Journal of Geochemical Exploration最新文献

{"title":"Evolution of and mechanisms controlling water chemistry in the Beijiang River Basin over the past four decades","authors":"Zaizhi Yang ,&nbsp;Tao Jiang ,&nbsp;Zuobin Liang ,&nbsp;Xinfeng Zhao ,&nbsp;Kun Ren ,&nbsp;Di Tian ,&nbsp;Lei Gao ,&nbsp;Qirui Wu ,&nbsp;Shaoheng Li ,&nbsp;Rui Li ,&nbsp;Lichun Xie ,&nbsp;Jianyao Chen","doi":"10.1016/j.gexplo.2025.107736","DOIUrl":"10.1016/j.gexplo.2025.107736","url":null,"abstract":"<div><div>This study investigated long-term hydrochemical data from the main channel (Beijiang) and three tributaries (Lianjiang, Wujiang, and Zhenjiang) in the middle and upper Beijiang River, the second-largest tributary of the Pearl River, from 1985 to 2023. The results showed that Ca²⁺ (&gt;44.1 %) and HCO₃⁻ (&gt;76.17 %) are the dominant cation and anion, respectively. These results indicate that weathering of carbonates and silicates was the primary natural factor influencing riverine chemistry in the basin. Total dissolved solids (TDS) fluctuated between 33.3 and 399 mg/L and pH between 6.5 and 9.2, with the highest TDS levels in Wujiang (191 mg/L), followed by Lianjiang (175 mg/L), Beijiang (149 mg/L), and Zhenjiang (84.7 mg/L). The TDS trend in Beijiang exhibited a significant decline before 2001, followed by a subsequent increase, while the average concentrations of acidic substances (Cl⁻, NO₃⁻, and SO₄²⁻) increased by &gt;38 %, while pH value does not decrease in response to the elevated SO₄²⁻ due to dissolution of carbonate. Ion concentrations mostly decline with discharge rate, except for NO₃⁻, which showed transport limitation and enrichment with increasing discharge rate. The ion flux patterns were classified as discharge-dominated or concentration-dominated. The annual TDS flux of Beijiang was approximately 5.0 × 10⁶ tons and the ionic runoff modulus was 148.4 t·km⁻²·yr⁻¹, which was relatively high compared to that of other rivers in the world. The correlation between ions concentrations and socioeconomic factors suggests that socio-economic activities significantly influence water chemistry. Industrial relocation and large hydraulics project may lead to abrupt fluctuations and sustained increases in water chemistry parameters. The generalized additive models showed that natural factors explained 40.8–50.7 % of the deviance, while socioeconomic factors related to anthropogenic activities explained &gt;79.5 % due to increasing SO₄²⁻, NO₃⁻ and Cl⁻ trends. Given the importance of the river to the Guangdong–Hong Kong–Macao Greater Bay Area, enhanced management and monitoring are needed to protect the regional water supply.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"273 ","pages":"Article 107736"},"PeriodicalIF":3.4,"publicationDate":"2025-02-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143511215","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":"Detrital zircon age distributions in Bayes-Hilbert spaces","authors":"J. Fernández-Suárez ,&nbsp;Vera Pawlowsky-Glahn ,&nbsp;J.J. Egozcue","doi":"10.1016/j.gexplo.2025.107710","DOIUrl":"10.1016/j.gexplo.2025.107710","url":null,"abstract":"<div><div>A growing number of researchers in the Earth Science community use the information provided by the U<img>Pb ages of detrital zircon in sedimentary environments, be these modern (sediments) or ancient (sedimentary or metasedimentary rocks). This information is key to understanding detritus's past and present flow on Earth and its attendant geological implications. An essential component of the investigation concerning detrital zircon age distributions (DZD) and their bearing on several sedimentological, tectonic, geodynamic, paleogeographic, or climatic issues is to compare DZD from different samples. Much theoretical and empirical research has been devoted to ascertaining how to best compare and measure the dissimilarity/distance between DZDs. This ongoing endeavour has generated a variety of metrics and statistical procedures to perform such tasks. In this contribution, a metric based on the Aitchison distance to measure the dissimilarity of any given set of DZD (samples represented by density functions) is presented. The Aitchison distance is used in the reference framework of the Bayes-Hilbert spaces, whose properties help to avoid some of the limitations of previously used metrics. The mathematical and methodological foundations are presented and illustrated with three geological examples taken from the recent literature, using both sedimentary rocks and recent sediments in different geological and geographical settings. The proposed approach results in a consistent statistical tool to determine whether a set of samples is likely to be derived from a common source or, at least, from indistinguishable sources based on DZD data alone.