Chemical Geology最新文献

{"title":"Comparisons of pretreatment extraction methods for tree-ring radiocarbon analysis","authors":"Jingdi Qin ,&nbsp;Zhenchuan Niu ,&nbsp;Weijian Zhou ,&nbsp;Yunfei Huang ,&nbsp;Xue Feng ,&nbsp;Dan Liang ,&nbsp;Guowei Wang ,&nbsp;Xuefeng Lu ,&nbsp;Yu Huang ,&nbsp;Hong Wang","doi":"10.1016/j.chemgeo.2025.122648","DOIUrl":"10.1016/j.chemgeo.2025.122648","url":null,"abstract":"<div><div>An appropriate method for tree-ring pretreatment is essential to ensure the reliability of ¹⁴C data. This study compared three pretreatment methods for tree rings: acid-base-acid-bleaching (ABA-B), Jayme-Wise and an improved method proposed in this research. The improved method utilizes an ultrasonic bath instead of Soxhlet extraction in the Jayme-Wise method. We assessed the ¹⁴C results of the three methods using subfossil tree-ring samples from the Sixth International Radiocarbon Intercomparison and contemporary tree-ring samples from Shangdianzi. The ¹⁴C results showed that both the improved and the Jayme-Wise methods were effective for extracting α-cellulose from subfossil and modern tree-ring samples. The ABA-B method was sufficient only for subfossil wood, while unstable for the modern tree-ring samples when the heartwood-sapwood transition was presence. The Fourier-Transform Infrared spectroscopy results indicated that the purity of α-cellulose extracted by the improved method was similar to that of pure α-cellulose. In comparison to the Jayme-Wise method, the improved method reduced the extraction time and the amount of organic solvent, while increased batch processing capacity.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122648"},"PeriodicalIF":3.6,"publicationDate":"2025-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143163785","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":"Microbial sulfate reduction regulated by relative sea level change in a Pleistocene – Holocene sedimentary record: Insights from Loch Duart, Scotland, UK","authors":"L.G. Podrecca ,&nbsp;A.L. Masterson ,&nbsp;M.T. Hurtgen ,&nbsp;J. Taylor ,&nbsp;J.M. Lloyd ,&nbsp;D. Selby ,&nbsp;B.B. Sageman","doi":"10.1016/j.chemgeo.2025.122633","DOIUrl":"10.1016/j.chemgeo.2025.122633","url":null,"abstract":"&lt;div&gt;&lt;div&gt;A Pleistocene–Holocene-aged sediment core recovered near Loch Duart, located in the coastal Assynt region of NW Scotland, UK, provides new insight into the relationship between the sulfur isotope composition of iron sulfides (pyrite) and organic sulfur under rapidly changing environmental conditions. Since the Late Glacial period, shifts in local marine connectivity at Loch Duart have been driven by the competition between two fundamental Earth surface processes: eustatic sea level rise due to post-glacial meltwater contributions since the Last Glacial Maximum and relative sea level (RSL) fall associated with glacial isostatic rebound. These processes, imprinted on the sedimentary record, have been evaluated via lithology, microfossil assemblages, elemental analysis, and isotopic measurements. Over the last 17 kyr, Loch Duart has transitioned from (1) marine conditions, when eustatic rise due to deglaciation exceeded glacial isostatic rebound, to (2) non-marine conditions, where land uplift caused by isostatic rebound exceeded eustatic rise, to (3) marine conditions, as the eustatic contribution outpaced isostatic rebound, followed by (4) brackish-water conditions, as the eustatic contribution reduced while glacial isostatic uplift continued, with marine inundation limited to part of the tidal cycle at the present day.&lt;/div&gt;&lt;div&gt;Here, we evaluate marked perturbations in the local sulfur (S) cycle related to the aforementioned environmental changes. The marine interval coincides with relatively stable and low δ&lt;sup&gt;34&lt;/sup&gt;S&lt;sub&gt;sulfide&lt;/sub&gt; values (average ∼ −27.2 ‰), the non-marine interval records an abrupt positive δ&lt;sup&gt;34&lt;/sup&gt;S&lt;sub&gt;sulfide&lt;/sub&gt; excursion of over 30 ‰ (average ∼ 9 ‰), and the brackish interval preserves intermediate values (average ∼ −16.2 ‰). The δ&lt;sup&gt;34&lt;/sup&gt;S&lt;sub&gt;org&lt;/sub&gt; values shift sympathetically with δ&lt;sup&gt;34&lt;/sup&gt;S&lt;sub&gt;sulfide&lt;/sub&gt;, although the magnitude of δ&lt;sup&gt;34&lt;/sup&gt;S&lt;sub&gt;org&lt;/sub&gt; change