Pub Date : 2024-11-18DOI: 10.1016/j.chemgeo.2024.122506
Zhe Zhang, Lixin Yi, Zhenlong Nie
The co-precipitation of radium (Ra) with minerals is prevalent in high-salinity environmental systems, with significant implications for geochemical cycling and radiation risk management. This study extensively investigated Ra co-precipitation through both indoor lake experiments and field investigations of saline lakes. 1) In the indoor experiments, calcium ions (Ca<ce:sup loc="post">2+</ce:sup>) concentration remained stable under high-salinity conditions, while barium ions (Ba<ce:sup loc="post">2+</ce:sup>) showed a marked and continuous decline. Ra is less likely to co-precipitate with Ca minerals but has a higher tendency to co-precipitate with Ba sulfates. However, field investigations provided limited support for co-precipitation based on water chemistry. Variations in Ca<ce:sup loc="post">2+</ce:sup> and Ba<ce:sup loc="post">2+</ce:sup> with total dissolved solids (TDS) in saline lakes showed no significant correlation, and both calcite and Ba sulfates may precipitate from solution. Thus, water chemistry profiles can provide an initial assessment of potential co-precipitation occurrences. 2) Our study revealed the responses of four Ra species in high-salinity solutions. Within the selected salinity range, the activity of long-lived Ra significantly decreased, and the calculated precipitation rates indicated their co-precipitation with minerals. Although the co-precipitation signals of short-lived Ra may be obscured by desorption and rapid decay, reasonable calculations confirm that they also underwent co-precipitation. The co-precipitation of all Ra species may be attributed to the compression of the anti-ionic diffusion layer around particles under high-salinity conditions. The molar ratio of Ra to Ba in Ba sulfates is significantly higher than that in gypsum and calcite (Ra/Ca), indicating the probably dominant role of Ba sulfates in co-precipitation. Additionally, variations in Ra/Ba ratios and concentrations of Ba and SO₄<ce:sup loc="post">2−</ce:sup> across these systems further elucidate the control exerted by Ba sulfates on Ra co-precipitation. 3) Previous studies have focused primarily on Ra co-precipitation mechanisms in groundwater and controlled experimental systems, while research on other high-salinity environments, such as saline lakes, remains limited. Findings from our saline lake systems further confirm the prevalence of Ra co-precipitation and provide important insights for other high-salinity natural systems (e.g., the Dead Sea) and polluted environments (e.g., mining sites) where Ra co-precipitation constraints may differ from those in saline lakes. In saline lake systems, salinity/TDS regulate mineral saturation indices (SI) by modulating Ra desorption and SO₄<ce:sup loc="post">2−</ce:sup> levels, thereby controlling (Ra, Ba)SO₄ formation, while the effects of pH and temperature are relatively minor. A limitation of this study is the lack of investigation into the influence of fine colloids and potential complexes on
镭（Ra）与矿物共沉淀现象在高盐度环境系统中十分普遍，对地球化学循环和辐射风险管理具有重要影响。本研究通过室内湖泊实验和盐湖实地调查对镭的共沉淀进行了广泛研究。1) 在室内实验中，钙离子（Ca2+）浓度在高盐度条件下保持稳定，而钡离子（Ba2+）则出现了明显的持续下降。Ra 与 Ca 矿物共沉淀的可能性较小，但与 Ba 硫酸盐共沉淀的可能性较大。然而，实地调查为基于水化学的共沉淀提供了有限的支持。盐湖中 Ca2+ 和 Ba2+ 随溶解固体总量（TDS）的变化没有显示出明显的相关性，方解石和硫酸钡都可能从溶液中析出。因此，水化学剖面可以对潜在的共沉淀现象进行初步评估。2) 我们的研究揭示了四种镭在高盐度溶液中的反应。在选定的盐度范围内，长寿命镭的活性显著降低，计算得出的沉淀率表明它们与矿物发生了共沉淀。虽然短寿命镭的共沉淀信号可能会被解吸和快速衰变所掩盖，但合理的计算证实它们也发生了共沉淀。所有镭元素的共沉淀都可能是由于在高盐度条件下颗粒周围的反离子扩散层受到了压缩。钡硫酸盐中 Ra 与 Ba 的摩尔比（Ra/Ca）明显高于石膏和方解石，这表明钡硫酸盐在共沉淀中可能起主导作用。此外，这些系统中 Ra/Ba 比率以及 Ba 和 SO₄2- 浓度的变化进一步阐明了 Ba 硫酸盐对 Ra 共沉淀的控制作用。3) 以前的研究主要集中在地下水和受控实验系统中的镭共沉淀机制，而对其他高盐度环境（如盐湖）的研究仍然有限。盐湖系统的研究结果进一步证实了镭共沉淀的普遍性，并为其他高盐度自然系统（如死海）和污染环境（如采矿场）提供了重要启示，在这些环境中，镭共沉淀的限制因素可能与盐湖中的不同。在盐湖系统中，盐度/TDS 通过调节 Ra 解吸和 SO₄2- 的水平来调节矿物饱和度指数 (SI)，从而控制 (Ra, Ba)SO₄ 的形成，而 pH 和温度的影响相对较小。这项研究的一个局限性是缺乏对细小胶体和潜在复合物对 Ra 物种影响的调查，而这一讨论可为 Ra 在其他高盐度系统中的迁移和应用提供初步见解。
{"title":"Co-precipitation of radium in high–salinity environments: Implications from laboratory experiments and field surveys","authors":"Zhe Zhang, Lixin Yi, Zhenlong Nie","doi":"10.1016/j.chemgeo.2024.122506","DOIUrl":"https://doi.org/10.1016/j.chemgeo.2024.122506","url":null,"abstract":"The co-precipitation of radium (Ra) with minerals is prevalent in high-salinity environmental systems, with significant implications for geochemical cycling and radiation risk management. This study extensively investigated Ra co-precipitation through both indoor lake experiments and field investigations of saline lakes. 1) In the indoor experiments, calcium ions (Ca<ce:sup loc=\"post\">2+</ce:sup>) concentration remained stable under high-salinity conditions, while barium ions (Ba<ce:sup loc=\"post\">2+</ce:sup>) showed a marked and continuous decline. Ra is less likely to co-precipitate with Ca minerals but has a higher tendency to co-precipitate with Ba sulfates. However, field investigations provided limited support for co-precipitation based on water chemistry. Variations in Ca<ce:sup loc=\"post\">2+</ce:sup> and Ba<ce:sup loc=\"post\">2+</ce:sup> with total dissolved solids (TDS) in saline lakes showed no significant correlation, and both calcite and Ba sulfates may precipitate from solution. Thus, water chemistry profiles can provide an initial assessment of potential co-precipitation occurrences. 2) Our study revealed the responses of four Ra species in high-salinity solutions. Within the selected salinity range, the activity of long-lived Ra significantly decreased, and the calculated precipitation rates indicated their co-precipitation with minerals. Although the co-precipitation signals of short-lived Ra may be obscured by desorption and rapid decay, reasonable calculations confirm that they also underwent co-precipitation. The co-precipitation of all Ra species may be attributed to the compression of the anti-ionic diffusion layer around particles under high-salinity conditions. The molar ratio of Ra to Ba in Ba sulfates is significantly higher than that in gypsum and calcite (Ra/Ca), indicating the probably dominant role of Ba sulfates in co-precipitation. Additionally, variations in Ra/Ba ratios and concentrations of Ba and SO₄<ce:sup loc=\"post\">2−</ce:sup> across these systems further elucidate the control exerted by Ba sulfates on Ra co-precipitation. 3) Previous studies have focused primarily on Ra co-precipitation mechanisms in groundwater and controlled experimental systems, while research on other high-salinity environments, such as saline lakes, remains limited. Findings from our saline lake systems further confirm the prevalence of Ra co-precipitation and provide important insights for other high-salinity natural systems (e.g., the Dead Sea) and polluted environments (e.g., mining sites) where Ra co-precipitation constraints may differ from those in saline lakes. In saline lake systems, salinity/TDS regulate mineral saturation indices (SI) by modulating Ra desorption and SO₄<ce:sup loc=\"post\">2−</ce:sup> levels, thereby controlling (Ra, Ba)SO₄ formation, while the effects of pH and temperature are relatively minor. A limitation of this study is the lack of investigation into the influence of fine colloids and potential complexes on ","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"25 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678902","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}
