Mineralogy and Petrology最新文献

{"title":"Geochemical evolution of uranium mineralization in the Mohuldih deposit, Singhbhum Shear Zone, India: constraints from uraninite and brannerite chemistry","authors":"Sarita Patel,&nbsp;Manoj Kumar Ozha","doi":"10.1007/s00710-025-00889-2","DOIUrl":"10.1007/s00710-025-00889-2","url":null,"abstract":"<div><p>The study reports textures and compositions of uraninite and brannerite from the Mohuldih uranium deposit of the Singhbhum Shear Zone. Three types of texturally varied uraninite are identified: (i) pre-tectonic (U_G−1), (ii) syn to post-tectonic (U_G−2), and (iii) inclusions (U_G−3). Based on UO₂ and PbO composition, these are further divided into five subgroups (U_G−1a, U_G−2a, U_G−1b, U_G−2b, and U_G−3). The negative correlation between the rare-earth elements including Y (ΣREE₂O₃ + Y₂O₃) and UO₂ of U_G−1a and U_G−2a uraninite indicates substitution of REE and Y for U⁴⁺ in the structure of these grains during primary crystallization, whereas U_G−1b and U_G−2b resulted from REE + Y + U-enrichment during secondary fluid-induced alteration. Compositional trends further reveal post-crystallization incorporation of Na, Si, K, Ca, Ti, and Fe, replacing radiogenic Pb in the structure of uraninite. The U-Th-Pb_Total dating of uraninite yields two clusters: older (~ 1.71−1.64 Ga; preserved by U_G−1a and U_G−2a) and younger (~ 0.93 Ga; U_G−1b and U_G−2b). Additionally, the extrapolated best-fit linear trend for uraninite in U_G−3 population preserves chemical dates ranging from ~ 1.71 to ~ 1.64 Ga. The ~ 1.64 Ga represents a U + Y + HREE + Ca + Fe hydrothermal event, resulting in the precipitation of uraninite, followed by dissolution-reprecipitation of the mineral along the grain boundary and fractures at ~ 0.93 Ga. The oldest mesured date (~ 1.71 Ga) is attributed to partial Pb-loss by older uraninite during the ~ 1.64 Ga hydrothermal event, with no evident geological significance in the area. The dissolution-reprecipitation of the early-formed uraninite also resulted in the formation of brannerite and ilmenite during the ~ 0.93 Ga event. </p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"119 1","pages":"105 - 125"},"PeriodicalIF":1.4,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826600","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":"Mineralogy, petrogenesis, and SHRIMP U–Pb age of the “Ore Horizon 330” sulfide PGE-Cu-Ni deposit from the Paleoproterozoic layered Monchegorsk pluton, Kola Region, Russia","authors":"Victor V. Chashchin,&nbsp;Yevgeny E. Savchenko,&nbsp;Sergey A. Sergeev","doi":"10.1007/s00710-025-00886-5","DOIUrl":"10.1007/s00710-025-00886-5","url":null,"abstract":"<div><p>The results of a comprehensive study of the Ore Horizon 330 (OH330) sulfide platinum group elements (PGE)-Cu-Ni deposit are presented. OH330 is located within the Sopcha intrusion orthopyroxenites of the layered Monchegorsk pluton (Monchepluton) in the Kola Region (Russia). It is a sill-like body, 3300 m long, 1200 m wide, and 4–6 m thick. The main rock-forming minerals of OH330 were olivine (Fo_87–84) and orthopyroxene (En_84–83). Light rare-earth element (LREE) fractionation is typical for all OH330 rocks, with the (Ce/Sm)_N (where the subscript N indicates normalization to the primitive mantle) values of 1.21 in dunite, 1.33–1.86 in harzburgite, and 1.86–2.15 in orthopyroxenite. The trace elements exhibited positive U and Ta anomalies in dunite and harzburgite and negative Nb and Ta anomalies in orthopyroxenite. The following crystallization parameters of the OH330 rocks were determined: liquidus temperature, 1220 °C; solidus temperature, 1190 °C; and pressure, 2.4 kbar. The SHRIMP (sensitive high-resolution ion microprobe) U–Pb age of magmatic zircon from the OH330 orthopyroxenite is 2492.5 ± 4.1 Ma. This indicates that OH330 was younger than the rocks of the Monchepluton ultramafic subchapter (about 2506 Ma). The calculated parental melt of OH330 has a boninite-like composition with an MgO content of 14 wt% and is contaminated with crustal material. The formation of OH330 occurred as a result of additional magma injection associated with the activation of a mantle diapir. Thus, the OH330 body is probably the ultramafic cumulate part of an intrusion associated with Paleoproterozoic continental rifting.