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The intermediate solid solution (ISS) of the Cu-Fe-S system: Phase equilibria calculation at elevated temperatures based on Gibbs energy modeling Cu-Fe-S体系的中间固溶体:基于Gibbs能量模型的高温相平衡计算
IF 3.6 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2026-01-05 DOI: 10.1016/j.chemgeo.2026.123245
Peter Waldner
The phase equilibria of the Cu-Fe-S system are calculated from liquidus to medium temperatures based on Gibbs energy modeling of the intermediate solid solution (ISS). The compound energy formalism is used for a suitable thermodynamic model to account for the pronounced solid solution character of ISS. The obtained Gibbs energy as a function of composition and temperature allows the computation of complex phase relations with high-temperature modifications of bornite and pyrrhotite, pyrite and chalcopyrite, of which a Gibbs energy expression as a function of temperature is also provided. For the first time, a direct comparison is made public between the well-known experimental isoplethal phase diagram along the CuFe–S join, which was provided more than fifty years ago by Barton (1973), and a thermodynamically computed phase diagram section. A detailed comparison with experimental phase equilibria data on the homogeneity range of ISS at 800 °C, 760 °C, 700 °C and 600 °C with calculated results is carried out. In total three isoplethal and four isothermal sections of the Cu-Fe-S phase diagram are computed, and the agreement with experimental data available in the literature ranges from fair to very satisfactory.
基于中间固溶体(ISS)的Gibbs能量模型,计算了Cu-Fe-S体系从液相到中温的相平衡。采用复合能量形式作为热力学模型来解释ISS明显的固溶体特性。得到的Gibbs能量随组成和温度的函数,可以计算出斑铁矿和磁黄铁矿、黄铁矿和黄铜矿在高温改性下的复杂相关系,并给出了Gibbs能量随温度的函数表达式。在50多年前由Barton(1973)提供的著名的CuFe-S连接处的实验等密度相图与热力学计算相图部分之间,首次公开进行了直接比较。在800°C、760°C、700°C和600°C时,ISS均匀性范围的实验相平衡数据与计算结果进行了详细的比较。计算了Cu-Fe-S相图的3个等温剖面和4个等温剖面,与文献实验数据的吻合程度从一般到非常满意。
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引用次数: 0
Geochemical systematics of spreading ridge-arc collision – Philippine Sea CBF rift and the Izu-Bonin arc 伸展脊弧碰撞的地球化学系统——菲律宾海CBF裂谷与伊豆-波宁弧
IF 3.6 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2026-01-05 DOI: 10.1016/j.chemgeo.2026.123232
Osamu Ishizuka , Rex N. Taylor , Taichi Sato , Gen Shimoda , Yumiko Harigane , Susumu Umino , Izumi Sakamoto , Yuka Yokoyama , Koki Mori , Kenichiro Tani , Yasuhiko Ohara , Chris E. Conway
Triple junctions between fundamental tectonic units are where different compositions and magmatic processes interact. We investigated the intersection of a spreading center with an island arc within the Philippine Sea Plate, i.e. an arc-ridge-arc triple junction, using a combination of submersible sampling and shipboard geophysics. We use ArAr dating, elemental concentrations and Sr-Nd-Pb radiogenic isotope ratios to constrain the structure, age and origin of magmatism as spreading interacted with the arc.
Between 33 and 31 Ma the tip of the West Philippine Basin spreading center was in the back-arc west of the Kyushu-Palau arc. Spreading volcanism had mantle-like Ce/Pb and Th/Ce indicating a lack of slab flux. Radiogenic isotopes form a trajectory towards low 143Nd/144Nd and high 20xPb/204Pb, but extend to Δ208Pb/204Pb > 85 which corresponds to an EM-2-like mantle component rather than pelagic sediment input from the slab.
The final stage of spreading-related activity occurred between 31 and 28.5 Ma when the spreading axis rotated from NW-SE to E-W and propagated eastwards into the arc. It resulted in magmatism contemporaneous with the adjacent frontal arc. This final magmatism extended the radiogenic isotopic trajectories observed in the earlier spreading towards less radiogenic Pb and higher 143Nd/144Nd, i.e. towards MORB from the EM-2 component. However, during the final stage magmatism La/Sm, Nb/Zr increased while Pb and Sr isotopes became progressively more radiogenic, demonstrating a progressive decrease in the degree of partial melting and preferential tapping of the EM-2 component. This change in melt generation and composition appears a common process at the end of spreading.