Pub Date : 2024-11-17DOI: 10.1016/j.chemgeo.2024.122502
Alban Petitjean, Olivier Musset, Christophe Thomazo, Ivan Jovovic, Kalle Kirsimäe
Sedimentary geochemistry is very often associated with the measurement of isotopic composition of carbon and oxygen from carbonates. The usual technique combining acid digestion and mass spectrometry analysis is slow, costly and non-ideal for spatially resolved analyses. When carbonates are processed using laser calcination and the gas produced during calcination is analyzed by infrared spectrometry, the time required for isotopic analysis is reduced to around 15 min to analyze 30 mg of carbonate in situ. Although the time saved is significant, it is hardly reasonable to carry out a high-resolution isotopic mapping of large samples. A fully resolved isotopic mapping, for example, of a sample with 25 cm2 surface area at resolution of a tenth of a millimeter, would require a continuous measurement carried out for a month. The aim of this study is, therefore, to explore possible strategies for constructing an isotopic map with a minimum number of analyses. Two approaches are pro-posed: (i) a mathematical approach that seeks to establish a correlation between the position of the sample and the carbon or oxy-gen isotopes, and (ii) an approach that looks for a correlation between the color (spectral characteristics) of the sample surface subdomains and their isotopic compositions. The choice of the second approach stems from the assumption that color contains a priori information about geological or geochemical processes. Several algorithms were developed and tested, notably using artificial intelligence tools. To testify the isotopic maps produced by these algorithms, posteriori isotopic measurements are taken and compared with the predictions from computed isotopic maps.
{"title":"Mapping applications of laser-laser isotopic measurement in carbonates","authors":"Alban Petitjean, Olivier Musset, Christophe Thomazo, Ivan Jovovic, Kalle Kirsimäe","doi":"10.1016/j.chemgeo.2024.122502","DOIUrl":"https://doi.org/10.1016/j.chemgeo.2024.122502","url":null,"abstract":"Sedimentary geochemistry is very often associated with the measurement of isotopic composition of carbon and oxygen from carbonates. The usual technique combining acid digestion and mass spectrometry analysis is slow, costly and non-ideal for spatially resolved analyses. When carbonates are processed using laser calcination and the gas produced during calcination is analyzed by infrared spectrometry, the time required for isotopic analysis is reduced to around 15 min to analyze 30 mg of carbonate in situ. Although the time saved is significant, it is hardly reasonable to carry out a high-resolution isotopic mapping of large samples. A fully resolved isotopic mapping, for example, of a sample with 25 cm<ce:sup loc=\"post\">2</ce:sup> surface area at resolution of a tenth of a millimeter, would require a continuous measurement carried out for a month. The aim of this study is, therefore, to explore possible strategies for constructing an isotopic map with a minimum number of analyses. Two approaches are pro-posed: (i) a mathematical approach that seeks to establish a correlation between the position of the sample and the carbon or oxy-gen isotopes, and (ii) an approach that looks for a correlation between the color (spectral characteristics) of the sample surface subdomains and their isotopic compositions. The choice of the second approach stems from the assumption that color contains a priori information about geological or geochemical processes. Several algorithms were developed and tested, notably using artificial intelligence tools. To testify the isotopic maps produced by these algorithms, posteriori isotopic measurements are taken and compared with the predictions from computed isotopic maps.","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"41 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678956","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}
Pub Date : 2024-11-14DOI: 10.1016/j.chemgeo.2024.122495
Zhao Liang Chen, Zhe-Xuan Zhang, Ruanhong Cai, Yuanbi Yi, Wenzhao Liang, Peter I. Macreadie, Christian J. Sanders, Shing Yip Lee, Faming Wang, Ding He
Mangroves are important organic carbon (OC) reservoirs that can mitigate climate changes. Although sedimentary dissolved organic matter (SDOM) has been established as a dominant OC component within these ecosystems, its molecular composition, origin, and fate remain largely unknown. This study examined SDOM molecules from one of the largest peri-urban mangroves and adjacent tidal flats in China by using techniques like absorption fluorescence spectroscopy and ultrahigh-resolution mass spectrometry. We found that SDOM in mangroves differs significantly from that in non-mangrove ecosystems. The presence of mangroves created higher levels of N- and S-containing SDOM molecules with depth and exhibited higher lability. However, the suboxic mangrove sediments may limit microbial activity, promoting labile SDOM preservation. Mangrove litter also contributed to the formation of carboxyl-rich alicyclic molecules in sediments, potentially transforming into biologically refractory SDOM that acts as OC sinks. As the understanding of molecular fingerprints of SDOM in mangroves is still at early stages, these findings provide molecular-level evidence that mangrove sediments promote the OC sequestration through preservation and transformation processes. This study offers crucial insights into the role of SDOM in carbon sequestration and the method could be applied into other blue carbon ecosystems.