is nominal by comparison, particularly during the transition from freshwater to marine facies. As expected, marine and brackish sections preserve higher δ&lt;sup&gt;34&lt;/sup&gt;S&lt;sub&gt;org&lt;/sub&gt; values than coeval δ&lt;sup&gt;34&lt;/sup&gt;S&lt;sub&gt;sulfide&lt;/sub&gt;. Interestingly, this relationship is reversed in the freshwater facies, where sulfides are &lt;sup&gt;34&lt;/sup&gt;S-enriched relative to organic S by as much as 20 ‰, suggesting that RSL modulates the isotopic composition of non-pyrite phases in the bulk S pool. We hypothesize that this inverse relationship (δ&lt;sup&gt;34&lt;/sup&gt;S&lt;sub&gt;org&lt;/sub&gt; &lt; δ&lt;sup&gt;34&lt;/sup&gt;S&lt;sub&gt;sulfide&lt;/sub&gt;) may arise from a spatial decoupling of pyrite and organic S formation within the water column and/or sediments in a system with low sulfate concentrations. Evaluating shifts in the local S-cycle associated with RSL changes allows for a novel comparison between S and osmium isotope records, demonstrating that these proxies may have joint applications for paleoenvironmental investigations in shallow coastal systems. We","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"677 ","pages":"Article 122633"},"PeriodicalIF":3.6,"publicationDate":"2025-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143061998","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":"Uranium isotope fractionation during magmatic-hydrothermal interactions in pegmatites","authors":"Jiaru Sheng ,&nbsp;Yikang Quan ,&nbsp;Dingsheng Jiang ,&nbsp;Gengxin Deng ,&nbsp;Guangwei Li ,&nbsp;Zhiqin Xu ,&nbsp;Fang Huang","doi":"10.1016/j.chemgeo.2025.122632","DOIUrl":"10.1016/j.chemgeo.2025.122632","url":null,"abstract":"<div><div>Uranium is a fluid-mobile and incompatible element and its isotopes can be used to trace the migration and enrichment of U in magmatic and fluid-related processes. To better understand the behavior of U isotopes during magmatic-hydrothermal interactions, this study presents U isotope data for a suite of borehole samples collected from the Jiajika granitic pegmatite field. Both pegmatites and aplites exhibit lower average δ²³⁸U of −0.37 ± 0.10 ‰ (2SD, <em>n</em> = 32) and − 0.36 ± 0.06 ‰ (2SD, <em>n</em> = 7), respectively, than the continental crust (−0.29 ± 0.03 ‰). Given the strong involvement of magmatic fluids during magma evolution in Jiajika pegmatites with low Zr/Hf (&lt;26), the low δ²³⁸U and high U contents likely reflect the signature of magmatic fluids derived from underlying magma. This study reveals that the magmatic-hydrothermal interactions play a key role in fractionating U isotopes in granitoids. The light U isotope characteristics of granitoids may serve as a novel tracer for fluid-related processes, providing insights into the migration and enrichment of U and other fluid-mobile elements associated with magmatic fluids.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"677 ","pages":"Article 122632"},"PeriodicalIF":3.6,"publicationDate":"2025-01-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143061997","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Apatite LA-ICP-MS UPb petrochronology: A comparative study of relative and absolute fission-track dating","authors":"Alejandro Piraquive ,&nbsp;João Pacífico Machado ,&nbsp;Magdalena H. Huyskens ,&nbsp;Thomas F. Redfield ,&nbsp;Roelant van der Lelij ,&nbsp;Jochen Knies","doi":"10.1016/j.chemgeo.2025.122626","DOIUrl":"10.1016/j.chemgeo.2025.122626","url":null,"abstract":"<div><div>Continuous advances in laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) throughout the last decades have enabled new, more accurate, and precise approaches to studying minerals in different geological contexts. This work presents the results of apatite fission track and U<img>Pb double dating (LAFT and AUPb) by LA-ICP-MS, coupled with multi-element analysis from a set of reference materials, control samples and unknowns. We introduce Trax®, a new open-source fission track dating software under development. Trax® facilitates systematic measurements of surface and confined track lengths, with an emphasis on pairing the fission-track data with mineral chemistry from ICP-MS. Our database comprises 16 analytical sessions performed throughout one year, during which multiple primary and secondary reference materials