基本构造单元之间的三联结是不同成分和岩浆作用相互作用的地方。我们利用潜水采样和船载地球物理相结合的方法,研究了菲律宾海板块内扩展中心与岛弧的交集,即弧-脊-弧三重交界处。利用ArAr定年、元素浓度和Sr-Nd-Pb放射性成因同位素比值对扩张与弧相互作用时岩浆活动的结构、年龄和成因进行了约束。在33 ~ 31 Ma之间,西菲律宾盆地扩张中心的尖端位于九州-帕劳弧以西的弧后。扩张火山作用具有幔状Ce/Pb和Th/Ce,表明缺乏板块通量。放射性成因同位素形成低143Nd/144Nd和高20xPb/204Pb的轨迹,但延伸到Δ208Pb/204Pb >; 85,对应于em -2类地幔成分,而不是来自板块的上层沉积物输入。传播活动的最后阶段发生在31 ~ 28.5 Ma之间,传播轴由NW-SE向E-W旋转,并向东传播到弧内。它导致岩浆活动与邻近的锋面弧同时发生。最后的岩浆活动扩展了早期观测到的放射性成因同位素轨迹,即从EM-2组分向低放射性成因Pb和高143Nd/144Nd方向扩展,即向MORB方向扩展。然而,在岩浆活动末期,La/Sm、Nb/Zr增加,Pb和Sr同位素的放射成因逐渐增强,表明部分熔融程度逐渐减弱,EM-2组分优先出露。熔体产生和组成的这种变化似乎是扩散结束时的一个共同过程。
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引用次数: 0
A survey of methoxyl and methyl isotopic clumping in a variety of biologic and synthetic materials 甲氧基和甲基同位素在各种生物和合成材料中的结块研究
IF 3.6 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2026-01-05 DOI: 10.1016/j.chemgeo.2026.123243
Rebekah S. Sprengel , Max K. Lloyd , Daniel A. Stolper
Stable isotope measurements are important tracers of sample origins and formational conditions, including distinguishing between samples formed via synthetic vs. biological pathways. Here we present results that establish the ability of multiply substituted isotopologues, colloquially termed clumped isotopes, of methoxyl and methyl groups (Δ13CH2D and Δ12CHD2) can be used to distinguish biologically- from synthetically- generated materials and related to these (bio)chemical formational pathways. Specifically, we demonstrate that there is a large distinction between Δ13CH2D values of plant-derived methoxyl groups vs. synthetic groups, including in the same molecule (e.g., vanillin). These distinctions are independent of bulk methoxyl and methyl hydrogen and carbon isotopic compositions. We discuss the processes that can generate these differences as well as implications for the study of methane clumped isotopes in the environment.
稳定同位素测量是样品来源和形成条件的重要示踪剂,包括区分通过合成途径和生物途径形成的样品。在这里,我们提出的结果表明,甲氧基和甲基(Δ13CH2D和Δ12CHD2)的多取代同位素,俗称团块同位素,可以用来区分生物和合成生成的材料,并与这些(生物)化学形成途径有关。具体来说,我们证明了植物衍生的甲氧基与合成基之间的Δ13CH2D值有很大的区别,包括在同一分子中(例如,香兰素)。这些区别与大量甲氧基和甲基氢和碳同位素组成无关。我们讨论了产生这些差异的过程,以及对环境中甲烷团块同位素研究的影响。
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引用次数: 0
Salinity and geochemical proxy responses to volcanism in small rift lakes: Insights from the Lower Cretaceous Erlian Basin 小裂谷湖火山作用的盐度和地球化学代理响应:来自二连盆地的启示
IF 3.6 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2026-01-04 DOI: 10.1016/j.chemgeo.2026.123242
Wei Si , Dujie Hou , Xiong Cheng , Zhe Zhao , Ronghua Zheng , Xiuli Wei , Piao Wu
The Early Cretaceous Erlian Basin, characterized by small-scale lacustrine sedimentary systems and syn-depositional volcanism, provides an exceptional setting to evaluate how volcanic forcing modulates lacustrine salinity. Through integrated organic/inorganic geochemical analyses (biomarkers, reduced sulfur/total organic carbon ratios [S/C], major and trace elements, carbonate isotopes) of volcanic ash-rich strata, this study demonstrates that volcanic forcing regulates lacustrine salinity through mineral dissolution, climatic feedbacks, chemical weathering, and hydrological alteration. Moderate volcanism elevates salinity (from brackish to saline) through ionic influx and evaporative concentration. However, large-scale eruptions (>40 m tuff) reduce salinity via sulfate aerosol-driven cooling, increased rainfall, and tectonic subsidence-induced lake expansion. Conventional salinity proxies (carbonate isotope, elements, and biomarkers) exhibit reduced reliability under volcanic influence and diagenetic alteration. Elemental indicators (B/Ga, Sr/Ba) exhibit diagnostic correlations: positive (pristine deposition), negative (volcanic ash input), and non-significant (diagenetic overprinting). Boron concentrations correlate directly with volcaniclastic flux rather than ambient water salinity. Notably, biomarker parameters exhibit non-linear evolutionary trends under intense volcaniclastic input, requiring multi-proxy validation for reliable paleo-salinity reconstruction. This study establishes a volcanic-lacustrine salinity dynamics model, highlighting the interplay between eruption magnitude, climatic responses, and basin hydrology. The findings enhance paleoclimate reconstruction in volcanic terrains and provide insights into organic matter accumulation in volcanically active lacustrine basins.
