Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-...Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-scale drilling expeditions to study the GH-bearing zone in the Ulleung Basin,the mineral composition of 488 sediment samples was analyzed using X-ray diffraction(XRD).Because the analysis is costly and dependent on experts,a machine learning model was developed to predict the mineral composition using XRD intensity profiles as input data.However,the model’s performance was limited because of improper preprocessing of the intensity profile.Because preprocessing was applied to each feature,the intensity trend was not preserved even though this factor is the most important when analyzing mineral composition.In this study,the profile was preprocessed for each sample using min-max scaling because relative intensity is critical for mineral analysis.For 49 test data among the 488 data,the convolutional neural network(CNN)model improved the average absolute error and coefficient of determination by 41%and 46%,respectively,than those of CNN model with feature-based pre-processing.This study confirms that combining preprocessing for each sample with CNN is the most efficient approach for analyzing XRD data.The developed model can be used for the compositional analysis of sediment samples from the Ulleung Basin and the Korea Plateau.In addition,the overall procedure can be applied to any XRD data of sediments worldwide.展开更多
When early explorers first crossed the Platte River in what is now Nebraska (USA), it was said the river was “a mile wide and an inch deep”(Mokler, 1923;Smith, 1971). This phrase was used to describe not only the di...When early explorers first crossed the Platte River in what is now Nebraska (USA), it was said the river was “a mile wide and an inch deep”(Mokler, 1923;Smith, 1971). This phrase was used to describe not only the difficulty in crossing the river but also in navigating its length. The trouble with a river being too wide is the risk that it won’t provide the depth necessary to be useful. The same thing can be said of multidisciplinary scientific journals. While a journal can claim to be multidisciplinary, there is a risk of it being so broad that its articles can only engage the reader at a superficial level. Nothing could be further from the truth with Geoscience Frontiers. Over the past ten years, this journal has successfully navigated the wide breadth of geoscience while providing a level of depth and detail that rivals discipline-specific journals.展开更多
This study assessed the impact of petrol service stations on physico-chemical water quality in Port Harcourt metropolis, Rivers State. This threw light on the extent of damage and alteration of water quality in Port H...This study assessed the impact of petrol service stations on physico-chemical water quality in Port Harcourt metropolis, Rivers State. This threw light on the extent of damage and alteration of water quality in Port Harcourt metropolis as a result of the proliferation of petrol service stations especially the condition of ground and nearby surface water. This serves as a useful tool to government and regulatory authorities for planning especially due to lack of central water supply system in Port Harcourt metropolis. The parameters studied were sampled, measured and analyzed using in situ and other standard methods. Remarkable results above permissible limits of interest for physicochemical parameter analysis revealed pH values from 4.6 to 6.8, electrical conductivity from 0.002 µS/cm to 0.42 µS/cm, salinity from 3 ppm to 4050 ppm, and temperatures from 19.9˚C to 32.6˚C. Total dissolved solids (TDS) varied from 7 ppm to 1000 ppm, biochemical oxygen demand (BOD) from 0.167 mg/L to 2.167 mg/L, chemical oxygen demand (COD) from 0.257 mg/L to 3.253 mg/L, and dissolved oxygen (DO) concentrations from 1.70 mg/L to 4.30 mg/L. Specifically, water samples from NNPC Filling Station (Choba) and Eneka Pond displayed “Poor” water quality with WQI values of 112.003 and 112.076, respectively. Similarly, ALLTEC Filling Station (Eneka) and TOTAL Filling Station (Rumuomasi) had “Poor” water quality with WQI values of 173.707 and 180.946, respectively. In contrast, Excelsis Filling Station (Akpajo) demonstrated “Good” water quality with a WQI of 85.2072, while Total Filling Stations (Slaughter) and Choba River revealed “unsuitable for drinking” water quality with WQI values of 552.461 and 654.601, respectively. Slaughter River also indicated very poor water quality with a WQI of 442.024. The physicochemical and nutrient analyses of the water samples showed that activities of the filling stations within the study area may have polluted groundwater in the environment posing poor aesthetics and great health risk to consumers of the water bodies. The findings underscore the need for immediate remediation efforts and stricter regulatory measures to protect water quality. The study concluded that surface and groundwater near petrol service stations in Port Harcourt are unfit for drinking and irrigation purposes without adequate treatment.展开更多
The gravitational curvatures(GC,the third-order derivatives of the gravitational potential)in gravity field modeling are gaining increased interest in geosciences.The crustal effects of the GC and Moho variation sense...The gravitational curvatures(GC,the third-order derivatives of the gravitational potential)in gravity field modeling are gaining increased interest in geosciences.The crustal effects of the GC and Moho variation sensed by the GC are not fully evaluated for the current study.In this contribution,the effects of the GC induced by topographic and anomalous crustal masses are investigated based on ETOPO1 and CRUST1.0 models using the tesseroids.By adopting the gravitational stripping correction,the residual GC sensed by the CRUST1.0 Moho depths are presented globally to examine whether the GC can sense crustal mass anomalies at the satellite altitude of 260 km.The spatial analysis using the Pearson correlations coefficient(PCC)between the residual GC and the CRUST1.0 Moho depths is performed.Among the 10 residual GC functionals,the PCC value of the residual radial-radial-radial componentδT^(res)_(zzz)is largest with 0.31,where this value is highly dependent on the spectral content removed from the EGM2008,e.g.signals assumed to relate to deeper mass anomalies.Numerical experiments show that with the increased order of the derivatives up to third-order,the fineness level of different global Moho sensed crustal mass anomalies increases correspondingly.Taking the Tibetan plateau for example,the values of theδT^(res)_(zzz)can better reveal the detailed features of the Tibetan plateau’s Moho depth than these of the lower-order residual radial functionals(i.e.disturbing potentialδTres,disturbing radial gravity vectorδT^(res)_(z),and disturbing radial-radial gravity gradient tensorδT^(res)_(zz)),especially for the Qaidam,Sichuan,Tarim,and Turpan basins.Numerical results over the Himalayan region demonstrate that the GC componentδT^(res)^(z)has some potential in geophysical inversion.These residual GC functionals would help to get a better knowledge of the internal structures of the Earth and other planetary objects.展开更多
Geothermal resources are a promising approach to clean renewable energy;90%of them are deep reservoirs of hot dry rock that require hydraulic fracturing to create a network of connections among wells to enable efficie...Geothermal resources are a promising approach to clean renewable energy;90%of them are deep reservoirs of hot dry rock that require hydraulic fracturing to create a network of connections among wells to enable efficient heat exchange,known as an Enhanced Geothermal System(EGS).The Pohang EGS project in south Korea led to a devasting Mw5.5 earthquake,triggered by the reservoir's EGS stimulation,the largest earthquake known to have been induced by EGS development.Detailed investigations have been conducted to understand the cause of the Pohang earthquake;the conclusion has been that overpressurized injected fluids migrated into an unknown fault triggering this large earthquake.Detailed velocity images for the source zone of the 2017 Pohang earthquake,which could be helpful for further understanding its inducing mechanism,are unavailable.However,we have assembled detailed aftershock data recorded by 41 local stations installed within about three months after the Mw5.5 Pohang earthquake,and have then applied the V_(p)/V_(s)model's consistency-constrained double-difference seismic tomography method to determine the high-resolution three-dimensional Vp(compressional wave velocity),Vs(shear wave velocity),and V_(p)/V_(s)models of the source region that we report here,as well as earthquake locations within the source region.The velocity images reveal that the deep source area of the 2017 Pohang earthquake is dominated by low Vp,high Vs,and low V_(p)/V_(s)anomalies,a pattern that can be caused by overpressurized vapors due to high temperatures at these depths.Based on aftershock locations and velocity features,our studies support the conclusion that the 2017Pohang earthquake was triggered by injected EGS fluids that migrated into a blind fault.展开更多
