Geological analysis,despite being a long-term method for identifying adverse geology in tunnels,has significant limitations due to its reliance on empirical analysis.The quantitative aspects of geochemical anomalies a...Geological analysis,despite being a long-term method for identifying adverse geology in tunnels,has significant limitations due to its reliance on empirical analysis.The quantitative aspects of geochemical anomalies associated with adverse geology provide a novel strategy for addressing these limitations.However,statistical methods for identifying geochemical anomalies are insufficient for tunnel engineering.In contrast,data mining techniques such as machine learning have demonstrated greater efficacy when applied to geological data.Herein,a method for identifying adverse geology using machine learning of geochemical anomalies is proposed.The method was identified geochemical anomalies in tunnel that were not identified by statistical methods.We by employing robust factor analysis and self-organizing maps to reduce the dimensionality of geochemical data and extract the anomaly elements combination(AEC).Using the AEC sample data,we trained an isolation forest model to identify the multi-element anomalies,successfully.We analyzed the adverse geological features based the multi-element anomalies.This study,therefore,extends the traditional approach of geological analysis in tunnels and demonstrates that machine learning is an effective tool for intelligent geological analysis.Correspondingly,the research offers new insights regarding the adverse geology and the prevention of hazards during the construction of tunnels and underground engineering projects.展开更多
The substantial emissions of greenhouse gases,particularly CO_(2),constitute a primary driver of global warming.CCUS is proposed as an effective mitigation strategy which is often estimated to account for about 15%of ...The substantial emissions of greenhouse gases,particularly CO_(2),constitute a primary driver of global warming.CCUS is proposed as an effective mitigation strategy which is often estimated to account for about 15%of cumulative carbon emission reduction.In-situ CO_(2) mineralization sequestration,compared to conventional geological storage methods such as depleted oil and gas reservoirs,unmineable coal seams,and deep saline aquifers,offers the advantage of permanent immobilization of injected carbon.However,uncertainties persist regarding the characteristics of geochemical interactions under reservoir pore conditions,as well as the kinetic mechanisms of mineralization reactions.Additionally,geochemical reactions may lead to solid particle transport and deposition,potentially causing pore throat occlusion.Pilot projects in Iceland and the United States have demonstrated the feasibility of this technology,but the field remains in the early deployment stage.In this review,the mechanisms of in-situ mineralization have been elucidated,the primary factors influencing the reaction kinetics have been discussed,and the current research status in this field has been summarized.It is emphasized that establishing a reliable system for evaluating storage capacity and understanding the kinetic mechanisms governing CO_(2) conversion into minerals at multi-phase interfaces are key priorities for future work.展开更多
Located in Southeastern Chad. The Iro lake offers a great opportunity for the study of Precambrian formations and their Phanerozoic cover. Pluton is a Cal-alkaline granite. Due to its geographical location and geologi...Located in Southeastern Chad. The Iro lake offers a great opportunity for the study of Precambrian formations and their Phanerozoic cover. Pluton is a Cal-alkaline granite. Due to its geographical location and geological features, it holds crucial information for understanding the evolution of the Saharan Meta craton (central Africa), which remains poorly studied. One of the objectives is to map the formations Precambrian age in Southeastern Chad. Based on the petrographic and geochemical results, we identified granitoids of pan-African age (biotite granite, aplite granite and pegmatite granite). This Precambrian basement is covered with sedimentary formations (clays, argillites, lateritic cuirasses, etc.). The mineral assemblage is characteristic of acid rocks. Geochemistry reveals rocks with a high SiO2 range (62% - 77%) giving sub-alkaline to calc-alkaline acid rocks with high k (4.62% to 6.39%). The granitoids are classified as S-type hyperaluminous granites. This classification is supported by the presence of peraluminous minerals (e.g., muscovite) within the Iro granitoids, which also have high (>1%). Geochemical variation within the granites is largely due to extensive crystal fractionation. The Pattern of REEs normalized to the primitive mantle shows a pronounced negative Eu anomaly, reflecting the crystallization process and fractional crystallization of plagioclase in the rock, and a positive Yb anomaly. The role of plagioclase fractionation was relatively major during the earlier intrusive stages (consistent with the presence of Eu anomalies) and slightly increased, together with biotite and K-feldspar fractionation, during the later (granitic) rock crystallization. The Pattern of the spider normalized to MORBs shows two pronounced negative anomalies in TiO2 and Cs and a slight negative anomaly in Ba. The loss of Ba, Ti and Cs may be caused by the plagioclase fractionation, apatite and ilmenite crystal. The Ba anomaly is also controlled by the presence of K-feldspar and mica. The observed Ti anomalies are due to the fractionation of magnetite indicating a subduction environment (or remelting of a source from a subduction environment).展开更多
The Malacca Strait(MS)is a vital conduit for the exchange of water and sediment between the Indian Ocean and the Pacific Ocean,serving as a critical‘gateway'for sediment transport.Here,we present the geochemical ...The Malacca Strait(MS)is a vital conduit for the exchange of water and sediment between the Indian Ocean and the Pacific Ocean,serving as a critical‘gateway'for sediment transport.Here,we present the geochemical characteristics of surface sediments in the MS to elucidate the relationship between terrestrial material inputs and modern oceanic dynamic transport processes in the strait.The results reveal that the MS can be divided into three distinct geochemical provinces.ProvinceⅠ,located in the central region of the strait,is characterized by residual deposits.The preservation of these residual deposits can be attributed to the restricted sediment supply and the relatively weaker modern sedimentary hydrodynamic conditions.ProvinceⅡ,situated to the north of ProvinceⅠ,exhibits provenance differences between its southern and northern regions.The northern region is primarily supplied by sediments originating from the eastern shelf of the Andaman Sea,whereas sediments derived from Sumatra and the Sunda Shelf are predominantly deposited in the southern part of ProvinceⅡ.ProvinceⅢextends along the western coast of the Malaysian Peninsula,with sediments primarily sourced from the Malaysian Peninsula and the Sunda Shelf,while contributions from Sumatra and the eastern shelf of the Andaman Sea are negligible.River sediments from the Malaysian Peninsula and Sumatra are transported northwestward along their respective coasts by prevailing currents,which also facilitate the transportation of Sunda Shelf sediments within the strait,while sediments from the eastern shelf of the Andaman Sea are delivered to the MS via southward coastal currents during the southwest monsoon period.The southward currents and well-developed eddies potentially impede the northward transport of sediments from the Sunda Shelf and restrict the distribution of Andaman Sea sediments within the strait.This study substantially enhances the understanding of source-to-sink processes in the Indo-Pacific region.展开更多
Lithium is a critical strategic metal with signifi-cant reserves in pegmatites,serving as the primary source for global Li production.Apatite has attracted increasing attention as an indicator in petrogenesis studies ...Lithium is a critical strategic metal with signifi-cant reserves in pegmatites,serving as the primary source for global Li production.Apatite has attracted increasing attention as an indicator in petrogenesis studies and for the exploration of ore deposits.In this study,we investigated the volatile compositions and major and trace elements of apatite from the Qiongjiagang pegmatite-type lithium deposit in Himalaya.Apatite derived from spodumene pegmatite exhibits relatively constant and high total rare earth element(ΣREE+Y)concentrations,ranging from 5899 to 8540 ppm.In contrast,apatite in barren pegmatite displays evidently lower(ΣREE+Y)concentrations,varying between 1345 and 3095 ppm.The REE patterns of apatite in spodumene pegmatite generally exhibit a flat shape[(La/Yb)N=1.55-2.15)],with distinctively negative Eu anomalies(Eu_(N)/Eu_(N)^(*)=0.14-0.22),slightly positive Ce anomalies(Ce_(N)/Ce_(N)^(*)=1.03-1.13),and low Y/Ho ratios(28-30).By contrast,apatite in barren pegmatite shows middle rare earth element(MREE)-depleted downward-convex patterns[(La/Yb)N=1.99-20.4)],strongly negative Eu anomalies(Eu_(N)/Eu_(N)^(*)=0.01-0.14),slightly positive Ce anomalies(Ce_(N)/Ce_(N)^(*)=1.10-1.24),and high Y/Ho ratios(30-55,with an average of 50).Overall,the high concentrations ofΣREE(and Y)and low Th/U and Y/Ho ratios can serve as diagnostic indicators to distinguish apatite in spodumene pegmatite from that in barren pegmatite.Furthermore,the flat REE pattern may represent a common feature of apatite from lithium deposits.Differences in the Ce and Eu anomalies between apatite from these two kinds of pegmatites likely reflect formation under different redox conditions.Consequently,based on calculations derived from apatite volatile compositions,the melt associated with spodumene pegmatite may contain higher water content compared to that of the barren one.Therefore,the mineralized pegmatite system may incorporate substantial amounts of H_(2)O-rich fluids,which play a crucial role in lithium mineralization.展开更多