were evaluated along with four control samples previously dated by the external detector method (EDM) and 10 new samples from the Finnmark region in northern Norway. We compared previously published EDM ages to our newly obtained LAFT ages, calculated using an empirical-modified calibration (ξ_ICP) based on U/Ca ratios and an absolute calibration based on U concentrations. Our results from the McClure, Fish Canyon Tuff and Durango apatites reproduce within uncertainties the previously published AUPb, LAFT and trace element compositions. At the same time, our AUPb-LAFT results from EDM-dated control samples and Finnmark samples show that AUPb-LAFT double-dating ages and elemental compositions agree with the tectonometamorphic histories of these varied geological settings. Furthermore, resulting LAFT ages, obtained both through calibrated (ξ_ICP) and absolute approaches, are indistinguishable within uncertainties when compared to the previously published EDM zeta-based (ζ) ages, demonstrating that LAFT absolute dating is a viable approach across a plethora of geotectonic contexts, providing a fast and efficient output that delivers comprehensive petro-thermochronological datasets enabling the tracing of crustal-scale processes from magmatic crystallisation, metamorphic overprinting to late cooling and exhumation.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"677 ","pages":"Article 122626"},"PeriodicalIF":3.6,"publicationDate":"2025-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143062000","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":"Modeling Li isotope fractionation during the coal-combustion process and evaluating its capacity as an environmental tracer","authors":"Jing Chen ,&nbsp;Yilin Xiao ,&nbsp;Jack Geary Murphy ,&nbsp;Dong-Bo Tan ,&nbsp;Yang-Yang Wang ,&nbsp;Biao Fu ,&nbsp;Guijian Liu ,&nbsp;Ru-Wei Wang ,&nbsp;Xiaoxia Wang ,&nbsp;Feng-Tai Tong","doi":"10.1016/j.chemgeo.2025.122631","DOIUrl":"10.1016/j.chemgeo.2025.122631","url":null,"abstract":"<div><div>Coal-fired power plants (CFPPs) utilizing lithium-rich coal are significant sources of anthropogenic Li emissions, highlighting the importance of effective tracing of potentially toxic Li for environmental monitoring and regulation. Lithium isotopes are a promising tracer, yet the dynamics of isotopic behavior during coal combustion are not well understood. This study investigates the elemental and isotopic behavior of Li in feed coals and combustion products from two pulverized coal-fired boilers (PC-H and PC-X) and one circulating fluidized bed boiler (CFB-H). The results showed that Li was primarily captured in fly ash (66.4 % to 84.8 %), with a fraction (1.3 % to 25.2 %) emitted into the atmosphere (stack emission). The isotopic composition of Li in feed coal ranged from −0.6 ‰ to +0.3 ‰, contrasting with δ⁷Li values in bottom ash and fly ash, which range from −2.7 ‰ to +0.1 ‰ and − 1.9 ‰ to +0.5 ‰, respectively. Notably, bottom ash samples consistently exhibit lower δ⁷Li values than their corresponding feed coal, suggesting the volatilization of heavier Li isotopes during combustion. Mass balance calculations reveal that stack emissions are enriched in heavier isotopes, with δ⁷Li values reaching up to +17.8 ‰. A Rayleigh fractionation model, with a fractionation factor of α = 1.0044, indicates that light lithium isotopes preferentially condense onto fly ash, while heavier isotopes are predominantly found in stack emissions. This model provides a quantitative framework for understanding isotopic segregation during cooling, significantly advancing methodologies for tracing and quantifying Li emissions for environmental impact assessments and source attribution of anthropogenic Li from CFPPs.