早白垩世二连盆地以小型湖相沉积体系和同沉积火山作用为特征,为评价火山强迫如何调节湖泊盐度提供了一个特殊的背景。通过对富火山灰地层有机/无机地球化学综合分析(生物标志物、还原硫/总有机碳比值[S/C]、主微量元素、碳酸盐同位素),表明火山强迫通过矿物溶解、气候反馈、化学风化和水文蚀变调节湖泊盐度。适度的火山作用通过离子流入和蒸发浓度使盐度升高(从半咸水到咸水)。然而,大规模喷发(40米凝灰岩)通过硫酸盐气溶胶驱动的冷却、降雨增加和构造沉降引起的湖泊扩张来降低盐度。常规盐度指标(碳酸盐同位素、元素和生物标志物)在火山影响和成岩蚀变下的可靠性降低。元素指标(B/Ga, Sr/Ba)表现出诊断相关性:正相关性(原始沉积),负相关性(火山灰输入)和不显著相关性(成岩叠印)。硼浓度与火山碎屑通量直接相关,而与环境水盐度无关。值得注意的是,在强烈的火山碎屑输入下,生物标志物参数呈现非线性演化趋势,需要多代理验证才能可靠地重建古盐度。本研究建立了火山-湖泊盐度动力学模型,强调了火山喷发强度、气候响应和盆地水文之间的相互作用。这一发现加强了火山地形古气候的重建,并为火山活动湖相盆地有机质聚集提供了新的认识。
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引用次数: 0
Seasonal and inter-estuarine Sr cycling controlled by water mixing and hydrogenous sediments: Low 87Sr/86Sr in groundwater loss via the Gulf of Cambay 受水混合和含氢沉积物控制的季节性和河口间Sr循环:低87Sr/86Sr经坎贝湾的地下水损失
IF 3.6 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2026-01-02 DOI: 10.1016/j.chemgeo.2025.123231
Abul Qasim , Satinder Pal Singh
Radiogenic Sr isotopes are widely used to quantify the coastal water balance and to determine the terrestrial Sr contributions to the oceans. Here, we present the novel seasonal distributions of dissolved Sr concentration and 87Sr/86Sr in the Gulf of Cambay estuarine waters (surface and subsurface samples, n = 189) collected during 2016–2017. The primary objective is to elucidate the seasonal and anthropogenic forcings of dissolved Sr cycling in the modernized Narmada and Tapi estuaries, specifically to quantify the less radiogenic Sr contribution from terrestrial groundwater discharge (TGD), which leaches extensive continental flood basalt (Deccan Trap) and ancient limestone deposits in the hinterland. The seasonal scatter plots of salinity versus dissolved Sr exhibit significant and strong correlations (r2 ≥ 0.99; p-value <0.0001) in the estuarine surface waters. However, the seasonal mixing of modern seawater and river waters fails to explain the reproducible and systematic variations in dissolved Sr concentration and 87Sr/86Sr, particularly during non-monsoon seasons. The estuarine Sr isotope budget reveals the vital roles of TGD and hydrogenous sediments, along with a possibility of minor anthropogenic input. The internally recycled Sr, most likely from hydrogenous sediments, reflects the riverine isotopic signature in the Narmada estuary during the monsoon and post-monsoon seasons, while it reflects the seawater signature in the Tapi estuary, irrespective of the seasons. In the Narmada estuary, the TGD fluxes of ∼2.1–3.8 × 107 m3/d, 2.7 × 106 m3/d, and ∼ 5.8 × 105 m3/d are calculated for the monsoon, post-monsoon, and pre-monsoon seasons, respectively. The TGD contribution is not essentially required in the water-stressed Tapi estuary. The collective riverine and TGD flux-weighted Sr supplies of ∼1.9–2.3 × 108 mol/y (87Sr/86Sr ∼ 0.70959–0.70964) and ∼ 5.2–8.5 × 107 mol/y (87Sr/86Sr ∼ 0.70878–0.70885) from the isotopically heterogeneous Narmada and Tapi estuaries, respectively, ultimately go to the Arabian Sea. Assuming an order of magnitude higher recycled seawater component as compared to TGD and the average Sr composition of vicinal groundwater, both estuaries together have the potential to contribute a massive supply of less radiogenic Sr ∼1.3–1.8 × 109 mol/y (87Sr/86Sr ∼ 0.70891–0.70895), which is equivalent to ∼0.3–0.5 % of the global marine radiogenic Sr isotope budget.