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"273 ","pages":"Article 107710"},"PeriodicalIF":3.4,"publicationDate":"2025-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143471203","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":"Quantification of hydrothermal alteration in Co-Ni-rich mineralized structures along fault segments crossing the Aït Ahmane and Ousdrat plutons, Bou Azzer El-Graara inlier, Central Anti-Atlas: Implications for genesis and mineral exploration","authors":"Saber Salmi ,&nbsp;Ezzoura Errami ,&nbsp;Abdellatif Jouhari ,&nbsp;David R. Lentz ,&nbsp;Mourad Essalhi ,&nbsp;Omar Outaaoui ,&nbsp;Nacer Ennih ,&nbsp;Lhoussayn Ouhoussa ,&nbsp;Abdelhaq Karfal","doi":"10.1016/j.gexplo.2025.107712","DOIUrl":"10.1016/j.gexplo.2025.107712","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Within the Bou Azzer El Graara inlier, Morocco, the analysis of hydrothermal alteration along the N120 and N040 composite faults hosting Co&lt;img&gt;Ni mineralization is of major importance in evaluation of petrogenesis and exploration potential. This research aims to address this through the use remote sensing data followed up with fieldwork linked with detailed sampling with follow-up petrographic and geochemical analyses. The combination of these approaches reveals a strong relationship between brittle deformation and hydrothermal alteration and mineralization, with zonation from core to fault margin; these variably mineralized faults cross-cut the &lt;em&gt;syn&lt;/em&gt;- to late-collisional Cryogenian Aït Ahmane and Ousdrat plutons. The mineralization and alteration is also visible at the nodes between the N120 and N040 faults. The Chlorite-Carbonate-Pyrite Index (CCPI) is used to generally geochemically characterize the alteration associated with the Co&lt;img&gt;Ni mineralization in Bou Azzer. The moderately low CCPI and high Alteration Index (AI) support the observations that sericite, propylitic, and chlorite alteration types are spatially associated with these mineralized veins. As a mineral exploration tool, we have adopted appropriate methods by calculating the Molar Element Ratios (MER) (precisely: PER and GER diagrams) and mass changes. These MER diagrams show that the samples from faulted zones in two quartz diorite plutons are the traps of K-Mg-Ca-Si metasomatism linked to gains of these elements with the probable release of others elements, such as Fe and Mg. Closer to the vein core, this metasomatism intensifies and can be correlated with some base and strategic metals (Co-Ni-As-Cu-Pb-Zn-Ag) forming an ore assemblage with rammelsbergite, skutterudite, nickeline, cobaltite, loellingite, and other sulfide species, etc. This ore assemblage is probably formed during the cycling of the ductile-brittle transition during epidodic faulting and fluid flow. The examination of the distribution and abundance of propylitic, chloritic, sericitic, and carbonate alteration and the analysis of mass change exhibit a gain of K, Ca, and Mg and significant loss of Si and Fe linked to those alteration types; these alteration features are regionally extensive, possibly considered as a geochemical 6. In addition, the intermediate plutons that host alteration-mineralization have changed from Mg-Ca-Fe to K-Mg-Si alteration assemblages; these are linked to the cogenetic mineralization episode (along the NE-veins), and triggered by the reactivation of NW-SE contact zones, with remobilization, and the generation of NE-SW faults. Following these findings, we propose that these faults, which were generated during the late Pan-African and the early Cadomian orogenies, respectively, are a good structural and geochemical metallotect. As such, they deserve in-depth study within a framework of regional exploration in the Bou-Azzer El Graara inlier and throughout the Anti Atla","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"273 ","pages":"Article 107712"},"PeriodicalIF":3.4,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143453530","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":"Understanding rare earth elements in heavy mineral sand systems","authors":"Sidy Morin-Ka ,&nbsp;Ignacio González-Álvarez ,&nbsp;Paul Duuring ,&nbsp;Christopher M. Gonzalez","doi":"10.1016/j.gexplo.2025.107705","DOIUrl":"10.1016/j.gexplo.2025.107705","url":null,"abstract":"<div><div>Heavy mineral sands (HMS) represent an alternative major