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"119 1","pages":"49 - 71"},"PeriodicalIF":1.4,"publicationDate":"2025-03-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826643","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":"Petrochemistry and geochronology of Middle Eocene high-K calc-alkaline I-type Kazıkbeli pluton, NE Turkey: implications from zircon U-Pb ages and Sr-Nd-Pb-Lu-Hf isotope data","authors":"Zikrullah Samet Güloğlu,&nbsp;Abdullah Kaygusuz","doi":"10.1007/s00710-024-00881-2","DOIUrl":"10.1007/s00710-024-00881-2","url":null,"abstract":"<div><p>The Kazıkbeli pluton, located in the Kürtün (Gümüşhane) region of the Eastern Pontides, NE Turkey, was studied by employing zircon U-Pb geochronology, whole-rock geochemistry, Sr-Nd-Pb and zircon Lu-Hf isotope geochemistry. LA-ICP-MS U-Pb zircon dating revealed that the gabbroic diorite and granodiorite components of the pluton solidified during the Lutetian epoch of the Middle Eocene, at approximately 46.10 ± 0.26 Ma and 45.37 ± 0.29 Ma, respectively. The pluton is composed of calc-alkaline rocks, ranging from gabbroic diorite to granite (SiO₂ = 55.3 to 72.4 wt%). These I-type rocks are typically metaluminous but exhibit peraluminous tendencies in some cases. They are enriched in large ion lithophile elements and display concave chondrite-normalized rare earth element patterns (La_N/Yb_N = 4.39 to 6.67) with negative Eu anomalies (Eu_N/Eu* = 0.45 to 0.80). The initial εNd values ranged from 1.85 to 2.24, and the initial ⁸⁷Sr/⁸⁶Sr_(i) ratios ranged from 0.70458 to 0.70484, consistent with a mantle source in the isotope ratio diagram. The initial ²⁰⁶Pb/²⁰⁴Pb_(i), ²⁰⁷Pb/²⁰⁴Pb_(i), and ²⁰⁸Pb/²⁰⁴Pb_(i) ratios ranged from 18.505 to 18.571, 15.595 to 15.601, and 38.560 to 38.590, respectively. They have positive εHf_(i) values (5.75 to 8.03), located between depleted mantle and chondrite evolution values. Fractional crystallization of plagioclase, hornblende, and Fe-Ti oxide minerals played a significant role in the magma evolution, while assimilation and magma mixing may have had a minor influence. Collectively, the evidence suggests that the primary magma source for these plutonic rocks was an enriched lithospheric mantle. Subsequent differentiation within crustal magma chambers, with limited crustal contamination, shaped the final magmatic evolution. </p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"119 1","pages":"73 - 103"},"PeriodicalIF":1.4,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826599","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":"Mineralogy and petrology of lava of the Goldberg volcano, West Eifel volcanic field, Germany","authors":"André Pouclet,&nbsp;Jacques-Marie Bardintzeff,&nbsp;Étienne Juvigné","doi":"10.1007/s00710-024-00885-y","DOIUrl":"10.1007/s00710-024-00885-y","url":null,"abstract":"<div><p>The Goldberg is the northwesternmost volcano of the West Eifel basanitic and nephelinitic volcanic field in Germany. It was built in the EARLY to MIDDLE PLEISTOCENE, during a monogenic eruption with successive phreatomagmatic and Strombolian activities. The lava is an olivine-, pyroxene-, and phlogopite-phyric leucite nephelinite. Olivine types comprise phenocrysts (Fo% 90–84) and some xenocrysts (Fo% 92). Different pyroxenes crystallised with compositions ranging from Mg-diopside in megacrysts to diopside in the green core of phenocrysts and fassaitic diopside in the rim of phenocrysts. These chemical variations are discussed in terms of correlation of the pyroxene solid solutions. They reveal complex processes with