Journal of Geochemical Exploration最新文献

{"title":"Differentiating Triassic W–Sn ore-bearing and ore-free plutons in the Xitian Ore Field (South China) using apatite geochemistry","authors":"Xiaojun Hu ,&nbsp;Huan Li ,&nbsp;Thomas J. Algeo ,&nbsp;Biao Liu ,&nbsp;Fan Kang ,&nbsp;Yiming Xie ,&nbsp;Dapeng Zhu","doi":"10.1016/j.gexplo.2024.107628","DOIUrl":"10.1016/j.gexplo.2024.107628","url":null,"abstract":"<div><div>Though the metallogenic process of the Xitian W–Sn deposit has been established, the key factors distinguishing Triassic W–Sn ore-bearing granites from ore-free granites remain uncertain, leaving an important gap in understanding the controls on Triassic W–Sn mineralization. In this study, we present a comprehensive investigation of apatite from the Triassic Longshang W–Sn ore-bearing and Goudalan ore-free granites, to trace the nature of parental magma and to provide constraints on the processes related to Triassic W–Sn mineralization in Xitian Ore Field (South China). Apatites from ore-bearing (AOB) granites and apatites from ore-free (AOF) granites exhibit distinct Cathodoluminescence (CL) images: AOB samples feature darker cores and brighter rims, with concentric oscillatory growth zoning in the rim sections, whereas AOF samples exhibit chaotic textures in CL images. The U–Pb age dating of AOB and AOF yield a lower intercept age of 227.3 ± 4.3 Ma (1σ, MSWD = 3.9) and 227.1 ± 7.8 Ma (1σ, MSWD = 2.4) on the Tera-Wasserburg diagrams, respectively. The similar ε_Nd(t) values (−10.91 to −9.82 for AOB; −10.42 to −8.77 for AOF) (expressed as deviation in parts per 10,000 from CHUR composition), relatively low Cl contents (&lt;0.05 wt%), and high F (~3 wt%) of studied apatites, suggest that W–Sn ore-bearing and ore-free granitic magmas were both generated by melting of old continental crust. The texture and high concentration of REE + Y and Th in AOB could be assumed as the result of fluid exsolution. The chaotic texture, broad variation in ¹⁴⁷Sm/¹⁴⁴Nd ratios, may imply that AOF might have experienced metasomatic modification. Lower Eu/Eu* value together with higher Ce/Ce* value in AOB suggests a more reduced environment for W–Sn ore-bearing granites. Lower Sr, Mg content, and higher Y contents suggest that W–Sn ore-bearing granites have a higher degree of fractionation than ore-free granites. We propose that the mobilization and transport ability of W and Sn by hydrothermal fluids play an important role in the enrichment of W and Sn, and redox state of magma and the degree of magma differentiation determine the final enrichment level of tungsten and tin.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"268 ","pages":"Article 107628"},"PeriodicalIF":3.4,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664303","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Calcium change of transported soils from 1995 to 2010 in acid rain areas in China","authors":"Xuemin Liu ,&nbsp;Xueqiu Wang ,&nbsp;Bimin Zhang ,&nbsp;Miao Xie ,&nbsp;Fang Yang ,&nbsp;Liang Tang","doi":"10.1016/j.gexplo.2024.107629","DOIUrl":"10.1016/j.gexplo.2024.107629","url":null,"abstract":"<div><div>Acid rain, a significant environmental threat, negatively impacts soil health and ecosystems. It can leach calcium (Ca) from soils, affecting plant growth and other ecological processes. China has experienced widespread acid rain, particularly in the southern regions. Two national geochemical mapping projects: Environmental Geochemical Monitoring Networks (EGMON) and China Geochemical Baselines (CGB), were conducted to establish baselines for soil Ca. This study compares these baselines to quantify Ca changes in China's acid rain areas from 1995 to 2010 and identify key controlling factors. Our analysis revealed a significant decrease in Ca content in transported soils across these regions during this period. Notably, the median Ca concentration in the top soil (TS) decreased from 0.47 % to 0.36 %, and in the deep soil (DS) from 0.39 % to 0.31 %. Areas experiencing Ca depletion contents were roughly twice as those with increases. Estimated net Ca change rates were −0.07 Pg/a for TS and 0.04 Pg/a for DS, indicating a net Ca loss of 1.25 Pg from the study region's top 125 cm of soil. This translates to a