resource of Rare Earth Elements (REE) deposits with over 90 % of these formed within the past 66 Myr. These deposits exhibit a diverse range of mineral compositions (i.e. ilmenite, rutile, zircon, monazite, xenotime, and garnet) and can be formed from a wide range of geological and surficial processes. However, few studies examined the in-depth geological characteristics and exploration strategies to specifically target HMS mineralisation, and particularly none have specifically focussed on the REE component of these deposits. Here we show a total of 1173 REE-HMS deposits that exhibit diverse heavy mineral compositions. The largest REE-HMS deposits show an average heavy mineral grade of 7 % (SD = 12) and an average resource size of 1337 Mt. (SD = 1932). REE-HMS deposits commonly concentrate along Quaternary coastlines that cluster within a 100 km radius and predominate in tropical humid areas within 25 degrees north and south of the Equator. Yet, 40 % of large REE-HMS deposits formed during the Neogene, Paleogene, and Cretaceous situated inland from modern coastlines. Another feature of REE-HMS clusters shows that coastal areas that are protected from major global oceanic currents show a higher prevalence than regions that remain unprotected. REE-HMS deposits originate from rocks found in high-grade metamorphic belts, orogenic belts, and cratons, transported by wind and well-developed river systems, particularly in tropical and humid climates. This study highlights the importance of geological, climatic, and surface process factors in shaping the distribution of REE-HMS deposits. Furthermore, we also consider socioeconomic factors, such as land accessibility, politics, exploration maturity, and market demand playing crucial roles. A mineral exploration approach is proposed that emphasises the use of specific datasets and exploration methodologies tailored to the footprints of REE-HMS deposits. Overall, this study's findings contribute to a better understanding of REE-HMS deposits, providing insights for future exploration and resource management.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"274 ","pages":"Article 107705"},"PeriodicalIF":3.4,"publicationDate":"2025-02-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143610333","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":"Provenance and uranium source tracing for uranium-bearing series in the south of Songliao Basin: Evidence from zircon UPb chronology and lithogeochemistry","authors":"Hu Peng ,&nbsp;Yangquan Jiao ,&nbsp;Xiaofei Fu ,&nbsp;Liqun Wu ,&nbsp;Xiaodan Guo ,&nbsp;Qingshuang Wang ,&nbsp;Chao Liu","doi":"10.1016/j.gexplo.2025.107703","DOIUrl":"10.1016/j.gexplo.2025.107703","url":null,"abstract":"<div><div>The study of uranium sources in sandstone-type uranium deposits has been significantly hindered by the absence of effective methodologies, thereby impeding uranium resource exploration efforts. This paper delves into the origin and evolution of sandstone-type uranium deposits, particularly in two newly discovered mineral localities in the southeastern Songliao Basin, employing zircon U<img>Pb geochronology and petrogeochemistry. Additionally, it examines the evolutionary history of these deposits within the Paleo-Asian Ocean tectonic domain. The research reveals that the uranium-bearing series in the study area primarily originate from intermediate-acid magmatic rocks located in the active belt of the northern margin of the North China Craton and the continental island arc tectonic environment. The detrital zircon in the uranium reservoir sandstone, with a peak age range of 270–236 Ma, bears witness to the orogenic events involving the subduction, closure, and collision of the Paleo-Asian Ocean and the back-arc ocean basin. Meanwhile, the peak age range of 181–154 Ma signifies the Paleo-Pacific Ocean subduction impact in the study area. A comprehensive comparative analysis of zircon U<img>Pb chronology and lithogeochemistry indicates that the highly differentiated granite (Baijiagou Pluton), which mixed with the crust in the Early Triassic <em>syn</em>-collisional orogenic environment, serves as a promising source of uranium in the study area. By utilizing the differences in weathering resistance between zircon and rock, specifically the stable Th/U ratio in zircon and the unstable Th/U ratio in rocks, this relationship can be used to trace favorable uranium sources. This method provides an effective approach for identifying uranium sources in the exploration of sedimentary uranium deposits. The ocean-arc system present on the active continental margins of the Paleo-Asian Ocean's northern and southern sides continuously facilitates the material cycle of uranium rich sediments and magmatic uranium elements. This process, coupled with multi-stage and multi-material magmatism, ultimately leads to the formation of a favorable uranium rich geological body. This serves as the material and uranium source basis for the formation of sedimentary uranium deposits in northern China.