Chemical Geology最新文献

{"title":"Petrology of alkali gabbro from the Messum Crater, Namibia (Paranà-Etendeka Province) – Melting of metasomatized carbonated lithospheric mantle sources","authors":"S. Jung , R.L. Romer , J.A. Pfänder","doi":"10.1016/j.chemgeo.2024.122547","DOIUrl":"10.1016/j.chemgeo.2024.122547","url":null,"abstract":"<div><div>Foid gabbros (alkali gabbros) are late-stage intrusive rocks into the alkaline core of the Cretaceous Messum complex, an anorogenic ring complex belonging to the Etendeka Large Igneous Province in NW Namibia. The mineralogy of the alkali gabbros is characterized by primary olivine, clinopyroxene (Ti-augite), nepheline and plagioclase and late-stage or secondary brown Ti-amphibole and biotite plus magnetite. The bulk rock compositions resemble low-SiO<sub>2</sub> alkaline melts with low TiO<sub>2</sub> and K<sub>2</sub>O/Na<sub>2</sub>O < 1. Some of them have Cr (up to 490 ppm) and Ni (up to 265 ppm) contents that approach values characteristic for primary mantle melts. The alkali gabbros are characterized by variable enrichment in incompatible trace elements (Ba: 750–1020 ppm, Zr: 131–173 ppm; Hf: 3.0–3.4 ppm, Nb: 66–90 ppm, Ta: 3.7–5.2 ppm, La: 32–43 ppm, Th: 4.0–5.5 ppm). Zr/Hf and Nb/Ta ratios are high and negatively correlated. The alkali gabbros display a small spread in initial <sup>87</sup>Sr/<sup>86</sup>Sr (0.7044–0.7046), εNd (+1.2 to +1.7) and Pb isotope ratios (<sup>206</sup>Pb/<sup>204</sup>Pb, 17.86–18.00, <sup>207</sup>Pb/<sup>204</sup>Pb: 15.54–15.56, <sup>208</sup>Pb/<sup>204</sup>Pb: 37.65–37.81). Variations of major and trace element data and Sr, Nd, and Pb isotopic compositions indicate that the more differentiated alkali gabbro samples evolved by fractional crystallization from the most mafic parent involving mainly olivine, clinopyroxene, and minor plagioclase and Fe<img>Ti oxides, whereas crustal contamination was negligible. In primitive mantle-normalized multi-element diagrams, alkali gabbros show depletions in Rb, Th, U, Pb, Hf, Zr and Ti and enrichments in Sr. Notably, high molar Ca/Al, high Ti/Eu, high Zr/Hf and Nb/Ta, low TiO<sub>2</sub>, low Zr/Nb at high Nb concentrations and low Zr/Sm in samples with high Lu/Hf and low Hf/Sm point to a carbonatitic component in the source of the alkali gabbros. REE modelling suggests that the parental melts form within the garnet stability field and may be modified either by partial re-equilibration or mixing with melts generated in the spinel stability field. Application of the thermobarometer proposed by <span><span>Lee et al. (2009)</span></span> (<span><span>Lee et al., 2009</span></span>. Constraints on the depths and temperatures of basaltic magma generation on Earth, and other terrestrial planets using new thermobarometers for mafic magmas. Earth Planet. Sci. Lett. 279, 20–33.) implies generation of the most primitive alkali gabbros at ∼4.5 GPa and ∼ 1480 °C, the latter value is in agreement with previous temperature estimates using Al-in-olivine thermometry and melt inclusion studies. The Sr-Nd-Pb isotope compositions of the alkali gabbros do not overlap with those of mafic lavas attributed to the Tristan or Gough hot spot or the newly defined Doros component. Trace element and isotope data indicate derivation of the Messum alkali gabbros from a heterogeneous m","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122547"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142858012","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":"Triple oxygen and hydrogen stable isotope composition of water in Murchison carbonaceous chondrite accessed by thermogravimetry-enabled laser spectroscopy","authors":"Erik J. Oerter ,&nbsp;Alexandre Garenne ,&nbsp;Miguel Cisneros ,&nbsp;George D. Cody ,&nbsp;Michael Singleton ,&nbsp;Conel M. O’D. Alexander","doi":"10.1016/j.chemgeo.2024.122557","DOIUrl":"10.1016/j.chemgeo.2024.122557","url":null,"abstract":"<div><div>We have developed the capability to measure ¹⁷O/¹⁶O in H₂O and OH⁻ of hydrous minerals by a technique using thermogravimetric analysis coupled with isotope ratio infrared spectroscopy (TGA-IRIS) on a suite of liquid water standards, terrestrial mineral standards, multi-mineral synthetic mixtures of terrestrial samples, and Murchison carbonaceous chondrite. This ¹⁷O/¹⁶O analytical capability is combined with the previously developed TGA-IRIS capability of ¹⁸O/¹⁶O, which enables us to calculate Δ`<sup>17</sup>O values. Additionally, we have made <sup>2</sup>H/<sup>1</sup>H measurements by TGA-IRIS on the suite of materials. Analyses of 328 standard water samples sealed into silver tubes (0.25 μL, 174 VSMOW and 154 GISP) analyzed over the course of three years yielded δ<sup>18</sup>O values by TGA-IRIS with precision of ±0.30 ‰, δ<sup>17</sup>O of ±0.24 ‰, Δ`¹⁷O of ±0.126 ‰, and δ²H ± 7.5 ‰ (± 1 Std. Dev.). TGA-IRIS analyses of a suite of hydrous minerals (oxy-hydroxide, mica, serpentines, sulfide, phyllosillicates) yields similar precision. TGA-IRIS analyses of the CM2 carbonaceous chondrite Murchison resulted in δ¹⁸O, δ¹⁷O, Δ`<sup>17</sup>O, and δ<sup>2</sup>H values of the H<sub>2</sub>O and/or OH<sup>−</sup> from its hydrous minerals. Δ`¹⁷O values of Murchison H₂O range from 1.034 ‰ at 350 °C, to −0.368 ‰ at 650 °C, to −1.75 ‰ at 850 °C. TGA-IRIS can generate Δ`¹⁷O values of H₂O and/or OH⁻ in hydrous materials that are well within the precision needed for the analysis of meteoritic samples, as well as samples returned from asteroids, such as Ryugu and Bennu.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122557"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142857885","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":"Mechanism of cadmium (Cd) enrichment in the soil of karst areas with high geochemical background in Southwest China","authors":"Bo Li ,&nbsp;Kun Lin ,&nbsp;Xu Liu ,&nbsp;Xudong Ma ,&nbsp;Xuezhen Li ,&nbsp;Zhiliang Wu ,&nbsp;Cheng Li ,&nbsp;Tao Yu ,&nbsp;Tiansheng Wu ,&nbsp;Zhongfang Yang","doi":"10.1016/j.chemgeo.2024.122523","DOIUrl":"10.1016/j.chemgeo.2024.122523","url":null,"abstract":"<div><div>Karst areas are formed from the dissolution of carbonate rocks and are present worldwide. The soil found in such areas is enriched in heavy metals, such as cadmium (Cd), lead (Pb) and Arsenic (As), and has geological high-background characteristics. However, this enrichment is anomalous depending on the type of bedrock, and the mechanism of enrichment has not yet been comprehensively elucidated. To explore the mechanisms of Cd enrichment in these soils, we investigated the distribution patterns and migration characteristics of Cd during the weathering and pedogenesis of carbonate rocks, and the causes of Cd enrichment and associated ecological risks were determined. The conclusions were as follows: (1) In the process of natural evolution, the boundary between the dissolution of carbonate rocks and the weathering of insoluble substances is unclear, resulting in the overlap of and interaction between the processes of dissolution-accumulation-weathering and pedogenesis. (2) In addition to the enrichment effects caused by the dissolution of carbonate rocks and the inheritance, the readsorption of insoluble substances and the retention of secondary carrier minerals are the main driving forces of Cd enrichment. (3) During the late stage of weathering of insoluble materials, soil acidification significantly promotes the Cd activation process. When the proportion of active Cd significantly increases, the ecological risk potential increases, especially in geological high-background areas rich in Cd.