loss rate of 0.083 Pg/a or 0.026 g Ca²⁺ kg⁻¹ soil per year. Calcium contents in transported soils were influenced by the interplay of acid rain, rainfall, and parent rocks. Acid rain could dissolve Ca from carbonate-rich rocks, enriching nearby rivers with Ca²⁺. Upon deposition, clay minerals in the soils could adsorb Ca²⁺, potentially increasing soil Ca content. However, intense acid rain (pH &lt;5.0) could leach Ca²⁺ from the soil and outweigh the positive influence of parent carbonate-rich rocks, leading to Ca depletion. Additionally, in regions with sufficient rainfall (&gt;1600 mm/a), combined with the leaching effect of acid rain, Ca content could decrease due to overall mobilization and transport out of the soil.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107629"},"PeriodicalIF":3.4,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719869","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Recycled mantle source for porphyry mineralization: U−Pb and Re−Os geochronology, and S–Pb–Cu isotopic constraints from the Urumieh-Dokhtar magmatic arc, central Iran","authors":"Shahrouz Babazadeh ,&nbsp;Davood Raeisi ,&nbsp;M. Santosh ,&nbsp;Miao Zhao ,&nbsp;Massimo D'Antonio","doi":"10.1016/j.gexplo.2024.107630","DOIUrl":"10.1016/j.gexplo.2024.107630","url":null,"abstract":"<div><div>The Urumieh−Dokhtar magmatic arc (UDMA) hosts some of the world-class porphyry copper deposits in Iran. Here, we present high-resolution geochronological and stable isotope data to gain insights into the timing and source of the metallogeny of Kahang porphyry Cu deposit. Zircon U−Pb data show crystallization age of <em>ca.</em> 15 Ma age for the host porphyry intrusion and Re−Os geochronology yields 14.5 Ma from the molybdenite associated with the ores. Sulfur isotope values on the sulphide minerals range from −1.6 ‰ to + 2.1 ‰, indicating a magmatic source for sulfur. Lead isotopic compositions of the S-bearing minerals are akin to those of the intrusive rocks, suggesting that the metal was likely sourced from mantle reservoirs. We propose a model for the UDMA involving slab break-off during the maturity of arc magmatism from the <em>syn</em>- to <em>post</em>-collisional stages of orogenesis. The δ⁶⁵Cu data trace a systematic change from the barren to the fertile magmas. We suggest that partial melting of the sub-continental lithospheric mantle that has previously been refertilized of Cu through time as the potential source for the formation of ore-bearing magmas.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"268 ","pages":"Article 107630"},"PeriodicalIF":3.4,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664323","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Implications for metallogenic evolution of the Balong gold deposit, East Kunlun metallogenic belt: Insights from in-situ trace elements and S isotopes of sulfides","authors":"Yanyan Zhao ,&nbsp;Jun Tan ,&nbsp;Mingyu Xin ,&nbsp;Yan Liu ,&nbsp;Ming Zhang ,&nbsp;Xiaoyang Liu ,&nbsp;Ziqing Yan ,&nbsp;Xiliang Jia","doi":"10.1016/j.gexplo.2024.107626","DOIUrl":"10.1016/j.gexplo.2024.107626","url":null,"abstract":"<div><div>The Balong gold deposit is one of numerous lode gold deposits in the East Kunlun metallogenic belt. Gold mineralization is hosted in Triassic granitoids, typified by auriferous quartz veins. Hydrothermal alteration includes sericite, quartz, sulfide, chlorite, and calcite. Pyrite, as the most abundant sulfide in the ore, is sometimes seen in the company of arsenopyrite. Three types of pyrite have been identified. The porous Py1 exhibits low Co and Ni contents, with an absence of gold. Subhedral Py2-1 shows higher Co (median 80 ppm) and Ni (median 10.5 ppm) contents and contains various Cu-Pb-Zn-Ag mineral inclusions. Py2-2 shows an increase in As (median 17, 073 ppm) and Au (median 3.79 ppm), exhibiting obvious distinctions between Py2-1 and Py2-2.</div><div>Gold in the Balong deposit consists of both visible and invisible gold. Gold occurs within micro-fractures of pyrite and arsenopyrite, appearing as irregular inclusions or as infillings. Apart from visible gold grains, the majority of invisible gold hosted in Py2-2 occurs as solid solutions (Au⁺). Coupled dissolution-reprecipitation reactions of early pyrite are a key factor for visible gold precipitation and later invisible gold enrichment. Pyrite records a narrow range of <em>δ</em>³⁴S values from −1.6 to 5.4 ‰, reflecting sulfur from a deep magmatic source. These findings indicate a connection between the ore-forming materials and the evolved magmatic-hydrothermal fluids.