Journal of Geochemical Exploration最新文献

{"title":"Fluid origins and ages of Au mineralization of the Hosen 8-2 vein, Hishikari deposit, Kagoshima, Japan","authors":"Jonathan Macuroy , Ryohei Takahashi , Akira Hara , Yoshinori Okaue , Akira Imai , Pearlyn Manalo , Hinako Sato , Andrea Agangi","doi":"10.1016/j.gexplo.2024.107602","DOIUrl":"10.1016/j.gexplo.2024.107602","url":null,"abstract":"<div><div>The oxygen and hydrogen isotope ratios of ore-forming fluids and formation ages were determined using quartz, adularia, and clay minerals in the Hosen 8-2 vein at −5 ML of the Hishikari deposit. Electrum, the dominant ore mineral, is found exclusively in the early band composed of microcrystalline quartz, granular adularia, and smectite. A relatively low Au-grade zone with Au grades below 100 ppm is identified in the southwestern part of the vein, while a ∼25-meter-wide bonanza zone with Au grades up to 10,800 ppm was identified in the central part. The northeastern part of the vein is referred to as the high Au-grade zone, with Au grades between 100 and 1000 ppm.</div><div>The calculated fluid δ<sup>18</sup>O values of the bonanza and high Au-grade zones calculated from quartz in the Hosen 8-2 vein are heterogenous (−6.3 to −0.8 ‰, and −6.8 to −2.9 ‰, respectively). This wide variation indicates the association of the mineralized zones with the boiling zone of upwelling deep fluids and the subsequent mixing with shallow meteoric water, which can be a useful vector of highly mineralized zones in the Hishikari deposit. Conversely, the low Au-grade zone is characterized by lower and more homogenous calculated fluid δ<sup>18</sup>O values (−5.2 to −4.0 ‰) that are closer to the isotopic composition of meteoric water.</div><div>The fluids that precipitated electrum and clay minerals have high δ<sup>18</sup>O values (+3.0 to +7.6 ‰) and low δD values (−132 to −100 ‰), which can be caused by the interaction between deeply circulating meteoric water and the sedimentary rocks of the Shimanto Supergroup at temperatures about 200–350 °C. It is also possible that δD values below −100 ‰ reflect contributions from waters released from Fe-poor hydrous sheet silicates in the host rocks.</div><div>The δ<sup>18</sup>O values of fluids calculated from adularia that formed after the early clay band range from −2.9 to +1.2 ‰. The progressive decrease of the fluid δ<sup>18</sup>O values across the paragenetic sequence can be attributed to the influx of <sup>18</sup>O-depleted meteoric waters that mixed with Au-bearing <sup>18</sup>O-enriched deep fluids.</div><div>The calculated fluid δD values of mixed smectite, illite, and interstratified chlorite-smectite from the altered host rock are much higher (−87 to −57 ‰) than those of the clays from the vein, although their fluid δ<sup>18</sup>O values are relatively similar (−0.3 to +10.2 ‰). These values indicate that the clays from the altered host rock may have originated from the water-rock interaction between shallow fluids and the volcanic rocks of the Hishikari Lower Andesites.</div><div><sup>40</sup>Ar/<sup>39</sup>Ar dating of four adularia separates from the Hosen 8-2 vein yielded plateau ages from 0.930 ± 0.002 to 0.945 ± 0.001 Ma. The crystallization age of the low Au-grade zone (0.930 ± 0.002 Ma) overlaps within error with that of the bonanza zone (0.932 ± 0.002 Ma), suggesting roughly similar ages ","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"268 ","pages":"Article 107602"},"PeriodicalIF":3.4,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142664308","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":"Characterization of pegmatites in the La Motte Batholith area, Preissac-La Corne Plutonic Suite, Abitibi Subprovince and its implications for exploration","authors":"Sabrine Rajhi ,&nbsp;Marc Legault ,&nbsp;Hubert Mvondo ,&nbsp;Robin Potvin","doi":"10.1016/j.gexplo.2024.107601","DOIUrl":"10.1016/j.gexplo.2024.107601","url":null,"abstract":"<div><div>This project focuses on the study of pegmatite characteristics in the La Motte Batholith (LMB) sector in the Abitibi Subprovince, located between the cities of Rouyn-Noranda and Val d'Or, and approximately 30 km west of the North American Lithium mine (101.9 Mt @ 1.06 % Li₂O; Sayona Québec). The study area hosts mineralizations in critical and strategic minerals, most notably the Authier deposit, which are exclusively associated with Li-Cs-Ta pegmatites. The aim of the study is to characterize the mineralogical and geochemical