{"title":"Molecular fingerprints of sedimentary dissolved organic matter in mangroves: Importance to blue carbon sequestration","authors":"Zhao Liang Chen, Zhe-Xuan Zhang, Ruanhong Cai, Yuanbi Yi, Wenzhao Liang, Peter I. Macreadie, Christian J. Sanders, Shing Yip Lee, Faming Wang, Ding He","doi":"10.1016/j.chemgeo.2024.122495","DOIUrl":"https://doi.org/10.1016/j.chemgeo.2024.122495","url":null,"abstract":"Mangroves are important organic carbon (OC) reservoirs that can mitigate climate changes. Although sedimentary dissolved organic matter (SDOM) has been established as a dominant OC component within these ecosystems, its molecular composition, origin, and fate remain largely unknown. This study examined SDOM molecules from one of the largest peri-urban mangroves and adjacent tidal flats in China by using techniques like absorption fluorescence spectroscopy and ultrahigh-resolution mass spectrometry. We found that SDOM in mangroves differs significantly from that in non-mangrove ecosystems. The presence of mangroves created higher levels of N- and S-containing SDOM molecules with depth and exhibited higher lability. However, the suboxic mangrove sediments may limit microbial activity, promoting labile SDOM preservation. Mangrove litter also contributed to the formation of carboxyl-rich alicyclic molecules in sediments, potentially transforming into biologically refractory SDOM that acts as OC sinks. As the understanding of molecular fingerprints of SDOM in mangroves is still at early stages, these findings provide molecular-level evidence that mangrove sediments promote the OC sequestration through preservation and transformation processes. This study offers crucial insights into the role of SDOM in carbon sequestration and the method could be applied into other blue carbon ecosystems.","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"25 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678718","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}
Pub Date : 2024-11-14DOI: 10.1016/j.chemgeo.2024.122496
Yue Xu, Quanshu Yan, Leiluo Xu, Kun Guo, Xianwu Bi
The factors contributing to the high magmatic oxygen fugacity (fO2) of post-subduction porphyry Cu deposits (PCDs) remain controversial. The prevailing hypothesis says that this high fO2 is inherited from the lithospheric mantle modified by previous seafloor subduction. However, recent discoveries pertaining to the prevalence of anoxic oceans, particularly the well-documented Paleo-Tethyan Ocean, would challenge this hypothesis. In order to address this matter, we studied representative primitive high-Mg igneous rocks (HMIRs) from the Yulong PCDs belt in Northern Qiangtang terrane of Tibet. These alkaline rocks are emplaced in a post-subduction setting after the closure of Paleo-Tethyan Ocean. In this study, we use newly generated in-situ mineral analyses on representative samples, together with meticulously reviewed and recalculated literature data, to elucidate the mechanism by which the oxidation process operated in the mantle source of these Cenozoic rocks. Our findings suggest that these post-subduction HMIRs exhibit characteristic compositions resembling those of continental crustal rocks and carbonatites. They display elevated fO2 levels and contain high concentrations of Cu ligands (S and Cl) derived from a source with mantle-like δ18O (4.09 to 5.39‰) and moderately low ɛHf(t=37Ma) values (4.0 to 9.3). This differs from the igneous rocks from the preceding Paleo-Tethyan arc remnants that exhibit lower fO2 levels and Cu ligand concentrations, sourced from a modified mantle with higher δ18O (5.6 to 7.9‰) and ɛHf(t=37Ma) values (9.3 to 13.4). Furthermore, through the application of zircon oxybarometry and existing experimental constraints, we have successfully identified the significance of oxidized mafic basement and overlying carbonates within the Songpan-Ganze terrane as influential oxidizing agents. Through detailed examination of geochemical and seismic data, we explore that these oxidizing agents are responsible for the formation of the oxidized HMIRs and copper mineralization. Our study thus provides significant insights into the role of subducted continental materials in generating carbonated silicate melts and causing oxidation of the mantle sources in a post-subduction setting for the petrogenesis of PCDs.
{"title":"Remelting of the Songpan-Ganze slab: Contribution to elevated magmatic oxygen fugacity and reactivation of copper in the Yulong porphyry copper deposits belt","authors":"Yue Xu, Quanshu Yan, Leiluo Xu, Kun Guo, Xianwu Bi","doi":"10.1016/j.chemgeo.2024.122496","DOIUrl":"https://doi.org/10.1016/j.chemgeo.2024.122496","url":null,"abstract":"The factors contributing to the high magmatic oxygen fugacity (f<ce:inf loc=\"post\">O2</ce:inf>) of post-subduction porphyry Cu deposits (PCDs) remain controversial. The prevailing hypothesis says that this high f<ce:inf loc=\"post\">O2</ce:inf> is inherited from the lithospheric mantle modified by previous seafloor subduction. However, recent discoveries pertaining to the prevalence of anoxic oceans, particularly the well-documented Paleo-Tethyan Ocean, would challenge this hypothesis. In order to address this matter, we studied representative primitive high-Mg igneous rocks (HMIRs) from the Yulong PCDs belt in Northern Qiangtang terrane of Tibet. These alkaline rocks are emplaced in a post-subduction setting after the closure of Paleo-Tethyan Ocean. In this study, we use newly generated in-situ mineral analyses on representative samples, together with meticulously reviewed and recalculated literature data, to elucidate the mechanism by which the oxidation process operated in the mantle source of these Cenozoic rocks. Our findings suggest that these post-subduction HMIRs exhibit characteristic compositions resembling those of continental crustal rocks and carbonatites. They display elevated f<ce:inf loc=\"post\">O2</ce:inf> levels and contain high concentrations of Cu ligands (S and Cl) derived from a source with mantle-like δ<ce:sup loc=\"post\">18</ce:sup>O (4.09 to 5.39‰) and moderately low ɛ<ce:inf loc=\"post\">Hf(<ce:italic>t</ce:italic></ce:inf> <ce:inf loc=\"post\">=37Ma)</ce:inf> values (4.0 to 9.3). This differs from the igneous rocks from the preceding Paleo-Tethyan arc remnants that exhibit lower f<ce:inf loc=\"post\">O2</ce:inf> levels and Cu ligand concentrations, sourced from a modified mantle with higher δ<ce:sup loc=\"post\">18</ce:sup>O (5.6 to 7.9‰) and ɛ<ce:inf loc=\"post\">Hf(<ce:italic>t</ce:italic></ce:inf> <ce:inf loc=\"post\">=37Ma)</ce:inf> values (9.3 to 13.4). Furthermore, through the application of zircon oxybarometry and existing experimental constraints, we have successfully identified the significance of oxidized mafic basement and overlying carbonates within the Songpan-Ganze terrane as influential oxidizing agents. Through detailed examination of geochemical and seismic data, we explore that these oxidizing agents are responsible for the formation of the oxidized HMIRs and copper mineralization. Our study thus provides significant insights into the role of subducted continental materials in generating carbonated silicate melts and causing oxidation of the mantle sources in a post-subduction setting for the petrogenesis of PCDs.","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"193 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678958","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}
Pub Date : 2024-11-13DOI: 10.1016/j.chemgeo.2024.122498
Aaron J. Goodman , Hark Karkee , Shiqiang Huang , Katharina Pfaff , Yvette D. Kuiper , Zhaoshan Chang , Alexander Gundlach-Graham , James F. Ranville
Studies of indicator minerals and mineral chemistry are widely used in geochemistry and are particularly useful in mineral exploration. Due to the low abundance of indicator mineral grains, large field samples and extensive laboratory processing are required for these studies. However, nano- and submicron-scale mineral particles (NPs, diameter < 1 μm) are highly abundant in geochemical sample media, containing millions to billions of particles per gram of soil or sediment. In this study, we analyze mineral NPs using single particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOFMS), a recently developed technique for high throughput elemental characterization of NPs. We investigate the limitations of the technique that arise from the working range of the ICP-TOFMS instrument and the analytical uncertainty of measured element masses in single particles. Despite these limitations, spICP-TOFMS can be used to determine accurate element mass ratios in NPs, which we validated through analysis of mineral specimens. Elemental mass ratios obtained from spICP-TOFMS in the mineral specimens were supported by SEM-EDS. We analyzed the mineral chemistry of two pairs of elements, ZrHf and NbTa in geochemical samples (sediments, soils, and mine waste) adjacent to a carbonatite and a lithium‑cesium‑tantalum-type pegmatite. Hundreds to thousands of NPs were detected in only 30–80 min of spICP-TOFMS analysis, indicating that these particle types are highly abundant. Pegmatite-associated samples contained Hf and Ta-rich NPs, compared to carbonatite-associated samples that displayed the chondritic or crustal abundance mass ratios in single particles. Zr:Hf mass ratios measured in NPs by spICP-TOFMS were supported by LA-ICP-MS analysis of zircons from selected samples. Diagnostic nano-mineral compositions including Nb-Ta-Bi-Sb (large grains of which are rarely found) were abundant in pegmatite-associated samples, but virtually absent in carbonatite-associated samples. In this study, we demonstrate that the chemistry of mineral nanoparticles can be used to discriminate between geological environments, and for the first time, we show that spICP-TOFMS is an effective tool for this type of analysis.
