Geochemistry International最新文献

{"title":"Unique Mineral Association and the First Finding of Extraterrestrial Ferrodimolybdenite in the Kunya-Urgench H5 Chondrite","authors":"S. N. Teplyakova,&nbsp;C. A. Lorenz,&nbsp;A. A. Kudryavtsev,&nbsp;P. A. Somov,&nbsp;S. E. Borisovskiy","doi":"10.1134/S0016702925600348","DOIUrl":"10.1134/S0016702925600348","url":null,"abstract":"<p>The mineral ferrodimolybdenite (FeMo₂S₄) and the associated mineral assemblage were identified for the first time in an extraterrestrial environment: in a sulfide–metal veinlet of the Kunya-Urgench (H5) ordinary chondrite. They were studied using optical microscopy, SEM, EPMA, and EBSD. Ferrodimolybdenite was found as an inclusion in troilite in terrestrial pyrometamorphic rocks in 2023. Its synthetic analogue has been known as a semiconductor since 1960. Experimental data and properties of the natural mineral assemblage suggest that ferrodimolybdenite should have crystallized from troilite melt at a temperature close to 1100–1000°C. The quenching of metal–sulfide melt enriched in Mo, Cu, and Mn probably formed the metastable phase FeMo₂S₄ in association with native copper, alabandite, and mercury sulfides. The presence of alabandite can indicate strongly reducing conditions (log <i>f</i>O₂ &lt; –4 IW), which are atypical of the impact melting of ordinary chondrites. The fact that this phenomenon occurs locally suggests that a reducing agent may have been locally involved, which was probably a carbon phase contained in the groundmass of the chondrite or brought from the meteoroid that initiated the impact event with the formation of the veinlet. The anomalously high concentrations of Mo (2 × 10² CI), Mn, Cu, and Hg in the Fe–S melt could not have been reached either during the fractional crystallization of large volumes of Fe–FeS melt or during the recurrent partial melting of metal sulfide and silicates during impact events. The ferrodimolybdenite and associated mineral phases were most likely formed during the impact melting of an foreign sulfide–metal aggregate that had been formed under conditions different from those characteristic of the formation of the chondrite matrix in which carbonaceous chondrites were presumably formed. An alternative explanation is hydrothermal activity on the parent body of H chondrites. Although prerequisites for this activity have been identified, its <i>P–T</i> boundary parameters remain uncertain.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 9","pages":"800 - 809"},"PeriodicalIF":0.8,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145122333","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metal-Rich Ungrouped Chondrite Northwest Africa 13202","authors":"M. A. Ivanova,&nbsp;K. M. Ryazantsev,&nbsp;S. N. Teplyakova,&nbsp;D. A. Sadilenko","doi":"10.1134/S0016702924601839","DOIUrl":"10.1134/S0016702924601839","url":null,"abstract":"<p>A meteorite of a new type, NWA 13202, was revealed for the first time in the collection of the Russian Academy of Sciences. It was assigned to metal-rich ungrouped chondrites and is paired with the NWA 12379/12273 chondrites. These chondrites consist of, on average, ∼70 vol % Fe–Ni metal and ∼20 vol % chondrules and contain small silicate inclusions embedded in the metal. Similar to other known metal-rich chondrites (G, CH, CBa, and CBb), these is no fine-grained matrix in NWA 13202. The chondrules are mainly of the porphyritic olivine–pyroxene, olivine, and pyroxene varieties (POP, OP, and PP). Nonporphyritic chondrules (BO, SO, CC, RC, and GC) are rare. Olivine has an L-chondrite composition, <i>Fa</i>25.9 ± 3.5 mol %, and low-Ca pyroxene is <i>Fs</i>17.2 ± 5.7 mol %, which resembles more closely H-chondrites. The degree of olivine heterogeneity corresponds to chondrites of petrological types 3–4. Accessory minerals are phosphates and chromite. The metal includes low-Ni kamacite and high-Ni taenite and tetrataenite, and the only sulfide is troilite. The oxygen isotope composition of silicates from the chondrules of these ungrouped chondrites supports their affinity to the oxygen isotope reservoir of LL chondrites (Jansen et al., 2019). The metal underwent partial melting, and was formed ~2.4 My after the formation of Ca–Al-rich inclusions (Liu et al., 2023). Chondrites of this type were probably formed by a catastrophic collision of metal and chondrite bodies. The intensity and conditions during this event were not sufficient to form chondrules with chondrules with quench textures, such as the CC and SO types. After the reaccretion of a new parent body of the metal-rich ungrouped chondrite, the material of NWA 13202 and NWA 12379/12273 was affected by aqueous alteration and metamorphism at a temperature of ∼600°C, which produced phosphates and rims of Fe-rich olivine around low-Ca pyroxene.