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A stability evaluation method for deep-seated toppling in the upper Lancang river,Southwestern China

Journal of Rock mechanics and Geotechnical Engineering 2024年第7期16卷 2388-2410页

作者： Yibing Ning Huiming Tang Jianbing Peng Yanjun Shen John V.Smith Bocheng Zhang College of Geological Engineering and Geomatics Chang’an UniversityXi’an710054China Academy of Yellow River Sciences of Shaanxi Province Chang’an UniversityXi’an710054China Badong National Observation and Research Station of Geohazards China University of GeosciencesWuhan430074China School of Engineering RMIT UniversityMelbourne3001Australia

Deep-seated toppling in the upper reaches of the Lancang River,southwest China involves deformations exceeding 100 m in *** slope deformation is initiated by river downcutting and evolves distinctive characteristics with a depth of river *** this study,we propose a system for evaluating the stability of deep-seated toppled slopes in different evolutionary *** system contains identification criteria for each evolutionary stage and provides the corresponding stability evaluation *** on the mechanical and kinematic analysis of slope blocks,the specific stage of slope movement can be identified in the field through outcrop mapping,in situ tests,surface displacement monitoring,and adit and borehole *** stability evaluation methods are established based on the limiting equilibrium theory and the strain compatibility between the undisturbed zone and the toppled ***,several sample slopes in different evolution stages have been investigated to verify the applicability and accuracy of the proposed stability evaluation *** results indicate that intense tectonic activity and rapid river incision lead to a maximum principal stress ratio exceeding 10 near the slope surface,thus triggering widespread toppling deformations along the river *** considering the losses of joint cohesion during the further rotation process,the safety factor of the slope drops by 7%e28%.The self-stabilization of toppling deformation can be recognized by the layer symmetry configuration after the free rotation of the deflected *** toppled rock blocks mainly suffer sliding failures beyond the layer symmetry *** factor of safety of the K73 rockslide decreased from 1.17 to 0.87 by considering the development of the potential sliding surface and the toesaturated zone.

关键词： Stability evaluation Deep-seated toppling Evolutionary process Reservoir impoundment Rock slope

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Formation mechanism of the Paleocene Basal Conglomerate, Southwest Tarim Basin

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Journal of Earth Science 2024年第05期 1513-1526页

作者： Yong Yue Jingchun Tian Chuanyan Huang Institute of Sedimentary Geology Chengdu University of Technology Shanghai Branch of CNOOC Ltd. Key Laboratory of Tectonics and Petroleum Resources Ministry of EducationFaculty of Earth ResourcesChina University of Geosciences

most knowledge about the Cretaceous–Paleogene strata in the Tarim Basin is mainly inferred from the outcrops at the basin's margin,but first time in the basin. The formation mechanism of the Paleocene basal conglomerate was determined using geochemical isotopes of the breccia from Well PBX1 in the southwestern Tarim Basin. The results showed that the global K/Pg(i.e., Cretaceous/Paleogene) clay layer boundary was located in the middle of the Paleocene basal conglomerate at the depth of 7 066.75 m in Well PBX1. In the Late Cretaceous, associated with volcanic activities and earthquakes, the caldera in the Well PBX1 Block formed an annular depression with large elevation differences in response to the Pamir Block collision. As a result, the collapsed breccia with storm tide genesis deposited at the periphery and inside of the depression, characterized by syn-sedimentary deformation. During the Paleocene, multiple sets of interbedded carbonate and collapsed breccia deposited in response to multi-phased transient transgression-regression cycles. The transportation of breccia exhibited near-source accumulation/extremely close or in-situ rapid accumulation. The studied region is located in the eastern end of the Tethys Sea, the Late Cretaceous–Early Paleocene breccia is of great significance for reconstructing the paleogeography of the Tarim basin in Tethys.