{"title":"Analysis of nano-mineral chemistry with single particle ICP-Time-of-Flight-MS; a novel approach to discriminate between geological environments","authors":"Aaron J. Goodman , Hark Karkee , Shiqiang Huang , Katharina Pfaff , Yvette D. Kuiper , Zhaoshan Chang , Alexander Gundlach-Graham , James F. Ranville","doi":"10.1016/j.chemgeo.2024.122498","DOIUrl":"10.1016/j.chemgeo.2024.122498","url":null,"abstract":"<div><div>Studies of indicator minerals and mineral chemistry are widely used in geochemistry and are particularly useful in mineral exploration. Due to the low abundance of indicator mineral grains, large field samples and extensive laboratory processing are required for these studies. However, nano- and submicron-scale mineral particles (NPs, diameter < 1 μm) are highly abundant in geochemical sample media, containing millions to billions of particles per gram of soil or sediment. In this study, we analyze mineral NPs using single particle inductively coupled plasma time-of-flight mass spectrometry (spICP-TOFMS), a recently developed technique for high throughput elemental characterization of NPs. We investigate the limitations of the technique that arise from the working range of the ICP-TOFMS instrument and the analytical uncertainty of measured element masses in single particles. Despite these limitations, spICP-TOFMS can be used to determine accurate element mass ratios in NPs, which we validated through analysis of mineral specimens. Elemental mass ratios obtained from spICP-TOFMS in the mineral specimens were supported by SEM-EDS. We analyzed the mineral chemistry of two pairs of elements, Zr<img>Hf and Nb<img>Ta in geochemical samples (sediments, soils, and mine waste) adjacent to a carbonatite and a lithium‑cesium‑tantalum-type pegmatite. Hundreds to thousands of NPs were detected in only 30–80 min of spICP-TOFMS analysis, indicating that these particle types are highly abundant. Pegmatite-associated samples contained Hf and Ta-rich NPs, compared to carbonatite-associated samples that displayed the chondritic or crustal abundance mass ratios in single particles. Zr:Hf mass ratios measured in NPs by spICP-TOFMS were supported by LA-ICP-MS analysis of zircons from selected samples. Diagnostic nano-mineral compositions including Nb-Ta-Bi-Sb (large grains of which are rarely found) were abundant in pegmatite-associated samples, but virtually absent in carbonatite-associated samples. In this study, we demonstrate that the chemistry of mineral nanoparticles can be used to discriminate between geological environments, and for the first time, we show that spICP-TOFMS is an effective tool for this type of analysis.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"671 ","pages":"Article 122498"},"PeriodicalIF":3.6,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652763","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}
Pub Date : 2024-11-13DOI: 10.1016/j.chemgeo.2024.122497
Pavel A. Serov
This paper presents the results of a SmNd study of sulfide minerals and whole-rock samples from Cu-Ni-PGE layered complexes of the Fennoscandian Shield. Syngenetic (early) and epigenetic (late) sulfides were analyzed in each complex using the SmNd method. Late sulfide minerals with low Sm/Nd values (the 147Sm/144Nd ratio is often in the range of 0.02–0.07) are associated with an increased mobility of Nd relative to Sm, resulting in a relative excess of Nd compared to Sm in these sulfides. Simultaneously, early sulfides, which are deposited during the magmatic stage of ore formation, typically exhibit higher Sm/Nd values (the 147Sm/144Nd ratio is frequently above 0.07). Additionally, SmNd isotope data for sulfide minerals were used to date ore-forming processes in two Cu-Ni-PGE complexes—Nyud-II (Monchegorsk area, Russia) and Ahmavaara (Finland). The SmNd ages of syngenetic and metamorphic ore from these complexes were determined. Syngenetic ores formed at 2496 ± 36 Ma (Nyud-II) and 2441 ± 93 Ma (Ahmavaara), while metamorphic ores formed at 1940 ± 32 Ma (Nyud-II) and 1904 ± 24 Ma (Ahmavaara). Thus, SmNd isochrons yield the timing of sulfide mineralization and its relationship with the ages of the rocks containing it, while Sm/Nd ratios in sulfides help understand the processes of ore formation. A comprehensive analysis of the full isotopic dataset (this study and other published data) showed the potential of using SmNd isotope data to trace the sequence of sulfide mineralization, which has been confirmed for some hydrothermal deposits. However, this sequence has not been confirmed for magmatic sulfides; this opens up the possibility for further research.
{"title":"Differences in Sm/Nd ratios between early magmatic and late sulfides: The role of fluids and Nd mobility","authors":"Pavel A. Serov","doi":"10.1016/j.chemgeo.2024.122497","DOIUrl":"10.1016/j.chemgeo.2024.122497","url":null,"abstract":"<div><div>This paper presents the results of a Sm<img>Nd study of sulfide minerals and whole-rock samples from Cu-Ni-PGE layered complexes of the Fennoscandian Shield. Syngenetic (early) and epigenetic (late) sulfides were analyzed in each complex using the Sm<img>Nd method. Late sulfide minerals with low Sm/Nd values (the <sup>147</sup>Sm/<sup>144</sup>Nd ratio is often in the range of 0.02–0.07) are associated with an increased mobility of Nd relative to Sm, resulting in a relative excess of Nd compared to Sm in these sulfides. Simultaneously, early sulfides, which are deposited during the magmatic stage of ore formation, typically exhibit higher Sm/Nd values (the <sup>147</sup>Sm/<sup>144</sup>Nd ratio is frequently above 0.07). Additionally, Sm<img>Nd isotope data for sulfide minerals were used to date ore-forming processes in two Cu-Ni-PGE complexes—Nyud-II (Monchegorsk area, Russia) and Ahmavaara (Finland). The Sm<img>Nd ages of syngenetic and metamorphic ore from these complexes were determined. Syngenetic ores formed at 2496 ± 36 Ma (Nyud-II) and 2441 ± 93 Ma (Ahmavaara), while metamorphic ores formed at 1940 ± 32 Ma (Nyud-II) and 1904 ± 24 Ma (Ahmavaara). Thus, Sm<img>Nd isochrons yield the timing of sulfide mineralization and its relationship with the ages of the rocks containing it, while Sm/Nd ratios in sulfides help understand the processes of ore formation. A comprehensive analysis of the full isotopic dataset (this study and other published data) showed the potential of using Sm<img>Nd isotope data to trace the sequence of sulfide mineralization, which has been confirmed for some hydrothermal deposits. However, this sequence has not been confirmed for magmatic sulfides; this opens up the possibility for further research.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"671 ","pages":"Article 122497"},"PeriodicalIF":3.6,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652762","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}