The Upper Permian Gohan Formation,a terrestrial stratum deposited in the foreland basin in central eastern Korea,provides information on the provenance,tectonic setting,and paleoclimatic conditions of the eastern marg...The Upper Permian Gohan Formation,a terrestrial stratum deposited in the foreland basin in central eastern Korea,provides information on the provenance,tectonic setting,and paleoclimatic conditions of the eastern margin of the Sino-Korean block(SKB)composed of the North China craton and the Korean Peninsula.Geochemical composition of Gohan mudrocks suggests that the source rocks consisted of a mixture of intermediate−mafic igneous rocks and some sedimentary rocks.The source terrain was situated in an Andean-type active continental margin setting.In the clay mineral composition,kaolinite predominates in the lower section,illite in the middle,and illite and chlorite in the upper section.Such upsection changes are consistent with the upward decrease of chemical weathering index,which indicates that the climatic conditions of Late Permian time changed from hot and humid to semiarid.展开更多
The volatility of water resources is increasing owing to climate change,and various developments are being undertaken for a stable supply of water resources.Among the many available water resources,groundwater is attr...The volatility of water resources is increasing owing to climate change,and various developments are being undertaken for a stable supply of water resources.Among the many available water resources,groundwater is attracting attention as one of the country’s most important resources in Korea.This study developed a groundwater potential map(GPM)for the exploration of groundwater in the Geumgang River basin,one of the four major river basins in Korea.This consisted of ten thematic layers(hydrogeology,fractured zone,depth to groundwater level,distance to surface water,lineament density,slope,stream drainage density,soil drainage,land cover,and annual rainfall)of remotely sensed data and satellite images to explore a wide range of areas.Each thematic layer was weighted through Analytical Hierarchal Process and Technique for Order Preference by Similarity to Ideal Solution,and the groundwater potential was determined.The final GPM are classified into five categories:very high,high,moderate,low,and very low.To verify the GPM,specific capacity data from a total of 2,671 wells was used.The GPM in this study make groundwater to be considered as promising and feasible alternative resource to surface water in case of future climate crisis such as heavy drought.展开更多
In the northeastern and southwestern areas of the Ogcheon folded belt where Mesozoic granites are distributed,healed microcracks and fluid inclusions in the granite bodies were measured to elucidate the paleostress fi...In the northeastern and southwestern areas of the Ogcheon folded belt where Mesozoic granites are distributed,healed microcracks and fluid inclusions in the granite bodies were measured to elucidate the paleostress field that acted on these areas.The predominant orientations of healed microcracks in the northeastern and southwestern areas of the Ogcheon folded belt are the N50°W for the Inje granite,N30°W for the Jecheon granite,N55°W for the Wolaksan granite,N5°W for the Sokrisan granite,N30°W for the Daebo granite,and N70°W for the foliated granite.The homogenization and trapping temperatures of fluid inclusions in the Jecheon granite are 170–290°C and 260–390°C,respectively,and the formation period of healed microcracks is estimated to be 209–149 Ma.In the Inje granite,the homogenization and trapping temperatures of fluid inclusions are 165–290°C and 250–400°C,respectively,and the formation period of healed microcracks is estimated to be 176–160 Ma.In the Wolaksan granite,the homogenization and trapping temperatures of fluid inclusions are 165–375°C and 230–570°C,respectively,and the formation period of healed microcracks is estimated to be 116–88 Ma.In the Sokrisan granite,the homogenization and trapping temperatures of fluid inclusions are 155–280°C and 210–410°C,respectively,and the formation period of healed microcracks is estimated to be 92–84 Ma.In the foliated granite,the homogenization and trapping temperatures of fluid inclusions are 150–310°C and 380–550°C,respectively,and the formation period of healed microcracks is estimated to be 120–166 Ma.In the Daebo granite,the homogenization and trapping temperatures of fluid inclusions are 150–320°C and 380–440°C,respectively,and the formation period of healed microcracks is estimated to be 183–166 Ma.Consequently,during the Mesozoic,the predominant maximum horizontal stress direction in the Korean Peninsula was NW-SE,with secondary influences from N-S and E-W directions.Moreover,the direction of these maximum horizontal stresses is thought to have rotated from NW–SE to N–S around the mid Cretaceous period.The directions and formation periods of healed microcracks in the study area coincide well with the Mesozoic orogenies of the Korean Peninsula.The Daebo orogeny of the Jurassic to early Cretaceous mainly influenced the Jecheon granite,Inje granite,Wolaksan granite,foliated granite,and Daebo granite in the NW-SE direction,while the Bulguksa orogeny of the mid to late Cretaceous mainly influenced the Sokrisan granite in the N-S direction.展开更多
For the Anthropocene to get recognized as a real geological era,first and foremost its strata must be identified.Several geological formations such as bogs,lakebeds,reefs,ice sheets,speleothems,river estuary deposits,...For the Anthropocene to get recognized as a real geological era,first and foremost its strata must be identified.Several geological formations such as bogs,lakebeds,reefs,ice sheets,speleothems,river estuary deposits,and sea floors have been considered as potential candidates for the Anthropocene strata.This consideration arises from the emergence of novel materials associated with the Anthropocene,including radioactive isotopes,plastics,and aluminum,started to be discovered in their sediments and dramatically increased since the mid-20th century.Yet,these deposits are no longer considered‘natural’because human activities are largely controlling the transport and depositional processes from source to sink.The Municipal Solid Waste(MSW)in landfills has been also‘unnaturally’transported and deposited(landfilled)by humans.Since the 1950s,the controlled landfills have been made worldwide,and thus the opening time of the landfills is clear.The MSW layers of landfills,which appeared globally,contemporaneously,and with distinct characteristics,are indeed the‘artificial(anthropogenic)’strata showing a new and clear aspect of human influence,unprecedented in geological time.The MSW layers can be considered valuable indicators of the Anthropocene era because they not only preserve the history of human life but also sensitively demonstrate the scale of human activities like mass production,consumption,and disposal.The MSW layers can be expected to serve as a unique window into the Anthropocene.展开更多
A comprehensive estimation of shale generation/storage capacity(original generative organic carbon(GOCo))and hydraulic fracturing characteristics(brittleness index(BI))was conducted in the Upper Devonian shale sequenc...A comprehensive estimation of shale generation/storage capacity(original generative organic carbon(GOCo))and hydraulic fracturing characteristics(brittleness index(BI))was conducted in the Upper Devonian shale sequence of the Liard Basin.GOCo was calculated from fraction of type II kerogen inferred from biogenic silica concentrations.BI was estimated from mechanical properties calculated from well-log data.Without well-log data,BI was converted from the relative contribution of biogenic and detrital silica concentrations.Based on GOCo and BI,the shale sequences were divided into four resource facies(RFs):RF1(GOCo<1 wt%,BI 20–40),RF2(GOCo 1–3 wt%,BI 20–60),RF3(GOCo 2–5 wt%,BI 60-95),and RF4(GOCo 5–14 wt%,BI 60–95).Shale with RF3 and RF4 characteristics were determined to have high hydraulic fracturing efficiency,high organic porosity,and capability to generate large amounts of gas.Considering the vertical variation of RFs,the Patry and Lower Exshaw formations are estimated as favorable shale gas reservoirs with abundant gas content and high hydraulic fracturing efficiency.If 30%of the total gas generation potential estimated from GOCo remains in the shale gas reservoir,the sum of residual gas volume of both formations in the study wells exceeds 280 bcf/section.展开更多