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"272 ","pages":"Article 107703"},"PeriodicalIF":3.4,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143395509","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":"Petrogenesis, tectonic setting and metallogenic potential of the Late Paleozoic and Late Mesozoic granitoids in the Central Great Xing'an Range, NE China","authors":"Yu Zhao ,&nbsp;Shuyi Dong ,&nbsp;Yongmei Zhang ,&nbsp;Huihui Yong ,&nbsp;Jie Zhang ,&nbsp;Yulang Lu","doi":"10.1016/j.gexplo.2025.107714","DOIUrl":"10.1016/j.gexplo.2025.107714","url":null,"abstract":"<div><div>Granitoids are widely distributed throughout the Central Great Xing'an Range (CGXR). Determining their emplacement timing and stages is essential for reconstructing the tectonic and magmatic evolution of northeastern China. This study integrates geochemical, isotopic, and geochronological analyses of the Jalaid Banner-Zhalantun pluton to constrain its magma sources, petrogenesis, and tectonic setting, while investigating the link between magmatism and Cu-Mo-Au mineralization. Geochronological data indicate that the CGXR are predominantly composed of Late Carboniferous–Early Permian and Early Cretaceous (early and late stage) granitoids. Geochemical analyses reveal that the Late Carboniferous–Early Permian granites are highly to moderately fractionated I-type, characteristic of typical continental arc magmatic rocks. The early Early Cretaceous granites are classified as adakites, resulting from partial melting of newly thickened lower crust, whereas the late Early Cretaceous granite porphyry is classified as A1-type granite, with its primary magma likely derived from partial melting of juvenile crustal rocks under low-pressure conditions. Integrating the geochronological, geochemical, and Hf isotope data of Late Paleozoic and Late Mesozoic granitoids, we propose that the collision orogenic time between Xing'an block and Songliao block in the CGXR is not later than the Late Carboniferous–Early Permian. Since the earliest Cretaceous, the Paleo-Pacific Ocean regime became the predominant geodynamic control in NE China, with the superposition of Mongolia-Okhotsk Ocean regime also playing a role during the early Early Cretaceous. Additionally, the positive correlation between zircon Ce⁴⁺/Ce³⁺ value, magmatic oxygen fugacity and porphyry Cu-Mo ore scale suggests that the early Early Cretaceous granodiorite porphyry has significant metallogenic potential.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"274 ","pages":"Article 107714"},"PeriodicalIF":3.4,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580758","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":"The Taragheh titanium-rich karst bauxite deposit, northwestern Iran: Constraints on REE fractionation, Ce anomaly, and provenance","authors":"Maryam Khosravi ,&nbsp;Ali Abedini","doi":"10.1016/j.gexplo.2025.107704","DOIUrl":"10.1016/j.gexplo.2025.107704","url":null,"abstract":"<div><div>The Taragheh Ti-rich bauxite ores occur as distinct stratiform layers at the contact between the middle–late Permian limestones of the Ruteh Formation and the Triassic dolomites of the Elika Formation. These ores are primarily composed of diaspore, hematite, pyrophyllite, and chlorite, with smaller amounts of boehmite, rutile, anatase, goethite, ilmenite, siderite, amesite, and illite. Cerianite and parisite-(Ce) were identified in the ores by SEM–ESD analysis. The studied bauxite samples exhibit ooidic, colloform, and nodular textures. The Al₂O₃–SiO₂–Fe₂O₃ ternary diagram indicates that the destruction of kaolinite and deferruginization were crucial in the formation and evolution of these ores. Variations in the La/Y ratio (0.35–4.51) along the profile suggest a change in pH of depositional environment from acidic to alkaline conditions downward. The increasing downward (LREE/HREE)_N and (La/Yb)_N ratios are attributed to bicarbonate complexation and the preferential adsorption of LREE onto hematite and goethite. Positive Ce anomalies in the upper part of the profile reflect the precipitation of cerianite, due to the oxidation of Ce³⁺ to Ce⁴⁺. Following the fall of the underground water table and the occurrence of Ce in the form of CeCO₃F⁰_(aq) close to carbonate bedrocks, parisite-(Ce) forms in the bottom of the deposit under alkaline conditions. Additionally, positive Ce anomalies in the basal part of the profile may result from the preferential adsorption of Ce onto hematite. Geochemical evidence suggests that the Eu/Eu* and Sm/Nd ratios were not affected by diagenetic processes. The shales of the Ruteh Formation and basaltic rocks are proposed as the provenance for the Taragheh karst bauxite deposit.