This study investigates the potential of natural Brown Coal(BC)as a sustainable,cost-effective adsorbent for the removal of manganese(Mn2+)from contaminated groundwater.A series of batch adsorp-tion experiments was co...This study investigates the potential of natural Brown Coal(BC)as a sustainable,cost-effective adsorbent for the removal of manganese(Mn2+)from contaminated groundwater.A series of batch adsorp-tion experiments was conducted to assess the influence of key operational parameters—such as solution pH,2+initial Mn concentration,BC dosage,temperature,and the presence of competing ions—on 2+Mn removal efficiency.The environmental compatibility and regeneration potential of BC were also evaluated to deter-mine its practical viability for repeated use.To better understand the adsorption behaviour,equilibrium and kinetic data were analysed using established isotherm and kinetic models,while thermodynamic parameters were computed to assess the spontaneity and thermal characteristics of the adsorption process.Furthermore,geochemical modelling and comprehensive BC characterization—including surface morphology,miner-alogical and elemental composition,and functional group analysis—were 2+performed to elucidate Mn speciation under varying environmental conditions and to uncover the underlying adsorption mechanisms.2+Results showed that Mn removal efficiency increased with higher pH,temperature,and BC dosage,but 2+declined at elevated initial Mn concentrations due to active site saturation.The process was spontaneous 2 and endothermic,with the Langmuir isotherm model(R=0.994)and pseudo-second-order kinetic model 2(R=0.996)providing the best fit to experimental data.Mechanistic analysis indicated that chemisorption,2+primarily through ion exchange and inner-sphere complexation,was the dominant mode of Mn uptake.3+The presence of competing cations,especially Fe and Cu2+,2+significantly hindered Mn removal due to preferential binding.Importantly,BC exhibited strong reusability,maintaining over 80%removal effi-ciency across four adsorption–desorption cycles without evidence of secondary pollutants.These findings demonstrate the potential of natural BC as an efficient,reusable,and environmentally benign material for treating manganese-contaminated groundwater.展开更多
Geochemistry of the fault gouge record information on fault behaviors and environmental conditions.We investigated variations in the mineralogical and geochemical compositions of the fault gouge sampled from the margi...Geochemistry of the fault gouge record information on fault behaviors and environmental conditions.We investigated variations in the mineralogical and geochemical compositions of the fault gouge sampled from the margin zone(MZ)to the slip central zone(CZ)of the fault gouge in the Beichuan-Yingxiu surface rupture zone of the Wenchuan Earthquake.Results show that the clay minerals contents increase from the MZ to CZ,and the quartz and plagioclase contents slight decrease.An increasing enrichment in Al_(2)O_(3),Fe_(2)O_(3),and K_(2)O are observed toward the CZ;the decomposition of quartz and plagioclase,as well as the depletion of Si O_(2),Ca O,Na_2O,and P_(2)O_(5)suggest that the alkaline-earth elements are carried away by the fluids.It can be explained that the stronger coseismic actions in the CZ allow more clay minerals to form,decompose quartz and plagioclase,and alter plagioclase to chlorite.The mass loss in the CZ is larger than that in MZ,which is maybe due to the more concentrated stress in the strongly deformed CZ,however other causes will not be excluded.展开更多
Rising global energy needs have intensified the search for unconventional hydrocarbon sources,especially in under-selected areas like the Northeast Java Basin.This region harbors promising unconventional hydrocarbon r...Rising global energy needs have intensified the search for unconventional hydrocarbon sources,especially in under-selected areas like the Northeast Java Basin.This region harbors promising unconventional hydrocarbon reserves,where source rocks function as dual-phase systems for both hydrocarbon generation and storage.This research investigates how metal-based catalysts,particularly iron(Fe),can expedite hydrocarbon maturation in such reservoirs.Combining well logging,geochemical assessments,seismic data,and advanced lab techniques,including X-ray Diffraction(XRD),we pinpoint optimal zones for exploration.Results indicate that the Tuban,Kujung,and Ngimbang formations contain economically viable unconventional deposits,exhibiting tight reservoir properties(permeability:0.01–1 md)and moderate to good Total Organic Carbon(TOC)levels(1%–2%).Spatial analysis reveals elevated density concentrations in the northern sector,indicative of high-viscosity hydrocarbons typical of unconventional plays.Crucially,Fe additives were found to markedly enhance organic matter conversion,shortening maturation periods and boosting hydrocarbon yield.XRD data confirms that Fe alters crystalline configurations,increasing reactivity and speeding up thermal breakdown(shifting immature organic compounds toward maturity at an accelerated rate).These findings contribute to the evolving discourse on unconventional resource exploitation by proposing an innovative recovery enhancement strategy.The study also sets a precedent for investigating metal-assisted hydrocarbon conversion in geologically comparable basins globally.展开更多
This research examines the hard-rock aquifer system within the Nagavathi River Basin(NRB)South India,by evaluating seasonal fluctuations in groundwater composition during the pre-monsoon(PRM)and post-monsoon(POM)perio...This research examines the hard-rock aquifer system within the Nagavathi River Basin(NRB)South India,by evaluating seasonal fluctuations in groundwater composition during the pre-monsoon(PRM)and post-monsoon(POM)periods.Seasonal variations significantly influence the groundwater quality,particularly fluoride(F−)concentrations,which can fluctuate due to changes in recharge,evaporation,and anthropogenic activities.This study assesses the dynamics of F−levels in PRM and POM seasons,and identifies elevated health risks using USEPA guidelines and Monte Carlo Simulations(MCS).Groundwater in the study area exhibits alkaline pH,with NaCl and Ca-Na-HCO_(3) facies increasing in the POM season due to intensified ion exchange and rock-water interactions,as indicated in Piper and Gibb’s diagrams.Correlation and dendrogram analyses indicate that F−contamination is from geogenic and anthropogenic sources.F−levels exceed the WHO limit(1.5 mg/L)in 51 PRM and 28 POM samples,affecting 371.74 km^(2) and 203.05 km^(2),respectively.Geochemical processes,including mineral weathering,cation exchange,evaporation,and dilution,are identified through CAI I&II.Health risk assessments reveal that HQ values>1 in 78%of children,73%of teens,and 68%of adults during PRM,decreasing to 45%,40%,and 38%,respectively,in POM.MCS show maximum HQ values of 5.67(PRM)and 4.73(POM)in children,with all age groups facing significant risks from fluoride ingestion.Managed Aquifer Recharge(MAR)is recommended in this study to minimize F−contamination,ensuring safe drinking water for the community.展开更多
Hemipelagic to pelagic(H/P)marls,representing pelitic deposits,accumulated within the foredeep sub-basin of the Dinaric Foreland Basin(northern Neotethyan margin,present-day Croatia)during the Middle to Late Eocene.Sy...Hemipelagic to pelagic(H/P)marls,representing pelitic deposits,accumulated within the foredeep sub-basin of the Dinaric Foreland Basin(northern Neotethyan margin,present-day Croatia)during the Middle to Late Eocene.Syn-sedimentary tectonic movements,paleogeographic position and exchanges of short-lived hyperthermal episodes affected the sedimentation and related mineral and geochemical record of these deposits.Mineral(clay)assemblages bear signature of prevailing physical weathering with significant illite and chlorite content,but climatic seasonality is suggested by smectite-interlayered phases and sporadical increase of kaolinite content.Illite crystallinity varies significantly,and the lowest crystallinity is recorded by the Lutetian samples.Illite chemistry index is always bellow 0.5,being characteristic for Fe-Mg-rich illite.The geochemical records are the most prominent(CIA up to 76,CIW up to 91)for the Istrian Lutetian(42.3-40.5 Ma),but also for Priabonian(35.8-34.3 Ma)samples of Hvar Island.The ICV values(the lowest 1.40 and the highest 10.85)of all studied samples fall above PAAS(ICV=0.85)and point to their chemical immaturity.The Ga/Rb ratios are lower than 0.2 and K_(2)O/Al_(2)O_(3) ratios are also low(0.16-0.22),implying transition between cold and dry,and warm and humid climate,obviously trending among several warming episodes.展开更多
This study selects geochemical data of basalts from different seamounts in the Mid-Pacific Mountains province and conducts analyses of major and trace elements as well as Sr-Nd-Pb isotopes to explore the tectonic evol...This study selects geochemical data of basalts from different seamounts in the Mid-Pacific Mountains province and conducts analyses of major and trace elements as well as Sr-Nd-Pb isotopes to explore the tectonic evolution,petrogenesis,and mantle-source magama characteristics of the Mid-Pacific Mountains.The basalts from the Mid-Pacific Mountains are predominantly alkali basalts,rich in alkalies,and changing in potassium.They exhibit geochemical features of ocean island basalts(OIB),with distinct fractionation between light and heavy rare-earth elements and a pronounced Ce negative anomaly(δ_(Ce)=0.16–1.10,average 0.84),along with enrichment in large ion lithophile elements(LILEs).The Mid-Pacific Mountains are intraplate ocean island basalts formed by mantle plume(hotspot)activity,originating mainly from an enriched mantle magma source region,and most of them have undergone low degree of partial melting and a certain degree of crystalline differentiation,with negligible contamination from oceanic crust materials.The Mid-Pacific Mountains exhibit ratios of^(87)Sr/^(86)Sr(i)(0.702733–0.704313,average 0.703452)and^(143)Nd/^(144)Nd(i)(0.512698–0.512996,average 0.512846)which are close to the HIMU mantle endmember,and ratios of 206Pb/204Pb(18.953–19.803),^(207)Pb/^(204)Pb(15.54–15.62)and^(208)Pb/^(204)Pb(38.813–39.514)which are close to the EMII mantle end-member.Combined with the isotopic geochemical characteristics in the West Pacific Seamounts province,the basalts from the Mid-Pacific Mountains were considered to represent a certain proportion of mixing mantle end-members between the HIMU and EMII,possibly formed by the mixing of the HIMU superplume in the South Pacific hotspot region with the EMII secondary mantle plume in the transition zone during their ascent.展开更多