The Permo-Triassic amalgamation of Northeast Asia began to receive much attention after discovering HP and UHP eclogites in the Dabie and Sulu areas in China.However,the Permo-Triassic tectonic evolution of Northeast ...The Permo-Triassic amalgamation of Northeast Asia began to receive much attention after discovering HP and UHP eclogites in the Dabie and Sulu areas in China.However,the Permo-Triassic tectonic evolution of Northeast Asia is still under argument.Over the past 30 years,several critical geological discoveries were reported from the Korean Peninsula;1)The Permo-Triassic eclogite in the Hongseong area,2)the Triassic post-collisional igneous rocks in the northern Gyeonggi Massif,Imjingang Belt,and the southern Nangrim Massif,3)the Permo-Triassic intermediate-P/T metamorphism in the Imjingang and Okcheon Belts and the Gyeonggi Massif,4)the strongest Permo-Triassic metamorphism along the E-W trending Hongseong-Yangpyeong-Odaesan Belt,and 5)the Devonian back arc origin for the Imjingang Belt.Besides these,the Honam Shear Zone was confirmed to be initiated in the early Jurassic.These dates indicate that the Qinling-Dabie-Sulu Continental Collision Belt in China extends not into the Imjingang Belt but into the Hongseong-Odaesan Belt within the Korean Peninsula.The Hongseong-Odaesan Belt extends into the inner part of southwest Japan and then into the Dumangang Belt in the northeast Korean Peninsula.展开更多
The mineralogy and petrography of EET 14017 were studied using optical microscope,scanning electron microscope,electron microprobe,and micro-Raman.The mineral chemistry of olivine,pyroxene,plagioclase,spinel,and Fe-Ni...The mineralogy and petrography of EET 14017 were studied using optical microscope,scanning electron microscope,electron microprobe,and micro-Raman.The mineral chemistry of olivine,pyroxene,plagioclase,spinel,and Fe-Ni metal in EET 14017 is comparable to that of previously studied L/LL3.0x chondrites.In particular,the Cr2O3 content in the ferroan chondrule olivine and the excess silica component,[]Si4O8,in the plagioclase lead us to conclude that EET 14017 belongs to subtype 3.05.Raman spectral data of carbonaceous matter from the matrix of EET 14017 suggest a higher degree of thermal metamorphism,probably due to terrestrial weathering in Antarctica.EET 14017 and some of the other L/LL3.0x chondrites from the EET region are possibly a pair,since they have similar Cr2O3 contents of ferroan chondrule olivines and Raman spectral data,and moreover they were also found in a restricted region of the blue ice field.The plagioclase in some chondrules is a late crystal phase in the chondrule melt,which may constrain the timing of chondrule formation and cooling rate.If more L/LL3.0x chondrites like EET 14017 from Antarctica are identified,they would be excellent source material for studying the early evolution of the Solar System.展开更多
Introduction.The International Union of Geological Sciences(IUGS)is a prominent non-governmental organization dedicated to promoting and fostering the study of geological sciences internationally.Established in 1961,t...Introduction.The International Union of Geological Sciences(IUGS)is a prominent non-governmental organization dedicated to promoting and fostering the study of geological sciences internationally.Established in 1961,the IUGS is a member of the International Science Council and plays a pivotal role in setting global standards in geological sciences,facilitating international collaboration,and supporting the coordination of major global geological events and research initiatives(Cheong and Kim,2021).One of the key events organized by the IUGS is the International Geological Congress(IGC),held every four years.This congress serves as a vital forum for geologists from around the world to share their latest research findings,discuss advancements in the field,and explore new directions in geological sciences.The IGC encompasses a wide range of topics including geology,geophysics,mineralogy,paleontology,and sedimentology,among others,reflecting the diversity and interdisciplinary nature of the field(Cheong and Kim,2021).展开更多
Lignocellulosic biomass is one of the viable solutions to alleviate the global warming. However, the limited utilization of biomass majorly focused on cellulose and hemicellulose restricts the economic and environment...Lignocellulosic biomass is one of the viable solutions to alleviate the global warming. However, the limited utilization of biomass majorly focused on cellulose and hemicellulose restricts the economic and environmental feasibilities. To cope with this issue, we proposed an integrated process of co-producing 1,6-hexanediol(1,6-HDO) with tetrahydrofuran and adipic acid from biomass, referred to as Strategy A. To compare the impacts of lignin upgrading and feedstock, Strategy B, which co-produces tetrahydrofuran alone, and Strategy C, which is the traditional route to produce 1,6-HDO from fossil fuels, were used. Heat networks are also designed to reduce operating costs and indirect carbon emissions due to energy consumption, saving 87% and 83% of the heat and cooling requirements, respectively, in Strategy A. The market competitiveness of Strategy A was evaluated by determining the minimum selling price through techno-economic analysis, and sustainability was thoroughly investigated by quantifying the environmental impacts through both midpoint and endpoint life-cycle assessments(LCAs).Strategy A was found to be the most favorable both economically(USRDSCHARDOLLAR3,402/ton) and environmentally(-26.9 kg CO_(2)eq.). This indicates that lignin valorization is not only economically but also environmentally preferred. Finally, changes in economic and environmental feasibilities depending on economic, process, and environmental parameters were investigated using sensitivity and uncertainty analyses. The results of these analyses provide valuable insight into bio-based chemical production.展开更多
Zircon U-Pb geochronology has become a keystone tool across Earth science, arguably providing the gold standard in resolving deep geological time. The development of rapid in situ analysis of zircon （via laser ablati...Zircon U-Pb geochronology has become a keystone tool across Earth science, arguably providing the gold standard in resolving deep geological time. The development of rapid in situ analysis of zircon （via laser ablation and secondary ionization mass spectrometry） has allowed for large amounts of data to be generated in a relatively short amount of time and such large volume datasets offer the ability to address a range of geological questions that would otherwise remain intractable （e.g. detrital zircons as a sedi- ment fingerprinting method）. The ease of acquisition, while bringing benefit to the Earth science com- munity, has also led to diverse interpretations of geochronological data. In this work we seek to refocus U -Pb zircon geochronology toward best practice by providing a robust statistically coherent workflow. We discuss a range of data filtering approaches and their inherent limitations （e.g. discordance and the reduced chi-squared; MSWD）. We evaluate appropriate mechanisms to calculate the most geologically appropriate age from both 238U/206pb and 207pb/206pb ratios and demonstrate the cross over position when chronometric power swaps between these ratios. As our in situ analytical techniques become progressively more precise, appropriate statistical handing of U-Pb datasets will become increasingly pertinent.展开更多
The study on the solvent extraction for quantitative and selective separation of total rare earth metals from the polymetallic nodule leach liquor was investigated. The typical leach liquor bearing 0. 094 g/L total ra...The study on the solvent extraction for quantitative and selective separation of total rare earth metals from the polymetallic nodule leach liquor was investigated. The typical leach liquor bearing 0. 094 g/L total rare earth, 0. 23 g/L Mn, 0.697 g/L Cu, 0.2 g/L Fe, 0.01 g/L Co and 0.735 g/L Ni was subjected to the removal iron content by precipitation method using Ca（OH）2 at pH 3.95, prior to solvent extraction of rare earth metals. Three different organo-phosphoric acid reagents（D2EHPA, PC88 A, Cyanex 272） were used to ascertain their performances and selectivity towards the loading of rare earth metals in presence of other base metals. Based on the results of eq. pH effect, the performances of above three extractants followed the order as： D2EHPA〉PC88A〉Cyanex 272. To ensure the absence of extraction of base metals（Cu, Co, Ni）, the eq. pH of the solution was optimized at the level of 2.21, though higher rare earth metal extraction efficiency was observed at higher eq. pH with either of the extractants. The complete process flow diagram for substantial recovery of total rare earth was developed using D2 EHPA. Extraction isotherm plot was constructed at A：O=12：1, 3-stages and pHe=2.21, using 0.8 mol/L D2 EHPA and the predicted condition of this study was further confirmed by 6-Cycles Counter Current Simulation（CCS） study. The stripping of total rare earth from loaded organic phase（LO） was conducted using HCl solution. Mc-Cabe Thiele diagram study carried out at A：O=1：5 using 4 mol/L HCl showed that three theoretical stages were needed for quantitative stripping of total rare earth. The subsequent stripped solution resulted thus led to contain total rare earth of 5.6 g/L indicating a very high enrichment of total metals by solvent extraction（SX） process.展开更多