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"673 ","pages":"Article 122523"},"PeriodicalIF":3.6,"publicationDate":"2025-02-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142815874","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":"A model explaining the anomalous enrichment of Pt in phosphatized crusts: The influence of phosphates and organic acids","authors":"Zhengkun Li ,&nbsp;Xiaoming Sun ,&nbsp;Dengfeng Li ,&nbsp;Yongjia Liang","doi":"10.1016/j.chemgeo.2025.122673","DOIUrl":"10.1016/j.chemgeo.2025.122673","url":null,"abstract":"<div><div>Numerous studies have reported a remarkable enrichment of platinum (Pt) in phosphatized ferromanganese crusts, with concentrations several times higher than in non-phosphatized crusts. Understanding the mechanism behind this extraordinary Pt enrichment requires investigating the influence of anoxic water layers, which are rich in various ions, on the accumulation and preservation of Pt in ferromanganese minerals during phosphorization events. This study combines adsorption/desorption experiments, Fourier transform infrared (FTIR) spectrum analysis, transmission electron microscope (TEM) observations, and X-ray absorption fine structure (XAFS) analysis using feroxyhyte (δ-FeOOH) and vernadite (δ-MnO2) as representative ferromanganese minerals in Fe<img>Mn crusts to examine the fixation and reactivation of Pt during phosphorization events. Our research findings reveal that changes in the ionic composition of water layers during phosphorization events have a significant impact on the adsorption and preservation of Pt by ferromanganese minerals. Fe²⁺, Mn²⁺, and phosphate ions were found to strongly inhibit the adsorption of Pt by feroxyhyte. On the other hand, citric acid enhances Pt adsorption by creating additional adsorption sites at the edges of vernadite through dissolution. Regarding Pt preservation, phosphate ions can lead to a substantial release of Pt adsorbed in feroxyhyte, while only a small amount of Pt in vernadite can be released by phosphate. FTIR analysis indicates that phosphate can reactivate Pt in feroxyhyte by competing for surface hydroxyl groups. XAFS analysis further reveals that phosphate ions weaken the bonding between Pt and vernadite, although not to an extent that causes significant Pt release.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122673"},"PeriodicalIF":3.6,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143369702","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":"Clay Li isotopes reveal contrasting responses of chemical weathering intensity to hydroclimate changes in South Asia","authors":"Jingrui Li ,&nbsp;Xuefa Shi ,&nbsp;Shengfa Liu ,&nbsp;Hui Zhang ,&nbsp;Zhaowei Jing ,&nbsp;Xiaoming Miao ,&nbsp;Kaikai Wu ,&nbsp;Rui Jiang ,&nbsp;Somkiat Khokiattiwong ,&nbsp;Narumol Kornkanitnan","doi":"10.1016/j.chemgeo.2025.122652","DOIUrl":"10.1016/j.chemgeo.2025.122652","url":null,"abstract":"<div><div>Weathering processes in orogenic belts play a pivotal role in Earth's climate regulation. However, the link between silicate weathering and hydroclimatic fluctuations remains elusive. Here, we investigate the lithium‑neodymium isotopic compositions (δ⁷Li, εNd) and clay mineralogy of sediments in the northeastern Bay of Bengal to determine if the δ⁷Li can be used as a reliable tracer of the chemical weathering intensity and to assess how weathering responses to hydroclimate changes. δ⁷Li and εNd values range from −2.4 ‰ to 0.4 ‰ and − 12.5 to −8.9, respectively, with clay mineralogy dominated by illite (57 % on average). A decline in δ⁷Li since 13.5 ka, averaging −1.3 ‰, compared to −0.7 ‰ between 25 ka and 13.5 ka, indicates intensified weathering aligned with monsoon variations. Prominent millennial-scale δ⁷Li fluctuations (2.8 ‰ in maximum) during the last deglaciation, showing lower values during the cold events (Younger Drys and Heinrich stadial 1), imply a different mechanism of weathering response to hydroclimate changes. Shift of high mountain- versus floodplain-dominated weathering regimes and hydrology induced changes in water-rock interaction time or water residence time, are suggested to be responsible for δ⁷Li changes at glacial-interglacial scale and millennial scale, respectively. Our study provides key evidence for weathering response to short-term climate change, and highlights the carbon sink role of silicate weathering in floodplains at short-term scales and the potential of Li isotopes in reconstructing past hydroclimate changes.