The Langrial iron ore deposits,located in the villages of Dubran and Darkot in Hazara,Pakistan,were evaluated using remote sensing,magnetic,and geochemical investigations.Data from ASTER,Landsat-8,and Sentinel-2 satel...The Langrial iron ore deposits,located in the villages of Dubran and Darkot in Hazara,Pakistan,were evaluated using remote sensing,magnetic,and geochemical investigations.Data from ASTER,Landsat-8,and Sentinel-2 satellites were utilized and processed through techniques such as band ratio analysis,band compositing,and NDVI masking to reduce vegetation effects and to delineate various lithological units and mineralogical signatures within the study area.Magnetic anomalies revealed multiple levels of iron mineralization,with the hematite zone showing the most significant potential for high-grade iron ore.Geochemical analyses confirmed the presence of iron,along with minerals such as chromium,calcium,magnesium,and lead.In Dubran,mean iron concentrations are recorded at 370.94 mg/kg,whereas in Darkot,they reach up to 2052 mg/kg.The integration of remote sensing,magnetic,and geochemical data delineates key mineralized zones in the various parts of the study area.This research highlights the importance of combining geophysical and geochemical methodologies to refine mineral exploration efforts.The findings enhance our understanding of the Langrial iron ore deposits and highlight their economic potential for sustainable mining practices.This study will contribute to meeting the growing demand for iron ore resources and reducing Pakistan's reliance on imports,thereby promoting the sustainable development of local industries.展开更多
Balancing CO2 emission reduction with enhanced gas recovery in carbonate reservoirs remains a key challenge in subsurface energy engineering.This study focuses on the Maokou Formation gas reservoir in the Wolonghe Gas...Balancing CO2 emission reduction with enhanced gas recovery in carbonate reservoirs remains a key challenge in subsurface energy engineering.This study focuses on the Maokou Formation gas reservoir in the Wolonghe Gas Field,Sichuan Basin,and employs a mechanistic model integrated with numerical simulations that couple CO2–water–rock geochemical interactions to systematically explore the principal engineering and chemical factors governing Carbon Capture,Utilization,and Storage–Enhanced Gas Recovery(CCUS–EGR).The analysis reveals that both the injection–production ratio and gas injection rate exhibit optimal ranges.Maximum gas output under single-parameter variation occurs at an injection–production ratio of 0.7 and an injection rate of 130,000 m3/d,while coordinated optimization of both parameters is essential to achieve the highest production enhancement.Excessively high injection–production ratios,however,may induce gas channeling and reduce the ultimate recovery factor.Chemical composition of the injected gas also strongly influences recovery.In the heterogeneous carbonate reservoir considered,a CO2–N2 mixed gas mitigates gravity segregation due to its lower density,expanding sweep efficiency and improving overall gas recovery compared to pure CO2 injection.CO2–water–rock reactions further modify reservoir properties.Near the injection well,acidic dissolution enhances porosity,whereas near the production well,a dynamic interplay of ion migration,pressure–temperature variations,and secondary mineral precipitation produces complex porosity evolution.Initial precipitation reduces porosity,while subsequent acidic dissolution partially restores it,creating a heterogeneous and time-dependent porosity profile.展开更多
Geochemical survey data are essential across Earth Science disciplines but are often affected by noise,which can obscure important geological signals and compromise subsequent prediction and interpretation.Quantifying...Geochemical survey data are essential across Earth Science disciplines but are often affected by noise,which can obscure important geological signals and compromise subsequent prediction and interpretation.Quantifying prediction uncertainty is hence crucial for robust geoscientific decision-making.This study proposes a novel deep learning framework,the Spatially Constrained Variational Autoencoder(SC-VAE),for denoising geochemical survey data with integrated uncertainty quantification.The SC-VAE incorporates spatial regularization,which enforces spatial coherence by modeling inter-sample relationships directly within the latent space.The performance of the SC-VAE was systematically evaluated against a standard Variational Autoencoder(VAE)using geochemical data from the gold polymetallic district in the northwestern part of Sichuan Province,China.Both models were optimized using Bayesian optimization,with objective functions specifically designed to maintain essential geostatistical characteristics.Evaluation metrics include variogram analysis,quantitative measures of spatial interpolation accuracy,visual assessment of denoised maps,and statistical analysis of data distributions,as well as decomposition of uncertainties.Results show that the SC-VAE achieves superior noise suppression and better preservation of spatial structure compared to the standard VAE,as demonstrated by a significant reduction in the variogram nugget effect and an increased partial sill.The SC-VAE produces denoised maps with clearer anomaly delineation and more regularized data distributions,effectively mitigating outliers and reducing kurtosis.Additionally,it delivers improved interpolation accuracy and spatially explicit uncertainty estimates,facilitating more reliable and interpretable assessments of prediction confidence.The SC-VAE framework thus provides a robust,geostatistically informed solution for enhancing the quality and interpretability of geochemical data,with broad applicability in mineral exploration,environmental geochemistry,and other Earth Science domains.展开更多
Geochemical reactions play a vital role in determining the efficiency of carbon capture,utilization,and storage combined with enhanced oil recovery(CCUS-EOR),particularly through their influence on reservoir propertie...Geochemical reactions play a vital role in determining the efficiency of carbon capture,utilization,and storage combined with enhanced oil recovery(CCUS-EOR),particularly through their influence on reservoir properties.To deepen the understanding of these mechanisms,this review investigates the interactions among injected CO_(2),formation fluids,and rock minerals and evaluates their implications for CCUS-EOR performance.The main results are summarized as follows.First,temperature,pressure,pH,and fluid composition are identified as key factors influencing mineral dissolution and precipitation,which in turn affect porosity,permeability,and CO_(2) storage.Second,carbonate minerals,such as calcite and dolomite,show high reactivity under lower temperature conditions,enhancing dissolution and permeability,while silicate minerals,including illite,kaolinite,quartz,and K-feldspar,are comparatively inert.Third,the formation of carbonic acid during CO_(2) injection promotes dissolution,whereas secondary precipitation,especially of clay minerals,can reduce pore connectivity and limit flow paths.Fourth,mineral transformation and salt precipitation can further modify reservoir characteristics,influencing both oil recovery and long-term CO_(2) trapping.Fifth,advanced experimental tools,such as Computed Tomography(CT)and Nuclear Magnetic Resonance(NMR)imaging,combined with geochemical modeling and reservoir simulation,are essential to predict petrophysical changes across scales.This review provides a theoretical foundation for integrating geochemical processes into CCUS-EOR design,offering technical support for field application and guiding sustainable CO_(2) management in oil reservoirs.展开更多
The presence of inorganic constituents in coal is controlled by different geological factors,which,in turn,affect the technological,environmental,and health impacts of the coal.The main aim of this study is to objecti...The presence of inorganic constituents in coal is controlled by different geological factors,which,in turn,affect the technological,environmental,and health impacts of the coal.The main aim of this study is to objectively assess the mineralogical and geochemical characteristics of a thickest low-rank coal seam in the Lower Indus Basin southeastern Pakistan,and further investigate different controlling factors.The analytical results of major oxides,trace elements,and rare earth elements revealed that the weathering conditions were progressively variable and moderate.The sediment source,mainly of felsic and intermediate composition,was dominated by granitic rocks.The geochemical assessment reveals different depositional factors like marine environment influenced,while transitional and freshwater sediments influenced the center of the coal peat mire.Strontium,Zinc,and several hazardous trace elements,including Cu,Ni,Cr,and Co,have higher concentrations in these coals compared to world low-rank,U.S.,and Chinese coals.The relatively higher concentration of Sr in the thick coal seam in the Lower Indus Basin,compared to other coals seams in Pakistan and the enrichment of Sr was primarily controlled by the denudation of crystalline rocks and marine influx in the coal-basin.The REY distribution pattern showed that enrichment of medium and heavy rare earth elements is higher than light rare earth elements in the coal seam.The Gd distribution pattern in the coal seam demonstrated that strong positive anomalies had a good affinity with paleo-acidic water concentration in the study area.The higher concentration of Sr and other elements enables a better assessment understanding of the coal geochemical history.展开更多