The Southern Great Xing’an Range (SGXR) which forms part of the eastern segment of the Central Asian Orogenic Belt (CAOB) is known as one of the most important Cu-Mo-Pb-Zn-Ag-Au metallogenic belts in China,hosting a ...The Southern Great Xing’an Range (SGXR) which forms part of the eastern segment of the Central Asian Orogenic Belt (CAOB) is known as one of the most important Cu-Mo-Pb-Zn-Ag-Au metallogenic belts in China,hosting a number of porphyry Mo (Cu),skarn Fe (Sn),epithermal Au-Ag,and hydrothermal veintype Ag-Pb-Zn ore deposits.Here we investigate the Bianjiadayuan hydrothermal vein-type Ag-Pb-Zn ore deposit in the southern part of the SGXR.Porphyry Sn ±Cu ± Mo mineralization is also developed to the west of the Ag-Pb-Zn veins in the ore field.We identify a five-stage mineralization process based on field and petrologic studies including (i) the early porphyry mineralization stage,(ii) main porphyry mineralization stage,(iii) transition mineralization stage,(iv) vein-type mineralization stage and (v) late mineralization stage.Pyrite is the predominant sulfide mineral in all stages except in the late mineralization stage,and we identify corresponding four types of pyrites: Py1 is medium-grained subhedral to euhedral occurring in the early barren quartz vein;Py2 is medium- to fine-grained euhedral pyrite mainly coexisting with molybdenite,chalcopyrite,minor sphalerite and galena;Py3 is fine-grained,subhedral to irregular pyrite and displays cataclastic textures with micro-fractures;Py4 occurs as euhedral microcrystals and forms irregularly shaped aggregate with sphalerite and galena.LA-ICP-MS trace element analyses of pyrite show that Cu,Pb,Zn,Ag,Sn,Cd and Sb are partitioned into pyrite as structurally bound metals or mineral micro/nano-inclusions,whereas Co,Ni,As and Se enter the lattice via isomorphism in all types of pyrite.The Cu,Zn,Ag,Cd concentrations gradually increase from Py1 to Py4,which we correlate with cooling and mixing of ore-forming fluid with meteoric water.Py2 contains the highest contents of Co,Ni,Se,Te and Bi,suggesting high temperature conditions for the porphyry mineralization stage.Ratios of Co/Ni (0.03-10.79,average 2.13) and sulphur isotope composition of sulfide indicate typical hydrothermal origin for pyrites.The δ^34SCDT values of Py1 (0.42‰-1.61‰,average 1.16‰),Py2 (-1.23‰ to 0.82‰,average 0.35‰),Py3 (-0.36‰ to 2.47‰,average 0.97‰),Py4 (2.51‰-3.72‰,average 3.06‰),and other sulfides are consistent with those of typical porphyry deposit (-5‰ to 5‰),indicating that the Pb-Zn polymetallic mineralization in the Bianjiadayuan deposit is genetically linked to the Yanshanian (JurassiceCretaceous) magmatic-hydrothermal events.Variations of d34S values are ascribed to the changes in physical and chemical conditions during the evolution and migration of the ore-forming fluid.We propose that the high Sn content of pyrite in the Bianjiadayuan hydrothermal vein-type PbeZn polymetallic deposit can be used as a possible pathfinder to prospect for Sn mineralization in the surrounding area or deeper level of the ore field in this region.展开更多
The identification of landslide-prone areas is an essential step in landslide hazard assessment and mitigation of landslide-related losses.In this study,we applied two novel deep learning algorithms,the recurrent neur...The identification of landslide-prone areas is an essential step in landslide hazard assessment and mitigation of landslide-related losses.In this study,we applied two novel deep learning algorithms,the recurrent neural network(RNN)and convolutional neural network(CNN),for national-scale landslide susceptibility mapping of Iran.We prepared a dataset comprising 4069 historical landslide locations and 11 conditioning factors(altitude,slope degree,profile curvature,distance to river,aspect,plan curvature,distance to road,distance to fault,rainfall,geology and land-sue)to construct a geospatial database and divided the data into the training and the testing dataset.We then developed RNN and CNN algorithms to generate landslide susceptibility maps of Iran using the training dataset.We calculated the receiver operating characteristic(ROC)curve and used the area under the curve(AUC)for the quantitative evaluation of the landslide susceptibility maps using the testing dataset.Better performance in both the training and testing phases was provided by the RNN algorithm(AUC=0.88)than by the CNN algorithm(AUC=0.85).Finally,we calculated areas of susceptibility for each province and found that 6%and 14%of the land area of Iran is very highly and highly susceptible to future landslide events,respectively,with the highest susceptibility in Chaharmahal and Bakhtiari Province(33.8%).About 31%of cities of Iran are located in areas with high and very high landslide susceptibility.The results of the present study will be useful for the development of landslide hazard mitigation strategies.展开更多
A 475-cm long sediment core (QH-2005) from Lake Qinghai was used to carry out multi-proxy analysis of δ18O and body length of ostracod valves and redness and grain size of sediments, in order to reconstruct environ-m...A 475-cm long sediment core (QH-2005) from Lake Qinghai was used to carry out multi-proxy analysis of δ18O and body length of ostracod valves and redness and grain size of sediments, in order to reconstruct environ-mental changes during the past 13500 cal. a BP. The age model was based on 6 14C dates for bulk orgnic carbon (BOC) and 2 14C dates for lignin. The lignin 14C dates are apparently younger than the corresponding layers' BOC 14C dates, indicating that the reservoir age varied from 728 to 1222 a since the Late Glacial and from 2390 to 2490 a immediately before the pre-bomb era. Hence, the 14C age model for Core QH-2005 was corrected by the changing reservoir age. Ostracod δ18O values were primarily related to dilution and evaporative enrichment of the lake water. The reconstructed salinity based on ostracod body length coincides well with ostracod δ18O values. High redness and mean grain size (MZ) values indicate increased riverine supply to Lake Qinghai associated with increasing monsoon rainfall. Multi-proxy results show that climate during 13500-10900 cal. a BP was relatively cold and dry with fre-quent short-term fluctuations; a warm and wet climate began at about 10900 cal. a BP and culminated around 6500 cal. a BP as a result of monsoon strengthening; the climate became cold and dry afterwards and has remained rela-tively stable since 3400 cal. a BP. Our data also reveal short-term (millennial/centennial timescales) climatic fluctua-tions including: Younger Dryas events, ice-rafting events 8 and 1 (by ～11000 cal. a BP and ～1600 cal. a BP respec-tively), 8200 cal. a BP cold event, Little Ice Age and the Medieval Warm Period.展开更多
In debris flow modelling,the viscosity and yield stress of fine-grained sediments should be determined in order to better characterize sediment flow.In particular,it is important to understand the effect of grain size...In debris flow modelling,the viscosity and yield stress of fine-grained sediments should be determined in order to better characterize sediment flow.In particular,it is important to understand the effect of grain size on the rheology of fine-grained sediments associated with yielding.When looking at the relationship between shear stress and shear rate before yielding,a high-viscosity zone(called pseudoNewtonian viscosity) towards the apparent yield stress exists.After yielding,plastic viscosity(called Bingham viscosity) governs the flow.To examine the effect of grain size on the rheological characteristics of fine-grained sediments,clay-rich materials(from the Adriatic Sea,Italy; Cambridge Fjord,Canada; and the Mediterranean Sea,Spain),silt-rich debris flow materials(from La Valette,France) and silt-rich materials(iron tailings from Canada) were compared.Rheological characteristics were examined using a modified Bingham model.The materials examined,including the Canadian inorganic and sensitive clays,exhibit typical shear thinning behavior and strong thixotropy.In the relationships between the liquidity index and rheological values(viscosity and apparent yield stress),the effect of grain size on viscosity and yield stress is significant at a given liquidity index.The viscosity and yield stress of debris flow materials are higher than those of low-activity clays at the same liquid state.However the viscosity and yield stress of the tailings,which are mainly composed of silt-sized particles,are slightly lower than those of low-activity clays.展开更多
基金supported by the Gas Hydrate R&D Organization and the Korea Institute of Geoscience and Mineral Resources(KIGAM)(GP2021-010)supported by the National Research Foundation of Korea(NRF)grant funded by the Korean government(MSIT)(No.2021R1C1C1004460)Korea Institute of Energy Technology Evaluation and Planning(KETEP)grant funded by the Korean government(MOTIE)(20214000000500,Training Program of CCUS for Green Growth).