polybaric crystallisation under decreasing pressure for the megacrysts and the green cores of phenocrysts in an initial batch of magma. Then, due to a new supply of magma and its ascent though the crust, the green cores were coated with a different composition and new phenocrysts developed. Amphibole is scarce and consists of Ti-rich pargasite. Mica consists of Al-rich and Ti-rich phlogopite. K-rich nepheline and leucite are common in the groundmass. Oxides, haüyne, and apatite complete the mineral composition. Petrological data indicate the successive emplacement of several batches of magma. The bulk geochemical composition of the lava and scoria is mafic, potassic and highly undersaturated. The volcano belongs to the Eifel F-suite (Foidite). The normalized trace element patterns show a lithophile element enrichment except for Th and U, and a high field strength element depletion. Compared with the composition of the nephelinites and basanites of the western Germany volcanic fields, the Goldberg’s magma shares similar mantle source and no crustal contamination. Geochemical data are consistent with a low degree of melting of an enriched mantle at the garnet-spinel transition region. Low Nb/Ta suggests a potential carbonatitic input into the melting region.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"119 1","pages":"127 - 147"},"PeriodicalIF":1.4,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826601","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":"A geological, geochemical and isotopic study of primary diamond deposits in the Siberian craton","authors":"Sergey I. Kostrovitsky,&nbsp;Dmitry A. Yakovlev,&nbsp;Benjamin R. Fosu,&nbsp;Sergey I. Dril,&nbsp;Konstantin V. Garanin","doi":"10.1007/s00710-024-00880-3","DOIUrl":"10.1007/s00710-024-00880-3","url":null,"abstract":"<div><p>We present an overview of published and newly obtained data, which provides general information about the diamond deposits, geochemical and isotopic of kimberlites from all primary diamond deposits of the Siberian craton (20 kimberlite pipes). These deposits are predominantly composed of pyroclastic kimberlites, typically forming as complex, multi-phase, and multi-channel intrusions. Age determinations, based on U-Pb dating of zircon and perovskite, place these deposits between 370 and 350 Ma. A discernible south-to-north gradation in diamond grade across the Siberian craton, particularly in the Yakutian Province correlates with variations in the chemical composition of the kimberlites. The richest diamondiferous deposits are predominantly high-Mg kimberlites. Strikingly, some of the largest deposits by size (such as Jubileynaya, Zarnitsa, and Mir) are Mg-Fe kimberlites and are noted for their lower proportions of high-quality diamonds. Pyroclastic kimberlites, which constitute most Siberian primary diamond deposits generally have higher diamond grades than coherent kimberlites.Apart from the Nakyn field, the distribution of incompatible elements within Siberian diamondiferous kimberlites appears to be independent of their MgO, total FeO, and TiO₂ content. The kimberlites exhibit ɛNd values ranging from + 1.9 to + 7.0 and initial ⁸⁷Sr/⁸⁶Sr ratios (denoted as ⁸⁷Sr/⁸⁶Sr_i) from 0.702 to 0.706 (except for the Nakyn field deposits), suggesting a provenance from a slightly depleted mantle source, akin to the prevalent mantle. The kimberlites of the Nakyn field deposits differ from other Siberian diamond deposits by an abnormally low content of incompatible elements, higher ⁸⁷Sr/⁸⁶Sr_i (0.706 to 0.710), and low ɛNd (-3.1 to + 2; Kononova et al. 2005). It is assumed that the kimberlites of the Nakyn field were derived from a mantle source, with an intermediate composition between prevalent mantle and enriched mantle I.