The Lower Cambrian shales in the Sichuan Basin are considered one of the most promising shale gas resources in China.However,large-scale commercial development has not been achieved due to the relatively low and signi...The Lower Cambrian shales in the Sichuan Basin are considered one of the most promising shale gas resources in China.However,large-scale commercial development has not been achieved due to the relatively low and significantly variable gas contents of the drilled shales.Excitingly,the first major breakthrough in deep and ultra-deep Lower Cambrian shale gas was made recently in the well Z201 in the southern Sichuan Basin,with a gas yield exceeding 73×10^(4)m^(3)/d.The success of well Z201 provides a favorable geological case to reveal the distinct enrichment mechanism of deep and ultra-deep Lower Cambrian shale gas.In this study,at drilling site of well Z201,fresh shale core samples with different gasin-place contents were collected,and their geochemical,pore development and water-bearing characteristics were analyzed systematically.The results showed that the Z201 organic-rich shales reached an overmature stage,with an average Raman maturity of 3.70%.The Z201 shales with high gas-in-place contents are mainly located in the Qiongzhusi 12section and the upper Qiongzhusi 11section,with an average gas-in-place content of 10.08 cm^(3)/g.Compared to the shales with low gas-in-place contents,the shales with high gas-in-place contents exhibit higher total organic carbon contents,greater porosities,and lower water saturations,providing more effective pore spaces for shale gas enrichment.The effective pore structures of the deep and ultra-deep Lower Cambrian shales are the primary factors affecting their gas-in-place contents.Similar to the shales with high gas-in-place contents of well Z201,the deep and ultra-deep Lower Cambrian shales in the Mianyang-Changning intracratonic sag,especially in the Ziyang area,generally developed in deep-water shelf facies with high total organic carbon contents and thick sedimentary thickness,providing favorable conditions for the development and preservation of effective pores.Therefore,they are the most promising targets for Lower Cambrian shale gas exploration.展开更多
The intertidal zone of mangroves has a significant impact on the ecological environment by serving as a crucial habitat for a wide range of organisms.When assessing heavy metal contamination in sediments within this z...The intertidal zone of mangroves has a significant impact on the ecological environment by serving as a crucial habitat for a wide range of organisms.When assessing heavy metal contamination in sediments within this zone,it is essential to establish a regional geochemical baseline that accounts for natural variations.In this study,regional geochemical baselines of heavy metals were established based on core sediment samples collected from Dongzhai Harbor in November 2015.Linear regression analysis was employed to examine the correlations between heavy metals and potential normalized elements.Subsequently,the sediment quality and intensity of pollutant input in the sediments of a mangrove intertidal zone were evaluated with enrichment factor(EF)and excessive influx of heavy metals.The EF values for Cr,Cd,Pb,Zn,and Ni in the study area were all below 1.5,indicating minimal levels of contamination;however,minor Cu contamination was observed in the high tidal flat area due to potential terrestrial inputs.These findings suggest that the overall environmental quality about heavy metals was good within the intertidal zone of mangroves.Moreover,as for the excess fluxes of heavy metals in intertidal sediments,there was consistency between influence and intervention of human activities on sedimentary environment during the selected period when examining variation trends.展开更多
Research on changes in the redox conditions of bottom waters is essential for understanding deep water circulation,global ocean currents,climate change,and ecosystem health.Through sedimentary geological methods,a dee...Research on changes in the redox conditions of bottom waters is essential for understanding deep water circulation,global ocean currents,climate change,and ecosystem health.Through sedimentary geological methods,a deeper understanding of the complex relationships between various environmental changes can be achieved,providing detailed evidence and theoretical support for global climate change research.The Ross Sea in Antarctica plays a key role in the formation of Antarctic bottom water(AABW),and the complex climate changes since the last glacial maximum(LGM)make it particularly significant for study.This research analyzes core ANT32-RB16C from the Ross Sea using geochemical proxies such as major and trace elements,grain size,and redox-sensitive indicators like Mn/Ti,Co/Ti,Mo/Ti,Cd/Ti,U/Th,and Ni/Co molar concentration ratios.Combining this data with a previously established chronological framework,the study explores the evolution of redox conditions in the Ross Sea’s deep waters since the LGM.The results show that the deep waters have remained oxygen-rich since the LGM,with significant changes in four stages.Stage 1(24.7–15.7 cal ka BP):Strong oxidizing conditions,likely due to enhanced formation of Ross Sea bottom water(RSBW),increasing oxygen levels.Stage 2(15.7–4.5 cal ka BP):Weakened oxidizing conditions as temperatures rose and ice shelves retreated,increasing primary productivity and depleting oxygen.Stage 3(4.5–1.5 cal ka BP):Continued decline in oxidizing conditions,possibly linked to high primary productivity and oxygen consumption.Stage 4(1.5 cal ka BP to present):A rapid recovery of oxidizing conditions,likely driven by temperature drops,increased RSBW formation,and decreased productivity.展开更多
This study highlights a new by-product source for cobalt by recycling Paleoproterozoic Mn deposits.We present a geochemical modeling approach utilizing Principal Component Analysis(PCA)for available geochemical data o...This study highlights a new by-product source for cobalt by recycling Paleoproterozoic Mn deposits.We present a geochemical modeling approach utilizing Principal Component Analysis(PCA)for available geochemical data of Paleoproterozoic manganese deposits found in Africa and Brazil,which exhibit anomalous cobalt contents(up to 1200 ppm)along with other metals such as copper,nickel,and vanadium.The PCA results for the correlation coefficient matrix of the Enrichment Factor(_(EF))values of major and trace elements from samples of eight Mn deposits found in Africa and Brazil(Kisenge-Kamata,Moanda,Nsuta in Africa,and Azul,Buritirama,Lagoa do Riacho,Morro da Mina,and Serra do Navio in Brazil)yielded a cumulative variance of 53.3%for PC1(34%)and PC2(19.3%).In PC1,the highest positive loadings correspond to the variables Mn_(EF),Ni_(EF),and Co_(EF),while the highest negative loadings correspond to the variables Si_(EF),Fe_(EF),K_(EF),Ti_(EF),Cr_(EF),and Zr_(EF).PC2 exhibits the highest positive loadings for the variables Ca_(_(EF)),Mg_(EF),and P_(EF),while the highest negative loadings are for Cu_(EF)and V_(EF).The biplot diagram representation showed that clusters of vectors Mn_(EF),Ni_(EF),Co_(EF),V_(EF),and Cu_(EF)influence samples of Mn-carbonate rock,Mn-carbonate-silicate rock,Mn-silicate rock,and Mn-carbonate-siliciclastic rock,all with high Co_(EF)values(up to 414).The cluster of vectors Ca_(_(EF)),Mg_(EF),and P_(EF)significantly influence carbonate rock and dolomite marble,which have low Co_(EF)values(close to 0).The cluster of vectors Si_(EF),Fe_(EF),K_(EF),Ti_(EF),Cr_(EF),and Zr_(EF)strongly influences siliciclastic rock,which exhibits low Co_(EF)values.On the other hand,the cluster of vectors Cu_(EF)and V_(EF)influences oxidized Mn ore,which exhibits Co_(EF)values of up to 108.The results reveal a dichotomy regarding the origin of cobalt and other metal enrichments in these deposits linked to the Mn redox cycle.This process involves the formation of Mn-oxyhydroxides with the adsorption of Co and other metals under oxic conditions,followed by the burial of these Mn oxides in an anoxic diagenetic environment,where microbial sulfate reduction leads to the nucleation of Mn-carbonates and the formation of metal-rich sulfides(Fe,Co,Ni,V).Additionally,detrital input and sulfide phases(e.g.,framboidal pyrite)for the formation of Mn-rich siliciclastic rocks associated with Mn-carbonate rocks are evidenced by proxies Si_(EF),Fe_(EF),K_(EF),Ti_(EF),Cr_(EF),and Zr_(EF).This new exploration approach,supported by geochemical modeling through PCA,enhances our understanding of the genesis of these Paleoproterozoic manganese deposits and highlights a new route for cobalt exploration.In the increasing global demand for cobalt,particularly in applications involving electric vehicle batteries and energy storage,exploring these deposits emerges as an alternative source to produce these critical metals.展开更多
基金the support from the National Natural Science Foundation of China(Nos.52279103,52379103)the Natural Science Foundation of Shandong Province(No.ZR2023YQ049)。
文摘Geological analysis,despite being a long-term method for identifying adverse geology in tunnels,has significant limitations due to its reliance on empirical analysis.The quantitative aspects of geochemical anomalies associated with adverse geology provide a novel strategy for addressing these limitations.However,statistical methods for identifying geochemical anomalies are insufficient for tunnel engineering.In contrast,data mining techniques such as machine learning have demonstrated greater efficacy when applied to geological data.Herein,a method for identifying adverse geology using machine learning of geochemical anomalies is proposed.The method was identified geochemical anomalies in tunnel that were not identified by statistical methods.We by employing robust factor analysis and self-organizing maps to reduce the dimensionality of geochemical data and extract the anomaly elements combination(AEC).Using the AEC sample data,we trained an isolation forest model to identify the multi-element anomalies,successfully.We analyzed the adverse geological features based the multi-element anomalies.This study,therefore,extends the traditional approach of geological analysis in tunnels and demonstrates that machine learning is an effective tool for intelligent geological analysis.Correspondingly,the research offers new insights regarding the adverse geology and the prevention of hazards during the construction of tunnels and underground engineering projects.