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"677 ","pages":"Article 122631"},"PeriodicalIF":3.6,"publicationDate":"2025-01-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143061999","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":"Distribution of bacterial 3-OH-FAs in Chinese saline lakes and its implication for paleoclimate reconstruction","authors":"Yi Yang ,&nbsp;Canfa Wang ,&nbsp;Yan Yan ,&nbsp;Ao Sun ,&nbsp;Huan Yang ,&nbsp;Shucheng Xie","doi":"10.1016/j.chemgeo.2025.122630","DOIUrl":"10.1016/j.chemgeo.2025.122630","url":null,"abstract":"<div><div>Microbial communities in saline lakes are sensitive to environmental changes and showed promise for paleoclimate reconstruction. However, how the Gram-negative bacterial communities and their related membrane lipids, 3-hydroxy fatty acid (3-OH-FA), adapt to salinity change is still unclear. Here, we report the potential impacts of salinity and pH on 3-OH-FA distributions, based on saline lake samples, including lacustrine sediments and surrounding soils, collected from the Balikun Lake of the Xinjiang Province and 12 shallow lakes of the Inner Mongolia Province, China. Our results revealed that 3-OH-FAs in saline lakes are mainly derived from in situ production. The 3-OH-FA distributions are sensitive to salinity and pH variations. Specifically, in brackish lakes (&lt; 30 ‰), salinity and pH dominated the distribution of 3-OH-FAs. However, in hypersaline lakes, salinity predominated the 3-OH-FA distributions. Moreover, multiple linear regression has been used to explore the potential salinity proxies based on 3-OH-FAs. The result revealed the promising potential of using 3-OH-FAs for paleoenvironment reconstruction, which provides alternative tools for investigating the paleoclimate changes in saline environments.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"677 ","pages":"Article 122630"},"PeriodicalIF":3.6,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143062001","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":"Formation of non-equilibrium accessory mineral paragenesis in S- / I-type granitic rocks (example from the Western Carpathians)","authors":"Sergii Kurylo,&nbsp;Igor Broska","doi":"10.1016/j.chemgeo.2025.122625","DOIUrl":"10.1016/j.chemgeo.2025.122625","url":null,"abstract":"<div><div>Granite typology in terms of identification I- and S-types is based on granite composition and accessory mineral characteristics. Mixing of mafic and felsic melts during the formation of granite massifs can lead to non-equilibrium accessory paragenesis formed from mixture of typical I- type accessory pragenesis (Ti-magnetite, allanite, titanite, low Mn apatite) and S-type composed typically from monazite and high Mn apatite. The extensive mixing processes in the tectonically northern tilted Kriváň Fatra granite massif, where the tonalite zone is situated below granodiorite, provide evidences for the formation of non-equilibrium accessory paragenesises by two recognisable stages. The first stage, a deep crustal mixing of the mafic melts into the formed felsic magmatic chamber is indicated in presence of 1) relic plagioclase P1 (An₃₃_–₃₇ and An₄₀_–₅₆); 2) quartz with rutile needles; 3) quartz ocelli surrounded by trioctahedral micas; 4) inclusions of pyroxene and V, Cr relic mineral phases in an accessory pyrite. Quartz antecryst with rutile rods, antiperthitic plagioclase, and Ti-magnetite disintegration at 780 °C indicates a high temperature mixing in the low crustal MASH zone. High portion of the apatite was probably late in the early stage transformed to monazite by fluids from early magmatic allanite-(Ce) giving an evolved sulphur content to this monazite. The second stage occurred in crustal conditions when the melt-mixing continued by convectional homogenization of initial mixed magma forming oscillatory-zoned plagioclases P2 (An₃₂_–₂₀), Ba and Na is high in K-feldspar giving a hybrid character of the Kriváň Fatra granodiorites. The late mixing stage effectively is indicated by abundant apatite with composite chemistry partly I-type (low Mn, Fe but high S, Cl) and partly S-type (high Mn, and LREEs). Apatite formation temperatures in the tonalite zone is 792 °C, and in the granodiorite zone is between 780 and 819 °C pointing to the evolution pathway from the inhomogeneous mixed granotonalite to relatively homogenous granotonalite in the granodiorite zone. The positional upper granodiorite zone with the transitional granite typology in the Kriváň Fatra granite massif resulted from high degree of magma mixing of former mafic gabbro (?) and felsic melt forming the non-equilibrium accessory paragenesis, as S-/I-type apatite mixture composition. In general view, not well homogenized granitic parts recognised in the upper north granodiorite zone of the Kriváň Fatra granite massif can be typologically defined according to <span><span>Castro (2001)</span></span> as a transitional mixed granotonalite.