric sciences 2024年第11期41卷 2141-2155页

作者： Rong FEI Yuqing WANG School of Atmospheric sciences and Remote Sensing Wuxi UniversityWuxi 214105China State Key Laboratory of Severe Weather Chinese Academy of Meteorological SciencesBeijing 100081China International Pacific Research Center Department of Atmospheric SciencesSchool of Ocean and Earth Science and TechnologyUniversity of Hawaii at ManoaHonoluluHawaii 96822USA

Recent observational and numerical studies have revealed the dependence of the intensification rate on the inner-core size of tropical cyclones(TCs). In this study, with the initial inner-core size(i.e., the radius of maximum wind—RMW)varied from 20–180 km in idealized simulations using two different numerical models, we found a nonmonotonic dependence of the lifetime maximum intensification rate(LMIR) on the inner-core size. Namely, there is an optimal innercore size for the LMIR of a TC. Tangential wind budget analysis shows that, compared to large TCs, small TCs have large inward flux of absolute vorticity due to large absolute vorticity inside the RMW. However, small TCs also suffer from strong lateral diffusion across the eyewall, which partly offsets the positive contribution from large inward flux of absolute vorticity. These two competing processes ultimately lead to the TC with an intermediate initial inner-core size having the largest LMIR. Results from sensitivity experiments show that the optimal size varies in the range of 40–120 km and increases with higher sea surface temperature, lower latitude, larger horizontal mixing length, and weaker initial TC intensity. The 40–120 km RMW corresponds to the inner-core size most commonly found for intensifying TCs in observations, suggesting the natural selection of initial TC size for intensification. This study highlights the importance of accurate representation of TC inner-core size to TC intensity forecasts by numerical weather prediction models.

关键词： tropical cyclones intensification inner-core size idealized simulations

Understanding arsenic behavior in alluvial aquifers:Evidence from sediment geochemistry,solute chemistry and environmental isotopes

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Geoscience Frontiers 2024年第5期15卷 222-238页

作者： Shailesh Kumar Yadav AL.Ramanathan Chidambaram Sabarathinam Alok Kumar Manoj Kumar Anshula Dhiman School of Environmental sciences Jawaharlal Nehru UniversityNew Delhi 110067India Water Research Center Kuwait Institute for Scientific ResearchKuwait department of Environmental Studies University of Delhi110007India department of earth and Environmental sciences Indian Institute of Science Education and Research MohaliSector 81140306India

The hydro-geochemistry and isotopic variations in groundwater,coupled with sediment geochemistry,were investigated in the Middle Gangetic Plain,India,to better understand the aquifer dynamics that influence the arsenic(As)evolution and ***-four groundwater samples,thirteen River water samples,and two sediment cores(33 mbgl)were *** samples were analyzed for major ions and trace metals,including As and stable isotopic variability(δ^(2)H,δ^(18)O,andδ^(13)C).The study area was categorized into older and younger alluvium based on existing geomorphological *** alluvium exhibits higher As enrichment in sediment and groundwater,ranging of 2.59–31.52 mg/kg and bdl to 0.62 mg/*** samples were thermodynamically more stable with As(OH)_(3)species ranging from 88.5%to 91.4%and FeOOH from 69%to 81%,*** and mineralogical analysis suggested goethite and siderite act as a source and sink for ***,statistical analysis suggested reductive dissolution as the primary mechanism for As mobilization in the study ***-temporal analysis revealed elevated concentrations of As in the central and northeastern regions of the study *** isotope(δ^(2)H andδ^(18)O)analysis inferred active recharge conditions primarily driven by *** depleted d-excess value and enrichedδ^(18)O in the groundwater of younger alluvium indicate the effect of groundwater recharge with significant evaporation *** recharge potentially decreased the quantity of arsenic in groundwater,whereas evaporation enrichment increased *** infiltration during recharge introduces oxygenated water into the aquifer,leading to changes in the redox conditions and facilitating biogeochemical *** carbon isotope(δ^(13)C)results suggest that high microbial activity in younger alluvium promotes As leaching from sediment into the groundwater.