文摘Gas hydrate(GH)is an unconventional resource estimated at 1000-120,000 trillion m^(3)worldwide.Research on GH is ongoing to determine its geological and flow characteristics for commercial produc-tion.After two large-scale drilling expeditions to study the GH-bearing zone in the Ulleung Basin,the mineral composition of 488 sediment samples was analyzed using X-ray diffraction(XRD).Because the analysis is costly and dependent on experts,a machine learning model was developed to predict the mineral composition using XRD intensity profiles as input data.However,the model’s performance was limited because of improper preprocessing of the intensity profile.Because preprocessing was applied to each feature,the intensity trend was not preserved even though this factor is the most important when analyzing mineral composition.In this study,the profile was preprocessed for each sample using min-max scaling because relative intensity is critical for mineral analysis.For 49 test data among the 488 data,the convolutional neural network(CNN)model improved the average absolute error and coefficient of determination by 41%and 46%,respectively,than those of CNN model with feature-based pre-processing.This study confirms that combining preprocessing for each sample with CNN is the most efficient approach for analyzing XRD data.The developed model can be used for the compositional analysis of sediment samples from the Ulleung Basin and the Korea Plateau.In addition,the overall procedure can be applied to any XRD data of sediments worldwide.
文摘When early explorers first crossed the Platte River in what is now Nebraska (USA), it was said the river was “a mile wide and an inch deep”(Mokler, 1923;Smith, 1971). This phrase was used to describe not only the difficulty in crossing the river but also in navigating its length. The trouble with a river being too wide is the risk that it won’t provide the depth necessary to be useful. The same thing can be said of multidisciplinary scientific journals. While a journal can claim to be multidisciplinary, there is a risk of it being so broad that its articles can only engage the reader at a superficial level. Nothing could be further from the truth with Geoscience Frontiers. Over the past ten years, this journal has successfully navigated the wide breadth of geoscience while providing a level of depth and detail that rivals discipline-specific journals.
文摘This study assessed the impact of petrol service stations on physico-chemical water quality in Port Harcourt metropolis, Rivers State. This threw light on the extent of damage and alteration of water quality in Port Harcourt metropolis as a result of the proliferation of petrol service stations especially the condition of ground and nearby surface water. This serves as a useful tool to government and regulatory authorities for planning especially due to lack of central water supply system in Port Harcourt metropolis. The parameters studied were sampled, measured and analyzed using in situ and other standard methods. Remarkable results above permissible limits of interest for physicochemical parameter analysis revealed pH values from 4.6 to 6.8, electrical conductivity from 0.002 µS/cm to 0.42 µS/cm, salinity from 3 ppm to 4050 ppm, and temperatures from 19.9˚C to 32.6˚C. Total dissolved solids (TDS) varied from 7 ppm to 1000 ppm, biochemical oxygen demand (BOD) from 0.167 mg/L to 2.167 mg/L, chemical oxygen demand (COD) from 0.257 mg/L to 3.253 mg/L, and dissolved oxygen (DO) concentrations from 1.70 mg/L to 4.30 mg/L. Specifically, water samples from NNPC Filling Station (Choba) and Eneka Pond displayed “Poor” water quality with WQI values of 112.003 and 112.076, respectively. Similarly, ALLTEC Filling Station (Eneka) and TOTAL Filling Station (Rumuomasi) had “Poor” water quality with WQI values of 173.707 and 180.946, respectively. In contrast, Excelsis Filling Station (Akpajo) demonstrated “Good” water quality with a WQI of 85.2072, while Total Filling Stations (Slaughter) and Choba River revealed “unsuitable for drinking” water quality with WQI values of 552.461 and 654.601, respectively. Slaughter River also indicated very poor water quality with a WQI of 442.024. The physicochemical and nutrient analyses of the water samples showed that activities of the filling stations within the study area may have polluted groundwater in the environment posing poor aesthetics and great health risk to consumers of the water bodies. The findings underscore the need for immediate remediation efforts and stricter regulatory measures to protect water quality. The study concluded that surface and groundwater near petrol service stations in Port Harcourt are unfit for drinking and irrigation purposes without adequate treatment.
基金supported by National Natural Science Foundation of China[Grant Nos.42030105,41721003,41804012,41631072,41874023].
文摘The gravitational curvatures(GC,the third-order derivatives of the gravitational potential)in gravity field modeling are gaining increased interest in geosciences.The crustal effects of the GC and Moho variation sensed by the GC are not fully evaluated for the current study.In this contribution,the effects of the GC induced by topographic and anomalous crustal masses are investigated based on ETOPO1 and CRUST1.0 models using the tesseroids.By adopting the gravitational stripping correction,the residual GC sensed by the CRUST1.0 Moho depths are presented globally to examine whether the GC can sense crustal mass anomalies at the satellite altitude of 260 km.The spatial analysis using the Pearson correlations coefficient(PCC)between the residual GC and the CRUST1.0 Moho depths is performed.Among the 10 residual GC functionals,the PCC value of the residual radial-radial-radial componentδT^(res)_(zzz)is largest with 0.31,where this value is highly dependent on the spectral content removed from the EGM2008,e.g.signals assumed to relate to deeper mass anomalies.Numerical experiments show that with the increased order of the derivatives up to third-order,the fineness level of different global Moho sensed crustal mass anomalies increases correspondingly.Taking the Tibetan plateau for example,the values of theδT^(res)_(zzz)can better reveal the detailed features of the Tibetan plateau’s Moho depth than these of the lower-order residual radial functionals(i.e.disturbing potentialδTres,disturbing radial gravity vectorδT^(res)_(z),and disturbing radial-radial gravity gradient tensorδT^(res)_(zz)),especially for the Qaidam,Sichuan,Tarim,and Turpan basins.Numerical results over the Himalayan region demonstrate that the GC componentδT^(res)^(z)has some potential in geophysical inversion.These residual GC functionals would help to get a better knowledge of the internal structures of the Earth and other planetary objects.
基金supported by the National Natural Science Foundation of China(42304056)the Natural Science Foundation of Hebei Province(D2023305007)+1 种基金supported by the Basic Research Project(GP2020-017,GP2020027)of the Korea Institute of Geoscience and Mineral Resources(KIGAM)funded by the Ministry of Science and ICT of Korea。
文摘Geothermal resources are a promising approach to clean renewable energy;90%of them are deep reservoirs of hot dry rock that require hydraulic fracturing to create a network of connections among wells to enable efficient heat exchange,known as an Enhanced Geothermal System(EGS).The Pohang EGS project in south Korea led to a devasting Mw5.5 earthquake,triggered by the reservoir's EGS stimulation,the largest earthquake known to have been induced by EGS development.Detailed investigations have been conducted to understand the cause of the Pohang earthquake;the conclusion has been that overpressurized injected fluids migrated into an unknown fault triggering this large earthquake.Detailed velocity images for the source zone of the 2017 Pohang earthquake,which could be helpful for further understanding its inducing mechanism,are unavailable.However,we have assembled detailed aftershock data recorded by 41 local stations installed within about three months after the Mw5.5 Pohang earthquake,and have then applied the V_(p)/V_(s)model's consistency-constrained double-difference seismic tomography method to determine the high-resolution three-dimensional Vp(compressional wave velocity),Vs(shear wave velocity),and V_(p)/V_(s)models of the source region that we report here,as well as earthquake locations within the source region.The velocity images reveal that the deep source area of the 2017 Pohang earthquake is dominated by low Vp,high Vs,and low V_(p)/V_(s)anomalies,a pattern that can be caused by overpressurized vapors due to high temperatures at these depths.Based on aftershock locations and velocity features,our studies support the conclusion that the 2017Pohang earthquake was triggered by injected EGS fluids that migrated into a blind fault.