properties of the pegmatites in the sector to better target lithium exploration. This characterization enables the subdivision of various families of pegmatites in the LMB sector, ranging from barren pods to spodumene-rich dykes. Within the LMB, the pegmatitic facies exhibit chemical characteristics similar to those of intersecting pegmatite dykes, suggesting a genetic link between the La Motte Batholith monzogranite and the different pegmatite families despite a possible age difference of several million years. The results also confirm that elemental ratios from whole-rock analyses (K/Rb, K/Cs, Nb/Ta, Mg/Li, and Zr/Hf) within lithium-bearing dykes show the lowest values compared to other dykes, regardless of the sampling location within the same dyke. Potassium feldspar and muscovite microprobe analyses from different pegmatites also reveal K/Rb and K/Cs ratios similar to whole-rock analyses, thereby strengthening the assessment of the fractionation degree of the LMB pegmatites. These ratios thus allow for targeting sectors hosting highly fractionated dykes even where spodumene has not yet been identified.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"267 ","pages":"Article 107601"},"PeriodicalIF":3.4,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142434178","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":"Advanced exploration of rare metal mineralization through integrated remote sensing and geophysical analysis of structurally-controlled hydrothermal alterations","authors":"Mohamed A. Abdelkader ,&nbsp;Yasushi Watanabe ,&nbsp;Ali Shebl ,&nbsp;Mohamed Badawi ,&nbsp;Maher Dawoud ,&nbsp;Hanaa A. El-Dokouny ,&nbsp;Árpád Csámer ,&nbsp;Mahmoud Abdellatif","doi":"10.1016/j.gexplo.2024.107598","DOIUrl":"10.1016/j.gexplo.2024.107598","url":null,"abstract":"<div><div>Fusing multi-source (remote sensing and geophysical) data and diverse approaches validation in targeting hydrothermal alteration and structural anomalies enhances the potential for accurately detecting and characterizing mineralization zones. Sentinel 2 data and ASTER were processed for lithological and hydrothermal alteration mapping in the rare metal-rich Umm Naggat area (Egypt). Different image processing techniques were implemented, including false color composites, minimum noise fraction, band rationing, band math, mineral indices, relative absorption band depth, and constrained energy minimization. The rare metal-bearing Umm Naggat younger granite (NYG) pluton was lithologically discriminated and intra-differentiated to mafic-rich biotite granites, mafic-poor alkali feldspar granites, and albitized granites. Extensive hydrothermal alterations, such as albitization, ferrugination, propylitization, argillization, and phyllitization, overprint the NYG pluton. Normalized standard deviation, automatic lineament extractions, and trend analysis highlighted the key structural directions (NW, NNW, NNE, and NE) and distinguished the NYG pluton as a moderate to high structural density zone. The high structural density and intensive alteration zones are spatially associated and more localized within the NYG pluton than the surrounding rocks. Spatial overlay analysis confirmed that the hydrothermal alterations and fluid circulation systems are structurally-controlled. Furthermore, the hydrothermal alteration mapping and structural analysis outcomes were verified by combining fieldwork, slab polishing, petrographic investigations, and mineral chemistry through semi-quantitative scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) and quantitative electron probe microanalysis (EPMA) analysis. As a result, the hydrothermal genesis of rare metal-bearing minerals (Nb-rutile, Nb-ilmenite, and columbite) close to or incorporated within alteration minerals (chlorite, muscovite, and hematite) is confirmed from the alteration zones (propylitic, phyllic, and ferruginated). In addition, biotite muscovitization and chloritization significantly contribute to the secondary rare metal enrichment. The current study emphasizes the extensive distribution of secondary rare metal-bearing minerals within the entire NYG pluton (not only limited to the northern albitized granite as depicted by previous studies), which might shed light on these hydrothermally-altered younger granites as a new potential source for Nb and Ta in Egypt.