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Conventional Geothermal Systems and Unconventional Geothermal Developments: An Overview

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Open Journal of Geology 2024年第2期14卷 196-246页

作者： maryam Khodayar Sveinbjörn Björnsson Consultant and Researcher in geosciences Reykjavík Iceland Formerly at National Energy Authority of Iceland Reykjavík Iceland

This paper provides an overview of conventional geothermal systems and unconventional geothermal developments as a common reference is needed for discussions between energy professionals. Conventional geothermal systems have the heat, permeability and fluid, requiring only drilling down to °C, normal heat flow or decaying radiogenic granite as heat sources, and used in district heating. medium-temperature (mT) 100°C - 190°C, and high-temperature (HT) 190°C - 374°C resources are mostly at plate boundaries, with volcanic intrusive heat source, used mostly for electricity generation. Single well capacities are °C - 500°C) and a range of depths (1 m to 20 Km), but lack permeability or fluid, thus requiring stimulations for heat extraction by conduction. HVAC is 1 - 2 m deep and shallow geothermal down to 500 m in wells, both capturing °C, with °C are either advanced by geothermal developers at m depth (Enhanced Geothermal Systems (EGS), drilling below brittle-ductile transition zones and under geothermal fields), or by the Oil & Gas industry (Advanced Geothermal Systems, heat recovery from hydrocarbon wells or reservoirs, Superhot Rock Geothermal, and millimeter-wave drilling down to 20 Km). Their primary aim is electricity generation, relying on closed-loops, but EGS uses fractures for heat exchange with earthquake risks during fracking. Unconventional approaches could be everywhere, with shallow geothermal already functional. The deeper and hotter unconventional alternatives are still experimental, overcoming costs and technological challenges to become fully commercial. meanwhile, the conventional geothermal resources remain the most proven opportunities for investments and development.

关键词： Conventional Geothermal Systems Unconventional Geothermal Developments Shallow and Deep Closed-Loops Enhanced Geothermal Systems Supercritical and millimeter-Wave Drilling

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Centrifuge modeling of unreinforced and multi-row stabilizing piles reinforced landslides subjected to reservoir water level fluctuation

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Journal of Rock mechanics and Geotechnical Engineering 2024年第5期16卷 1600-1614页

作者： Chenyang Zhang Yueping Yin Hui Yan Sainan Zhu ming Zhang Luqi Wang Department of Civil Engineering The University of Hong KongHong KongChina China Institute of Geo-environment monitoring BeijingChina Chongqing 107 municipal Construction Engineering Co. Ltd.ChongqingChina Faculty of Engineering China University of GeosciencesWuhanChina School of Civil Engineering Chongqing UniversityChongqingChina

With the construction of the Three Gorges Reservoir dam,frequent reservoir landslide events have been *** recent years,multi-row stabilizing piles(mRSPs)have been used to stabilize massive reservoir landslides in *** this study,two centrifuge model tests were carried out to study the unreinforced and mRSP-reinforced slopes subjected to reservoir water level(RWL)operation,using the Taping landslide as a *** results indicate that the RWL rising can provide lateral support within the submerged zone and then produce the inward seepage force,eventually strengthening the slope ***,a rapid RWL drawdown may induce outward seepage forces and a sudden debuttressing effect,consequently reducing the effective soil normal stress and triggering partial pre-failure within the RWL fluctuation ***,partial deformation and subsequent soil structure damage generate excess pore water pressures,ultimately leading to the overall failure of the reservoir *** study also reveals that a rapid increase in the downslope driving force due to RWL drawdown significantly intensifies the lateral earth pressures exerted on the ***,the mRSPs possess a considerable reinforcement effect on the reservoir landslide,transforming the overall failure into a partial deformation and failure situated above and in front of the *** mechanical transfer behavior observed in the mRSPs demonstrates a progressive alteration in relation to RWL *** the RWL rises,the mechanical states among mRSPs exhibit a growing *** shear force transfer factor(*** ratio of shear forces on pile of the n th row to that of the first row)increases significantly with the RWL *** indicates that the mechanical states among mRSPs tend toward an enhanced *** insights gained from this study contribute to a more comprehensive understanding of the failure mechanisms of reservoir landslides and the mechanical behavior of m

关键词： Reservoir landslide Failure mechanism multi-row stabilizing piles mechanical behavior

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Rastall gravity:accretion disk image in the context of radiation fields and visual transformations compared to Reissner-Nordström black hole

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Chinese Physics C 2024年第4期48卷 174-182页

作者：黄宇翔郭森梁宇崔宇昊蒋青权林恺 School of Physics and Astronomy China West Normal UniversityNanchong 637000China Guangxi Key Laboratory for Relativistic Astrophysics School of Physical Science and TechnologyGuangxi UniversityNanning 530004China Hubei Subsurface multi-scale Imaging Key Laboratory Institute of Geophysics and GeomaticsChina University of GeosciencesWuhan 430074China