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"119 1","pages":"21 - 47"},"PeriodicalIF":1.4,"publicationDate":"2025-01-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826642","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":"The thermal stability of ·S2- and ·S3- radicals in afghanite","authors":"Yinghua Rao,&nbsp;Qingfeng Guo,&nbsp;Libing Liao","doi":"10.1007/s00710-024-00883-0","DOIUrl":"10.1007/s00710-024-00883-0","url":null,"abstract":"<div><p>Polysulfide ions play a crucial role in both the lithospheric and biospheric sulfur cycles. This study reveals the coexistence of various polysulfides (·S₂^-, ·S₃^- and S₂²⁻) alongside sulfates (SO₄²⁻) and sulfites (SO₃²⁻) in afghanite. Upon subjecting afghanite to heat treatment across a range of temperature, sulfur species within the mineral undergo interconversion, leading to alterations in colour, fluorescence, and other properties. In this paper, variations in the content of different sulfur species in afghanite before and after heat treatment were observed. The findings indicate a significant conversion of ·S₂^-, ·S₃^- and S₂²⁻ to SO₄²⁻ at 300 ℃, with some ·S₂^- and ·S₃^- regenerating at higher temperature intervals due to the oxidation of S₂²⁻. This study also discusses the generation of chlorine vacancies in afghanite resulting from the inequivalent replacement of Cl⁻ by S₂²⁻, with the vacancy concentration decreasing gradually as the temperature rises. This study offers a potential approach for using the ratio of oxidized and reduced sulfur species in afghanite to assist in determining the oxygen fugacity (<i>f</i>_O2) of the formation environment in the future. Furthermore, the ε-cage of afghanite has the ability to encapsulate a specific amount of ·S₂^- and ·S₃^-, suggesting its potential use as a new mineral pigment.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"119 1","pages":"149 - 159"},"PeriodicalIF":1.4,"publicationDate":"2024-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826640","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":"Lattice strain model for rare earth element partitioning between apatite and silicate melt: effect of apatite/melt composition and temperature with implications for lunar basalts","authors":"Markéta Jirků,&nbsp;Václav Špillar,&nbsp;Alessandro Fabbrizio","doi":"10.1007/s00710-024-00878-x","DOIUrl":"10.1007/s00710-024-00878-x","url":null,"abstract":"<div><p>We present new parameterized lattice strain models to predict the apatite/silicate melt partition coefficients of the rare earth elements (REE) in natural magmatic systems as a function of temperature and melt composition with high accuracy and precision. We collected published experimental REE partition coefficients for apatite coexisting with melt ranging from picrobasaltic to rhyolitic and phonolitic composition. Resulting dataset was analysed using the lattice strain model to assess the data quality. The three lattice strain parameters (<i>D</i>₀, <i>r</i>₀, and <i>E</i>) were subjected to a multivariate nonlinear least-squares analysis as a function of intensive variables, and we attempted to develop two independent models, on the basis of melt and apatite composition. In melt composition-based model, it was found that the <i>D</i>₀ parameter increases with increasing melt polymerization, which can be expressed by the newly proposed simplified melt polymerization index P.I. = (<span>(:{X}_{{text{S}text{i}text{O}}_{2}})</span>+2<span>(:{X}_{{text{A}text{l}}_{2}{text{O}}_{3}})</span>+<span>(:{X}_{{text{T}text{i}text{O}}_{2}})</span>+2<span>(:{X}_{{text{P}}_{2}{text{O}}_{5}})</span>)/(<span>(:{X}_{text{M}text{g}text{O}})</span>+<span>(:{X}_{text{F}text{e}text{O}})</span>+<span>(:{X}_{text{C}text{a}text{O}})</span>+2<span>(:{X}_{text{a}text{l}text{k}})</span>), where individual <span>(:{X}_{i})</span> variables represent the molar fractions of the oxides in the melt. By disentangling the effect of each component of the P.I., it was found that the CaO content of the melt is the oxide that affects more the <i>D</i>₀ parameter. Thus, the <i>D</i>₀ parameter is expressed as a power law function