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107626"},"PeriodicalIF":3.4,"publicationDate":"2024-11-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142719982","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Using UAVs to collect filtered water samples for mineral exploration: Will it take off?","authors":"James A. Kidder ,&nbsp;Alain Grenier ,&nbsp;Bradley J.A. Harvey ,&nbsp;Christopher E. Beckett-Brown ,&nbsp;M. Beth McClenaghan ,&nbsp;Pierre Pelchat ,&nbsp;Jing Zhang ,&nbsp;Daniel Layton-Matthews ,&nbsp;Frank Oliva","doi":"10.1016/j.gexplo.2024.107617","DOIUrl":"10.1016/j.gexplo.2024.107617","url":null,"abstract":"<div><div>The advent of unmanned aerial vehicle (UAV) assisted surface water sampling and ongoing technological advances in sampling and data acquisition, offers many opportunities to conduct high-quality hydrogeochemical surveys with low cost, high efficiency, and reduced human interactions. Hydrogeochemical mineral exploration is one area that could greatly benefit from a UAV sampling revolution, with survey sites often located in highly remote areas with limited existing infrastructure. Currently, a lack of point source filtration and complicated physiochemical data acquisition hinder mainstream UAV deployment in the context of hydrogeochemical studies. The aim of this paper is to provide guidance on effective UAV sampling methods and physiochemical data collection for use in surface water hydrogeochemical mineral exploration. To date, case study surveys have utilized sampling systems where sampled waters are filtered after collection or analyzed for ‘total’ (unfiltered) concentrations. This paper details a methodology for point-source filtration of water samples using a UAV system to recover filter sample aliquots for the determination of ‘dissolved’ (&lt;0.45 μm) trace element concentrations and compares UAV methods to conventional sampling strategies. This study systematically compares the quality of analytical data collected from lakes, ponds, and rivers in the Long Lake area of southern Ontario, using conventional manual sampling (from a boat or canoe) and a series of UAV-based sampling methodologies. The waters sampled within the study area are highly meteoric and show evidence of solute input from water-rock interaction with local country rocks. The results of this study show that in general, conventional sampling methodologies are statistically comparable to samples collected using UAVs. However, there is some evidence of element variation related to lake stratification, with dissolved Cu concentrations higher in samples collected at depth compared to those from the surface. Similarly, samples filtered after collection typically have lower concentrations of Fe and Mn, potentially resulting from precipitation before filtration. An enclosed sampling system offered from peristaltic pumping with in-line filtration removes the potential for contamination from the surrounding environment and from the UAV itself.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107617"},"PeriodicalIF":3.4,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142748596","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Numerical simulation of a base metal deposit related to a fossil geothermal system","authors":"David Calisto ,&nbsp;Daniel Moncada ,&nbsp;Eric Sonnenthal ,&nbsp;Lorena Ortega ,&nbsp;Darío Chinchilla","doi":"10.1016/j.gexplo.2024.107613","DOIUrl":"10.1016/j.gexplo.2024.107613","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Fossil and active geothermal systems that produce ore deposits are sites of complex physicochemical processes and a favorable combination of factors related to the amount of metal-bearing fluid that flows through the system, ore fluid metal concentrations, depositional efficiency, and the duration of ore deposition. Of all these factors, the length of the mineralizing event is one of the least understood aspects of ore genesis.