In this study,we investigated the astronomical implications of Rastall gravity,particularly its behavior amidst a radiation field compared to Reissner-Nordström(RN)black *** found a crucial correlation between the dynamics of the accretion disk and the parameters Q and Nr,which properly reflect the influence of spacetime metrics on the disk’s *** electric charge Q causes contraction in the disk’s orbit due to enhanced gravitational effects,while higher Nr values lead to outward expansion,influenced by the attributes of the radiation ***,the charged black holes surrounded by radiation fields exhibit distinct visual disparities from RN black *** decreases and expansion occurs within the innermost stable circular orbit of the accretion disk with rising Nr *** study also reveals the process by which the accretion disk transitions from a conventional disk-like structure to a hat-like form at different observation angles,with the redshift effect gradually ***,the results of the considered Rastall gravity radiation field are consistent with the constraints of the gravitational lensing of the host galaxy on Rastall gravity parameters,thereby enhancing the consistency between theoretical predictions and actual observations.

关键词： Rastall theory optical appearance thin accretion disk

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Genetic source,migration and accumulation of helium under deep thermal fluid activities:A case study of Ledong diapir area in Yinggehai Basin,South China Sea

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Petroleum Exploration and Development 2024年第3期51卷 753-766页

作者： FENG Ziqi HAO Fang HU Lin HU Gaowei ZHANG Yazhen LI Yangming WANG Wei LI Hao XIAO Junjie TIAN Jinqiang State Key Laboratory of Deep Oil and Gas China University of Petroleum(East China)Qingdao 266580China School of geosciences China University of Petroleum(East China)Qingdao 266580China Laboratory for marine mineral Resources Qingdao Marine Science and Technology CenterQingdao 266237China Hainan Branch of CNOOC(China)Co. Ltd.Haikou 570312China

Based on the geochemical parameters and analytical data,the heat conservation equation,mass balance law,Rayleigh fractionation model and other methods were used to quantify the in-situ yield and external flux of crust-derived helium,and the initial He concentration and thermal driving mechanism of mantle-derived helium,in the Ledong Diapir area,the Yinggehai Basin,in order to understand the genetic source,migration and accumulation mechanisms of helium under deep thermal fluid *** average content of mantle-derived He is only 0.0014%,the ^(3)He/^(4)He value is(0.002–2.190)×10^(−6),and the R/Ra value ranges from 0.01 to 1.52,indicating the contribution of mantle-derived He is 0.09%–19.84%,while the proportion of crust-derived helium can reach over 80%.Quantitative analysis indicates that the crust-derived helium is dominated by external input,followed by in-situ production,in the Ledong diapir *** crust-derived helium exhibits an in-situ 4 He yield rate of(7.66–7.95)×10^(−13)cm^(3)/(a·g),an in-situ 4 He yield of(4.10–4.25)×10^(−4)cm^(3)/g,and an external 4 He influx of(5.84–9.06)×10^(−2)cm^(3)/*** results may be related to atmospheric recharge into formation fluid and deep rock-water *** ratio of initial mole volume of 3 He to enthalpy(W)is(0.004–0.018)×10^(−11) cm^(3)/J,and the heat contribution from the deep mantle(X_(m))accounts for 7.63%–36.18%,indicating that deep hot fluid activities drive the migration of mantle-derived 3 *** primary helium migration depends on advection,while the secondary migration is controlled by hydrothermal degassing and gas-liquid *** deep to shallow layers,the CO_(2/3) He value rises from 1.34×10^(9)to 486×10^(9),indicating large amount of CO_(2)has *** the influence of deep thermal fluid,helium migration and accumulation mechanisms include:deep heat driven diffusion,advection release,vertical hydrothermal degassing,shallow lateral migration,accumulation in traps far from faults,

关键词： deep thermal fluid helium genetic source migration and accumulation mechanism Yinggehai Basin

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Interannual evolution of the chemical composition,sources and processes of Pm_(2.5)in Chengdu,China:Insights from observations in four winters

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Journal of Environmental Sciences 2024年第4期138卷 32-45页

作者： Junke Zhang Jiaqi Li Yunfei Su Chunying Chen Luyao Chen Xiaojuan Huang Fangzheng Wang Yawen Huang Gehui Wang Faculty of geosciences and Environmental Engineering Southwest Jiaotong UniversityChengdu 611756China Department of Environmental Science&Engineering Shanghai Key Laboratory of Atmospheric Particle Pollution and Prevention(LAP3)Fudan UniversityShanghai 200438China Key Lab of Geographic Information Science of the ministry of Education School of Geographic SciencesEast China Normal UniversityShanghai 200241China