放射性成因Sr同位素被广泛用于量化沿海水平衡和确定陆地Sr对海洋的贡献。本文研究了2016-2017年Cambay湾河口水域(表层和地下样品,n = 189)溶解Sr浓度和87Sr/86Sr的新季节分布。主要目的是阐明现代纳尔马达和塔皮河口溶解Sr循环的季节和人为强迫,特别是量化陆地地下水排放(TGD)的低放射性Sr贡献,这些排放淋滤了内陆广泛的大陆洪水玄武岩(德干圈闭)和古石灰岩矿床。河口地表水盐度与溶解锶的季节散点图表现出显著的强相关性(r2≥0.99;p值<;0.0001)。然而,现代海水和河水的季节性混合不能解释溶解Sr浓度和87Sr/86Sr的可重复和系统变化,特别是在非季风季节。河口Sr同位素收支揭示了TGD和含氢沉积物的重要作用,以及少量人为输入的可能性。内循环Sr主要来自于含氢沉积物,反映了纳尔玛达河口季风和后季风季节的河流同位素特征,而塔皮河口的海水同位素特征则与季节无关。在纳尔玛达河口,季风、季风后和季风前季节的TGD通量分别为~ 2.1 ~ 3.8 × 107 m3/d、2.7 × 106 m3/d和~ 5.8 × 105 m3/d。在缺水的Tapi河口,基本上不需要TGD的贡献。河流和TGD通量加权Sr的总量分别为~ 1.9 ~ 2.3 × 108 mol/y (87Sr/86Sr ~ 0.70959 ~ 0.70964)和~ 5.2 ~ 8.5 × 107 mol/y (87Sr/86Sr ~ 0.70878 ~ 0.70885),分别来自同位素不均匀的Narmada河口和Tapi河口,最终进入阿拉伯海。假设与TGD和附近地下水的平均Sr组成相比,再生海水成分高一个数量级,两个河口一起有可能提供大量的低放射性Sr - 1.3-1.8 × 109 mol/y (87Sr/86Sr - 0.70891-0.70895),相当于全球海洋放射性Sr同位素预算的~ 0.3 - 0.5%。
{"title":"Seasonal and inter-estuarine Sr cycling controlled by water mixing and hydrogenous sediments: Low 87Sr/86Sr in groundwater loss via the Gulf of Cambay","authors":"Abul Qasim ,&nbsp;Satinder Pal Singh","doi":"10.1016/j.chemgeo.2025.123231","DOIUrl":"10.1016/j.chemgeo.2025.123231","url":null,"abstract":"<div><div>Radiogenic Sr isotopes are widely used to quantify the coastal water balance and to determine the terrestrial Sr contributions to the oceans. Here, we present the novel seasonal distributions of dissolved Sr concentration and <sup>87</sup>Sr/<sup>86</sup>Sr in the Gulf of Cambay estuarine waters (surface and subsurface samples, <em>n</em> = 189) collected during 2016–2017. The primary objective is to elucidate the seasonal and anthropogenic forcings of dissolved Sr cycling in the modernized Narmada and Tapi estuaries, specifically to quantify the less radiogenic Sr contribution from terrestrial groundwater discharge (TGD), which leaches extensive continental flood basalt (Deccan Trap) and ancient limestone deposits in the hinterland. The seasonal scatter plots of salinity versus dissolved Sr exhibit significant and strong correlations (r<sup>2</sup> ≥ 0.99; <em>p</em>-value &lt;0.0001) in the estuarine surface waters. However, the seasonal mixing of modern seawater and river waters fails to explain the reproducible and systematic variations in dissolved Sr concentration and <sup>87</sup>Sr/<sup>86</sup>Sr, particularly during non-monsoon seasons. The estuarine Sr isotope budget reveals the vital roles of TGD and hydrogenous sediments, along with a possibility of minor anthropogenic input. The internally recycled Sr, most likely from hydrogenous sediments, reflects the riverine isotopic signature in the Narmada estuary during the monsoon and post-monsoon seasons, while it reflects the seawater signature in the Tapi estuary, irrespective of the seasons. In the Narmada estuary, the TGD fluxes of ∼2.1–3.8 × 10<sup>7</sup> m<sup>3</sup>/d, 2.7 × 10<sup>6</sup> m<sup>3</sup>/d, and ∼ 5.8 × 10<sup>5</sup> m<sup>3</sup>/d are calculated for the monsoon, post-monsoon, and pre-monsoon seasons, respectively. The