基金support from the National Natural Science Foundation of China(51604288)the Beijing Natural Science Foundation(IS23043)+1 种基金the Science Foundation of China University of Petroleum-Beijing(ZX20200133)the Research and Development Fund of China Huaneng Group Clean Energy Technology Research Institute(QNYJJ22-21).
文摘The substantial emissions of greenhouse gases,particularly CO_(2),constitute a primary driver of global warming.CCUS is proposed as an effective mitigation strategy which is often estimated to account for about 15%of cumulative carbon emission reduction.In-situ CO_(2) mineralization sequestration,compared to conventional geological storage methods such as depleted oil and gas reservoirs,unmineable coal seams,and deep saline aquifers,offers the advantage of permanent immobilization of injected carbon.However,uncertainties persist regarding the characteristics of geochemical interactions under reservoir pore conditions,as well as the kinetic mechanisms of mineralization reactions.Additionally,geochemical reactions may lead to solid particle transport and deposition,potentially causing pore throat occlusion.Pilot projects in Iceland and the United States have demonstrated the feasibility of this technology,but the field remains in the early deployment stage.In this review,the mechanisms of in-situ mineralization have been elucidated,the primary factors influencing the reaction kinetics have been discussed,and the current research status in this field has been summarized.It is emphasized that establishing a reliable system for evaluating storage capacity and understanding the kinetic mechanisms governing CO_(2) conversion into minerals at multi-phase interfaces are key priorities for future work.
文摘Located in Southeastern Chad. The Iro lake offers a great opportunity for the study of Precambrian formations and their Phanerozoic cover. Pluton is a Cal-alkaline granite. Due to its geographical location and geological features, it holds crucial information for understanding the evolution of the Saharan Meta craton (central Africa), which remains poorly studied. One of the objectives is to map the formations Precambrian age in Southeastern Chad. Based on the petrographic and geochemical results, we identified granitoids of pan-African age (biotite granite, aplite granite and pegmatite granite). This Precambrian basement is covered with sedimentary formations (clays, argillites, lateritic cuirasses, etc.). The mineral assemblage is characteristic of acid rocks. Geochemistry reveals rocks with a high SiO2 range (62% - 77%) giving sub-alkaline to calc-alkaline acid rocks with high k (4.62% to 6.39%). The granitoids are classified as S-type hyperaluminous granites. This classification is supported by the presence of peraluminous minerals (e.g., muscovite) within the Iro granitoids, which also have high (>1%). Geochemical variation within the granites is largely due to extensive crystal fractionation. The Pattern of REEs normalized to the primitive mantle shows a pronounced negative Eu anomaly, reflecting the crystallization process and fractional crystallization of plagioclase in the rock, and a positive Yb anomaly. The role of plagioclase fractionation was relatively major during the earlier intrusive stages (consistent with the presence of Eu anomalies) and slightly increased, together with biotite and K-feldspar fractionation, during the later (granitic) rock crystallization. The Pattern of the spider normalized to MORBs shows two pronounced negative anomalies in TiO2 and Cs and a slight negative anomaly in Ba. The loss of Ba, Ti and Cs may be caused by the plagioclase fractionation, apatite and ilmenite crystal. The Ba anomaly is also controlled by the presence of K-feldspar and mica. The observed Ti anomalies are due to the fractionation of magnetite indicating a subduction environment (or remelting of a source from a subduction environment).
基金the National Natural Science Foundation of China(Nos.42206076,42476078)the National Program on Global Change and Air-Sea Interaction(No.GASI-02-SCSCJB01)the China-Malaysia Cooperation Project‘Effect on variability of seasonal monsoon on sedimentary process in Peninsular Malaysia waters’。
文摘The Malacca Strait(MS)is a vital conduit for the exchange of water and sediment between the Indian Ocean and the Pacific Ocean,serving as a critical‘gateway'for sediment transport.Here,we present the geochemical characteristics of surface sediments in the MS to elucidate the relationship between terrestrial material inputs and modern oceanic dynamic transport processes in the strait.The results reveal that the MS can be divided into three distinct geochemical provinces.ProvinceⅠ,located in the central region of the strait,is characterized by residual deposits.The preservation of these residual deposits can be attributed to the restricted sediment supply and the relatively weaker modern sedimentary hydrodynamic conditions.ProvinceⅡ,situated to the north of ProvinceⅠ,exhibits provenance differences between its southern and northern regions.The northern region is primarily supplied by sediments originating from the eastern shelf of the Andaman Sea,whereas sediments derived from Sumatra and the Sunda Shelf are predominantly deposited in the southern part of ProvinceⅡ.ProvinceⅢextends along the western coast of the Malaysian Peninsula,with sediments primarily sourced from the Malaysian Peninsula and the Sunda Shelf,while contributions from Sumatra and the eastern shelf of the Andaman Sea are negligible.River sediments from the Malaysian Peninsula and Sumatra are transported northwestward along their respective coasts by prevailing currents,which also facilitate the transportation of Sunda Shelf sediments within the strait,while sediments from the eastern shelf of the Andaman Sea are delivered to the MS via southward coastal currents during the southwest monsoon period.The southward currents and well-developed eddies potentially impede the northward transport of sediments from the Sunda Shelf and restrict the distribution of Andaman Sea sediments within the strait.This study substantially enhances the understanding of source-to-sink processes in the Indo-Pacific region.
基金funded by the Major Research Plan of the National Natural Science Foundation of China(92162323)Strategic Priority Research Program of the Chinese Academy of Sciences(XDA0430101)Guizhou Provincial Science and Technology Projects No.ZK[2023]052.
文摘Lithium is a critical strategic metal with signifi-cant reserves in pegmatites,serving as the primary source for global Li production.Apatite has attracted increasing attention as an indicator in petrogenesis studies and for the exploration of ore deposits.In this study,we investigated the volatile compositions and major and trace elements of apatite from the Qiongjiagang pegmatite-type lithium deposit in Himalaya.Apatite derived from spodumene pegmatite exhibits relatively constant and high total rare earth element(ΣREE+Y)concentrations,ranging from 5899 to 8540 ppm.In contrast,apatite in barren pegmatite displays evidently lower(ΣREE+Y)concentrations,varying between 1345 and 3095 ppm.The REE patterns of apatite in spodumene pegmatite generally exhibit a flat shape[(La/Yb)N=1.55-2.15)],with distinctively negative Eu anomalies(Eu_(N)/Eu_(N)^(*)=0.14-0.22),slightly positive Ce anomalies(Ce_(N)/Ce_(N)^(*)=1.03-1.13),and low Y/Ho ratios(28-30).By contrast,apatite in barren pegmatite shows middle rare earth element(MREE)-depleted downward-convex patterns[(La/Yb)N=1.99-20.4)],strongly negative Eu anomalies(Eu_(N)/Eu_(N)^(*)=0.01-0.14),slightly positive Ce anomalies(Ce_(N)/Ce_(N)^(*)=1.10-1.24),and high Y/Ho ratios(30-55,with an average of 50).Overall,the high concentrations ofΣREE(and Y)and low Th/U and Y/Ho ratios can serve as diagnostic indicators to distinguish apatite in spodumene pegmatite from that in barren pegmatite.Furthermore,the flat REE pattern may represent a common feature of apatite from lithium deposits.Differences in the Ce and Eu anomalies between apatite from these two kinds of pegmatites likely reflect formation under different redox conditions.Consequently,based on calculations derived from apatite volatile compositions,the melt associated with spodumene pegmatite may contain higher water content compared to that of the barren one.Therefore,the mineralized pegmatite system may incorporate substantial amounts of H_(2)O-rich fluids,which play a crucial role in lithium mineralization.