基金supported by the National Research Foundation of Korea(grant number 2014R1A2A2A01005404)H.Kwon acknowledges support from the SEES-BK21+Program at SNU.M.G.Kim also acknowledges support from the Korea Institute of Geoscience and Mineral Resources(GP2020-003)funded by the Ministry of Science and ICT,Korea.
文摘The Upper Permian Gohan Formation,a terrestrial stratum deposited in the foreland basin in central eastern Korea,provides information on the provenance,tectonic setting,and paleoclimatic conditions of the eastern margin of the Sino-Korean block(SKB)composed of the North China craton and the Korean Peninsula.Geochemical composition of Gohan mudrocks suggests that the source rocks consisted of a mixture of intermediate−mafic igneous rocks and some sedimentary rocks.The source terrain was situated in an Andean-type active continental margin setting.In the clay mineral composition,kaolinite predominates in the lower section,illite in the middle,and illite and chlorite in the upper section.Such upsection changes are consistent with the upward decrease of chemical weathering index,which indicates that the climatic conditions of Late Permian time changed from hot and humid to semiarid.
基金supported by the Basic Research Project(21-3411)of the Korea Institute of Geoscience and Mineral Resourcesthe National Research Foundation of Korea(NRF)under the Ministry of Science and ICT(No.RS-2023-00210810).
文摘The volatility of water resources is increasing owing to climate change,and various developments are being undertaken for a stable supply of water resources.Among the many available water resources,groundwater is attracting attention as one of the country’s most important resources in Korea.This study developed a groundwater potential map(GPM)for the exploration of groundwater in the Geumgang River basin,one of the four major river basins in Korea.This consisted of ten thematic layers(hydrogeology,fractured zone,depth to groundwater level,distance to surface water,lineament density,slope,stream drainage density,soil drainage,land cover,and annual rainfall)of remotely sensed data and satellite images to explore a wide range of areas.Each thematic layer was weighted through Analytical Hierarchal Process and Technique for Order Preference by Similarity to Ideal Solution,and the groundwater potential was determined.The final GPM are classified into five categories:very high,high,moderate,low,and very low.To verify the GPM,specific capacity data from a total of 2,671 wells was used.The GPM in this study make groundwater to be considered as promising and feasible alternative resource to surface water in case of future climate crisis such as heavy drought.
文摘In the northeastern and southwestern areas of the Ogcheon folded belt where Mesozoic granites are distributed,healed microcracks and fluid inclusions in the granite bodies were measured to elucidate the paleostress field that acted on these areas.The predominant orientations of healed microcracks in the northeastern and southwestern areas of the Ogcheon folded belt are the N50°W for the Inje granite,N30°W for the Jecheon granite,N55°W for the Wolaksan granite,N5°W for the Sokrisan granite,N30°W for the Daebo granite,and N70°W for the foliated granite.The homogenization and trapping temperatures of fluid inclusions in the Jecheon granite are 170–290°C and 260–390°C,respectively,and the formation period of healed microcracks is estimated to be 209–149 Ma.In the Inje granite,the homogenization and trapping temperatures of fluid inclusions are 165–290°C and 250–400°C,respectively,and the formation period of healed microcracks is estimated to be 176–160 Ma.In the Wolaksan granite,the homogenization and trapping temperatures of fluid inclusions are 165–375°C and 230–570°C,respectively,and the formation period of healed microcracks is estimated to be 116–88 Ma.In the Sokrisan granite,the homogenization and trapping temperatures of fluid inclusions are 155–280°C and 210–410°C,respectively,and the formation period of healed microcracks is estimated to be 92–84 Ma.In the foliated granite,the homogenization and trapping temperatures of fluid inclusions are 150–310°C and 380–550°C,respectively,and the formation period of healed microcracks is estimated to be 120–166 Ma.In the Daebo granite,the homogenization and trapping temperatures of fluid inclusions are 150–320°C and 380–440°C,respectively,and the formation period of healed microcracks is estimated to be 183–166 Ma.Consequently,during the Mesozoic,the predominant maximum horizontal stress direction in the Korean Peninsula was NW-SE,with secondary influences from N-S and E-W directions.Moreover,the direction of these maximum horizontal stresses is thought to have rotated from NW–SE to N–S around the mid Cretaceous period.The directions and formation periods of healed microcracks in the study area coincide well with the Mesozoic orogenies of the Korean Peninsula.The Daebo orogeny of the Jurassic to early Cretaceous mainly influenced the Jecheon granite,Inje granite,Wolaksan granite,foliated granite,and Daebo granite in the NW-SE direction,while the Bulguksa orogeny of the mid to late Cretaceous mainly influenced the Sokrisan granite in the N-S direction.
基金supported by the National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(NRF-2018R1A5A7025409,NP2018-026)the Energy&Mineral Resources Development Association of Korea(EMRD)grant funded by the Korea government(MOTIE)(2021060001).
文摘For the Anthropocene to get recognized as a real geological era,first and foremost its strata must be identified.Several geological formations such as bogs,lakebeds,reefs,ice sheets,speleothems,river estuary deposits,and sea floors have been considered as potential candidates for the Anthropocene strata.This consideration arises from the emergence of novel materials associated with the Anthropocene,including radioactive isotopes,plastics,and aluminum,started to be discovered in their sediments and dramatically increased since the mid-20th century.Yet,these deposits are no longer considered‘natural’because human activities are largely controlling the transport and depositional processes from source to sink.The Municipal Solid Waste(MSW)in landfills has been also‘unnaturally’transported and deposited(landfilled)by humans.Since the 1950s,the controlled landfills have been made worldwide,and thus the opening time of the landfills is clear.The MSW layers of landfills,which appeared globally,contemporaneously,and with distinct characteristics,are indeed the‘artificial(anthropogenic)’strata showing a new and clear aspect of human influence,unprecedented in geological time.The MSW layers can be considered valuable indicators of the Anthropocene era because they not only preserve the history of human life but also sensitively demonstrate the scale of human activities like mass production,consumption,and disposal.The MSW layers can be expected to serve as a unique window into the Anthropocene.
基金supported by 2023 Research Grant from Kangwon National University,by National Research Foundation of Korea(NRF)grant funded by the Korea government(MSIT)(No.2022R1F1A1075039)by the International Energy Joint R&D Program of Korea Institute of Energy Technology Evaluation and Planning(KETEP),granted financial resource from the Ministry of Trade,Industry&Energy(MOTIE)of the Republic of Korea(No.20225B10300050).
文摘A comprehensive estimation of shale generation/storage capacity(original generative organic carbon(GOCo))and hydraulic fracturing characteristics(brittleness index(BI))was conducted in the Upper Devonian shale sequence of the Liard Basin.GOCo was calculated from fraction of type II kerogen inferred from biogenic silica concentrations.BI was estimated from mechanical properties calculated from well-log data.Without well-log data,BI was converted from the relative contribution of biogenic and detrital silica concentrations.Based on GOCo and BI,the shale sequences were divided into four resource facies(RFs):RF1(GOCo<1 wt%,BI 20–40),RF2(GOCo 1–3 wt%,BI 20–60),RF3(GOCo 2–5 wt%,BI 60-95),and RF4(GOCo 5–14 wt%,BI 60–95).Shale with RF3 and RF4 characteristics were determined to have high hydraulic fracturing efficiency,high organic porosity,and capability to generate large amounts of gas.Considering the vertical variation of RFs,the Patry and Lower Exshaw formations are estimated as favorable shale gas reservoirs with abundant gas content and high hydraulic fracturing efficiency.If 30%of the total gas generation potential estimated from GOCo remains in the shale gas reservoir,the sum of residual gas volume of both formations in the study wells exceeds 280 bcf/section.
基金supported by National Research Foundation of Korea(NRF)Grant funded by the Korean Government(NRF–2017K1A1A2013180).