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"272 ","pages":"Article 107704"},"PeriodicalIF":3.4,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143403168","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":"Evaluation on rare earth elements and microbial communities in abandoned rare earth tailings","authors":"Bing Zhang ,&nbsp;Junli Wu ,&nbsp;Guiping Mou ,&nbsp;Mengrui Xiao ,&nbsp;Shuangshuang Chu ,&nbsp;Zhongyi Yang","doi":"10.1016/j.gexplo.2025.107715","DOIUrl":"10.1016/j.gexplo.2025.107715","url":null,"abstract":"<div><div>Rare earth elements (REEs) tailings present a pressing issue in terms of resource waste, with a lack of effective methods for evaluating and recycling these resources. This study aimed to establish an evaluation system and assess the potential for reutilization of REEs tailings. The study measured the contents of 14 REEs in two layers (0–15 cm, L1 and 15–30 cm, L2) of the tailings across different abandoned durations of 1.5-year (1.5-Y), 7-year (7-Y), 10-year (10-Y), and 14-year (14-Y), as well as an unmined site (CK), using inductively coupled plasma mass spectrometry (ICP-MS). Additionally, the characteristics and functions of microbial communities in the tailings were investigated; The amplified 16S rRNA gene and ITS gene were used to detect bacteria and fungi respectively. Results showed that total REEs content in surface tailings increased from 851.46 μg/g at 1.5-Y to 2133.81 μg/g at 14-Y, which can be attributed to vertical migration. The residue degree of REEs in the tailings ranged from 10.03 % to 21.57 %. The maximal fold to extraction ultimate value of REEs ranged from 1.31 (Ce) to 4.54 (Nd), while the maximal rate to initial ore value of REEs ranged from 0.279 (Ce) to 0.610 (Nd). Moreover, the maximal phyto-remining potential index ranged from 0.365 (Ce) to 2.768 (Nd), with values above 1.0 indicating potential for phyto-remining. <em>Bradyrhizobium</em> showed a positive correlation with all 14 individual REEs, whereas <em>Burkholderia</em> exhibited negative correlations with all 14 individual REEs among bacteria, In terms of fungi, <em>Sagenomella</em>, <em>Suillus</em>, and <em>Trichoderma</em> were positively correlated with all 14 tested REEs, while <em>Chalara</em>, <em>Cenococcum</em>, and <em>Pseudotomentella</em> displayed negative correlations with all 14 tested REEs. The REEs content significantly influenced the microbial communities in the tailings, particularly impacting fungal species during ecological restoration. The REEs tailings demonstrated promising potential for phyto-remining. These findings offer valuable insights into the recycling of REEs tailings.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"272 ","pages":"Article 107715"},"PeriodicalIF":3.4,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421458","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":"Apatite as a proxy for imaging the link between multistage hydrothermal alteration and anomalous gold enrichment in orogenic gold deposits: Evidence from the Jiaodong Peninsula, Eastern China","authors":"Dong Xie ,&nbsp;Liqiang Yang ,&nbsp;Xue Gao ,&nbsp;Gary O'Sullivan ,&nbsp;M. Santosh ,&nbsp;Wei Yang ,&nbsp;Zengsheng Li ,&nbsp;Tao Feng ,&nbsp;Jun Deng","doi":"10.1016/j.gexplo.2025.107716","DOIUrl":"10.1016/j.gexplo.2025.107716","url":null,"abstract":"<div><div>Orogenic gold deposits account for &gt;30 % of the global gold resources. To understand the abnormal enrichment process of gold and to improve their exploration efficiency, it is important to gain insights into the contribution of hydrothermal alteration to gold enrichment. The giant Jiaodong gold province is a world-class gold-mineralized region and is also the largest gold producer in China (with Au reserves of 5760 t). However, the relationship between multistage hydrothermal alteration and gold mineralization here remains equivocal. In this study, cathodoluminescence (CL) and elemental analysis of apatite from the Wang'ershan gold deposit are applied to different alteration assemblages to trace the multistage hydrothermal alteration and to evaluate its contribution to gold enrichment in orogenic gold deposits.