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 9","pages":"763 - 777"},"PeriodicalIF":0.8,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145122374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Phosphates in the Impact Associations of the Chelyabinsk Meteorite","authors":"V. V. Sharygin","doi":"10.1134/S0016702925600476","DOIUrl":"10.1134/S0016702925600476","url":null,"abstract":"<p>Na–Fe and Na–Ca–Mg–Fe phosphates were found in the impact melt associations of the Chelyabinsk meteorite (Chebarkul fragment). They drastically differ in composition from phosphates of the initial chondrite (chlorapatite and merrillite). Chladniite Na_2.25Ca_2.14Mg_6.47Fe_3.76Mn_0.17(PO₄)₉ and a merrillite-like phase Na_1.32Ca_6.80Mg_2.07Fe_0.98Mn_0.04(PO₄)₇ were found in the silicate part in quenched interstitial groundmass between olivine grains; merrillite and chlorapatite are rare in it. The spongy metal–sulfide aggregate in the large vugs and metal–sulfide blebs in the silicate part contain Na–Fe phosphate globules. They consist of sarcopside and graftonite (Fe²⁺,Mn²⁺)₃(PO₄)₂, galileiite Na(Fe²⁺,Mn²⁺)₄(PO₄)₃, xenophyllite Na₄(Fe²⁺,Mn²⁺)₇(PO₄)₆, an unidentified Na–Fe phosphate Na₂(Fe²⁺,Mn²⁺)₁₇(PO₄)₁₂, and sometimes chromite-2. Dendritic–skeletal growth of crystals (providing evidence of very rapid quenching) is found in all associations of the impact melt (silicate part, vugs, metal–sulfide aggregate, metal–sulfide blebs, and phosphate globules). The following crystallization sequence is revealed in the Na–Fe phosphate globules: chromite-2 → sarcоpside/graftonite → galileiite → xenophyllite. They are thought to have formed due to the separation of Na–Fe phosphate liquid from homogenous Fe–Ni metal–sulfide melt enriched in Na, P, Cr, and O. The Na–Ca–Mg–Fe phosphates crystallized without involvement of any processes of liquid immiscibility, directly from silicate melt. The paper provides data on the chemical composition and Raman spectroscopy of all studied phosphates and the major minerals of the impact melt associations of the Chelyabinsk meteorite.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 9","pages":"778 - 799"},"PeriodicalIF":0.8,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145122332","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Fe-Oxide Microspherule Fragment from Chang’E-5 Soil Sample: Possible Evidence for Lunar Fumarole Activity","authors":"S. I. Demidova,&nbsp;C. A. Lorenz,&nbsp;D. D. Badyukov","doi":"10.1134/S0016702925600269","DOIUrl":"10.1134/S0016702925600269","url":null,"abstract":"<p>Earlier discovery of magnetite in the Chang’E-5 regolith raised the question about a source of oxidized material in young basaltic volcanism area of the landing site. Here we report the find of Fe-oxide microspherule fragment found in the Chang’E-5 sample, which retained its original structure suggesting it could be magnetite polyframboid or dendrite-like microspherule. The size and texture of the object suggest its prolonged formation from a Fe-rich oxidized environment. Shape and the growth morphology observed on the microcrystals surface suggest a possible free growth from gaseous or fluid phase. Volcanic gas/fluid accumulated within erupted lava flow could be an oxidizing agent at the late stage of eruption or during post-eruption fumarolic activity. If fumaroles existed in the volcanic complexes of Oceanus Procellarum, then the products should be reworked during regolith gardening afterwards, having preserved traces of such processes in the regolith.