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122652"},"PeriodicalIF":3.6,"publicationDate":"2025-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143207238","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 oxygen (δ18O, δ17O) and hydrogen (δ2H) isotopes in the Northern Limb of the Bushveld Igneous Complex to assess the extent of footwall contamination","authors":"Sharlotte C. Mkhonto ,&nbsp;Matthew I. Leybourne ,&nbsp;Derek Knaack ,&nbsp;Pedro J. Jugo ,&nbsp;Daniel Layton-Matthews ,&nbsp;Danie F. Grobler","doi":"10.1016/j.chemgeo.2025.122665","DOIUrl":"10.1016/j.chemgeo.2025.122665","url":null,"abstract":"<div><div>The Platreef in the Northern Limb is in the same stratigraphic position as the Critical Zone (i.e. Merensky Reef) in the Eastern and Western limbs of the Bushveld Igneous Complex (BIC). However, in some areas, the Platreef is in direct contact with Archean granitic gneisses and Transvaal Supergroup metasedimentary rocks. Although there is significant evidence of assimilation of Transvaal Supergroup metasedimentary rocks in the southern parts of the Platreef, there is no consensus on the extent of contamination and if contamination is proximal or distal to the Pt, Pd, Au mineralized zone/Merensky Reef equivalent. For this study, we report δ’¹⁸O, Δ’¹⁷O, and δ²H values of samples from the downdip portion of the Flatreef (part of the Platreef) on Turfspruit. The results show that δ’¹⁸O values range from ∼4 to 7 ‰ in intervals with little to no evidence of assimilation and can reach up to 17 ‰ in intervals with evidence of pervasive assimilation. The δ’¹⁸O values in areas with no evidence of assimilation are similar to previously reported values in the Eastern and Western limbs of the BIC. The Δ’¹⁷O values range from −0.200 to 0.050 ‰ throughout the stratigraphy. Most of the positive Δ’¹⁷O values are associated with intervals showing evidence of assimilation. The δ²H values (which range from −92 to −30 ‰) show no correlation between intervals with pervasive assimilation and those with little to no contamination. Samples from the Turfspruit area of the Northern Limb have δ’¹⁸O values of -5.53 to 17.14 ‰ which shows the extent of footwall assimilation of the Transvaal metasedimentary rocks. The triple oxygen isotope values show that the Northern Limb of the BIC records two separate episodes of crustal contamination: (1) a proximal contamination by local footwall lithologies; and (2) a deeper, more pervasive (with respect to the entire BIC) contamination, prior to injection of the BIC magmas into the middle/upper crust.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122665"},"PeriodicalIF":3.6,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143377007","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":"Fluorapatite fingerprints on magmatic-hydrothermal fluid evolution of the Lianyunshan Nb-Ta-Sn deposit, NE Hunan (South China)","authors":"Nuerkanati Madayipu ,&nbsp;Huan Li ,&nbsp;Thomas J. Algeo ,&nbsp;Safiyanu Muhammad Elatikpo ,&nbsp;Han Zheng ,&nbsp;Biao Liu ,&nbsp;Da-Peng Zhu ,&nbsp;Nuo Li ,&nbsp;Victor Ikechukwu Vincent","doi":"10.1016/j.chemgeo.2025.122669","DOIUrl":"10.1016/j.chemgeo.2025.122669","url":null,"abstract":"<div><div>The textures and compositions of apatite grains have been reported for many types of economic and non-economic deposits, but apatites in hydrothermal Nb<img>Ta (rare-metal) deposits have received scant attention to date. Apatite is common in magmatic–pegmatites and metasedimentary cover rocks of the Lianyunshan Complex (LYSC) of northeastern Hunan Province in South China, potentially providing insights into Nb<img>Ta metallogenic systems. Here, we present integrated textural, major- and trace-elemental, and in situ U-Pb-Sr isotopic data for hydrothermal