文摘The Permo-Triassic amalgamation of Northeast Asia began to receive much attention after discovering HP and UHP eclogites in the Dabie and Sulu areas in China.However,the Permo-Triassic tectonic evolution of Northeast Asia is still under argument.Over the past 30 years,several critical geological discoveries were reported from the Korean Peninsula;1)The Permo-Triassic eclogite in the Hongseong area,2)the Triassic post-collisional igneous rocks in the northern Gyeonggi Massif,Imjingang Belt,and the southern Nangrim Massif,3)the Permo-Triassic intermediate-P/T metamorphism in the Imjingang and Okcheon Belts and the Gyeonggi Massif,4)the strongest Permo-Triassic metamorphism along the E-W trending Hongseong-Yangpyeong-Odaesan Belt,and 5)the Devonian back arc origin for the Imjingang Belt.Besides these,the Honam Shear Zone was confirmed to be initiated in the early Jurassic.These dates indicate that the Qinling-Dabie-Sulu Continental Collision Belt in China extends not into the Imjingang Belt but into the Hongseong-Odaesan Belt within the Korean Peninsula.The Hongseong-Odaesan Belt extends into the inner part of southwest Japan and then into the Dumangang Belt in the northeast Korean Peninsula.
基金supported by Korea Polar Research Institute project PE24050.
文摘The mineralogy and petrography of EET 14017 were studied using optical microscope,scanning electron microscope,electron microprobe,and micro-Raman.The mineral chemistry of olivine,pyroxene,plagioclase,spinel,and Fe-Ni metal in EET 14017 is comparable to that of previously studied L/LL3.0x chondrites.In particular,the Cr2O3 content in the ferroan chondrule olivine and the excess silica component,[]Si4O8,in the plagioclase lead us to conclude that EET 14017 belongs to subtype 3.05.Raman spectral data of carbonaceous matter from the matrix of EET 14017 suggest a higher degree of thermal metamorphism,probably due to terrestrial weathering in Antarctica.EET 14017 and some of the other L/LL3.0x chondrites from the EET region are possibly a pair,since they have similar Cr2O3 contents of ferroan chondrule olivines and Raman spectral data,and moreover they were also found in a restricted region of the blue ice field.The plagioclase in some chondrules is a late crystal phase in the chondrule melt,which may constrain the timing of chondrule formation and cooling rate.If more L/LL3.0x chondrites like EET 14017 from Antarctica are identified,they would be excellent source material for studying the early evolution of the Solar System.
文摘Introduction.The International Union of Geological Sciences(IUGS)is a prominent non-governmental organization dedicated to promoting and fostering the study of geological sciences internationally.Established in 1961,the IUGS is a member of the International Science Council and plays a pivotal role in setting global standards in geological sciences,facilitating international collaboration,and supporting the coordination of major global geological events and research initiatives(Cheong and Kim,2021).One of the key events organized by the IUGS is the International Geological Congress(IGC),held every four years.This congress serves as a vital forum for geologists from around the world to share their latest research findings,discuss advancements in the field,and explore new directions in geological sciences.The IGC encompasses a wide range of topics including geology,geophysics,mineralogy,paleontology,and sedimentology,among others,reflecting the diversity and interdisciplinary nature of the field(Cheong and Kim,2021).
基金Material Parts Technology Development Program (20017461, Development and Performance Improvement of Air Operated Valve for 105 MPa Hydrogen Charging Station) funded by the Ministry of Trade,Industry and Energy(MOTIE, Republic of Korea)Korea Evaluation Institute of Industrial Technology (KEIT, Republic of Korea)+1 种基金financial support from the Korea Institute of Energy Technology Evaluation and Planning (KETEP)Ministry of Trade,Industry&Energy (MOTIE) of the Republic of Korea(RS-2024-00419764)。
文摘Lignocellulosic biomass is one of the viable solutions to alleviate the global warming. However, the limited utilization of biomass majorly focused on cellulose and hemicellulose restricts the economic and environmental feasibilities. To cope with this issue, we proposed an integrated process of co-producing 1,6-hexanediol(1,6-HDO) with tetrahydrofuran and adipic acid from biomass, referred to as Strategy A. To compare the impacts of lignin upgrading and feedstock, Strategy B, which co-produces tetrahydrofuran alone, and Strategy C, which is the traditional route to produce 1,6-HDO from fossil fuels, were used. Heat networks are also designed to reduce operating costs and indirect carbon emissions due to energy consumption, saving 87% and 83% of the heat and cooling requirements, respectively, in Strategy A. The market competitiveness of Strategy A was evaluated by determining the minimum selling price through techno-economic analysis, and sustainability was thoroughly investigated by quantifying the environmental impacts through both midpoint and endpoint life-cycle assessments(LCAs).Strategy A was found to be the most favorable both economically(USRDSCHARDOLLAR3,402/ton) and environmentally(-26.9 kg CO_(2)eq.). This indicates that lignin valorization is not only economically but also environmentally preferred. Finally, changes in economic and environmental feasibilities depending on economic, process, and environmental parameters were investigated using sensitivity and uncertainty analyses. The results of these analyses provide valuable insight into bio-based chemical production.
文摘Zircon U-Pb geochronology has become a keystone tool across Earth science, arguably providing the gold standard in resolving deep geological time. The development of rapid in situ analysis of zircon （via laser ablation and secondary ionization mass spectrometry） has allowed for large amounts of data to be generated in a relatively short amount of time and such large volume datasets offer the ability to address a range of geological questions that would otherwise remain intractable （e.g. detrital zircons as a sedi- ment fingerprinting method）. The ease of acquisition, while bringing benefit to the Earth science com- munity, has also led to diverse interpretations of geochronological data. In this work we seek to refocus U -Pb zircon geochronology toward best practice by providing a robust statistically coherent workflow. We discuss a range of data filtering approaches and their inherent limitations （e.g. discordance and the reduced chi-squared; MSWD）. We evaluate appropriate mechanisms to calculate the most geologically appropriate age from both 238U/206pb and 207pb/206pb ratios and demonstrate the cross over position when chronometric power swaps between these ratios. As our in situ analytical techniques become progressively more precise, appropriate statistical handing of U-Pb datasets will become increasingly pertinent.
基金Project supported by Ministry of Oceans and Fisheries,Korea
文摘The study on the solvent extraction for quantitative and selective separation of total rare earth metals from the polymetallic nodule leach liquor was investigated. The typical leach liquor bearing 0. 094 g/L total rare earth, 0. 23 g/L Mn, 0.697 g/L Cu, 0.2 g/L Fe, 0.01 g/L Co and 0.735 g/L Ni was subjected to the removal iron content by precipitation method using Ca（OH）2 at pH 3.95, prior to solvent extraction of rare earth metals. Three different organo-phosphoric acid reagents（D2EHPA, PC88 A, Cyanex 272） were used to ascertain their performances and selectivity towards the loading of rare earth metals in presence of other base metals. Based on the results of eq. pH effect, the performances of above three extractants followed the order as： D2EHPA〉PC88A〉Cyanex 272. To ensure the absence of extraction of base metals（Cu, Co, Ni）, the eq. pH of the solution was optimized at the level of 2.21, though higher rare earth metal extraction efficiency was observed at higher eq. pH with either of the extractants. The complete process flow diagram for substantial recovery of total rare earth was developed using D2 EHPA. Extraction isotherm plot was constructed at A：O=12：1, 3-stages and pHe=2.21, using 0.8 mol/L D2 EHPA and the predicted condition of this study was further confirmed by 6-Cycles Counter Current Simulation（CCS） study. The stripping of total rare earth from loaded organic phase（LO） was conducted using HCl solution. Mc-Cabe Thiele diagram study carried out at A：O=1：5 using 4 mol/L HCl showed that three theoretical stages were needed for quantitative stripping of total rare earth. The subsequent stripped solution resulted thus led to contain total rare earth of 5.6 g/L indicating a very high enrichment of total metals by solvent extraction（SX） process.