文摘This study investigates the potential of natural Brown Coal(BC)as a sustainable,cost-effective adsorbent for the removal of manganese(Mn2+)from contaminated groundwater.A series of batch adsorp-tion experiments was conducted to assess the influence of key operational parameters—such as solution pH,2+initial Mn concentration,BC dosage,temperature,and the presence of competing ions—on 2+Mn removal efficiency.The environmental compatibility and regeneration potential of BC were also evaluated to deter-mine its practical viability for repeated use.To better understand the adsorption behaviour,equilibrium and kinetic data were analysed using established isotherm and kinetic models,while thermodynamic parameters were computed to assess the spontaneity and thermal characteristics of the adsorption process.Furthermore,geochemical modelling and comprehensive BC characterization—including surface morphology,miner-alogical and elemental composition,and functional group analysis—were 2+performed to elucidate Mn speciation under varying environmental conditions and to uncover the underlying adsorption mechanisms.2+Results showed that Mn removal efficiency increased with higher pH,temperature,and BC dosage,but 2+declined at elevated initial Mn concentrations due to active site saturation.The process was spontaneous 2 and endothermic,with the Langmuir isotherm model(R=0.994)and pseudo-second-order kinetic model 2(R=0.996)providing the best fit to experimental data.Mechanistic analysis indicated that chemisorption,2+primarily through ion exchange and inner-sphere complexation,was the dominant mode of Mn uptake.3+The presence of competing cations,especially Fe and Cu2+,2+significantly hindered Mn removal due to preferential binding.Importantly,BC exhibited strong reusability,maintaining over 80%removal effi-ciency across four adsorption–desorption cycles without evidence of secondary pollutants.These findings demonstrate the potential of natural BC as an efficient,reusable,and environmentally benign material for treating manganese-contaminated groundwater.
基金supported by the research grant from Institute of Crustal Dynamics,China Earthquake Administration(No.ZDJ2019-02)。
文摘Geochemistry of the fault gouge record information on fault behaviors and environmental conditions.We investigated variations in the mineralogical and geochemical compositions of the fault gouge sampled from the margin zone(MZ)to the slip central zone(CZ)of the fault gouge in the Beichuan-Yingxiu surface rupture zone of the Wenchuan Earthquake.Results show that the clay minerals contents increase from the MZ to CZ,and the quartz and plagioclase contents slight decrease.An increasing enrichment in Al_(2)O_(3),Fe_(2)O_(3),and K_(2)O are observed toward the CZ;the decomposition of quartz and plagioclase,as well as the depletion of Si O_(2),Ca O,Na_2O,and P_(2)O_(5)suggest that the alkaline-earth elements are carried away by the fluids.It can be explained that the stronger coseismic actions in the CZ allow more clay minerals to form,decompose quartz and plagioclase,and alter plagioclase to chlorite.The mass loss in the CZ is larger than that in MZ,which is maybe due to the more concentrated stress in the strongly deformed CZ,however other causes will not be excluded.
文摘Rising global energy needs have intensified the search for unconventional hydrocarbon sources,especially in under-selected areas like the Northeast Java Basin.This region harbors promising unconventional hydrocarbon reserves,where source rocks function as dual-phase systems for both hydrocarbon generation and storage.This research investigates how metal-based catalysts,particularly iron(Fe),can expedite hydrocarbon maturation in such reservoirs.Combining well logging,geochemical assessments,seismic data,and advanced lab techniques,including X-ray Diffraction(XRD),we pinpoint optimal zones for exploration.Results indicate that the Tuban,Kujung,and Ngimbang formations contain economically viable unconventional deposits,exhibiting tight reservoir properties(permeability:0.01–1 md)and moderate to good Total Organic Carbon(TOC)levels(1%–2%).Spatial analysis reveals elevated density concentrations in the northern sector,indicative of high-viscosity hydrocarbons typical of unconventional plays.Crucially,Fe additives were found to markedly enhance organic matter conversion,shortening maturation periods and boosting hydrocarbon yield.XRD data confirms that Fe alters crystalline configurations,increasing reactivity and speeding up thermal breakdown(shifting immature organic compounds toward maturity at an accelerated rate).These findings contribute to the evolving discourse on unconventional resource exploitation by proposing an innovative recovery enhancement strategy.The study also sets a precedent for investigating metal-assisted hydrocarbon conversion in geologically comparable basins globally.
文摘This research examines the hard-rock aquifer system within the Nagavathi River Basin(NRB)South India,by evaluating seasonal fluctuations in groundwater composition during the pre-monsoon(PRM)and post-monsoon(POM)periods.Seasonal variations significantly influence the groundwater quality,particularly fluoride(F−)concentrations,which can fluctuate due to changes in recharge,evaporation,and anthropogenic activities.This study assesses the dynamics of F−levels in PRM and POM seasons,and identifies elevated health risks using USEPA guidelines and Monte Carlo Simulations(MCS).Groundwater in the study area exhibits alkaline pH,with NaCl and Ca-Na-HCO_(3) facies increasing in the POM season due to intensified ion exchange and rock-water interactions,as indicated in Piper and Gibb’s diagrams.Correlation and dendrogram analyses indicate that F−contamination is from geogenic and anthropogenic sources.F−levels exceed the WHO limit(1.5 mg/L)in 51 PRM and 28 POM samples,affecting 371.74 km^(2) and 203.05 km^(2),respectively.Geochemical processes,including mineral weathering,cation exchange,evaporation,and dilution,are identified through CAI I&II.Health risk assessments reveal that HQ values>1 in 78%of children,73%of teens,and 68%of adults during PRM,decreasing to 45%,40%,and 38%,respectively,in POM.MCS show maximum HQ values of 5.67(PRM)and 4.73(POM)in children,with all age groups facing significant risks from fluoride ingestion.Managed Aquifer Recharge(MAR)is recommended in this study to minimize F−contamination,ensuring safe drinking water for the community.
基金supported by Croatian Science Foundation Research Project Dinaridic Foreland Basin between Two Eocene Thermal Optima:A Possible Scenario for the Northern Adriatic BREEMECO(No.2019-04-5775)。
文摘Hemipelagic to pelagic(H/P)marls,representing pelitic deposits,accumulated within the foredeep sub-basin of the Dinaric Foreland Basin(northern Neotethyan margin,present-day Croatia)during the Middle to Late Eocene.Syn-sedimentary tectonic movements,paleogeographic position and exchanges of short-lived hyperthermal episodes affected the sedimentation and related mineral and geochemical record of these deposits.Mineral(clay)assemblages bear signature of prevailing physical weathering with significant illite and chlorite content,but climatic seasonality is suggested by smectite-interlayered phases and sporadical increase of kaolinite content.Illite crystallinity varies significantly,and the lowest crystallinity is recorded by the Lutetian samples.Illite chemistry index is always bellow 0.5,being characteristic for Fe-Mg-rich illite.The geochemical records are the most prominent(CIA up to 76,CIW up to 91)for the Istrian Lutetian(42.3-40.5 Ma),but also for Priabonian(35.8-34.3 Ma)samples of Hvar Island.The ICV values(the lowest 1.40 and the highest 10.85)of all studied samples fall above PAAS(ICV=0.85)and point to their chemical immaturity.The Ga/Rb ratios are lower than 0.2 and K_(2)O/Al_(2)O_(3) ratios are also low(0.16-0.22),implying transition between cold and dry,and warm and humid climate,obviously trending among several warming episodes.
基金Supported by the National Natural Science Foundation of China(No.U2244222).