Pub Date : 2024-11-13DOI: 10.1016/j.chemgeo.2024.122486
M.M. Repczyńska, J.F. Molina, A. Cambeses, P. Montero, F. Bea, K. Itano, N. Pujol-Solà, I. Novo-Fernández, L. Barcos, A. Garcia-Casco
Biotite plays an important role in the geochemical cycle of Li, Rb, Cs, and Ba in the upper continental crust, as it is a significant carrier of Li and large-ion lithophile elements in felsic igneous rocks and high-grade detrital metasedimentary rocks. During its interaction with meteoric and hydrothermal fluids, biotite can be transformed into various types of clay minerals (mostly, interlayer-deficient biotite, vermiculites and smectites). These transformations can cause fractionation of the alkaline trace-element ratios Rb/Li, Cs/Li and Rb/Cs between biotite and its replacement products. This study examines the mineral transformations that occur when biotite interacts with aqueous and saline fluids and the poorly understood geochemical behaviour of the resulting phyllosilicates. For this purpose, we performed batch hydrothermal experiments of the interaction of biotite + quartz ± graphite with ultrapure H<ce:inf loc="post">2</ce:inf>O, and 2 M NaCl, 2 M CaCl<ce:inf loc="post">2</ce:inf> and 1 M NaF brine fluids at 170 °C and 10 bar using Teflon bombs, and at 550 °C and 800 to 1400 bar using autoclave apparatus. At <ce:italic>lower-T conditions</ce:italic>, biotite was replaced by 2:1 trioctahedral clay minerals (interlayer-deficient biotite, smectite, vermiculite, and other phyllosilicate species with higher interlayer charge) and Fe oxy-hydroxide minerals by coupled dissolution-precipitation mechanisms. At <ce:italic>higher-T conditions</ce:italic>, these mechanisms caused the transformation of biotite into the mineral assemblages (quartz ± graphite): diopside + anorthite + titanite (CaCl<ce:inf loc="post">2</ce:inf> brine experiments), albite + ilmenite + clay minerals (NaCl brine experiments), and cryolite + alkali feldspar with albite rimmed by K-feldspar + Fe-oxides (NaF brine experiments). Therefore, a significant reduction of the clay mineral stability in the presence of NaF and CaCl<ce:inf loc="post">2</ce:inf> brine fluids is inferred. The biotite replacements by phyllosilicates were mostly controlled by the ion exchange of K<ce:sup loc="post">+</ce:sup> by H<ce:sup loc="post">+</ce:sup> (or its hydrate state H<ce:inf loc="post">3</ce:inf>O<ce:sup loc="post">+</ce:sup>), hydrated Na<ce:sup loc="post">+</ce:sup> and Ca<ce:sup loc="post">2+</ce:sup>, and NaF in the interlayer site. Conservation of the total mass and the Si, Al and Mg abundances occurred in most experimental phyllosilicates. However, in the products of the low-T NaF brine ± graphite experiments, the total mass may have a gain of 5.3–11 % assuming Mg conservation. Sc, V, Nb and Ta abundances were also conserved, but a significant fractionation of the Rb/Li, Cs/Li, and Ba/Li ratios occurred in the experimental phyllosilicates. The experiments predict the generation of highly fractionated Rb/Li and Cs/Li phyllosilicates by replacement of biotite during interaction with aqueous fluids and, mostly, NaCl and NaF brine fluids at high-T and low-T conditions, respectively. This d
生物岩在上部大陆地壳锂、铷、铯和钡的地球化学循环中发挥着重要作用，因为它是长粒火成岩和高品位碎屑变质岩中锂和大离子亲岩元素的重要载体。在与流体和热液相互作用的过程中，黑云母可转化为各种类型的粘土矿物（主要是层间缺失黑云母、蛭石和烟云母）。这些转化可导致碱性痕量元素比 Rb/Li、Cs/Li 和 Rb/Cs 在生物岩及其置换产物之间的分馏。本研究探讨了生物橄榄岩与水性流体和盐性流体相互作用时发生的矿物转化，以及由此产生的植硅酸盐的地球化学行为，但人们对其了解甚少。为此，我们使用聚四氟乙烯炸弹，在 170 °C、10 巴和 550 °C、800 至 1400 巴条件下，使用高压釜装置，对生物硅石 + 石英 ± 石墨与超纯水、2 M NaCl、2 M CaCl2 和 1 M NaF 盐水的相互作用进行了批量热液实验。在较低的温度条件下，通过溶解-沉淀耦合机制，生物黄铁矿被 2:1 的三八面体粘土矿物（层间缺失的生物黄铁矿、直闪石、蛭石和其他具有较高层间电荷的植硅酸盐种类）和氧化铁-氢氧化物矿物所取代。在较高的 T 条件下，这些机制导致生物硅酸盐转变为矿物组合（石英±石墨）：透辉石+阳起石+榍石（CaCl2 盐水实验）、白云石+钛铁矿+粘土矿物（NaCl 盐水实验），以及冰晶石+碱长石，白云石边缘为 K 长石+铁氧化物（NaF 盐水实验）。因此，可以推断粘土矿物在 NaF 和 CaCl2 盐水中的稳定性大大降低。辉绿硅酸盐对斜长石的置换作用主要受 H+（或其水合物状态 H3O+）、水合 Na+、Ca2+ 和层间部位 NaF 对 K+的离子交换控制。大多数实验用植硅酸盐的总质量以及硅、铝和镁丰度都保持不变。然而，在低 T NaF 盐水±石墨实验的产物中，假定镁元素保持不变，总质量可能会增加 5.3-11%。Sc、V、Nb和Ta的丰度也保持不变，但在实验的植硅酸盐中，Rb/Li、Cs/Li和Ba/Li的比率发生了显著的分馏。实验预测，在高T和低T条件下，在与水流体（主要是NaCl和NaF盐水流体）的相互作用过程中，由于生物岩的置换作用，会生成高度分馏的Rb/Li和Cs/Li绿泥石。这表明在长岩火成岩的热液蚀变过程中，生物岩在 Rb/Li、Cs/Li 和 Rb/Cs 的分馏过程中起着关键作用。相反，在相对较低的T条件下，当生物硅酸盐与NaCl或CaCl2盐水流体相互作用时，植硅酸盐产物中Li相对于Rb和Cs的移动性发生了逆转。这些实验结果凸显了生物岩-流体相互作用过程在控制大陆地壳碱性痕量元素预算方面的关键作用。
{"title":"Geochemical behaviour of biotite during interaction with aqueous and brine fluids: Constraints from hydrothermal batch experiments","authors":"M.M. Repczyńska, J.F. Molina, A. Cambeses, P. Montero, F. Bea, K. Itano, N. Pujol-Solà, I. Novo-Fernández, L. Barcos, A. Garcia-Casco","doi":"10.1016/j.chemgeo.2024.122486","DOIUrl":"https://doi.org/10.1016/j.chemgeo.2024.122486","url":null,"abstract":"Biotite plays an important role in the geochemical cycle of Li, Rb, Cs, and Ba in the upper continental crust, as it is a significant carrier of Li and large-ion lithophile elements in felsic igneous rocks and high-grade detrital metasedimentary rocks. During its interaction with meteoric and hydrothermal fluids, biotite can be transformed into various types of clay minerals (mostly, interlayer-deficient biotite, vermiculites and smectites). These transformations can cause fractionation of the alkaline trace-element ratios Rb/Li, Cs/Li and Rb/Cs between biotite and its replacement products. This study examines the mineral transformations that occur when biotite interacts with aqueous and saline fluids and the poorly understood geochemical behaviour of the resulting phyllosilicates. For this purpose, we performed batch hydrothermal experiments of the interaction