基金financially supported by National Key Research and Development Program of China (2016YFC0600504)Fundamental Research Funds for the Central Universities (2652017218)
文摘The Southern Great Xing’an Range (SGXR) which forms part of the eastern segment of the Central Asian Orogenic Belt (CAOB) is known as one of the most important Cu-Mo-Pb-Zn-Ag-Au metallogenic belts in China,hosting a number of porphyry Mo (Cu),skarn Fe (Sn),epithermal Au-Ag,and hydrothermal veintype Ag-Pb-Zn ore deposits.Here we investigate the Bianjiadayuan hydrothermal vein-type Ag-Pb-Zn ore deposit in the southern part of the SGXR.Porphyry Sn ±Cu ± Mo mineralization is also developed to the west of the Ag-Pb-Zn veins in the ore field.We identify a five-stage mineralization process based on field and petrologic studies including (i) the early porphyry mineralization stage,(ii) main porphyry mineralization stage,(iii) transition mineralization stage,(iv) vein-type mineralization stage and (v) late mineralization stage.Pyrite is the predominant sulfide mineral in all stages except in the late mineralization stage,and we identify corresponding four types of pyrites: Py1 is medium-grained subhedral to euhedral occurring in the early barren quartz vein;Py2 is medium- to fine-grained euhedral pyrite mainly coexisting with molybdenite,chalcopyrite,minor sphalerite and galena;Py3 is fine-grained,subhedral to irregular pyrite and displays cataclastic textures with micro-fractures;Py4 occurs as euhedral microcrystals and forms irregularly shaped aggregate with sphalerite and galena.LA-ICP-MS trace element analyses of pyrite show that Cu,Pb,Zn,Ag,Sn,Cd and Sb are partitioned into pyrite as structurally bound metals or mineral micro/nano-inclusions,whereas Co,Ni,As and Se enter the lattice via isomorphism in all types of pyrite.The Cu,Zn,Ag,Cd concentrations gradually increase from Py1 to Py4,which we correlate with cooling and mixing of ore-forming fluid with meteoric water.Py2 contains the highest contents of Co,Ni,Se,Te and Bi,suggesting high temperature conditions for the porphyry mineralization stage.Ratios of Co/Ni (0.03-10.79,average 2.13) and sulphur isotope composition of sulfide indicate typical hydrothermal origin for pyrites.The δ^34SCDT values of Py1 (0.42‰-1.61‰,average 1.16‰),Py2 (-1.23‰ to 0.82‰,average 0.35‰),Py3 (-0.36‰ to 2.47‰,average 0.97‰),Py4 (2.51‰-3.72‰,average 3.06‰),and other sulfides are consistent with those of typical porphyry deposit (-5‰ to 5‰),indicating that the Pb-Zn polymetallic mineralization in the Bianjiadayuan deposit is genetically linked to the Yanshanian (JurassiceCretaceous) magmatic-hydrothermal events.Variations of d34S values are ascribed to the changes in physical and chemical conditions during the evolution and migration of the ore-forming fluid.We propose that the high Sn content of pyrite in the Bianjiadayuan hydrothermal vein-type PbeZn polymetallic deposit can be used as a possible pathfinder to prospect for Sn mineralization in the surrounding area or deeper level of the ore field in this region.
基金the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources(KIGAM)Project of Environmental Business Big Data Platform and Center Construction funded by the Ministry of Science and ICT.
文摘The identification of landslide-prone areas is an essential step in landslide hazard assessment and mitigation of landslide-related losses.In this study,we applied two novel deep learning algorithms,the recurrent neural network(RNN)and convolutional neural network(CNN),for national-scale landslide susceptibility mapping of Iran.We prepared a dataset comprising 4069 historical landslide locations and 11 conditioning factors(altitude,slope degree,profile curvature,distance to river,aspect,plan curvature,distance to road,distance to fault,rainfall,geology and land-sue)to construct a geospatial database and divided the data into the training and the testing dataset.We then developed RNN and CNN algorithms to generate landslide susceptibility maps of Iran using the training dataset.We calculated the receiver operating characteristic(ROC)curve and used the area under the curve(AUC)for the quantitative evaluation of the landslide susceptibility maps using the testing dataset.Better performance in both the training and testing phases was provided by the RNN algorithm(AUC=0.88)than by the CNN algorithm(AUC=0.85).Finally,we calculated areas of susceptibility for each province and found that 6%and 14%of the land area of Iran is very highly and highly susceptible to future landslide events,respectively,with the highest susceptibility in Chaharmahal and Bakhtiari Province(33.8%).About 31%of cities of Iran are located in areas with high and very high landslide susceptibility.The results of the present study will be useful for the development of landslide hazard mitigation strategies.
基金supported jointly by the National Basic Research Program of China (No.2010CB833404)the Nanjing Institute of Geography and Limnology, CAS (NIGLAS2011KXJ002)+2 种基金the National Natural Science Foundation of China for Distinguished Young Scholars (No.40625007)the National Natural Science Foundation of China (Nos.40872117 and 40902047)the Knowledge Innovation Program of the Chinese Academy of Sciences (No.NIGLAS2009QD03)
文摘A 475-cm long sediment core (QH-2005) from Lake Qinghai was used to carry out multi-proxy analysis of δ18O and body length of ostracod valves and redness and grain size of sediments, in order to reconstruct environ-mental changes during the past 13500 cal. a BP. The age model was based on 6 14C dates for bulk orgnic carbon (BOC) and 2 14C dates for lignin. The lignin 14C dates are apparently younger than the corresponding layers' BOC 14C dates, indicating that the reservoir age varied from 728 to 1222 a since the Late Glacial and from 2390 to 2490 a immediately before the pre-bomb era. Hence, the 14C age model for Core QH-2005 was corrected by the changing reservoir age. Ostracod δ18O values were primarily related to dilution and evaporative enrichment of the lake water. The reconstructed salinity based on ostracod body length coincides well with ostracod δ18O values. High redness and mean grain size (MZ) values indicate increased riverine supply to Lake Qinghai associated with increasing monsoon rainfall. Multi-proxy results show that climate during 13500-10900 cal. a BP was relatively cold and dry with fre-quent short-term fluctuations; a warm and wet climate began at about 10900 cal. a BP and culminated around 6500 cal. a BP as a result of monsoon strengthening; the climate became cold and dry afterwards and has remained rela-tively stable since 3400 cal. a BP. Our data also reveal short-term (millennial/centennial timescales) climatic fluctua-tions including: Younger Dryas events, ice-rafting events 8 and 1 (by ～11000 cal. a BP and ～1600 cal. a BP respec-tively), 8200 cal. a BP cold event, Little Ice Age and the Medieval Warm Period.
基金funded by the Natural Sciences and Engineering Research Council,Canada,via the COSTA(Continental Slope Stability)-Canada projectsupported by the Public Welfare & Safety Research Program through the National Research Foundation of Korea(NRF)+1 种基金funded by the Ministry of Science,ICT&Future Planning(Grant No.2012M3A2A1050983)the Research Project (11-7622,13-3212)of the Korea Institute of Geoscience and Mineral Resources(KIGAM)
文摘In debris flow modelling,the viscosity and yield stress of fine-grained sediments should be determined in order to better characterize sediment flow.In particular,it is important to understand the effect of grain size on the rheology of fine-grained sediments associated with yielding.When looking at the relationship between shear stress and shear rate before yielding,a high-viscosity zone(called pseudoNewtonian viscosity) towards the apparent yield stress exists.After yielding,plastic viscosity(called Bingham viscosity) governs the flow.To examine the effect of grain size on the rheological characteristics of fine-grained sediments,clay-rich materials(from the Adriatic Sea,Italy; Cambridge Fjord,Canada; and the Mediterranean Sea,Spain),silt-rich debris flow materials(from La Valette,France) and silt-rich materials(iron tailings from Canada) were compared.Rheological characteristics were examined using a modified Bingham model.The materials examined,including the Canadian inorganic and sensitive clays,exhibit typical shear thinning behavior and strong thixotropy.In the relationships between the liquidity index and rheological values(viscosity and apparent yield stress),the effect of grain size on viscosity and yield stress is significant at a given liquidity index.The viscosity and yield stress of debris flow materials are higher than those of low-activity clays at the same liquid state.However the viscosity and yield stress of the tailings,which are mainly composed of silt-sized particles,are slightly lower than those of low-activity clays.