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"267 ","pages":"Article 107598"},"PeriodicalIF":3.4,"publicationDate":"2024-10-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426858","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":"Geochemical and isotopic characterization of the shallow aquifers from the Mugello Basin (Tuscany, central Italy): Implications for assessing a monitoring network in a seismically active area","authors":"Lorenzo Chemeri ,&nbsp;Jacopo Cabassi ,&nbsp;Franco Tassi ,&nbsp;Francesco Capecchiacci ,&nbsp;Andrea L. Rizzo ,&nbsp;Stefano Caliro ,&nbsp;Orlando Vaselli","doi":"10.1016/j.gexplo.2024.107600","DOIUrl":"10.1016/j.gexplo.2024.107600","url":null,"abstract":"<div><div>The Mugello Intermontane Basin (MIB) is located 30 km north of Florence (Tuscany, central Italy) and shows high seismicity with historical events characterized by M_w ≥ 6, e.g., on June 13, 1542 (M_w = 6.0) and June 29, 1919 (M_w = 6.4). Progresses in the identification of seismic tracers in geofluids has been made in the last decades, although reference values for a given area are necessary to assess hydrogeochemical anomalies prior to earthquakes. In this study, a detailed characterization of the chemical and isotopic composition of the natural waters discharging from MIB was performed. The aims were to (i) constrain the geochemical processes controlling the chemistry of waters and dissolved gases, (ii) assess the influence of deep-seated fluids in the shallow environment, and (iii) evaluate the suitability of geochemical parameters as reliable tracers for seismic activity. Two different types of waters were recognized, being characterized by: (A) calcium-bicarbonate (Ca-HCO₃) composition, positive Eh values (150–200 mV), slightly alkaline pH (&lt;8.3), and an N₂-dominated dissolved gas phase; (B) sodium-bicarbonate waters (Na-HCO₃,) composition, negative Eh (&lt; −180 mV), pH &gt; 8.5, high contents in F, B and Li, and enrichments in dissolved CO₂ and CH₄. The chemistry of waters of group (A) is controlled by dissolution processes involving carbonate rocks, while the Na-HCO₃ waters likely result by prolonged water-silicate rock interactions and probably associated with longer circulation pathways. Argon (⁴⁰Ar/³⁶Ar) and carbon (δ¹³C in CO₂ and CH₄) isotopes indicate a predominant circulation within local aquifers by shallow fluids. Instead, helium (³He/⁴He) isotopes in dissolved gases highlighted a contribution up to 6 % by mantle/magmatic fluids probably rising through deep faults. The results obtained suggest that trace elements and the isotopic signatures of dissolved CO₂, CH₄, and He may represent reliable seismic tracers for the MIB on the basis of which a monitoring network could be deployed.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"267 ","pages":"Article 107600"},"PeriodicalIF":3.4,"publicationDate":"2024-10-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426864","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":"Mineralogy and environmental geochemistry of copper slag from Butte, Montana","authors":"Christopher H. Gammons,&nbsp;Jenna Kaplan","doi":"10.1016/j.gexplo.2024.107599","DOIUrl":"10.1016/j.gexplo.2024.107599","url":null,"abstract":"<div><div>Herein we characterize the mineralogy, chemical composition, and environmental geochemistry of slag formed by historic (1880s to circa 1910) smelting of the copper-rich lodes of Butte, Montana. The air-cooled slag exists as monolithic “walls” that border Silver Bow Creek, the headwaters of the upper Clark Fork River Superfund site. The slag is mainly comprised of fayalite, hedenbergite, wollastonite, magnetite, and glass. Zinc is present at per cent levels in all of these phases. The overall high zinc content of the slag is partly due to the polymetallic character of the Butte ore bodies. Copper occurs mainly as tiny spheres, or “prills”, which are remnants of the molten Cu-sulfide matte that failed to separate from the slag during smelting. Minerals in the prills include bornite, chalcopyrite, chalcocite, pyrrhotite, pyrite, sphalerite, galena, elemental copper, and elemental silver. The prills are variably oxidized along shrinkage cracks that penetrate into the enclosing slag matrix. Secondary minerals, including hydrous ferric oxide and ferric clay, coat the cracks. Where the cracks meet the surface of the slag, secondary encrustations of calcite, Fe-Mn oxyhydroxides, and mixed Ca-Cu-Zn-Mn-Al-Fe sulfates have locally accumulated. Acid-base accounting tests show that the unweathered slag is non-acid-generating, with the acid potential from Fe-Cu sulfides offset by the neutralization