apatite grains from the metasedimentary (schist)–magmatic (muscovite monzogranite)–pegmatite systems of the LYSC, to investigate its crystallization and mineralization processes in detail. Four types of fluorapatite (S-ap1 and S-ap2 in schist, G-ap in muscovite monzogranite, and P-ap in pegmatite) are recognized. The first three types crystallized in a magmatic-hydrothermal (transitional-stage) setting at ∼132–129 Ma, whereas the P-ap crystallized during a late-stage hydrothermal Nb<img>Ta mineralization event at ∼123 Ma. All four types show similar and low Cl content (&lt; 0.01 wt%) and high F content (2.70–4.49 wt%), suggesting their precipitation from a melt derived through partial melting of crustal material rich in F-bearing minerals. Relatively homogeneous (⁸⁷Sr/⁸⁶Sr)_i ratios are shown by the S-ap1 and S-ap2 grains (0.75067 ± 0.00010), contrasting with higher and variable values in the G-ap (0.75242 to 0.75943, mean 0.75610) and P-ap grains (0.75350–0.75776, mean 0.75533). The Sr isotope signatures of the LYSC appear to be inherited from Lengjiaxi Group metasedimentary strata. Our study highlights application of integrated petrographic-geochemical analyses of fluorapatites to trace the nature of ore-forming fluids in hydrothermal Nb<img>Ta (rare-metal) deposits of metasedimentary–magmatic–pegmatite systems.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122669"},"PeriodicalIF":3.6,"publicationDate":"2025-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143378317","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":"Magmatic tempo within the Paleoproterozoic ophiolitic mélange, Northern Kongling Complex, Yangtze Craton: Dynamics of a Paleoproterozoic subduction zone","authors":"Hao Deng ,&nbsp;Chao Chen ,&nbsp;Di Wang ,&nbsp;Songbai Peng ,&nbsp;Wensong Lang ,&nbsp;He Zhang ,&nbsp;Ziyu Dong","doi":"10.1016/j.chemgeo.2025.122666","DOIUrl":"10.1016/j.chemgeo.2025.122666","url":null,"abstract":"<div><div>Paleoproterozoic ophiolitic mélanges, which are rare worldwide, provide significant insights into the structures of ancient orogens and the onset of modern plate tectonics. Here, we report a spatially and temporally linked arc magmatic association comprising circa 2.1–2.0 Ga EMORB-affinity gabbros and diabases, arc-affinity basalts, hornblendites, high-Mg andesites, and granites from the Paleoproterozoic Shuiyuesi ophiolitic mélange in the Northern Kongling Complex, Yangtze Craton. Structural analyses reveal that the mélange is characterized by a series of imbricated NEE-trending reverse faults and late-stage NNW-trending normal faults. Zircon U<img>Pb dating indicates that mafic rocks within the mélange belt primarily formed at ca. 2.1 Ga and metamorphosed at ca. 2.0 Ga, while granites mainly formed at ca. 2.0 Ga. The gabbros and diabases are characterized by enriched LREE patterns without negative Nb and Zr anomalies, displaying an EMORB-like geochemical affinity. In contrast, the arc-affinity basalts exhibit slightly enriched LREE patterns with negative Nb and Zr anomalies. The hornblendites and high-Mg andesites have higher MgO, Ni and Cr contents and display more fractionated REE patterns and larger negative Nb and Zr anomalies compared to the arc-affinity basalts. We propose that tholeiitic EMORB-affinity gabbros and diabases, arc-affinity basalts and calc-alkaline high‑magnesium andesites record a geological transition from subduction initiation to mature island arc magmatism. Granites are characterized by highly fractionated REE patterns, negative zircon εHf(t) values (−6.3 to −19.3) with Archean Hf isotope T_DM1 ages. We suggest that they formed through the partial melting of thickened Archean crusts during a <em>syn</em>-collision stage. Together with the existing studies, the Shuiyuesi mélange preserves an intact record of subduction-related and syn-collision magmatism and high-pressure metamorphism, indicating that modern-style plate tectonics characterized by cold and deep subduction has been operated since at least 2.1–2.0 Ga during Paleoproterozoic.