&lt;/div&gt;&lt;div&gt;We used fluid inclusion data, chemical compositions of base metal sulfides, and fluid flow rates to constrain a reactive-transport model of a fossil geothermal system - the Patricia Zn-Pb-Ag deposit in northern Chile. The Patricia deposit consists of quartz and base metal sulfide veins of hydrothermal origin with structural control, hosted in a volcanic succession with intense propylitic alteration. The fluid inclusions are liquid-rich, with homogenization temperatures ranging from 250 to 150 °C and salinities between 22 and 1 wt% NaCl equiv., with an early fluid mixing trend and no evidence of boiling in the system. Sulfide mineralogy indicates intermediate sulfidation conditions.&lt;/div&gt;&lt;div&gt;To identify the most relevant geochemical and transport parameters controlling the formation of this fossil geothermal system &gt;1000 simulations were performed using the reactive-transport code TOUGHREACT. The paragenesis of the deposit is mimicked by a model of successive stages of fluid circulation consistent with the observed mineral assemblage distribution, the fluid inclusion data, and the estimated resources in the deposit.&lt;/div&gt;&lt;div&gt;The entire geothermal activity of the system was modeled considering 10,000 years of fluid-rock interaction, with periods of circulation of metal-barren fluids followed by metal-rich fluids driving the ore formation. In the initial model, base metal solubility with predominant chloride complexing suggests that the most efficient ore-forming mechanism for the Patricia deposit was the result of the interaction of two different fluids, one fluid transporting metals and another fluid transporting reduced sulfur, mixing in a rock volume of high permeability. Mass balance estimations with this model give a period of 3500 to 5000 years for the ore stage duration in which all the ore resources of the Patricia deposit could have been precipitated by fluid mixing.&lt;/div&gt;&lt;div&gt;In a second model, the previous estimates for the duration of the main ore stage were used to simulate the fluid-rock interaction during the ore stage for 3500 years. The results indicated the importance of the permeability of the host rock enhanced by fractures to concentrate the volume of the mineralization and the role of the hydrothermal alteration assemblage in controlling the circulating fluid acidity. A higher efficiency in forming sulfide minerals appears to coincide with pH values ranging from 5.1 to 5.3.&lt;/div&gt;&lt;div&gt;The results of both models are validated by replicating the system evolution, reproducing the sa","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"268 ","pages":"Article 107613"},"PeriodicalIF":3.4,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effect of passive jaw opening on the electromyographic activity of the temporalis, masseter, digastric, and infrahyoid muscles in healthy adults.","authors":"Jeong-Seung Kwon, Sang-Ho Han, Yeong-Gwan Im","doi":"10.1080/08869634.2022.2048225","DOIUrl":"10.1080/08869634.2022.2048225","url":null,"abstract":"<p><strong>Objective: </strong>To investigate the surface electromyography (EMG) activity of the temporalis, masseter, digastric, and infrahyoid muscles during passive jaw opening in healthy adults.</p><p><strong>Methods: </strong>The EMG activity of the masseter, temporalis, digastric anterior belly, and infrahyoid muscles on the right side was recorded during the four jaw-opening tasks: active opening to 20 mm (AO20); active opening to 40 mm (AO40); passive opening to 40 mm with a rubber mouth prop on the right posterior teeth (POR40); and passive opening to 40 mm with a mouth prop on the left posterior teeth (POL40).</p><p><strong>Results: </strong>The EMG amplitude of the digastric anterior belly and infrahyoid muscles in either POL40 or POR40 was significantly less than that in AO20 or AO40, respectively.</p><p><strong>Conclusion: </strong>Passive jaw opening reduces the EMG activity of the digastric and infrahyoid muscles significantly and could help reduce the load on these muscles during prolonged mouth-opening conditions.</p>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"174 1","pages":"736-744"},"PeriodicalIF":2.