</div><div>On the basis of petrographic features, four types of apatite are identified as: unaltered apatite (Ap1), apatite from K-feldspar alteration (Ap2), apatite from hematite-rutile alteration (Ap3), and apatite from pyrite-sericite-quartz alteration, which is directly associated with gold mineralization (Ap4). In general, the geochemical characteristics of apatite in K-feldspar alteration (Ap2) are similar to those of magmatic apatite (Ap1), and the fluids are rich in Ca, P, and REEs, which we correlate with magmatic differentiation in a reducing environment. The K-feldspar alteration is genetically related to Mesozoic magmatism but has no direct contribution to the enrichment of gold. In contrast, apatite from the hematite-rutile alteration (Ap3), which shows high oxygen fugacity, F enrichment, and depletion in REEs, is different from the chemistry of hydrothermal apatite in orogenic gold deposits. Combined with the behavior of Fe and Ti and the wide spatial distribution s of the hematite-rutile alteration process, we infer activation and enrichment of ore-forming materials before mineralization, which may also be a potential reason for the high gold endowment in Jiaodong. In the process of hematite-rutile alteration (Ap3) to pyrite-sericite-quartz alteration (Ap4), the fluid temperature, pressure, and oxygen fugacity decreased. The apatite from pyrite-sericite-quartz alteration (Ap4) have higher S, Cl, and Na contents than those from the former alteration, indicating that volatiles were involved in the mineralization process. The halo of hematite-rutile alteration in Ap3 apatite, formed prior to the mineralization. We propose that hematite-rutile alteration is a key indicator of mineralization in orogenic gold deposits.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"272 ","pages":"Article 107716"},"PeriodicalIF":3.4,"publicationDate":"2025-02-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143430243","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":"Unconformity-related mineralization and fluid transfers in the northern Aquitaine Basin (France) revealed by fluid inclusions and S-Sr isotopes studies","authors":"Loïc Bouat ,&nbsp;Pierre Strzerzynski ,&nbsp;Véronique Gardien ,&nbsp;Guillaume Barré ,&nbsp;Yannick Branquet ,&nbsp;Jérémie Melleton ,&nbsp;Régis Mourgues","doi":"10.1016/j.gexplo.2025.107713","DOIUrl":"10.1016/j.gexplo.2025.107713","url":null,"abstract":"<div><div>In sedimentary basins, unconformity between basement and sediments is the ideal site where fluids from different sources can flow and mix, initiating the formation of ore deposits. In western Europe there are numerous F-Pb-Zn-Ba (±Ag, Ge) basin-hosted deposits located near the unconformity between Mesozoic Basins and the Variscan basement as for example the deposits of the Vendée Coast (France) containing fluorite, baryte, pyrite and quartz. Here, microthermometric data on the primary fluid inclusions of these minerals indicate salinity ranging from 1 to 20 wt% eq. NaCl and homogenization temperatures between 100 and 390 °C. We interpret these data as resulting of a fluids circulation in the ore deposit zone, with an early incursion of basin brines expelled by the leaching of Hettangian evaporites buried several tens of kilometers away, followed by an ascent of basement-derived fluids and, finally, a recharge of seawater. In other French deposits, the δ³⁴S isotopes of baryte are also consistent with a source of fluids from buried evaporites. The ⁸⁷Sr/⁸⁶Sr ratio of baryte demonstrates a crustal source of elements associated with brines-leached base metals and F<img>Ba. The process of buried-derived evaporites brines altering the basement along the unconformity is ubiquitous in all unconformity deposits in France.</div><div>With our results, we confirm that the basin deposits in the Southeastern Massif Central occur along structures formed during Tethys rifting at around 200 Ma, whereas in the Western part they form at ca. 145 Ma in link with the opening of the Bay of Biscay. This highlights that these basin-hosted deposits are preferentially formed during extensional activity in rifting settings, rather than in compressive settings.</div></div>","PeriodicalId":16336,"journal":{"name":"Journal of Geochemical Exploration","volume":"272 ","pages":"Article 107713"},"PeriodicalIF":3.4,"publicationDate":"2025-02-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143421459","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}