TGD contribution is not essentially required in the water-stressed Tapi estuary. The collective riverine and TGD flux-weighted Sr supplies of ∼1.9–2.3 × 10<sup>8</sup> mol/y (<sup>87</sup>Sr/<sup>86</sup>Sr ∼ 0.70959–0.70964) and ∼ 5.2–8.5 × 10<sup>7</sup> mol/y (<sup>87</sup>Sr/<sup>86</sup>Sr ∼ 0.70878–0.70885) from the isotopically heterogeneous Narmada and Tapi estuaries, respectively, ultimately go to the Arabian Sea. Assuming an order of magnitude higher recycled seawater component as compared to TGD and the average Sr composition of vicinal groundwater, both estuaries together have the potential to contribute a massive supply of less radiogenic Sr ∼1.3–1.8 × 10<sup>9</sup> mol/y (<sup>87</sup>Sr/<sup>86</sup>Sr ∼ 0.70891–0.70895), which is equivalent to ∼0.3–0.5 % of the global marine radiogenic Sr isotope budget.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"703 ","pages":"Article 123231"},"PeriodicalIF":3.6,"publicationDate":"2026-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145893635","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}
引用次数: 0
Calcite TLM as a new natural reference material for in situ U-Pb geochronology and its geological implications 方解石TLM作为原位U - Pb年代学的新型天然参考物质及其地质意义
IF 3.6 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2025-12-29 DOI: 10.1016/j.chemgeo.2025.123230
Tianyi Li , Ranran Chen , Shitou Wu , Rolf L. Romer , Nick M.W. Roberts , Kerstin Drost , David Chew , Marcel Guillong , Qian Ma , Yahui Yue , Shuangjian Li , Bohang Xie , Ahmatjan Abdurahman , Hao Wang , Huixi Lin , Yueheng Yang , Xusheng Guo
Calcite (CaCO3) forms in a wide variety of geological environments as both a primary and secondary mineral phase and may contain sufficient U for U-Pb geochronology. The limited availability of well-characterized calcite reference materials, however, has impeded its broader application in microanalysis. In this study, a natural calcite sample (TLM) was characterized and assessed as a potential primary reference material for in situ U-Pb geochronology. U-Pb isotopic analyses were conducted across nine independent laboratories using laser ablation (Q, SF, MC)-ICP-MS and isotope dilution (ID)-TIMS, to examine the homogeneity and to determine the U-Pb age of TLM. Calcite TLM has an age homogeneity at the level of ∼ 1.0 %, as indicated by multiple analyses from different laboratories. ID-TIMS analysis of 14 aliquots yielded an intercept age of 222.5 ± 2.8 Ma (2 s) with an initial 207Pb/206Pb value of 0.8380 ± 0.0013. Calcite TLM has an age uncertainty of 1.28 %, which is considerably lower than that of WC-1 (∼2.5 %). Calcite TLM has U and Pb contents of ∼0.35 μg g−1 and ∼ 0.02 μg g−1. Additional C and O stable isotope, radiogenic Sr isotope and trace element compositional data indicate that calcite TLM is likely sourced from meteoric water and indicate that the recurrent karstification may have affected the studied area as late as the Triassic.