potential of the Ca-Fe silicates (olivine, pyroxene). Interaction of the slag with synthetic precipitation (SPLP tests) confirms the slag's ability to buffer pH to values &gt;8. Nonetheless, the SPLP leachate solutions contain ppb levels of copper, arsenic, zinc, and lead that approach or exceed current regulatory standards for protection of aquatic life (Cu, Pb, Zn) and human health (As). Leaching experiments using Silver Bow Creek water show an increase in dissolved As and W, but variable results for Cu, Pb, and Zn. Leaching of the secondary sulfate-salt deposits produced much higher concentrations of dissolved metals and metalloids which could be a source of contamination to Silver Bow Creek during heavy rain events. Based on bulk analyses, some metals in the slag, including Fe, As, Co, Mn, Pb, Zn, and W, exceed USEPA screening levels for residential and/or urban soils. Leachates containing organic acids (TCLP tests) show Pb concentrations that approach levels for the slag to be classified as hazardous waste. Rather than removing the slag walls, which have value as a form of industrial architecture, an alternate remedy currently under evaluation is to divert Silver Bow Creek around the smelter site and preserve the slag as part of a non-motorized recreational trail system in the reclaimed Butte-Anaconda mine-scape.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"267 ","pages":"Article 107599"},"PeriodicalIF":3.4,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426863","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":"Late mesozoic exhumation of silurian – Devonian and permian Ni-Co sulfide deposits in the East Kunlun orogenic belt: Constraints from zircon fission track ages","authors":"Xueyu Yan ,&nbsp;Yuxin Fan ,&nbsp;Qingsong Cai ,&nbsp;Minmin Gao ,&nbsp;Dengdong Lu ,&nbsp;Ke Bi ,&nbsp;Chuanying Zhu ,&nbsp;Mingjie Zhang ,&nbsp;Ying Wang ,&nbsp;Guangliang Yang ,&nbsp;Xiaohu Li ,&nbsp;Buqing Wang","doi":"10.1016/j.gexplo.2024.107591","DOIUrl":"10.1016/j.gexplo.2024.107591","url":null,"abstract":"<div><div>Ni-Co sulfide deposits of late Silurian – early Devonian and Permian ages hosted within in basic-ultrabasic rock bodies in the East Kunlun orogenic belt have been extensively investigated. Nevertheless, we have only a limited understanding of the history and dynamics of uplift, exhumation, and tectonic deformation of the basic-ultrabasic ore-bearing rock bodies of these Ni-Co sulfide deposits. We used the zircon fission track ages of seven samples obtained from basic-ultrabasic ore-bearing rocks to determine the timing of the exhumation of these Ni-Co sulfide deposits. Combining our results with published data on the timing of orogenesis, cooling events, magmatic activities, and basin infilling in adjacent areas, we conclude the following: 1) The ZFT ages obtained in this study indicate the exhumation during 169.6 ± 5.5–142.2 ± 3.2 Ma; 2) Combined with previous results, our data indicate that the exhumation during the Jurassic – Cretaceous occurred across a large area along the East Kunlun orogenic belt to the Alxa block; 3) The synchroneity of orogeny, magmatic activity, and basin infilling events suggests that the late Mesozoic exhumation was a geomorphological response to the Lhasa-Qiangtang collision driven by the breakup of Gondwanaland.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"267 ","pages":"Article 107591"},"PeriodicalIF":3.4,"publicationDate":"2024-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426861","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":"Mercury in the natural environment: Biogeochemical cycles and associated health risks","authors":"Amit Kumar ,&nbsp;Vinod Kumar ,&nbsp;Palak Bakshi ,&nbsp;Ripu Daman Parihar ,&nbsp;Maja Radziemska ,&nbsp;Rupesh Kumar","doi":"10.1016/j.gexplo.2024.107594","DOIUrl":"10.1016/j.gexplo.2024.107594","url":null,"abstract":"<div><div>Mercury (Hg) is an integral part of Earth's biogeochemical cycles, yet anthropogenic activities significantly elevate its environmental presence, posing considerable ecological and human health risks. Human exposure primarily arises from the consumption of Hg-contaminated freshwater and marine fish. The Minamata Convention on Mercury, initiated by the United Nations Environment Programme (UNEP), aims to mitigate global Hg emissions, reinforced by comprehensive monitoring efforts. The biogeochemical cycling of Hg is complex, encompassing intricate processes of distribution, transformation, and bioaccumulation