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 9","pages":"837 - 847"},"PeriodicalIF":0.8,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145122329","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbonaceous Chondrite Clast Captured in Collision Event by the Elga Iron Meteorite (Group IIE)","authors":"N. R. Khisina,&nbsp;S. N. Teplyakova,&nbsp;A. V. Korochantsev,&nbsp;A. M. Abdrakhimov","doi":"10.1134/S0016702925600397","DOIUrl":"10.1134/S0016702925600397","url":null,"abstract":"<p>A melt pocket (MP) found in only one of the silicate inclusions in the Elga iron meteorite was studied using TEM, SEM, EMPA, and Raman spectroscopy methods. The MP demonstrates the liquid immiscibility of the FeCO₃–Fe₃(PO₄)₂–SiO₂–(Fe, Ni)₃P melts, the mineralogical and bulk chemical composition of which is inconsistent with that of the silicate inclusions in the Elga meteorite. Key differences include: (1) The high content of Fe oxide in the MP is inconsistent with the low FeO content (≈3 wt %) in the SiO₂ glass of silicate inclusions; (2) Ca and Mg, the main phase-forming cations of silicate inclusions, are absent in the MP; (3) Siderite and sarcopside, the main oxygen-bearing phases in the MP, were not found in other silicate inclusions of Elga; (4) carbon compounds (aromatized <i>sp</i>² carbon, phenols) identified in the MP were not found in the host silicate substance. These contradictions lead to the conclusion that the melt pocket is a melted fragment of carbonaceous chondrite captured by Elga’s parent body during a collision with carbonaceous asteroid.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 9","pages":"848 - 859"},"PeriodicalIF":0.8,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145122334","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Thermodynamic Properties of Oxide Compounds Occurring in Ca–Al-Rich Inclusions","authors":"S. I. Shornikov","doi":"10.1134/S0016702925600324","DOIUrl":"10.1134/S0016702925600324","url":null,"abstract":"<p>Based on the analysis of experimental evidence on the high-temperature thermodynamic properties of oxide compounds occurring in Ca–Al-rich inclusions of chondrites, the enthalpies, entropies, and energies of mixing in molten oxide compounds were recommended. They can be used to calculate the activities of oxides and oxide compounds in melts of refractory inclusions in chondrites at temperatures of 1500–2700 K. The advantages and correctness of the developed approach to the obtaining of thermodynamic data were demonstrated by the agreement of calculated evolutionary changes during fractional evaporation of residual melts of Ca–Al-rich inclusions in chondrites and other meteoritic materials with experimental data.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 9","pages":"810 - 836"},"PeriodicalIF":0.8,"publicationDate":"2025-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145122373","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Erratum to: Assessment of Kinetic Conditions of Quartz Geothermometer Application: Experiment and Modeling","authors":"V. A. Alekseyev","doi":"10.1134/S0016702925240012","DOIUrl":"10.1134/S0016702925240012","url":null,"abstract":"","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 8","pages":"759 - 759"},"PeriodicalIF":0.8,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0016702925240012.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062292","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Erratum to: Geochemical Characteristics and Tectonic Setting of the Elashan Formation Volcanic Rocks in the Aksu River Region, East Kunlun, Xinjiang","authors":"Xiaoyang Wang,&nbsp;Yang Zhao,&nbsp;Zhongyue Zhang,&nbsp;Xiao Sun,&nbsp;Guanghao Tian,&nbsp;Xinzhuo Hu,&nbsp;Xiaoxiao Wang","doi":"10.1134/S0016702925230016","DOIUrl":"10.1134/S0016702925230016","url":null,"abstract":"","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 8","pages":"758 - 758"},"PeriodicalIF":0.8,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1134/S0016702925230016.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"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":"Modeling of Intraplate Basaltic Magma Crystallization and the Evaluation of the Influence of Metamorphism on Rock Composition: The Anyui Gabbro-Dolerite Complex, Western Chukotka","authors":"B. A. Bazylev,&nbsp;G. V. Ledneva","doi":"10.1134/S0016702925600415","DOIUrl":"10.1134/S0016702925600415","url":null,"abstract":"<p>The petrography, mineralogy and geochemistry of metamorphosed Permian–Triassic to Early Triassic rocks of the Anyui gabbro-dolerite complex, composing sills in metaterrigenous rocks of the Keperveem and Malyi Anyui uplifts of western Chukotka, were studied to determine the composition of the parental melt of these rocks and to assess the mobility of elements during their metamorphism. To solve these