of biotite + quartz ± graphite with ultrapure H<ce:inf loc=\"post\">2</ce:inf>O, and 2 M NaCl, 2 M CaCl<ce:inf loc=\"post\">2</ce:inf> and 1 M NaF brine fluids at 170 °C and 10 bar using Teflon bombs, and at 550 °C and 800 to 1400 bar using autoclave apparatus. At <ce:italic>lower-T conditions</ce:italic>, biotite was replaced by 2:1 trioctahedral clay minerals (interlayer-deficient biotite, smectite, vermiculite, and other phyllosilicate species with higher interlayer charge) and Fe oxy-hydroxide minerals by coupled dissolution-precipitation mechanisms. At <ce:italic>higher-T conditions</ce:italic>, these mechanisms caused the transformation of biotite into the mineral assemblages (quartz ± graphite): diopside + anorthite + titanite (CaCl<ce:inf loc=\"post\">2</ce:inf> brine experiments), albite + ilmenite + clay minerals (NaCl brine experiments), and cryolite + alkali feldspar with albite rimmed by K-feldspar + Fe-oxides (NaF brine experiments). Therefore, a significant reduction of the clay mineral stability in the presence of NaF and CaCl<ce:inf loc=\"post\">2</ce:inf> brine fluids is inferred. The biotite replacements by phyllosilicates were mostly controlled by the ion exchange of K<ce:sup loc=\"post\">+</ce:sup> by H<ce:sup loc=\"post\">+</ce:sup> (or its hydrate state H<ce:inf loc=\"post\">3</ce:inf>O<ce:sup loc=\"post\">+</ce:sup>), hydrated Na<ce:sup loc=\"post\">+</ce:sup> and Ca<ce:sup loc=\"post\">2+</ce:sup>, and NaF in the interlayer site. Conservation of the total mass and the Si, Al and Mg abundances occurred in most experimental phyllosilicates. However, in the products of the low-T NaF brine ± graphite experiments, the total mass may have a gain of 5.3–11 % assuming Mg conservation. Sc, V, Nb and Ta abundances were also conserved, but a significant fractionation of the Rb/Li, Cs/Li, and Ba/Li ratios occurred in the experimental phyllosilicates. The experiments predict the generation of highly fractionated Rb/Li and Cs/Li phyllosilicates by replacement of biotite during interaction with aqueous fluids and, mostly, NaCl and NaF brine fluids at high-T and low-T conditions, respectively. This d","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"14 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678959","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}
Pub Date : 2024-11-12DOI: 10.1016/j.chemgeo.2024.122485
Leguang Li, Lianxun Wang, Rolf L. Romer, Changqian Ma, Liang Cao, Yang Tian
Granites and rare metal pegmatites of the Mufushan granitic batholith form a continuous magmatic sequence linked by fractional crystallization. Tourmaline is present in muscovite leucogranites and all types of pegmatites, including highly evolved Li-rich pegmatites. We utilized major element, trace element and in-situ B isotope analyses of tourmaline to investigate the effects of magmatic fractional crystallization and magmatic volatile phase (MVP) exsolution on Li migration and exceptional Li enrichment. Eight types of tourmaline are identified across three rock units: (i) Isolated (Tur Ia) and nodular (Tur Ib) tourmaline within muscovite leucogranites; (ii) black tourmaline in veins and/or clusters (Tur IIa), as isolated crystals (Tur IIb) and in tourmaline-quartz segregations (Tur IIc) within Li-poor pegmatites; and (iii) tourmaline as isolated pink crystals with zoning patterns (Tur IIIa), as isolated pink crystals and/or radiating clusters (Tur IIIb), and as isolated crystals enclosed in quartz block (Tur IIIc) within Li-rich pegmatites. Tourmaline in Mufushan muscovite leucogranites and Li-poor pegmatites belongs to the alkali-group and schorl series with Mg/(Mg + Fe) ratios of 0.10–0.31 and 0.12–0.48, respectively, containing almost no Li* and F (apfu, based on X + Y + Z = 15). In contrast, tourmaline in Li-rich pegmatites exhibits schorl-elbaite and elbaite-rossmanite compositions with low Mg/(Mg + Fe) ratio (avg. = 0.01), and evolved Li* (0.01–0.90 apfu, avg. = 0.41 apfu) and F (0.00–0.91 apfu, avg. = 0.36 apfu) contents. A pronounced increase in <ce:sup loc="post">Y</ce:sup>Al, (Li* + Mn) contents, and <ce:sup loc="post">Y</ce:sup>[Al/(Al + Fe)] ratio is observed across the transition from Li-poor to Li-rich pegmatites, consistent with the anticipated pattern of fractional crystallization. The concentration of Li exhibits a sharp increase in Li-rich pegmatites (avg. Li = 6786 ppm) compared to Li-poor pegmatites (avg. Li = 114 ppm) and leucogranites (avg. Li = 469 ppm). Lithium contents increase and reach a peak during the crystallization of Tur IIIb (6686–11,667 ppm), and have lower peak contents during the precipitation of Tur IIIc (8261–9160 ppm), indicating that the incorporation of Li is influenced by MVP accumulation and exsolution. MVP exsolution significantly reduces the solubility of Nb, Ta, and Be in the residual melt, promoting the precipitation of beryl and columbite group minerals and facilitating the migration of fluid-mobile elements such as Li, Rb, Cs, and Ga to form lepidolite. The B isotope compositions of tourmaline range from −14.8 ‰ ∼ −12.6 ‰ in Li-poor pegmatites to −17.1 ‰ ∼ −14.0 ‰ in Li-rich pegmatites. Rayleigh fractionation modeling reveals that MVP saturation occurs after approximately 60 % B was removed from the pegmatite melt. The compositional variation of tourmaline demonstrates that Li enrichment is not only governed by continuous fractional crystallization, but also by MVP-related accumulation and exsolu
幕阜山花岗岩浴成岩的花岗岩和稀有金属伟晶岩形成了一个连续的岩浆序列，并通过分块结晶连接起来。电气石存在于白云母花岗岩和所有类型的伟晶岩中，包括高度演化的富锂辉石。我们利用电气石的主要元素、微量元素和原位硼同位素分析，研究岩浆分块结晶和岩浆挥发相（MVP）外溶对锂迁移和特殊锂富集的影响。在三个岩石单元中发现了八种类型的电气石：(i)在白雲母白榴石中的孤立電氣石（Tur Ia）和節狀電氣石（Tur Ib）；(ii)在貧鋰偉晶岩中的脈狀和/或簇狀（Tur IIa）、孤立晶體（Tur IIb）和電氣石-石英分離（Tur IIc）的黑色電氣石；(iii) 在富鋰偉晶岩中，以獨立粉紅色晶體及帶有分帶圖案的電氣石 (Tur IIIa) 、獨立粉紅色晶體及／或放射狀晶體簇 (Tur IIIb) ，以及被石英塊包圍的獨立晶體 (Tur IIIc) 形態出現的電氣石。在幕阜山白雲母白榴石和貧鋰偉晶岩中的電氣石屬於鹼群和蛭石系列，鎂/（鎂+鐵）比率分別為0.10-0.31和0.12-0.48，幾乎不含鋰*和鐵（apfu，以X + Y + Z = 15計算）。相比之下，富含鋰的偉晶岩中的電氣石則呈現錳/（鎂+鐵）比率較低（平均值=0.01）的矽卡岩-白雲母和埃爾白雲母-紅雲母成分，以及逐漸增加的鋰*（0.01-0.90apfu，平均值=0.41apfu）和鈣（0.00-0.91apfu，平均值=0.36apfu）含量。在从贫锂辉石向富锂辉石过渡的过程中，观察到 YAl、（Li* + Mn）含量和 Y[Al/（Al + Fe）]比率明显增加，这与预期的分块结晶模式一致。与贫锂伟晶岩（平均 Li = 114 ppm）和白云母（平均 Li = 469 ppm）相比，富锂伟晶岩（平均 Li = 6786 ppm）中的锂含量急剧增加。锂含量在 Tur IIIb 的结晶过程中增加并达到峰值（6686-11667 ppm），而在 Tur IIIc 的沉淀过程中峰值含量较低（8261-9160 ppm），这表明锂的掺入受到 MVP 累积和外溶的影响。MVP的外溶显著降低了残余熔体中Nb、Ta和Be的溶解度，促进了绿柱石和铌铁矿族矿物的沉淀，并促进了Li、Rb、Cs和Ga等流体移动元素的迁移，形成鳞片岩。電氣石的硼同位素組合介乎貧鋰偉晶岩的-14.8‰∼-12.6‰至富鋰偉晶岩的-17.1‰∼-14.0‰。瑞利分馏模型显示，MVP饱和是在伟晶岩熔体中约60%的B被去除之后发生的。电气石的成分变化表明，锂的富集不仅受制于连续的分馏结晶，还受制于与MVP有关的累积和外溶机制。