关键词： Groundwater recharge Reductive dissolution Older alluvium Younger alluvium Ghazipur Stable isotope

An Advanced Image Processing Technique for Backscatter-Electron Data by Scanning Electron Microscopy for Microscale Rock Exploration

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Journal of earth Science 2024年第1期35卷 301-305页

作者： Zhaoliang Hou Kunfeng Qiu Tong Zhou Yiwei Cai Frontiers Science Center for Deep-time Digital earth China University of GeosciencesBeijing 100083China department of Geology University of ViennaVienna 1090Austria State Key Laboratory of Geological Processes and Mineral Resources School of Earth Sciences and ResourcesChinaUniversity of GeosciencesBeijing 100083China

Backscatter electron analysis from scanning electron microscopes(BSE-SEM)produces high-resolution image data of both rock samples and thin-sections,showing detailed structural and geochemical(mineralogical)*** allows an in-depth exploration of the rock microstructures and the coupled chemical characteristics in the BSE-SEM image to be made using image processing *** image processing is a powerful tool for revealing the more subtle data“hidden”in a picture,it is not a commonly employed method in geoscientific microstructural ***,we briefly introduce the general principles of image processing,and further discuss its application in studying rock microstructures using BSE-SEM image data.

关键词： Image processing rock microstructures electron-based imaging data mining

Distributed fiber optic sensors for tunnel monitoring:A state-of-the-art review

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Journal of Rock Mechanics and Geotechnical Engineering 2024年第9期16卷 3841-3863页

作者： Xuehui Zhang Honghu Zhu Xi Jiang Wout Broere Geo-Engineering Section Department of Geoscience and EngineeringDelft University of TechnologyDelft2628CNthe Netherlands School of earth sciences and Engineering Nanjing UniversityNanjing210023China department of Civil and Environmental Engineering The Hong Kong Polytechnic UniversityKowloonHong KongChina

Distributed fiber optic sensors(DFOSs)possess the capability to measure strain and temperature variations over long distances,demonstrating outstanding potential for monitoring underground *** study presents a state-of-the-art review of the DFOS applications for monitoring and assessing the deformation behavior of typical tunnel infrastructure,including bored tunnels,conventional tunnels,as well as immersed and cut-and-cover *** systems based on Brillouin and Rayleigh scattering principles are both *** implementing DFOS monitoring,the fiber optic cable can be primarily installed along transverse and longitudinal directions to(1)measure distributed strains by continuously adhering the fiber to the structure’s surface or embedding it in the lining,or(2)measure point displacements by spot-anchoring it on the lining *** are four critical aspects of DFOS monitoring,including proper selection of the sensing fiber,selection of the measuring principle for the specific application,design of an effective sensor layout,and establishment of robust field sensor *** four issues are comprehensively discussed,and practical suggestions are provided for the implementation of DFOS in tunnel infrastructure monitoring.

关键词： Distributed fiber optic sensor(DFOS) Tunnel infrastructure Distributed strain sensing Point displacement monitoring Field instrumentation

Altered oceanic crust source for the alkaline rocks with superchondritic Nb/Ta ratios due to the steep subduction

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Journal of earth Science 2024年

作者： Xu Zhao Ning-Bo Li He-Cai Niu Shu-Cheng Tan department of Geology， School of earth sciences， Yunnan university CAS Key Laboratory of Mineralogy and Metallogeny， Guangzhou Institute of Geochemistry， Chinese Academy of sciences CAS Center for Excellence in Deep earth Science

The cause resulting in alkaline rocks with superchondritic Nb/Ta ratios remains a geochemical enigma. This paper present zircon and apatite geochronology， mineralogy， geochemistry， and Nd-Hf-Zn isotope investigation on the Ejinao nepheline syenite from South China to constrain the petrogenesis of alkaline rocks. The occurrence of alkaline minerals， including alkaline feldspar， arfvedsonite， and nepheline， indicate an alkaline feature of the Ejinao nepheline syenite. Zircon and apatite from the rock show U-Pb concordia age of 135.4±0.9 Ma and 137.5±5.8Ma， respectively， suggesting generation in the Early Cretaceous. The rock is characterized by low MgO （0.17 wt.%–0.26 wt.%） contents， but high Fe2O3T（4.66 wt.%–6.16 wt.%） and total alkalis (Na2O + K2O = 12.1 wt.%–13.1 wt.%) contents， consistent with the melts from subducting oceanic crust rather than mantle peridotite. The rock has low TiO2（0.13 wt.%–0.21 wt.%） contents and superchondritic Nb/Ta and Zr/Hf ratios， resulting from rutile residue in the source area. The εNd（t）（-1.35 to -1.09）， εHf（t）（-3.03 to -1.52）， and δ66Zn （0.32‰ to 0.34‰） values of the nepheline syenite manifest the involvement of 15%–20% carbonate-bearing sediments in the altered oceanic crust. Geochemical modeling further reveals that the nepheline syenite was sourced from 10%–20% melting of such a source. This superchondritic Nb/Ta nepheline syenite was generated during the steep subduction of the Paleo-Pacific Ocean， which is needed to bring oceanic slab to a hot mantle and resulted in the altered oceanic crust melting. Our study highlights that the altered oceanic crust represents a novel source for superchondritic Nb/Ta alkaline rocks.

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