方解石(CaCO3)在各种地质环境中形成,作为初级和次级矿物相,可能含有足够的U- pb地质年代学。然而,表征良好的方解石标准物质的有限可用性阻碍了其在微量分析中的广泛应用。在本研究中,对天然方解石样品(TLM)进行了表征和评估,作为原位U-Pb地质年代学的潜在主要参考物质。利用激光烧蚀(Q, SF, MC)-ICP-MS和同位素稀释(ID)-TIMS,在9个独立实验室进行了U-Pb同位素分析,以检查TLM的均匀性并确定U-Pb年龄。来自不同实验室的多次分析表明,方解石TLM的年龄均匀性在~ 1.0%的水平。对14份样品进行ID-TIMS分析,截距年龄为222.5±2.8 Ma (2 s), 207Pb/206Pb初始值为0.8380±0.0013。方解石TLM的年龄不确定度为1.28%,大大低于WC-1的年龄不确定度(~ 2.5%)。方解石TLM的U和Pb含量分别为~ 0.35 μg−1和~ 0.02 μg−1。附加的C、O稳定同位素、放射性成因Sr同位素和微量元素组成数据表明,方解石TLM可能来源于大气降水,表明反复岩溶作用可能晚于三叠纪影响了研究区。
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引用次数: 0
The evolution of phototrophic Fe(II)-oxidizing bacteria shaping the distribution of iron-bound phosphorus in water columns 光养铁(II)氧化细菌的进化决定了水柱中铁结合磷的分布
IF 3.6 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2025-12-29 DOI: 10.1016/j.chemgeo.2025.123229
Shan Huang , Yuanyuan Ren , Chao Peng , Chao Zhong , Jiahao Chen , Yurong Deng , Geng Wu , Yuanyuan Liu , Hailiang Dong , Juan Liu
The evolution of Fe(II)-oxidizing microorganisms has been closely linked to the evolution of Earth's iron biogeochemical cycle and redox history. However, its impact on the coupled biogeochemical cycling of iron and phosphorus, particularly the distribution of iron-bound phosphate (PFe) in water columns, remains largely unexplored. This study elucidates the distinct Fe(II) oxidation mechanisms of the anoxygenic Rhodobacter ferrooxidans SW2 and the oxygenic Synechococcus sp. PCC 7002, along with the properties, transformation processes, and phosphate interactions of their biogenic iron (oxyhydr)oxides. SW2-mediated Fe(II) oxidation via iron oxidase drove sequential transformation from ferrihydrite to green rust and then to goethite. The resulting cell-mineral aggregates had a large hydrodynamic diameter (Dh, up to 26 μm), a high Fe/C ratio (∼2.5), and a rapid sedimentation rate (up to 57.7 m/day), efficiently transporting PFe to deep-sea sediments. In contrast, PCC 7002 indirectly oxidized Fe(II) via oxygen production, forming poorly crystalline iron (oxyhydr)oxides stabilized by extracellular polymeric substances. The resultant small aggregates (Dh = ∼6.9 μm), with a slower sedimentation rate (∼3.9 m/day), exhibited high phosphorus retention and were susceptible to dissimilatory iron reduction, facilitating PFe recycling in surface waters. These findings suggest that biogenic iron (oxyhydr)oxides from anoxygenic iron oxidizers act as carriers, transporting phosphorus to deep sediments, whereas those from oxygenic cyanobacteria function as phosphorus traps in surface waters. This study provides new insights into how the evolution of Fe(II)-oxidizing microorganisms reshapes PFe cycling and distribution in water columns, emphasizing the need to integrate microbiological and geochemical perspectives in understanding Earth's biogeochemical cycles.