The air quality in China has improved significantly in the last decade and,correspondingly,the characteristics of Pm_(2.5)have also *** studied the interannual variation of Pm_(2.5)in Chengdu,one of the most heavily polluted megacities in southwest China,during the most polluted season(winter).Our results show that the mass concentrations of Pm_(2.5)decreased significantly year-by-year,from 195.8±91.0μg/m~3in winter 2016 to 96.1±39.3μg/m^(3)in winter *** mass concentrations of organic matter(Om),SO_()4^(2-),NH_(4)^(+)and NO_(3)^(-)decreased by 49.6%,57.1%,49.7% and 28.7%,*** differential reduction in the concentrations of chemical components increased the contributions from secondary organic carbon and NO_(3)^(-)and there was a larger contribution from mobile *** contribution of Om and NO_(3)^(-)not only increased with increasing levels of pollution,but also increased year-by-year at the same level of *** sources of Pm_(2.5)were identified:combustion sources,vehicular emissions,dust and secondary *** aerosols made the highest contribution and increased year-by-year,from 40.6%in winter 2016 to 46.3% in winter *** contrast,the contribution from combustion sources decreased from 14.4% to 8.7%.Our results show the effectiveness of earlier pollution reduction policies and emphasizes that priority should be given to key pollutants(e.g.,Om and NO_(3)^(-))and sources(secondary aerosols and vehicular emissions)in future policies for the reduction of pollution in Chengdu during the winter months.

关键词： Pm_(2.5) Chemical composition Sources Interannual evolution Winter Chengdu

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Constraints on Characteristics and Distribution of Gas Hydrate and Free Gas Using Broad-Band Processing of Three-Dimensional Seismic Data

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Journal of Ocean University of China 2024年第5期23卷 1233-1247页

作者： WANG Xiujuan ZHOU Jilin LI Sanzhong LI Lixia LI Jie LI Yuanping WANG Linfei SU Pibo JIN Jiapeng GONG Zhi State Key Laboratory of Offshore Natural Gas Hydrate Frontiers Science Center for Deep Ocean multispheres and Earth System Key Laboratory of Submarine Geosciences and Prospecting Techniques MOE and College of Marine Geosciences Ocean University of China Laboratory for marine mineral Resources Qingdao Marine Science and Technology Center CNOOC Research Institute Co. Ltd. CNOOC China Limited Shenzhen Branch Guangzhou marine Geological Survey China Geological Survey

Gas hydrate drilling expeditions in the Pearl River mouth Basin, South China Sea, have identified concentrated gas hydrates with variable thickness. moreover, free gas and the coexistence of gas hydrate and free gas have been confirmed by logging, coring, and production tests in the foraminifera-rich silty sediments with complex bottom-simulating reflectors(BSRs). The broad-band processing is conducted on conventional three-dimensional(3D) seismic data to improve the image and detection accuracy of gas hydratebearing layers and delineate the saturation and thickness of gas hydrate-and free gas-bearing sediments. Several geophysical attributes extracted along the base of the gas hydrate stability zone are used to demonstrate the variable distribution and the controlling factors for the differential enrichment of gas hydrate. The inverted gas hydrate saturation at the production zone is over 40% with a thickness of 90 m, showing the interbedded distribution with different boundaries between gas hydrate-and free gas-bearing layers. However, the gas hydrate saturation value at the adjacent canyon is 70%, with 30-m-thick patches and linear features. The lithological and fault controls on gas hydrate and free gas distributions are demonstrated by tracing each gas hydrate-bearing layer. moreover, the BSR depths based on broad-band reprocessed 3D seismic data not only exhibit variations due to small-scale topographic changes caused by seafloor sedimentation and erosion but also show the upward shift of BSR and the blocky distribution of the coexistence of gas hydrate and free gas in the Pearl River mouth Basin.