of melt CaO content. Through extensive search of the parameter space, the <i>E</i> and <i>r</i>₀ variables were found to correlate strongly with linear combination of melt CaO, P₂O₅ and of reciprocal temperature, 1/<i>T</i>. Based on the apatite composition, we could not find any dependence of the partitioning parameters on compositional variables that would outperform solely a reciprocal temperature-based fit. The new parameterization was applied to predict REE partition coefficients in lunar basalts and suggests that lunar apatite could only equilibrate with evolved melt at late stages of fractional crystallisation.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"119 1","pages":"1 - 19"},"PeriodicalIF":1.4,"publicationDate":"2024-12-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-024-00878-x.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143826641","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":"Lithostratigraphy of the chole section, Southeastern Ethiopian volcanic province","authors":"Andualem Getaw,&nbsp;Dereje Ayalew,&nbsp;Karen Fontijn","doi":"10.1007/s00710-024-00877-y","DOIUrl":"10.1007/s00710-024-00877-y","url":null,"abstract":"<div><p>This study presents a detailed flow-by-flow petrographic modal description and major element data integrated into the stratigraphic framework for the central part of the southeastern Ethiopian plateau (the Chole Section). The stratigraphic data are placed in the context of the regional stratigraphic framework and correlated with existing geochronology of the province, allowing us to estimate the timing and duration of volcanic activity in the area. Based on petrographic variations and physical volcanological features, the Chole section is divided into: (1) lower basalt; (2) middle basalt; and (3) upper basalt. The phase assemblages and major element data show that the lower and upper basalts underwent possible fractionation involving olivine, plagioclase, and augite. In contrast, the middle basalt equilibrium phase and major element data exhibits low-degree fractionation involving olivine, clinopyroxene, and orthopyroxene at greater depths. The stratigraphic position and the petrographic data suggests, the lower and middle basalt successions likely correlate with the Oligocene to Early Miocene basaltic succession (28–15.5 Ma) of the southeastern Ethiopian volcanic province. The presence of several volcanic hiatuses and the decrease in flow thickness in the middle basalt suggest a waning of magmatic activity during this period. The upper basalt of the Chole section correlates with the upper Miocene basalt of the southeastern volcanic province (15.5–11 Ma). From this, we determine that volcanic activity in the southeastern Ethiopian volcanic province is well constrained within the broader tectono-magmatic framework of the East African volcanic province.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"118 4","pages":"513 - 533"},"PeriodicalIF":1.4,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142737001","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":"Ore-forming fluid characteristics of Jiaodong-type gold deposits in the North China Craton: constraints from the geochemistry of auriferous pyrite","authors":"Shisheng Li,&nbsp;Mingliang Wang,&nbsp;Lin Li,&nbsp;Shengrong Li,&nbsp;Songbao Feng","doi":"10.1007/s00710-024-00875-0","DOIUrl":"10.1007/s00710-024-00875-0","url":null,"abstract":"<div><p>The Early Cretaceous gold deposits in the North China Craton are known as Jiaodong-type gold deposits. Here, we summarize a quantity of reported (including this study) pyrite trace element, δ³⁴S, and Pb isotope data from the Jiaodong, Xiaoqinling, and Central Taihangshan gold fields to comprehensively reveal the characteristics of the ore-forming fluids in Jiaodong-type gold deposits. The results show that the Au concentrations in the pyrites from the Jiaodong-type gold deposits are typically less than 8.12 ppm