铁(II)氧化微生物的演化与地球铁生物地球化学循环和氧化还原历史的演化密切相关。然而,其对铁和磷的耦合生物地球化学循环的影响,特别是对水柱中铁结合磷酸盐(PFe)分布的影响仍未得到充分研究。本研究阐明了无氧氧化亚铁红杆菌SW2和氧合球菌PCC 7002不同的铁(II)氧化机制,以及它们的生物源铁(氧)氧化物的性质、转化过程和磷酸盐相互作用。sw2介导的铁氧化酶对铁(II)的氧化推动了铁水合铁到绿锈再到针铁矿的顺序转化。所得到的细胞-矿物聚集体具有大的水动力直径(Dh,高达26 μm),高铁/碳比(~ 2.5)和快速沉降速率(高达57.7 m/天),有效地将PFe输送到深海沉积物中。相比之下,pcc7002通过产氧间接氧化Fe(II),形成由胞外聚合物稳定的低结晶铁(氧合)氧化物。由此产生的小团聚体(Dh = ~ 6.9 μm),具有较慢的沉降速率(~ 3.9 m/天),具有高磷保留率,并且易于同化铁还原,促进了地表水中PFe的回收。这些发现表明,来自无氧铁氧化剂的生物源铁(氧)氧化物作为载体,将磷运送到深层沉积物中,而来自含氧蓝藻的生物源铁(氧)氧化物则在地表水中起着磷捕集器的作用。该研究为Fe(II)氧化微生物的进化如何重塑水体中PFe的循环和分布提供了新的见解,强调了在理解地球生物地球化学循环时需要将微生物学和地球化学观点结合起来。
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引用次数: 0
Insights from XAS, FTIR, and PHREEQC into mono- and poly-vanadate (V(V)O43−) adsorption to Hematite XAS, FTIR和PHREEQC对单钒酸盐和多钒酸盐(V(V)O43−)在赤铁矿上吸附的研究
IF 3.6 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2025-12-26 DOI: 10.1016/j.chemgeo.2025.123228
Jing Zhang , Victoria S. Coker , J. Frederick W. Mosselmans , Thomas L. Goût , Luís A.E. Batista de Carvalho , Samuel Shaw
Vanadium (V) is a widespread trace element in the environment. At high concentration, due to anthropogenic emission such as mining activities and fossil fuels, it can be toxic to marine systems and terrestrial plants. However, the geochemical behaviour of V remains poorly understood. Here, this study aimed to understand the molecular scale V speciation, adsorption behaviour and bonding mechanisms of V(V) onto hematite as a function of geochemical factors (pH, ionic strength, and V(V) concentration), applying a multi-technique approach comprising aqueous chemical analysis and XAS supported by ATR-FTIR and PHREEQC geochemical speciation calculations. From these data, tetrahedral monovanadate formed a corner-sharing bidentate surface complex at 1.20 mM V(V) and pH 9 and 0.12 mM V(V) at all pH, while octahedral decavanadate formed at a V(V) concentration of 1.20 mM and pH < 7. The dominant coordination environment changed gradually from a mixture of octahedrally and tetrahedrally coordinated V at pH 3 to tetrahedral monovanadate at pH 9. These results demonstrate the marked effects of pH and initial V concentration on V(V) speciation at hematite surfaces, in turn affording predictions of the environmental behaviour of heavy metals released during a variety of anthropogenic activities (e.g. mining) across a range of geochemical conditions. It is envisioned these results will contribute to strategies for the treatment of lands contaminated with heavy metals predominantly through adsorption processes (e.g. mine sites).
钒(V)是环境中广泛存在的微量元素。在高浓度的情况下,由于采矿活动和化石燃料等人为排放,它可能对海洋系统和陆地植物有毒。然而,V的地球化学行为仍然知之甚少。本研究旨在通过ATR-FTIR和PHREEQC地球化学形态计算支持的水化学分析和XAS技术,了解分子尺度上V(V)在赤铁矿上的形态、吸附行为和键合机制,以及地球化学因素(pH、离子强度和V(V)浓度)的函数。从这些数据可以看出,在1.20 mM V(V)和pH值9和0.12 mM V(V)条件下,单钒酸四面体形成了共享角的双齿状表面配合物,而十钒酸八面体在V(V)浓度为1.20 mM和pH <; 7的条件下形成了共享角的双齿状表面配合物。主导配位环境由pH为3时的八面体和四面体配位V的混合物逐渐转变为pH为9时的单钒酸盐四面体配位环境。这些结果证明了pH值和初始V浓度对赤铁矿表面V(V)形态的显著影响,进而提供了在一系列地球化学条件下各种人为活动(如采矿)期间释放的重金属的环境行为的预测。预计这些结果将有助于制定主要通过吸附过程(例如矿场)处理受重金属污染土地的战略。
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引用次数: 0
Global variation in Cr-spinel trace elements 铬尖晶石微量元素的全球变化
IF 3.6 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2025-12-26 DOI: 10.1016/j.chemgeo.2025.123227
Emil Akseli Koskinen Tonboe , Ikuya Nishio , Pedro Waterton
The major element composition of Cr-spinel [(Mg,Fe2+)(Cr,Al,Fe3+)2O4] has long been used to infer the petrogenesis and tectonic setting of its host rocks. However, overlaps in major element compositions and susceptibility of Mg and Fe2+ to secondary alteration limit its diagnostic utility. In contrast, some trace elements may be particularly diagnostic of certain petrogenic processes or retain primary signatures even when major elements are modified, offering a complementary tool for petrogenetic interpretation. However, a comprehensive evaluation of the systematics of trace elements in Cr-spinel has not yet been undertaken.