文摘This study selects geochemical data of basalts from different seamounts in the Mid-Pacific Mountains province and conducts analyses of major and trace elements as well as Sr-Nd-Pb isotopes to explore the tectonic evolution,petrogenesis,and mantle-source magama characteristics of the Mid-Pacific Mountains.The basalts from the Mid-Pacific Mountains are predominantly alkali basalts,rich in alkalies,and changing in potassium.They exhibit geochemical features of ocean island basalts(OIB),with distinct fractionation between light and heavy rare-earth elements and a pronounced Ce negative anomaly(δ_(Ce)=0.16–1.10,average 0.84),along with enrichment in large ion lithophile elements(LILEs).The Mid-Pacific Mountains are intraplate ocean island basalts formed by mantle plume(hotspot)activity,originating mainly from an enriched mantle magma source region,and most of them have undergone low degree of partial melting and a certain degree of crystalline differentiation,with negligible contamination from oceanic crust materials.The Mid-Pacific Mountains exhibit ratios of^(87)Sr/^(86)Sr(i)(0.702733–0.704313,average 0.703452)and^(143)Nd/^(144)Nd(i)(0.512698–0.512996,average 0.512846)which are close to the HIMU mantle endmember,and ratios of 206Pb/204Pb(18.953–19.803),^(207)Pb/^(204)Pb(15.54–15.62)and^(208)Pb/^(204)Pb(38.813–39.514)which are close to the EMII mantle end-member.Combined with the isotopic geochemical characteristics in the West Pacific Seamounts province,the basalts from the Mid-Pacific Mountains were considered to represent a certain proportion of mixing mantle end-members between the HIMU and EMII,possibly formed by the mixing of the HIMU superplume in the South Pacific hotspot region with the EMII secondary mantle plume in the transition zone during their ascent.
文摘The Langrial iron ore deposits,located in the villages of Dubran and Darkot in Hazara,Pakistan,were evaluated using remote sensing,magnetic,and geochemical investigations.Data from ASTER,Landsat-8,and Sentinel-2 satellites were utilized and processed through techniques such as band ratio analysis,band compositing,and NDVI masking to reduce vegetation effects and to delineate various lithological units and mineralogical signatures within the study area.Magnetic anomalies revealed multiple levels of iron mineralization,with the hematite zone showing the most significant potential for high-grade iron ore.Geochemical analyses confirmed the presence of iron,along with minerals such as chromium,calcium,magnesium,and lead.In Dubran,mean iron concentrations are recorded at 370.94 mg/kg,whereas in Darkot,they reach up to 2052 mg/kg.The integration of remote sensing,magnetic,and geochemical data delineates key mineralized zones in the various parts of the study area.This research highlights the importance of combining geophysical and geochemical methodologies to refine mineral exploration efforts.The findings enhance our understanding of the Langrial iron ore deposits and highlight their economic potential for sustainable mining practices.This study will contribute to meeting the growing demand for iron ore resources and reducing Pakistan's reliance on imports,thereby promoting the sustainable development of local industries.
基金funded by the National Science Foundation of China(52204033)the Science&Technology Department of Sichuan Province(2024NSFSC0201)Scientific research Project of Petro China Southwest Oil&Gas Field Company(No.2024D112-01-01).
文摘Balancing CO2 emission reduction with enhanced gas recovery in carbonate reservoirs remains a key challenge in subsurface energy engineering.This study focuses on the Maokou Formation gas reservoir in the Wolonghe Gas Field,Sichuan Basin,and employs a mechanistic model integrated with numerical simulations that couple CO2–water–rock geochemical interactions to systematically explore the principal engineering and chemical factors governing Carbon Capture,Utilization,and Storage–Enhanced Gas Recovery(CCUS–EGR).The analysis reveals that both the injection–production ratio and gas injection rate exhibit optimal ranges.Maximum gas output under single-parameter variation occurs at an injection–production ratio of 0.7 and an injection rate of 130,000 m3/d,while coordinated optimization of both parameters is essential to achieve the highest production enhancement.Excessively high injection–production ratios,however,may induce gas channeling and reduce the ultimate recovery factor.Chemical composition of the injected gas also strongly influences recovery.In the heterogeneous carbonate reservoir considered,a CO2–N2 mixed gas mitigates gravity segregation due to its lower density,expanding sweep efficiency and improving overall gas recovery compared to pure CO2 injection.CO2–water–rock reactions further modify reservoir properties.Near the injection well,acidic dissolution enhances porosity,whereas near the production well,a dynamic interplay of ion migration,pressure–temperature variations,and secondary mineral precipitation produces complex porosity evolution.Initial precipitation reduces porosity,while subsequent acidic dissolution partially restores it,creating a heterogeneous and time-dependent porosity profile.
基金supported by the National Natural Science Foundation of China(Nos.42530801,42425208)the Natural Science Foundation of Hubei Province(China)(No.2023AFA001)+1 种基金the MOST Special Fund from State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences(No.MSFGPMR2025-401)the China Scholarship Council(No.202306410181)。
文摘Geochemical survey data are essential across Earth Science disciplines but are often affected by noise,which can obscure important geological signals and compromise subsequent prediction and interpretation.Quantifying prediction uncertainty is hence crucial for robust geoscientific decision-making.This study proposes a novel deep learning framework,the Spatially Constrained Variational Autoencoder(SC-VAE),for denoising geochemical survey data with integrated uncertainty quantification.The SC-VAE incorporates spatial regularization,which enforces spatial coherence by modeling inter-sample relationships directly within the latent space.The performance of the SC-VAE was systematically evaluated against a standard Variational Autoencoder(VAE)using geochemical data from the gold polymetallic district in the northwestern part of Sichuan Province,China.Both models were optimized using Bayesian optimization,with objective functions specifically designed to maintain essential geostatistical characteristics.Evaluation metrics include variogram analysis,quantitative measures of spatial interpolation accuracy,visual assessment of denoised maps,and statistical analysis of data distributions,as well as decomposition of uncertainties.Results show that the SC-VAE achieves superior noise suppression and better preservation of spatial structure compared to the standard VAE,as demonstrated by a significant reduction in the variogram nugget effect and an increased partial sill.The SC-VAE produces denoised maps with clearer anomaly delineation and more regularized data distributions,effectively mitigating outliers and reducing kurtosis.Additionally,it delivers improved interpolation accuracy and spatially explicit uncertainty estimates,facilitating more reliable and interpretable assessments of prediction confidence.The SC-VAE framework thus provides a robust,geostatistically informed solution for enhancing the quality and interpretability of geochemical data,with broad applicability in mineral exploration,environmental geochemistry,and other Earth Science domains.
基金support from the National Natural Science Foundation of China(No.52304048)supported by the Sichuan Science and Technology Program(No.2025ZNSFSC1355)the Open Fund(No.PLN202428)of the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation at Southwest Petroleum University.
文摘Geochemical reactions play a vital role in determining the efficiency of carbon capture,utilization,and storage combined with enhanced oil recovery(CCUS-EOR),particularly through their influence on reservoir properties.To deepen the understanding of these mechanisms,this review investigates the interactions among injected CO_(2),formation fluids,and rock minerals and evaluates their implications for CCUS-EOR performance.The main results are summarized as follows.First,temperature,pressure,pH,and fluid composition are identified as key factors influencing mineral dissolution and precipitation,which in turn affect porosity,permeability,and CO_(2) storage.Second,carbonate minerals,such as calcite and dolomite,show high reactivity under lower temperature conditions,enhancing dissolution and permeability,while silicate minerals,including illite,kaolinite,quartz,and K-feldspar,are comparatively inert.Third,the formation of carbonic acid during CO_(2) injection promotes dissolution,whereas secondary precipitation,especially of clay minerals,can reduce pore connectivity and limit flow paths.Fourth,mineral transformation and salt precipitation can further modify reservoir characteristics,influencing both oil recovery and long-term CO_(2) trapping.Fifth,advanced experimental tools,such as Computed Tomography(CT)and Nuclear Magnetic Resonance(NMR)imaging,combined with geochemical modeling and reservoir simulation,are essential to predict petrophysical changes across scales.This review provides a theoretical foundation for integrating geochemical processes into CCUS-EOR design,offering technical support for field application and guiding sustainable CO_(2) management in oil reservoirs.
基金supported by the National Natural Science Foundation of China,funding numbers 41690131,41572327,51874280 and 5264015.
文摘The presence of inorganic constituents in coal is controlled by different geological factors,which,in turn,affect the technological,environmental,and health impacts of the coal.The main aim of this study is to objectively assess the mineralogical and geochemical characteristics of a thickest low-rank coal seam in the Lower Indus Basin southeastern Pakistan,and further investigate different controlling factors.The analytical results of major oxides,trace elements,and rare earth elements revealed that the weathering conditions were progressively variable and moderate.The sediment source,mainly of felsic and intermediate composition,was dominated by granitic rocks.The geochemical assessment reveals different depositional factors like marine environment influenced,while transitional and freshwater sediments influenced the center of the coal peat mire.Strontium,Zinc,and several hazardous trace elements,including Cu,Ni,Cr,and Co,have higher concentrations in these coals compared to world low-rank,U.S.,and Chinese coals.The relatively higher concentration of Sr in the thick coal seam in the Lower Indus Basin,compared to other coals seams in Pakistan and the enrichment of Sr was primarily controlled by the denudation of crystalline rocks and marine influx in the coal-basin.The REY distribution pattern showed that enrichment of medium and heavy rare earth elements is higher than light rare earth elements in the coal seam.The Gd distribution pattern in the coal seam demonstrated that strong positive anomalies had a good affinity with paleo-acidic water concentration in the study area.The higher concentration of Sr and other elements enables a better assessment understanding of the coal geochemical history.