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"677 ","pages":"Article 122625"},"PeriodicalIF":3.6,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143062002","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":"Effect of HA-Fe(III) coprecipitation on •OH production in Fe(III)/O2 systems perturbed by sulfide","authors":"Elias Niyuhire ,&nbsp;Wenjing Xie ,&nbsp;Songhu Yuan","doi":"10.1016/j.chemgeo.2025.122612","DOIUrl":"10.1016/j.chemgeo.2025.122612","url":null,"abstract":"<div><div>Dark •OH production from sulfide perturbation of Fe(III)/O₂ and NOM/O₂ systems has been recently documented. In spite of the ubiquity of natural organic matter (NOM)-Fe(III) coprecipitates in the environment, the effect of NOM-Fe coprecipitation on •OH production in such systems remains unexplored. This study showed that •OH production from sulfide reaction with oxic HA-Fe(III) coprecipitates was influenced by sulfide concentration and C/Fe molar ratios. With increasing sulfide concentration from 0 to 5 mM, the cumulative •OH concentration within 120 min increased to 71.8 μM for 11.2 mM Fe in HA-Fe(III) coprecipitates (C/Fe molar ratio = 1.4). At this C/Fe ratio, the cumulative •OH concentrations at this C/Fe ratio in the presence of ≤2.5 mM S(-II) were lower than those produced from lepidocrocite control mineral, while it was higher at 5 mM S(-II). •OH production was attributed to enhanced HA-Fe(II)/FeS production coupled to HA desorption and reduction. These reduced species could activate O₂ to generate •OH. In the presence of 2.5 mM S(-II), the cumulative •OH concentration decreased with C/Fe molar ratios of the HA-Fe(III) coprecipitates. Depending on the carbon content of the NOM-Fe coprecipitates, •OH production might be affected by the interaction of NOM and sulfide. The addition of 2.5 mM S(-II) into 100 g/L of field sediments also produced significant levels of •OH, and it was more efficient with clayed sediments than sandy sediments. The results of this study suggest that the influence of HA-Fe(III) coprecipitation should be cautiously considered for •OH production in sulfide-perturbed Fe(III)/O₂ systems.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"678 ","pages":"Article 122612"},"PeriodicalIF":3.6,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143437590","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":"P-T-ƒO2-X constraints on the partitioning behavior of trace elements between clinopyroxene and alkali melts: An experimental study","authors":"Andrés Fabián Salazar-Naranjo,&nbsp;Silvio Roberto Farias Vlach","doi":"10.1016/j.chemgeo.2025.122629","DOIUrl":"10.1016/j.chemgeo.2025.122629","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Titanian Ca-clinopyroxene (Ti-Cpx) is one of the most characteristic phases and main carriers of trace elements in alkali ultrabasic to intermediate magmas, making it a key mineral for geochemical studies on the origin and evolution of this type of system. Starting from natural basanite and tephrite compositions, we conducted a series of experiments under one atmosphere pressure (1-atm) with oxygen fugacity (&lt;em&gt;fO&lt;/em&gt;&lt;sub&gt;&lt;em&gt;2&lt;/em&gt;&lt;/sub&gt;) controlled from QFM-2 to QFM+2 and moderate pressure (0.5–2.0 GPa) with &lt;em&gt;f&lt;/em&gt;O&lt;sub&gt;2&lt;/sub&gt; around the CCO buffer. The results allowed a better examination of the &lt;em&gt;P&lt;/em&gt;, &lt;em&gt;T&lt;/em&gt;, ƒO&lt;sub&gt;2&lt;/sub&gt;, and compositional controls on &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mrow&gt;&lt;mi&gt;element&lt;/mi&gt;&lt;mspace&gt;&lt;/mspace&gt;&lt;mi&gt;i&lt;/mi&gt;&lt;/mrow&gt;&lt;mrow&gt;&lt;mi&gt;Cpx&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;melt&lt;/mi&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt;, and indicated that: (1) the Lattice Strain Model (LSM) successfully fits the divalent and trivalent cations into the M2 site and trivalent cations into the M1 site; (2) divalent cations are strongly influence by clinopyroxene composition, with their compatibility decreasing at the M1 site and increasing at the M2 site as the DiHd component rises; (3) redox-sensitive elements, such as Cr, V, and Eu exhibit systematic variation with ƒO&lt;sub&gt;2&lt;/sub&gt; and &lt;em&gt;T&lt;/em&gt;; (4) high-field strength elements (HFSEs) replace Mg