{"title":"Using tourmaline to trace Li mineralization in the Mufushan granitic batholith, South China","authors":"Leguang Li, Lianxun Wang, Rolf L. Romer, Changqian Ma, Liang Cao, Yang Tian","doi":"10.1016/j.chemgeo.2024.122485","DOIUrl":"https://doi.org/10.1016/j.chemgeo.2024.122485","url":null,"abstract":"Granites and rare metal pegmatites of the Mufushan granitic batholith form a continuous magmatic sequence linked by fractional crystallization. Tourmaline is present in muscovite leucogranites and all types of pegmatites, including highly evolved Li-rich pegmatites. We utilized major element, trace element and in-situ B isotope analyses of tourmaline to investigate the effects of magmatic fractional crystallization and magmatic volatile phase (MVP) exsolution on Li migration and exceptional Li enrichment. Eight types of tourmaline are identified across three rock units: (i) Isolated (Tur Ia) and nodular (Tur Ib) tourmaline within muscovite leucogranites; (ii) black tourmaline in veins and/or clusters (Tur IIa), as isolated crystals (Tur IIb) and in tourmaline-quartz segregations (Tur IIc) within Li-poor pegmatites; and (iii) tourmaline as isolated pink crystals with zoning patterns (Tur IIIa), as isolated pink crystals and/or radiating clusters (Tur IIIb), and as isolated crystals enclosed in quartz block (Tur IIIc) within Li-rich pegmatites. Tourmaline in Mufushan muscovite leucogranites and Li-poor pegmatites belongs to the alkali-group and schorl series with Mg/(Mg + Fe) ratios of 0.10–0.31 and 0.12–0.48, respectively, containing almost no Li* and F (apfu, based on X + Y + Z = 15). In contrast, tourmaline in Li-rich pegmatites exhibits schorl-elbaite and elbaite-rossmanite compositions with low Mg/(Mg + Fe) ratio (avg. = 0.01), and evolved Li* (0.01–0.90 apfu, avg. = 0.41 apfu) and F (0.00–0.91 apfu, avg. = 0.36 apfu) contents. A pronounced increase in <ce:sup loc=\"post\">Y</ce:sup>Al, (Li* + Mn) contents, and <ce:sup loc=\"post\">Y</ce:sup>[Al/(Al + Fe)] ratio is observed across the transition from Li-poor to Li-rich pegmatites, consistent with the anticipated pattern of fractional crystallization. The concentration of Li exhibits a sharp increase in Li-rich pegmatites (avg. Li = 6786 ppm) compared to Li-poor pegmatites (avg. Li = 114 ppm) and leucogranites (avg. Li = 469 ppm). Lithium contents increase and reach a peak during the crystallization of Tur IIIb (6686–11,667 ppm), and have lower peak contents during the precipitation of Tur IIIc (8261–9160 ppm), indicating that the incorporation of Li is influenced by MVP accumulation and exsolution. MVP exsolution significantly reduces the solubility of Nb, Ta, and Be in the residual melt, promoting the precipitation of beryl and columbite group minerals and facilitating the migration of fluid-mobile elements such as Li, Rb, Cs, and Ga to form lepidolite. The B isotope compositions of tourmaline range from −14.8 ‰ ∼ −12.6 ‰ in Li-poor pegmatites to −17.1 ‰ ∼ −14.0 ‰ in Li-rich pegmatites. Rayleigh fractionation modeling reveals that MVP saturation occurs after approximately 60 % B was removed from the pegmatite melt. The compositional variation of tourmaline demonstrates that Li enrichment is not only governed by continuous fractional crystallization, but also by MVP-related accumulation and exsolu","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"252 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142678960","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}
Pub Date : 2024-11-10DOI: 10.1016/j.chemgeo.2024.122494
Chenhui Wei , Heyun Fu , Xiaolei Qu , Shu Tao , Patrick G. Hatcher , Dongqiang Zhu
Photooxidation of dissolved organic sulfur (DOS) in soils and natural waters plays an important role in the sulfur biogeochemical cycle. However, the structural-dependent photoliabilities of DOS from different sources remain unclear. Here, the molecular structures and photooxidation behaviors of DOS in pyrogenic dissolved black matter (PyDOM) derived from rice straw-pyrolyzed biochar (referred to as PyDOM-S and considered to be representative of black carbon from prairie fires) were thoroughly characterized and compared with those of DOS in leached dissolved organic matter (LDOM) derived from aerobically decomposed rice straw (referred to as LDOM-S and considered to be generally representative of organic-rich horizons in soils and peats). The Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis revealed that both PyDOM-S and LDOM-S were, respectively, dominated by aliphatic (60.4 % and 41.1 %) and lignin-like compounds (35.1 % and 40.1 %), followed by minimal aromatic and polyaromatic compounds (2.8 % and 11.9 % in total). As demonstrated by the sulfur K-edge X-ray absorption near-edge structure (S-XANES) analysis, PyDOM-S consisted mainly of organosulfate (80.4 %) contrasting to the diversified and mingled reduced sulfurs (62.7 %) and oxidized sulfurs (37.3 %) of LDOM-S. Under simulated sunlight irradiation, 74 % of sulfur in PyDOM-S was photomineralized to sulfate within 24 h and totaling 89 % after 168 h, but only 9 % and 42 % for LDOM-S given the same periods of time, confirming the much faster photomineralization of PyDOM-S. After 168-h irradiation, almost all molecules in PyDOM-S disappeared, whereas a large proportion (44.2 %) of LDOM-S molecules (mainly aliphatic and lignin-like compounds) were photo-resistant. Furthermore, the photomineralization of PyDOM-S was mainly contributed by the final and complete oxidation of organosulfate to sulfate; however, the photooxidation of LDOM-S was dominated by the sequential oxidation of exocyclic sulfur and heterocyclic sulfur to organosulfate prior to releasing sulfate. These results highlight that pyrogenic-sourced PyDOM-S and diagenesis-derived LDOM-S exhibit contrasting photooxidation behaviors due to the associated distinct molecular structures.