基金supported by the National Natural Science Foundation of China(41925014).
文摘The Lower Cambrian shales in the Sichuan Basin are considered one of the most promising shale gas resources in China.However,large-scale commercial development has not been achieved due to the relatively low and significantly variable gas contents of the drilled shales.Excitingly,the first major breakthrough in deep and ultra-deep Lower Cambrian shale gas was made recently in the well Z201 in the southern Sichuan Basin,with a gas yield exceeding 73×10^(4)m^(3)/d.The success of well Z201 provides a favorable geological case to reveal the distinct enrichment mechanism of deep and ultra-deep Lower Cambrian shale gas.In this study,at drilling site of well Z201,fresh shale core samples with different gasin-place contents were collected,and their geochemical,pore development and water-bearing characteristics were analyzed systematically.The results showed that the Z201 organic-rich shales reached an overmature stage,with an average Raman maturity of 3.70%.The Z201 shales with high gas-in-place contents are mainly located in the Qiongzhusi 12section and the upper Qiongzhusi 11section,with an average gas-in-place content of 10.08 cm^(3)/g.Compared to the shales with low gas-in-place contents,the shales with high gas-in-place contents exhibit higher total organic carbon contents,greater porosities,and lower water saturations,providing more effective pore spaces for shale gas enrichment.The effective pore structures of the deep and ultra-deep Lower Cambrian shales are the primary factors affecting their gas-in-place contents.Similar to the shales with high gas-in-place contents of well Z201,the deep and ultra-deep Lower Cambrian shales in the Mianyang-Changning intracratonic sag,especially in the Ziyang area,generally developed in deep-water shelf facies with high total organic carbon contents and thick sedimentary thickness,providing favorable conditions for the development and preservation of effective pores.Therefore,they are the most promising targets for Lower Cambrian shale gas exploration.
基金Supported by the Project of Investigation on the Background and Quality of Representative Intertidal Sediments in China and Compilation of Atlas,Ministry of Science and Technology of the People’s Republic of China(No.2014FY210600)the National Natural Science Foundation of China(No.41807247)。
文摘The intertidal zone of mangroves has a significant impact on the ecological environment by serving as a crucial habitat for a wide range of organisms.When assessing heavy metal contamination in sediments within this zone,it is essential to establish a regional geochemical baseline that accounts for natural variations.In this study,regional geochemical baselines of heavy metals were established based on core sediment samples collected from Dongzhai Harbor in November 2015.Linear regression analysis was employed to examine the correlations between heavy metals and potential normalized elements.Subsequently,the sediment quality and intensity of pollutant input in the sediments of a mangrove intertidal zone were evaluated with enrichment factor(EF)and excessive influx of heavy metals.The EF values for Cr,Cd,Pb,Zn,and Ni in the study area were all below 1.5,indicating minimal levels of contamination;however,minor Cu contamination was observed in the high tidal flat area due to potential terrestrial inputs.These findings suggest that the overall environmental quality about heavy metals was good within the intertidal zone of mangroves.Moreover,as for the excess fluxes of heavy metals in intertidal sediments,there was consistency between influence and intervention of human activities on sedimentary environment during the selected period when examining variation trends.
基金The National Key R&D Program of China under contract No. 2023YFC28 11305the Scientific Research Fund of the Second Institute of Oceanography,MNR under contract No. SZ2405the Impact and Response of Antarctic Seas to Climate Change under contract No. IRASCC
文摘Research on changes in the redox conditions of bottom waters is essential for understanding deep water circulation,global ocean currents,climate change,and ecosystem health.Through sedimentary geological methods,a deeper understanding of the complex relationships between various environmental changes can be achieved,providing detailed evidence and theoretical support for global climate change research.The Ross Sea in Antarctica plays a key role in the formation of Antarctic bottom water(AABW),and the complex climate changes since the last glacial maximum(LGM)make it particularly significant for study.This research analyzes core ANT32-RB16C from the Ross Sea using geochemical proxies such as major and trace elements,grain size,and redox-sensitive indicators like Mn/Ti,Co/Ti,Mo/Ti,Cd/Ti,U/Th,and Ni/Co molar concentration ratios.Combining this data with a previously established chronological framework,the study explores the evolution of redox conditions in the Ross Sea’s deep waters since the LGM.The results show that the deep waters have remained oxygen-rich since the LGM,with significant changes in four stages.Stage 1(24.7–15.7 cal ka BP):Strong oxidizing conditions,likely due to enhanced formation of Ross Sea bottom water(RSBW),increasing oxygen levels.Stage 2(15.7–4.5 cal ka BP):Weakened oxidizing conditions as temperatures rose and ice shelves retreated,increasing primary productivity and depleting oxygen.Stage 3(4.5–1.5 cal ka BP):Continued decline in oxidizing conditions,possibly linked to high primary productivity and oxygen consumption.Stage 4(1.5 cal ka BP to present):A rapid recovery of oxidizing conditions,likely driven by temperature drops,increased RSBW formation,and decreased productivity.
基金the Department of Geology at the Federal University of Ceará(DEGEO-UFC)and Prof.Dr.Felipe Holanda dos Santos for their support and guidance during the research process.FHS would like to thank the Society of Economic Geologists(SEG)for the Student Research Grant.WAS is funded by CNPq,under grant number(407255/2022-2).
文摘This study highlights a new by-product source for cobalt by recycling Paleoproterozoic Mn deposits.We present a geochemical modeling approach utilizing Principal Component Analysis(PCA)for available geochemical data of Paleoproterozoic manganese deposits found in Africa and Brazil,which exhibit anomalous cobalt contents(up to 1200 ppm)along with other metals such as copper,nickel,and vanadium.The PCA results for the correlation coefficient matrix of the Enrichment Factor(_(EF))values of major and trace elements from samples of eight Mn deposits found in Africa and Brazil(Kisenge-Kamata,Moanda,Nsuta in Africa,and Azul,Buritirama,Lagoa do Riacho,Morro da Mina,and Serra do Navio in Brazil)yielded a cumulative variance of 53.3%for PC1(34%)and PC2(19.3%).In PC1,the highest positive loadings correspond to the variables Mn_(EF),Ni_(EF),and Co_(EF),while the highest negative loadings correspond to the variables Si_(EF),Fe_(EF),K_(EF),Ti_(EF),Cr_(EF),and Zr_(EF).PC2 exhibits the highest positive loadings for the variables Ca_(_(EF)),Mg_(EF),and P_(EF),while the highest negative loadings are for Cu_(EF)and V_(EF).The biplot diagram representation showed that clusters of vectors Mn_(EF),Ni_(EF),Co_(EF),V_(EF),and Cu_(EF)influence samples of Mn-carbonate rock,Mn-carbonate-silicate rock,Mn-silicate rock,and Mn-carbonate-siliciclastic rock,all with high Co_(EF)values(up to 414).The cluster of vectors Ca_(_(EF)),Mg_(EF),and P_(EF)significantly influence carbonate rock and dolomite marble,which have low Co_(EF)values(close to 0).The cluster of vectors Si_(EF),Fe_(EF),K_(EF),Ti_(EF),Cr_(EF),and Zr_(EF)strongly influences siliciclastic rock,which exhibits low Co_(EF)values.On the other hand,the cluster of vectors Cu_(EF)and V_(EF)influences oxidized Mn ore,which exhibits Co_(EF)values of up to 108.The results reveal a dichotomy regarding the origin of cobalt and other metal enrichments in these deposits linked to the Mn redox cycle.This process involves the formation of Mn-oxyhydroxides with the adsorption of Co and other metals under oxic conditions,followed by the burial of these Mn oxides in an anoxic diagenetic environment,where microbial sulfate reduction leads to the nucleation of Mn-carbonates and the formation of metal-rich sulfides(Fe,Co,Ni,V).Additionally,detrital input and sulfide phases(e.g.,framboidal pyrite)for the formation of Mn-rich siliciclastic rocks associated with Mn-carbonate rocks are evidenced by proxies Si_(EF),Fe_(EF),K_(EF),Ti_(EF),Cr_(EF),and Zr_(EF).This new exploration approach,supported by geochemical modeling through PCA,enhances our understanding of the genesis of these Paleoproterozoic manganese deposits and highlights a new route for cobalt exploration.In the increasing global demand for cobalt,particularly in applications involving electric vehicle batteries and energy storage,exploring these deposits emerges as an alternative source to produce these critical metals.