and do not correlate with As but have significant positive correlations with Bi and Te, implying that Bi and Te may govern Au enrichment in pyrite. The overall As concentrations in the pyrites are relatively low, and only the Jiaodong gold field is significantly higher, which may be caused by fluid flowing through As-rich metamorphic sedimentary rocks. In Jiaodong-type gold deposits, Au is dominantly found as visible gold, followed by invisible gold. Invisible gold generally occurs as a solid solution (Au⁺), and only the proportion of nanoparticles (Au⁰) in the Xiaoqinling gold field is slightly higher (20%). Sulfidation and fluid immiscibility or boiling were the key mechanisms leading to visible gold precipitation. The Co/Ni ratio, δ³⁴S, and Pb isotopes indicate that the ore-forming fluids in the Jiaodong-type gold deposits exhibit remarkable magmatic features, and the ore-forming materials are primarily derived from a mixture of lower crust and mantle sections. Among them, the ore-forming materials from the lower crust of the Central Taihangshan gold field are slightly higher.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"118 4","pages":"555 - 568"},"PeriodicalIF":1.4,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142737023","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":"Ca2.68Fe10.32Si1.00O20 - a strongly disordered SFCA-related phase in the system CaO-Fe2O3-SiO2","authors":"Michael F. Salzmann,&nbsp;Volker Kahlenberg,&nbsp;Biljana Krüger,&nbsp;Hannes Krüger,&nbsp;Janina Grabowski","doi":"10.1007/s00710-024-00874-1","DOIUrl":"10.1007/s00710-024-00874-1","url":null,"abstract":"<div><p>As part of a systematic investigation into the ternary system CaO-Fe₂O₃-SiO₂, we discovered a phase with a general chemical composition of A₁₄O₂₀ (where A represents Ca, Fe, and Si) and previously unknown symmetry. Synthesis experiments were conducted at 1200 °C in air with an oxide ratio of CaO:Fe₂O₃:SiO₂ = 3:5:1 in the starting mixture. In addition to β-Ca₂SiO₄, and hematite (Fe₂O₃), powder X-ray diffraction analysis indicated the presence of compounds related to the aluminum-free counterpart of a silico-ferrite of calcium and aluminum (SFCA), one of the major bonding phases in iron ore sinter. Single crystals of this so-called SFC phase, large enough for diffraction experiments, were found in the sintered pellet fragments under a digital microscope. The compound with composition Ca_2.68Fe_10.32Si_1.00O₂₀ crystallizes in space group <i>I</i>2/<i>c</i> and has the following basic crystallographic data: <i>a</i> = 10.4643(10) Å, <i>b</i> = 15.2740(11) Å, <i>c</i> = 5.3050(5) Å, β = 110.017(9)°, <i>V</i> = 796.69(13) ų and Z = 2. The final composition, as determined by crystal structure refinement, differs slightly from the weight-specified starting mixture of Ca₃Fe₁₀SiO₂₀ and suggests the presence of both Fe(III) and small amounts of Fe(II) in the sample. The crystal structure is related to that of the triclinic polytype-1A of SFC, but exhibits a higher degree of disorder due to the partial occupation of additional octahedrally and tetrahedrally coordinated sites. This results in a smaller unit cell and an increased space-group symmetry. The described phase can be regarded as a basic or family structure, from which the two simplest polytypes (1A and hypothetical 2M) can be derived through ordering processes of cations among different possible vacancies. The chemical similarity to one of the phases of the SFCA-family suggests that such disordered compounds could also occur in industrial sinters.</p></div>","PeriodicalId":18547,"journal":{"name":"Mineralogy and Petrology","volume":"118 4","pages":"485 - 499"},"PeriodicalIF":1.4,"publicationDate":"2024-10-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://link.springer.com/content/pdf/10.1007/s00710-024-00874-1.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142736818","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}