via the Tschermak reaction, resulting in a variation in &lt;span&gt;&lt;math&gt;&lt;msubsup&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;HFSE&lt;/mi&gt;&lt;mrow&gt;&lt;mi&gt;Cpx&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;melt&lt;/mi&gt;&lt;/mrow&gt;&lt;/msubsup&gt;&lt;/math&gt;&lt;/span&gt; along the clinopyroxene compositional trend from Mg-rich augite to ferroan diopside; (5) the crystal and melt compositions determine the compatibility of the rare earth elements (REEs), where the latter particularly substitute Na instead of Ca; (6) the thermodynamic model based on the activity of the Na&lt;sub&gt;0.5&lt;/sub&gt;(REE)&lt;sub&gt;0.5&lt;/sub&gt;MgSi&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;6&lt;/sub&gt; component reproduces closely the observed partitioning of the REEs under 1-atm. Esseneite (CaFe&lt;sup&gt;3+&lt;/sup&gt;AlSiO&lt;sub&gt;6&lt;/sub&gt;) component increases with the oxygen fugacity and facilitates the incorporation of REEs, meaning that Ti-Cpx crystallized under oxidizing conditions will be REE-rich (except Eu). &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;Ta&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;Nb&lt;/mi&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mrow&gt;&lt;mi&gt;Cpx&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;melt&lt;/mi&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; and &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;Zr&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;Hf&lt;/mi&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mrow&gt;&lt;mi&gt;Cpx&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;melt&lt;/mi&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; remains almost constant, while &lt;span&gt;&lt;math&gt;&lt;msup&gt;&lt;mfenced&gt;&lt;mrow&gt;&lt;msub&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;U&lt;/mi&gt;&lt;/msub&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;msub&gt;&lt;mi&gt;D&lt;/mi&gt;&lt;mi&gt;Th&lt;/mi&gt;&lt;/msub&gt;&lt;/mrow&gt;&lt;/mfenced&gt;&lt;mrow&gt;&lt;mi&gt;Cpx&lt;/mi&gt;&lt;mo&gt;/&lt;/mo&gt;&lt;mi&gt;melt&lt;/mi&gt;&lt;/mrow&gt;&lt;/msup&gt;&lt;/math&gt;&lt;/span&gt; correlates positively with the EnFs component, generating fractionation degrees variable of U/Th and constant of Ta/Nb and Zr/Hf during the evolution of cr","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"677 ","pages":"Article 122629"},"PeriodicalIF":3.6,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143062003","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":"Re-evaluation of the spherules proposed origin recovered from the Pacific Ocean site of the CNEOS 2014-01-08 (IM1) bolide","authors":"N.G. Rudraswami ,&nbsp;V.P. Singh ,&nbsp;M. Pandey","doi":"10.1016/j.chemgeo.2025.122628","DOIUrl":"10.1016/j.chemgeo.2025.122628","url":null,"abstract":"<div><div>In a recent publication by Loeb et al. (2024), the collection of spherules from the Pacific Ocean was classified as extraterrestrial, specifically micrometeorites. We critically evaluate their findings and conclusions, pointing out inaccuracies in their data interpretation. A comprehensive re-examination of these spherules is essential to classify them as micrometeorites accurately. We argue that the spherules they studied are primarily volcanic or terrestrial in origin, and we emphasize that a revision of their classification is crucial given the flawed observations. This work highlights the challenges faced by researchers and specialists who are not focused on micrometeorites when attempting to locate specific meteor particles from the ocean's depths, a task often regarded as nearly impossible due to the complexities involved in identifying and retrieving these objects. It is advisable to adopt standardized protocols to reduce the possibilities of unreliable interpretations in micrometeorite research. Additionally, “cosmic spherules” should not be used indiscriminately to describe recovered particles, underscoring the importance of adhering to specific chemical and textural characteristics.</div></div>","PeriodicalId":9847,"journal":{"name":"Chemical Geology","volume":"677 ","pages":"Article 122628"},"PeriodicalIF":3.6,"publicationDate":"2025-01-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143021232","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}