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122666"},"PeriodicalIF":3.6,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143207233","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":"Corrigendum to “Chemical variability in volcanic gas plumes and fumaroles along the East African Rift System: New insights from the Western Branch” [Chemical Geology 596 (2022) 120811]","authors":"G. Boudoire ,&nbsp;G. Giuffrida ,&nbsp;M. Liuzzo ,&nbsp;N. Bobrowski ,&nbsp;S. Calabrese ,&nbsp;J. Kuhn ,&nbsp;J.-C. Kazadi Mwepu ,&nbsp;F. Grassa ,&nbsp;S. Caliro ,&nbsp;A.L. Rizzo ,&nbsp;F. Italiano ,&nbsp;M. Yalire ,&nbsp;K. Karume ,&nbsp;A. Muhindo Syavulisembo ,&nbsp;D. Tedesco","doi":"10.1016/j.chemgeo.2025.122643","DOIUrl":"10.1016/j.chemgeo.2025.122643","url":null,"abstract":"","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122643"},"PeriodicalIF":3.6,"publicationDate":"2025-01-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143102402","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":"Calibrating elemental salinity proxies in Holocene sedimentary environments","authors":"Mariano Remírez ,&nbsp;Geoffrey J. Gilleaudeau ,&nbsp;Randolph McBride ,&nbsp;Chelsea Pederson ,&nbsp;Carrie M. Miller ,&nbsp;Davin J. Wallace ,&nbsp;Lucía Guerra ,&nbsp;Eduardo Piovano ,&nbsp;Joonas J. Virtasalo ,&nbsp;Erin Culver-Miller ,&nbsp;Isaac Bondzie-Selby ,&nbsp;Chaowen Wang ,&nbsp;Thomas J. Algeo","doi":"10.1016/j.chemgeo.2025.122664","DOIUrl":"10.1016/j.chemgeo.2025.122664","url":null,"abstract":"<div><div>Most information regarding salinity in deep-time paleoenvironments is derived from fossil assemblages and paleogeographic configurations, although salinity interpretations based on fossils can be problematic due to, for instance, the unknown salinity tolerances of extinct clades. Although recently developed elemental salinity proxies (i.e., B/Ga, Sr/Ba, and S/TOC) for shales and mudstones have indicated that some ancient seas may have been less saline than previously assumed, the calibrations of these proxies in modern environments and the limits of their application to deep-time systems require further testing. In this contribution, we compare watermass salinity with elemental salinity proxies in modern and Holocene sedimentary environments representing a wide range of salinity conditions―from freshwater to marine―in North America (Lake Superior, Chesapeake Bay, and Gulf of Mexico), northern Europe (Baltic Sea), and Argentina (Laguna Mar Chiquita). Our results show agreement between observed watermass salinity and interpretations based on sedimentary salinity proxies with a single exception: two marine sites on the inner continental shelf of the Gulf of Mexico yielded B/Ga ratios indicative of freshwater to brackish conditions. The anomalously low boron concentrations at these sites may be related to upward diffusion of freshwater from underlying coastal plain facies deposited during the Last Glacial Maximum. In contrast, the Sr/Ba proxy accurately records the terrestrial-to-marine transition at these sites. Paradoxically, Sr/Ba in lake sediments shows wide ranges related to differences in sediment sources and lake-water chemistry, which highlights the necessity of accurately understanding lake dynamics before interpreting sedimentary salinity proxies. Finally, we tested the influence of clay-mineral assemblages on sediment B/Ga, demonstrating that clay mineralogy is generally not a first-order control on salinity interpretations. Our results strongly support the general robustness of elemental proxies for paleosalinity reconstruction while highlighting the need to take potential confounding factors into consideration.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122664"},"PeriodicalIF":3.6,"publicationDate":"2025-01-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143207239","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}