关键词： broad-band processing free gas gas hydrate shift of BSR

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SS-LASS Zircon Dating Deciphering multiple Episodes of Anatexis in a Deeply-Subducted Continental Crust:An Example from Sulu Orogen,China

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Journal of Earth Science 2024年第1期35卷 85-98页

作者： Peng Feng Lu Wang Xiawen Li Wenjie Ding Zhe Chen School of Resource&Environment and Safety Engineering University of South ChinaHengyang 421001China State Key Laboratory of Geological Processes and mineral Resources Center for Global TectonicsSchool of Earth SciencesChina University of GeosciencesWuhan 430074China No.8 Institute of Geology and mineral Resources Exploration of Shandong Province Rizhao 276826China

‘Single shot'laser-ablation split-stream(SS-LASS)technique analyzing unpolished zircon grains makes their thin rims tenable for determination,which thus offers great potential in deciphering the timing of multiple and short-lived episodes of anatexis and metamorphism in deeplysubducted continental *** granitic gneisses in the deeply subducted continental crust undergoing considerable fluid-melt activities persist multistage growth of ***,a comparative study of SS-LASS and laser ablation inductively coupled plasma mass spectrometer(LA-ICP-mS)zircon dating was conducted on the granitic gneisses from the Sulu belt in this *** mostly show a core-mantle-rim structure with CL-bright rims thinner than 5μ*** LA-ICP-mS dating,relict magmatic zircon cores yield protolith ages of ca.756-747 ma;whereas the dark mantles record synexhumation anatexis at ca.214 *** contrast,according to the U-Pb dates,trace element features,zircon crystallization temperatures and geological context,SS-LASS zircon petrochronology deciphers three episodes of anatectic events,as follows:(i)the first episode of anatexis at ca.218-217 ma dominated by phengite-breakdown melting,likely facilitating the exhumation of the UHP slice from mantle depth;(ii)the second episode of anatexis at ca.193–191 ma indicating part of northern Dabie-Sulu belt was still“hot”because of buried in the thickened orogenic crust at that time;(iii)the third episode of anatexis(ca.162–161 ma)consistent with the intrusion ages(ca.161–141 ma)of the Jurassic to Cretaceous granitoids in this orogen,suggesting the initial collapse of the orogenic root of the Sulu belt occurred at Late Jurassic due to the Izanagi plate initially subducting beneath the margin of Eastern *** study sheds new light upon the utilization of SS-LASS petrochronology deciphering multiple anatectic events in the deeply-subducted continental crust and supports us in better understanding the tectonic evolution of Dabie-

关键词： anatexis laser ablation laser-ablation split-stream ultrahigh-pressure metamorphic belt Sulu Orogen

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Identification of the non-stationarity of extreme temperature events and teleconnections with solar activity and large-scale atmospheric circulation: A case study in the Yangtze River Economic Belt

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Journal of Earth Science 2024年

作者： Lin Zhang Jingyun Ling Shengzhi Huang Hongbin Zhan Yi Wu menggui Jin Qiang Huang State Key Laboratory of Eco-hydraulics in Northwest Arid Region， Xi'an University of Technology College of Design and Engineering， National University of Singapore Yinshanbeilu Grassland Eco-Hydrology National Observation and Research Station， China Institute of Water Resources and Hydropower Research Department of Geology and Geophysics， Texas A&m University， College Station School of Earth System Science， Tianjin University School of Environmental Studies， China University of geosciences

In recent decades， extreme climate events have become a major problem worldwide. To understand the uncertainty in the response of extreme events to global warming， regional assessments are required for various climatic and geographic regions. The spatiotemporal distribution of extreme temperature events in the Yangtze River Economic Belt (YREB) from 1960 to 2019， including interannual changes and their teleconnections with solar activity and large-scale atmospheric circulation， were analyzed using eight indices of extreme temperature events. Over the past six decades， the climate in the YREB region has seen a warming trend， characterized by an increase in extreme warm events and a decrease in extreme cold events. The extreme temperature indices exhibit strong spatial variability. The warm extremes display a significant upward trend across the YREB， while cold extremes are primarily concentrated in the western part of the region. In recent decades， both warm and cold extremes have significant interannual variations， and these events predominantly oscillate over periods of less than four years. After 1985， the relationship between El Ni?o-Southern Oscillation (ENSO)， Arctic Oscillation (AO)， Pacific Decadal Oscillation (PDO) and extreme temperature events has changed significantly compared with pre-1985， and the direction of the phase angle can determine the positive and negative effects of the two time-series. ENSO， AO and PDO mainly have positive impacts on extreme temperature events， with ENSO and AO exerting greater impacts than PDO. In contrast， solar activity mainly has a negative impact on these events. Furthermore， the notable interdecadal changes in extreme temperature events， especially warm extremes， may be caused by the shift in the PDO phase. Therefore， the results of the study are important for the YREB region to take effective measures to mitigate the potential impacts of human activities on regional warming.

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