This study compiles major and trace element data from Cr-spinel-bearing samples worldwide to assess global variability and to identify robust geochemical indicators. Based on a larger, more representative set of Mid-Ocean Ridge Basalt (MORB) spinel data we present new MORB spinel normalization values and a recommended element order for spinel multi-element plots. We document systematic variations in trace elements (Sc, Ga, V, Ni, Mn) with Cr# (Cr# = Cr/(Cr + Al) mol.), particularly in mantle-derived spinels, and show that these trends reflect mantle depletion. Melting models and regression of literature partition coefficients demonstrate that partitioning of Sc, Ga, Ni, Mn, and Ti is likely compositionally controlled.
We also show that Cr-spinels from lavas and intrusions can be distinguished based on late-stage re-equilibration with interstitial melt, evident from the low Ru and Cu contents and Sc/Ga ratios in Cr-spinels from intrusions. Our findings highlight the potential of trace element systematics in Cr-spinel as a powerful tool for reconstructing the petrogenesis of mafic-ultramafic rocks.
铬尖晶石的主元素组成[(Mg,Fe2+)(Cr,Al,Fe3+)2O4]一直被用来推断其寄主岩的成因和构造背景。然而,主要元素组成的重叠以及Mg和Fe2+对次生蚀变的敏感性限制了其诊断价值。相比之下,一些微量元素可能对某些成岩过程具有特别的诊断作用,甚至在主元素被修改后仍保留了原始特征,为岩石成因解释提供了补充工具。然而,对铬尖晶石中微量元素的分类学尚未进行全面评价。本研究收集了来自世界各地含铬尖晶石样品的主要元素和微量元素数据,以评估全球变化并确定可靠的地球化学指标。基于一组更具代表性的中洋脊玄武岩(MORB)尖晶石资料,提出了新的MORB尖晶石归一化值和尖晶石多元素图的推荐元素顺序。我们记录了微量元素(Sc, Ga, V, Ni, Mn)随Cr# (Cr# = Cr/(Cr + Al) mol.)的系统变化,特别是在地幔源尖晶石中,并表明这些趋势反映了地幔枯竭。熔融模型和文献分配系数回归表明,Sc、Ga、Ni、Mn和Ti的分配可能是由成分控制的。岩浆和侵入体中的cr尖晶石可以通过后期再平衡和间隙熔融来区分,这可以从侵入体中cr尖晶石的低Ru、Cu含量和Sc/Ga比值中看出。研究结果表明,铬尖晶石微量元素系统学研究可作为重建镁质-超镁质岩石成因的有力工具。
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引用次数: 0
Optimization of lithium diffusion modelling in plagioclase: implications for the assessment of pre-eruptive timescales 斜长石中锂扩散模型的优化:对喷发前时间尺度评估的影响
IF 3.9 2区 地球科学 Q1 GEOCHEMISTRY & GEOPHYSICS Pub Date : 2025-12-24 DOI: 10.1016/j.chemgeo.2025.123222
Simone Costa, Matteo Masotta, Fabio Colle, Pier Paolo Giacomoni, Claudia D’Oriano, Patrizia Landi
{"title":"Optimization of lithium diffusion modelling in plagioclase: implications for the assessment of pre-eruptive timescales","authors":"Simone Costa, Matteo Masotta, Fabio Colle, Pier Paolo Giacomoni, Claudia D’Oriano, Patrizia Landi","doi":"10.1016/j.chemgeo.2025.123222","DOIUrl":"https://doi.org/10.1016/j.chemgeo.2025.123222","url":null,"abstract":"","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"161 1","pages":""},"PeriodicalIF":3.9,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145823497","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}
引用次数: 0
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Chemical Geology
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