that connect sources to exposure pathways. Thus, evaluating Hg biogeochemical behavior and potential environmental hazards is crucial in the global scientific fraternity. Although global policies address direct Hg emissions, comprehending its biogeochemical cycling remains challenging and continues to spur scientific investigation. Coal combustion is a significant source, accounting for approximately 60 % of Hg emissions, especially in geologically predisposed regions, with atmospheric deposition being a key factor, leading to elevated Hg levels in terrestrial soils. Health risks associated with Hg exposure are more acute in soil-contaminated environments than in aquatic systems, with ingestion posing greater risks than dermal contact. This review focuses on the biogeochemical cycling of Hg in the natural environment, highlighting contamination patterns and providing updated insights into Hg's impact on aquatic and terrestrial ecosystems.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"267 ","pages":"Article 107594"},"PeriodicalIF":3.4,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142426859","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":"Fluid inclusions and H–O isotopes of the super-large Nanyangtian tungsten deposit in southeastern Yunnan, southwestern China","authors":"Tao Ren ,&nbsp;Qi Zhang ,&nbsp;Cai-Yan Wang ,&nbsp;Die Wang ,&nbsp;Shen-Jin Guan","doi":"10.1016/j.gexplo.2024.107593","DOIUrl":"10.1016/j.gexplo.2024.107593","url":null,"abstract":"<div><div>The Nanyangtian deposit is a super-large reduced skarn tungsten deposit located in the Laojunshan W<img>Sn polymetallic ore province in southeastern Yunnan (SW China). The deposit is represented by three flat-lying mineralized zones formed vertically by the replacement of limestone or minor calcareous schist. The tungsten orebodies are mainly stratiform, lenticular, and vein types, hosted in the Paleoproterozoic Nanyangtian Formation. Three mineral formation stages have been identified based on the mineral assemblages and vein crosscutting relationships (pre-, syn-, and post-ore). The Nanyangtian is a calcic skarn deposit, dominated by a grossular-diopside-tremolite-actinolite assemblage. Scheelite, pyrrhotite, pyrite, and chalcopyrite are the main ore minerals. Detailed petrographic observations show three types of fluid inclusions (FIs) in various hydrothermal minerals: liquid-rich two-phase (type-I), gas-rich two-phase (type-II), daughter mineral-bearing three-phase (type-III). Their homogenization temperatures (193–298 °C) and salinities (1.2–9.3 wt% NaCl eq.) indicate that the Nanyangtian ore-forming fluids were of medium to low temperature and low salinity compared to the statistical data from representative skarn tungsten deposits in South China. Laser Raman microprobe analysis of the FIs shows that the inclusions are dominated by H₂O with minor CH₄ and N₂. The δD values (relative to Vienna-Standard Mean Ocean Water, VSMOW) of fluid inclusions and calculated δ¹⁸O_water values (relative to VSMOW) of the fluids in equilibrium with hydrothermal minerals are −105 to −69 ‰ and − 1.9 to 7.6 ‰, respectively. These oxygen–hydrogen isotopic compositions indicate that the ore-forming fluids were magmatic-derived, which may have metasomatized the Nanyangtian Formation carbonaceous calcareous rocks along interlayer structures to form the prograde skarn minerals. Then the fluids mixed with meteoric water migrated along faults to form the retrograde skarn and tungsten ore. Mixing of magmatic fluid with meteoric water is likely the main factor for the ore precipitation at Nanyangtian.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"267 ","pages":"Article 107593"},"PeriodicalIF":3.4,"publicationDate":"2024-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322477","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":"Characterization of lead and zinc in catchment sediments and their relationship with lead‑zinc mineralization from the Sino–Mongolian border region","authors":"Wei Wang ,&nbsp;Lanshi Nie ,&nbsp;Haibo Wang ,&nbsp;Xueqiu Wang ,&nbsp;Hanliang Liu ,&nbsp;Shojin Davaa ,&nbsp;Qinghua Chi ,&nbsp;Dongsheng Liu ,&nbsp;Jian Zhou ,&nbsp;Qinghai Hu ,&nbsp;Xinbin Cheng ,&nbsp;Yining Zhou","doi":"10.1016/j.gexplo.2024.107597","DOIUrl":"10.1016/j.gexplo.2024.107597","url":null,"abstract":"<div><div>The Sino–Mongolian border region is one of the most important metallogenic belts in Central Asia and is an important source of Au, Ag, Pb, Zn, Sn, Cu, and