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86959825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Iron and phosphate species regulates arsenic speciation and potential mobility in contaminated soils","authors":"Xueqing Zhang ,&nbsp;Jiahong Chen ,&nbsp;Tiancai Ye ,&nbsp;Hulong Yi ,&nbsp;Shan Lei ,&nbsp;Xiangxiang Cui ,&nbsp;Dinggui Luo ,&nbsp;Tangfu Xiao ,&nbsp;Jinli Cui","doi":"10.1016/j.gexplo.2024.107610","DOIUrl":"10.1016/j.gexplo.2024.107610","url":null,"abstract":"<div><div>Arsenic in soils poses a high environmental risk. The understanding of arsenic geochemical speciation, mobility, and other potential factors in contaminated soils is crucial for appropriate remediation strategy development and environmental assessment. The objective of this study was to investigate the arsenic oxidation state and its form in each step of sequential extraction applied to different types of contaminated soils, and to analyze the impact of sequential extraction forms of soil Fe and phosphate. Soil samples were collected from three agricultural regions: acid mine drainage (AMD)-impacted red soils (<em>n</em> = 5, 61.1–248.6 mg As/kg) and As-contaminated groundwater-impacted soil including yellow soils (<em>n</em> = 6, 23.2–32.1 mg As/kg) and chestnut soils (<em>n</em> = 5, 9.0–13.3 mg As/kg). The results of sequential extraction revealed that As was primarily associated with Fe(III) oxyhydroxides. The highest proportion of amorphous Fe(III) oxyhydroxide-bound As was observed in the southern red soils, which was attributable to the coprecipitation/immobilization of high Fe and As concentration levels in AMD during irrigation. The amount of adsorbed As (mass fraction) increased linearly with increasing amounts of As and is related to the presence of both amorphous and crystalline Fe phases in the soils. This demonstrates the immobilization role of reactive Fe phases in controlling the potential mobility of As in contaminated soils impacted by As-contaminated groundwater and AMD. Soil phosphate, with mass concentrations 2–4 orders of magnitude higher than those of As, occupied most of the Fe(III) oxyhydroxide reactive sites. Phosphate-extractable As was 4.3–80.7 mg/kg, accounting for 18.3–76.0 % (median of 33.5 %) of total As, indicating the competitive effect of phosphate on the desorptive release of As. The AMD-impacted paddy soil exhibited much higher proportions of phosphate-extractable As and a predominance of As(III) in the water-soluble extract, revealing the high potential mobility and toxicity of As in flooded soil. The dominant occupation of Fe adsorption sites by soil phosphate likely contributes to low efficiency of soil Fe in immobilizing As. To reduce As mobility, it is imperative to develop future strategies for phosphates used as sustainable fertilizer to support crop culture.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"268 ","pages":"Article 107610"},"PeriodicalIF":3.4,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664304","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mapping hydrothermal alteration in regolith using white micas and chlorite as vectors towards gold mineralization","authors":"Walid Salama,&nbsp;Naina Goswami,&nbsp;Heta Lampinen,&nbsp;Michael Verrall,&nbsp;Louise Schoneveld","doi":"10.1016/j.gexplo.2024.107603","DOIUrl":"10.1016/j.gexplo.2024.107603","url":null,"abstract":"<div><div>Mineral exploration through regolith-dominated terrains poses a significant challenge to cost-effective exploration techniques. Due to missing surface expression, undercover mineral exploration relies on understanding ore-forming processes and characterizing alteration regimes to decipher suitable vectors towards ore deposits. The work presented focuses on the Archean granite-greenstones of the Yilgarn Craton, east of the Meekatharra area in Western Australia, and characterizes the weathering profiles by understanding metal dispersion mechanisms and identifying mineralogical vectors towards gold mineralization within regolith. Mineral mapping of gold mineralization using TESCAN Integrated Mineral Analyzer and laser ablation ICP-MS shows gold is associated with multiple generations of pyrite, and base metal