{"title":"Contrasting molecular structures and photooxidation behaviors between dissolved organic sulfur released from rice straw-biochar and aerobically decomposed rice straw","authors":"Chenhui Wei , Heyun Fu , Xiaolei Qu , Shu Tao , Patrick G. Hatcher , Dongqiang Zhu","doi":"10.1016/j.chemgeo.2024.122494","DOIUrl":"10.1016/j.chemgeo.2024.122494","url":null,"abstract":"<div><div>Photooxidation of dissolved organic sulfur (DOS) in soils and natural waters plays an important role in the sulfur biogeochemical cycle. However, the structural-dependent photoliabilities of DOS from different sources remain unclear. Here, the molecular structures and photooxidation behaviors of DOS in pyrogenic dissolved black matter (PyDOM) derived from rice straw-pyrolyzed biochar (referred to as PyDOM-S and considered to be representative of black carbon from prairie fires) were thoroughly characterized and compared with those of DOS in leached dissolved organic matter (LDOM) derived from aerobically decomposed rice straw (referred to as LDOM-S and considered to be generally representative of organic-rich horizons in soils and peats). The Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) analysis revealed that both PyDOM-S and LDOM-S were, respectively, dominated by aliphatic (60.4 % and 41.1 %) and lignin-like compounds (35.1 % and 40.1 %), followed by minimal aromatic and polyaromatic compounds (2.8 % and 11.9 % in total). As demonstrated by the sulfur K-edge X-ray absorption near-edge structure (S-XANES) analysis, PyDOM-S consisted mainly of organosulfate (80.4 %) contrasting to the diversified and mingled reduced sulfurs (62.7 %) and oxidized sulfurs (37.3 %) of LDOM-S. Under simulated sunlight irradiation, 74 % of sulfur in PyDOM-S was photomineralized to sulfate within 24 h and totaling 89 % after 168 h, but only 9 % and 42 % for LDOM-S given the same periods of time, confirming the much faster photomineralization of PyDOM-S. After 168-h irradiation, almost all molecules in PyDOM-S disappeared, whereas a large proportion (44.2 %) of LDOM-S molecules (mainly aliphatic and lignin-like compounds) were photo-resistant. Furthermore, the photomineralization of PyDOM-S was mainly contributed by the final and complete oxidation of organosulfate to sulfate; however, the photooxidation of LDOM-S was dominated by the sequential oxidation of exocyclic sulfur and heterocyclic sulfur to organosulfate prior to releasing sulfate. These results highlight that pyrogenic-sourced PyDOM-S and diagenesis-derived LDOM-S exhibit contrasting photooxidation behaviors due to the associated distinct molecular structures.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"671 ","pages":"Article 122494"},"PeriodicalIF":3.6,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652395","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}
Pub Date : 2024-11-08DOI: 10.1016/j.chemgeo.2024.122483
Yousef Zoleikhaei , Trisrota Chaudhuri , Peter A. Cawood , Rajat Mazumder , Oliver Nebel , Shuvabrata De
The western part of the Singhbhum Craton preserves Paleo-Mesoarchean mafic greenstone lava flows, felsic tonalite-trondhjemite-granodiorite (TTG)-granite associations, and high-K granite and volcanic suites, similar to other Archean cratonic blocks. These successions are crucial components of early continental crust, and unravelling their respective petrogenetic relations is important for understanding the evolution from mafic to felsic crust. This study presents detailed investigations of zircon UPb age and Hf isotope data from the Bonai TTG/gneiss-granite Suite, and the overlying Tamperkola high-K granite and rhyolite Suite. Our results indicate concurrent crystallization of the Bonai TTG gneiss (3316 ± 9 Ma), associated porphyritic high-K granite (3299 ± 9 Ma), and their amphibolite enclaves (3325 ± 9 Ma) with older, inherited zircon grains intercepting at 3586 ± 25 Ma. The entire Bonai Suite yields an overall juvenile Hf isotope composition (ɛHf(t) = −1.7 to +4.6, 95 % ɛHf(t) > 0). Combined with the mantle-like Hf isotope signatures of the inherited zircons grains (ɛHf(t) = +1.7 to +6.2), this indicates a Hf isotope evolution array with a mafic crustal 176Lu/177Hf ≈ 0.022. Considering that these grains represent the source of the TTGs, this implies lower crustal residence of ca. 300 Myr of the mafic precursor rocks. The Tamperkola high-K magmatic suite yields a crystallization age of 2810 ± 8 Ma with subchondritic Hf isotope composition (ɛHf(t) = −3.2 to −0.6). This Tamperkola Suite plots on the Hf isotope evolutionary array defined by the Bonai Suite and its mafic precursor, suggesting remelting of the Bonai (transitional) TTGs to produce these high-K granitoids in an internal reworking process. Our new and published data yield a threefold crustal evolution with (i) initial formation of the mafic crust at ca. 3586 Ma, (ii) subsequent residence for ca. 300 Myr and crustal reworking at ca. 3316–3299 Ma to form TTGs and (iii) their melting at ca. 2810 Ma to form high-K magmas. This succession of re-melting of igneous rocks drove the transition from mafic to felsic continental crust in the Singhbhum Craton. Given the consistent lithological sequence of predominantly mafic greenstone rocks, TTG-granite suites, and high-K granites observed across global cratons, this Paleo-Mesoarchean process likely reflects the order of crustal maturation in the Archean continental crust.
{"title":"Magmatic maturation of Archean continental crust via a three-step crustal reworking, western Singhbhum Craton","authors":"Yousef Zoleikhaei , Trisrota Chaudhuri , Peter A. Cawood , Rajat Mazumder , Oliver Nebel , Shuvabrata De","doi":"10.1016/j.chemgeo.2024.122483","DOIUrl":"10.1016/j.chemgeo.2024.122483","url":null,"abstract":"<div><div>The western part of the Singhbhum Craton preserves Paleo-Mesoarchean mafic greenstone lava flows, felsic tonalite-trondhjemite-granodiorite (TTG)-granite associations, and high-K granite and volcanic suites, similar to other Archean cratonic blocks. These successions are crucial components of early continental crust, and unravelling their respective petrogenetic relations is important for understanding the evolution from mafic to felsic crust. This study presents detailed investigations of zircon U<img>Pb age and Hf isotope data from the Bonai TTG/gneiss-granite Suite, and the overlying Tamperkola high-K granite and rhyolite Suite. Our results indicate concurrent crystallization of the Bonai TTG gneiss (3316 ± 9 Ma), associated porphyritic high-K granite (3299 ± 9 Ma), and their amphibolite enclaves (3325 ± 9 Ma) with older, inherited zircon grains intercepting at 3586 ± 25 Ma. The entire Bonai Suite yields an overall juvenile Hf isotope composition (ɛHf<sub>(t)</sub> = −1.7 to +4.6, 95 % ɛHf<sub>(t)</sub> > 0). Combined with the mantle-like Hf isotope signatures of the inherited zircons grains (ɛHf<sub>(t)</sub> = +1.7 to +6.2), this indicates a Hf isotope evolution array with a mafic crustal <sup>176</sup>Lu/<sup>177</sup>Hf ≈ 0.022. Considering that these grains represent the source of the TTGs, this implies lower crustal residence of ca. 300 Myr of the mafic precursor rocks. The Tamperkola high-K magmatic suite yields a crystallization age of 2810 ± 8 Ma with subchondritic Hf isotope composition (ɛHf<sub>(t)</sub> = −3.2 to −0.6). This Tamperkola Suite plots on the Hf isotope evolutionary array defined by the Bonai Suite and its mafic precursor, suggesting remelting of the Bonai (transitional) TTGs to produce these high-K granitoids in an internal reworking process. Our new and published data yield a threefold crustal evolution with (i) initial formation of the mafic crust at ca. 3586 Ma, (ii) subsequent residence for ca. 300 Myr and crustal reworking at ca. 3316–3299 Ma to form TTGs and (iii) their melting at ca. 2810 Ma to form high-K magmas. This succession of re-melting of igneous rocks drove the transition from mafic to felsic continental crust in the Singhbhum Craton. Given the consistent lithological sequence of predominantly mafic greenstone rocks, TTG-granite suites, and high-K granites observed across global cratons, this Paleo-Mesoarchean process likely reflects the order of crustal maturation in the Archean continental crust.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"671 ","pages":"Article 122483"},"PeriodicalIF":3.6,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142652394","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}
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