problems, the methods of petrological and geochemical modeling of melt crystallization were applied using the COMAGMAT version 3.72 program. It was established that the rocks (hypabyssal gabbros, gabbrodiorites, and diorites) are derivatives of a single parental melt formed in a large lower crustal magma chamber. These rocks are shown to have crystallized from intraplate continental tholeiitic basaltic parental melt that had a moderately differentiated composition with Mg# 52.1 corresponding to the <i>Cpx–Pl</i> cotectic and exhibited signals of crustal contamination. During regional metamorphism to the greenschist facies, the contents of a number of major, minor, and trace elements in the most of the studied rocks have been changed, with the estimated relative mobility of elements increasing as follows: Eu, V &lt; Mn &lt; Zn, U, Co &lt; Cu, Pb &lt; Sr &lt; Fe, Ba, K, Rb &lt; Ni &lt; Cs &lt; Mg &lt; Ca, Na &lt; Li. The elements immobile during metamorphism were Si, Al, Ti, P, REE (except Eu), Y, Sc, Nb, Ta, and probably also Zr, Hf, and Th (although the contents of the latter in some rocks may reflect the presence of xenogenic accessory minerals). The COMAGMAT program was applied to model the phase crystallization sequence established based on petrographic and mineralogical data on rocks, and the parameters of the compositions of the coexisting minerals during the fractionation stages of the parental melt before magnetite started to crystallize. The application of the petrological–geochemical modeling method in combination with data on the geochemistry and mineralogy of the gabbroids thus allows one to evaluate not only the compositions of the magmas and melts and their changes during fractionation but also an input/output of elements during metamorphism and the degree of their mobility.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 8","pages":"641 - 664"},"PeriodicalIF":0.8,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062289","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Dissolved Molybdenum, Tungsten, and Vanadium at the Oxic–Anoxic Interface in the Black Sea","authors":"M. N. Rimskaya-Korsakova,&nbsp;A. V. Dubinin","doi":"10.1134/S0016702925600300","DOIUrl":"10.1134/S0016702925600300","url":null,"abstract":"<p>The distribution of dissolved molybdenum, tungsten, and vanadium was investigated in the northeastern part of the Black Sea down to a depth of 320 m. The depth of hydrogen sulfide appearance (the onset of the anaerobic zone) in the studied area was about 165 m (at a potential density of ∼16.2 kg m^–3). Water samples with dissolved (&lt;0.45 μm) species and dissolved plus labile particulate species of the elements were collected in July 2016 and 2017. The concentration of dissolved Mo increased with depth in the oxic zone, from 36 to 39 nmol/kg, and showed no difference from the sum of dissolved and particulate forms. In the anoxic zone, molybdenum decreased when the hydrogen sulfide concentration exceeded ∼8 μM and reached 3.3 nmol/kg at 320 m. The tungsten concentration decreased from 160 pmol/kg at the surface to 113 pmol/kg at the redox interface (in the suboxic layer at depth 150 m) in the presence of particulate manganese. As Mn oxyhydroxides dissolved in the hydrogen sulfide zone, W concentrations increased to 221 pmol/kg at a depth of 180 m, along with an increase in dissolved Mn. The distribution of W at the redox interface is controlled by the sorption properties of Mn oxide. Dissolved vanadium was depleted at a depth of 5 m and increased with depth in the oxic zone to 13 nmol/kg, with a decrease in the suboxic zone (down to 7.1 nmol/kg). In the anoxic zone, a maximum of V concentration (up to 15.2 nmol/kg) was observed, coinciding with the maximum of dissolved Mn. The calculated balance of Mo and V in the Black Sea showed that about 1200 t of Mo and 1200 t of V are annually buried in the sediments. Tungsten is thought to be supplied in significant amounts to the Black Sea in the form of suspended and colloidal matter in riverine waters, and this matter passes then into seawater in the process of suboxic diagenesis in sediments.</p>","PeriodicalId":12781,"journal":{"name":"Geochemistry International","volume":"63 8","pages":"730 - 745"},"PeriodicalIF":0.8,"publicationDate":"2025-09-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145062205","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}