sulfides and sulfosalts hosted in felsic to intermediate volcanics and volcaniclastics. Intensive weathering generated a thick regolith profile dominated by a leached zone of kaolinitic and micaceous saprolite underlain by a supergene Au-Cu deposit blanket at the base. The supergene deposit is dominated by colloform and framboidal pyrite, with pure microcrystalline Au, chalcocite, bornite, malachite, and alunite. Hyperspectral analyses were used to trace the composition and abundance of chlorite and white mica variations in the host rock and the weathering profile. The mineral assemblage in the hydrothermal alteration halo proximal to and intersecting gold mineralization is dominated by Fe-rich chlorite and Na-rich white mica (paragonite). Fe-rich chlorite and paragonite are spatially tied to elevated Au concentration and trends to Fe-Mg-rich chlorite and K-rich white mica (muscovite) distal to the alteration. The variations in chlorite chemistry were detected mainly in bedrock and saprock. Conversely, the white mica chemistry variations were detected in bedrock and the regolith profile, in which white micas resist intensive weathering. The spectral signatures identified through short-wave and thermal infrared data are verified through X-ray diffraction, mineral chemistry, and bulk geochemical analyses. This distinctive spectral signature of white mica and chlorite is a cost-effective exploration method for regional mapping of mineral systems to identify hydrothermal alteration footprints in the regolith developed over felsic and intermediate rocks.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"268 ","pages":"Article 107603"},"PeriodicalIF":3.4,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664310","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ion sources and seasonal recharge characteristics of groundwater around Dali Lake in semi-arid region of Inner Mongolia Plateau, China","authors":"Xueru Pan ,&nbsp;Biao Sun ,&nbsp;Sheng Zhang ,&nbsp;Guohua Li ,&nbsp;Zhiqiang Tian ,&nbsp;Ziyang Guo ,&nbsp;Haifeng Yu ,&nbsp;Zhaoxia Yang","doi":"10.1016/j.gexplo.2024.107612","DOIUrl":"10.1016/j.gexplo.2024.107612","url":null,"abstract":"<div><div>The interaction between groundwater and surface water around an inland lake in semi-arid regions creates a unique ecological pattern and is a key link in the regional ecohydrological cycle. In this paper, the major ions and hydrogen and oxygen isotope characteristics of groundwater, lake water, river water, and rain water were analyzed, which were sampled in Dali Lake and its surrounding areas in the dry and wet seasons. The ion ratio method and the end-member mixing analysis (EMMA) based on principal component analysis (PCA) were applied. The causes of the major ions in groundwater during the dry and wet seasons were analyzed. The temporal and spatial recharge sources and characteristics of groundwater were identified and quantified. The hydraulic relation between groundwater and surface water was clarified. The main hydrochemical type of groundwater was Ca-HCO₃ with changed to Ca-Mg-Cl type in some areas in the wet seasons. Rock weathering was the main genetic mechanism of groundwater hydrochemistry which mainly from the dissolution of silicate. River water and precipitation were the main sources of groundwater recharge. However, there was a large difference in spatio-temporal distribution and recharge contribution. Gongar River water and precipitation were the main recharge sources of groundwater during the dry season with a contribution rate of 49 % and 48 % respectively. Haolai River water and Liangzi River water together became the main recharge sources of groundwater during the wet season with a contribution rate of between 83 % and 92 %. Rain water covered from 7 % to 13 % of groundwater recharge during the wet season. Overall, compared with river water and precipitation, the contribution of lake water to groundwater recharge was almost negligible, ranging from 0 % to 6 %.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"269 ","pages":"Article 107612"},"PeriodicalIF":3.4,"publicationDate":"2024-10-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142720925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}