rare metals in southern Mongolia and northern China. The variations in Pb and Zn concentrations and their spatial distribution in the region can indirectly reflect the distribution pattern of mineral resources in the region and provide reference data for the exploration of elements associated with Pb and Zn (e.g., Au, Ag, Cu, and Mn). Moreover, Pb and Zn data are valuable in environmental research because the elements are persistent and potentially toxic heavy metals. Although numerous geological and geochemical surveys of Pb<img>Zn resources have been conducted in China, the Sino–Mongolian border region remains under studied. Therefore, in this study, we performed an integrated and comprehensive analytical study of single-element and combined Pb<img>Zn geochemical anomalies. A total of 10,452 catchment sediment samples were collected. Pb concentrations in the samples ranged from 1.90 to 494 mg/kg, while Zn concentrations ranged from 3.00 to 1940 mg/kg. Of these, the median and mean values for Pb were 19.4 mg/kg and 55.0 mg/kg, respectively, while the median and mean values for Zn were 19.9 mg/kg and 58.0 mg/kg, respectively. To characterize the concentration and spatial distribution of Pb and Zn in the study area, we conducted an exhaustive study across several dimensions, considering the geological setting, mineral development, and utilization, and explored the key factors affecting these characteristics. A total of 53 Pb, Zn geochemical anomalies (geochemical province/domain, Pb &gt; 23.1 mg/kg and Zn &gt; 75 mg/kg, &gt; Q85%), including 17 Pb<img>Zn combined geochemical anomalies, were identified in this study. The Pb<img>Zn combined geochemical anomalies were mainly concentrated in the Altai region in the west and the Daxinganling region in the east of the study area and are closely related to the distribution of known Pb<img>Zn deposits. The high-quality geochemical data produced during this study could be an important reference for future mineral exploration work and environmental change studies in the Sino–Mongolian border region.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"267 ","pages":"Article 107597"},"PeriodicalIF":3.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142359026","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":"Hidden deposit exploration using the tectono-geochemistry method in the western Xicheng ore field, China","authors":"Zhizhong Cheng ,&nbsp;Qiang Wang ,&nbsp;Junchen Liu ,&nbsp;Zhenshan Pang ,&nbsp;Tingjie Yan ,&nbsp;Zezhong Du ,&nbsp;Mingming Bing ,&nbsp;Huixiang Yuan ,&nbsp;Chenggui Lin","doi":"10.1016/j.gexplo.2024.107592","DOIUrl":"10.1016/j.gexplo.2024.107592","url":null,"abstract":"<div><div>Geochemical anomalies involve complex geological and geochemical processes. Integrating metallogenic processes into the interpretation of geochemical data can promote mineral exploration. In this study, 3080 subsamples were collected from the western Xicheng ore field and combined into 1312 composite samples using the tectono-geochemistry method. Nineteen elements were analyzed for each composite sample. Factor analysis based on the CLR-transformed data yielded four factors, including the Ag–Sb–Hg–Pb–Au–(B–Ba) association of F1, Zn–Cd–Pb association of F2, Bi–Sn–(Au–As) association of F3, and W–Sn–(Cu) association of F4. Thresholds of each factor were obtained using the concentration–number (C–N) fractal model. Six targets were delineated based on the factor anomaly maps, and one Pb–Zn and two Au deposits were discovered in Targets I and II, respectively. These discoveries and the good spatial correspondence between known deposits and anomalies provide compelling evidence for the effectiveness of the tectono-geochemistry method in the study area. More importantly, a model for the genetic relationship between geochemical anomalies and metallogenesis was constructed. The late tectonic-magmatic-hydrothermal transformation dominated the geochemical pattern in the study area. The degree of interaction between the Au-rich magmatic-hydrothermal fluids and SEDEX-style Pb–Zn mineralizations yielded leakage halos with various elemental assemblages. In addition, W–Sn anomalies may serve as auxiliary exploration indicators for Au mineralizations.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"267 ","pages":"Article 107592"},"PeriodicalIF":3.4,"publicationDate":"2024-09-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142322475","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}