Chemie Der Erde-Geochemistry最新文献

{"title":"Fluid inclusion, mineralogical, geochemical, and isotopic (O, S) evidence for the genesis of the Khan-Khatun Zn-Pb deposit, Tabas Block, Iran","authors":"Abdulmajid Jamili,&nbsp;Balandeh Aminzadeh","doi":"10.1016/j.chemer.2024.126084","DOIUrl":"10.1016/j.chemer.2024.126084","url":null,"abstract":"<div><p>The Khan-Khatun Zn<img>Pb deposit is located in the southeast margin of the Tabas Block of the Central Iranian Microcontinent. The stratabound Zn<img>Pb mineralization is of epigenetic origin and hosted by the Late Cretaceous limestones. The ore deposition occurred in structural open spaces and much less as a disseminated replacement in carbonate rocks. The deposit consists of sulfide and non-sulfide base metal ore types. Sulfide ores include sphalerite, galena, and minor amounts of pyrite and chalcopyrite. Three paragenetic stages are recognized: pre-, hydrothermal, and supergene mineralization. Fine-grained pyrite and chalcopyrite (0.02 to 0.15 mm) precipitated during the early stages of hydrothermal mineralization. Galena formed with or sometimes after sphalerite. The δ³⁴S values of sphalerite and galena range from +10.4 ‰ to +13.7 ‰ and + 10.2 ‰ to +14.1 ‰, respectively, and are consistent with thermochemical sulfate reduction (TSR) of the Jurassic evaporites. Willemite is an abundant non-sulfide mineral characterized by red-brown to white colors. The red-brown willemite formed during the late stages of the hydrothermal mineralization. The δ¹⁸O values of red-brown and white-colored willemite vary from +14.3 to +16.1 ‰ and − 9.62 to −8.1 ‰, respectively. Differences in δ¹⁸O values between red-brown willemite and white-colored willemite are probably the result of hydrothermal and supergene processes. Homogenization temperatures of primary fluid inclusions in calcite coexisting with sulfide ores and red-brown willemite range from 110 to 210 °C and 112 to 177 °C, respectively. The salinities of aqueous fluid inclusions of calcite and red-brown willemite vary from 11.1 to 21.26 wt% NaCl equiv. and 10.61 to 16.15 wt% NaCl equiv., respectively. Microthermometric measurements, isotopic analyses, geochemical, mineralogical, and textural evidence indicate that the mineralization process at the Khan-Khatun Zn<img>Pb deposit is consistent with Mississippi Valley-type (MVT) deposits.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 1","pages":"Article 126084"},"PeriodicalIF":0.0,"publicationDate":"2024-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281924000084/pdfft?md5=f7482ec147a45fdbfd1d23a6fd9a5663&pid=1-s2.0-S0009281924000084-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139577934","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"The layered gabbroic intrusion in the Southern Eastern Desert of Egypt: Implications for Fe-Ti-rich magmatism at the end of the East African Orogeny","authors":"Mohamed Zaki Khedr ,&nbsp;Christoph Hauzenberger ,&nbsp;Tomoaki Morishita ,&nbsp;Akihiro Tamura ,&nbsp;Abdullah O. Bamousa ,&nbsp;Scott A. Whattam ,&nbsp;Shehata Ali","doi":"10.1016/j.chemer.2024.126077","DOIUrl":"10.1016/j.chemer.2024.126077","url":null,"abstract":"&lt;div&gt;&lt;p&gt;The Rahaba layered intrusion in the Southern Eastern Desert of Egypt is mainly composed of pyroxene hornblende-, and hornblende gabbros. It hosts thick Fe&lt;img&gt;Ti oxide ore layers that are composed of titanomagnetite with subordinate ilmenite and magnetite. To understand the petrogenesis of the Fe&lt;img&gt;Ti rich gabbroic rocks, the nature of their parent high-Fe primitive mantle melts and condition of Fe&lt;img&gt;Ti oxide layer formation, we obtained new mineral chemistry and whole-rock major and trace element compositions. The geochemical characteristics of the gabbroic rocks resemble those of picro-basalts, suggesting generation from picritic basaltic-like melts of tholeiitic affinity. Their high-Fe-Ti-Mg nature (TiO&lt;sub&gt;2&lt;/sub&gt;, ∼1.91 wt%; MgO, ∼11.0 wt%; Fe&lt;sub&gt;2&lt;/sub&gt;O&lt;sub&gt;3&lt;/sub&gt;, ∼14 wt%) probably indicates elevated mantle potential temperatures due to upwelling of hot asthenospheric mantle. Rare earth elements (REEs) of clinopyroxene show flat patterns with depletion in LREEs, similar to those of the host gabbros and picritic basaltic lava, suggesting a mantle origin for their parental melts. Moreover, clinopyroxene compositions show differentiation trends similar to low-pressure igneous intrusions, and reveal a rift-related origin. Chemistry of plagioclase (An&lt;sub&gt;45&lt;/sub&gt;–&lt;sub&gt;62&lt;/sub&gt;), clinopyroxene (Wo&lt;sub&gt;38.4&lt;/sub&gt;&lt;sub&gt;–&lt;/sub&gt;&lt;sub&gt;45.3&lt;/sub&gt;, En&lt;sub&gt;39.9&lt;/sub&gt;&lt;sub&gt;–&lt;/sub&gt;&lt;sub&gt;43&lt;/sub&gt;, Fs&lt;sub&gt;14&lt;/sub&gt;&lt;sub&gt;–&lt;/sub&gt;&lt;sub&gt;19.3&lt;/sub&gt;; Mg#: 0.71–0.92) and olivine (Fo&lt;sub&gt;56&lt;/sub&gt;–&lt;sub&gt;80&lt;/sub&gt;) shows wide compositional ranges due to variable degrees of crystal fractionation. The calculated equilibrium temperature for the Rahaba Fe-Ti-rich gabbros is mainly 820–1000 °C, at pressure below 5 kbar, reflecting depth of rock solidification of &lt;15 Km. These rocks show both subduction-like and rift-related geochemical signatures comparable to other post-collisional layered intrusions in the Arabian-Nubian Shield. The low average Ce/Pb (8.3) and high Ba/Nb (391) ratios together with the enriched large-ion lithophile elements (Cs, Ba, K and Sr) and depleted high-field strength elements (Th, Nb, Ta and Zr) reflect the contribution from a preceding subduction event. The lineament map, structural lineament and lineament density map reveal main WNW-ESE and NW-SE structural trends of the Najd System in the Rahaba area. The Rahaba Fe&lt;img&gt;Ti rich gabbroic intrusion was likely formed by initial impact of a mantle plume head with Fe-rich streaks at the base of metasomatized lithospheric mantle during an extensional phase associated with activity of the Najd-related strike-slip faults, at the end of the East African Orogeny. The resultant mantle-derived melt compositions and Najd-related structures possibly controlled the distribution of Fe&lt;img&gt;Ti ore deposits during this Orogeny. The Rahaba gabbroic intrusion was emplaced during post-collisional extension after slab break-off and lithospheric delamination following collision of accreted island-arcs with t","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 1","pages":"Article 126077"},"PeriodicalIF":0.0,"publicationDate":"2024-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281924000011/pdfft?md5=fcc410181b03365c872c5c7df9f14dc4&pid=1-s2.0-S0009281924000011-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139415174","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"The geochemistry of leucite-bearing lavas from early stages of the Somma-Vesuvius volcanic complex: Feeder systems and mantle enrichment processes in the Neapolitan district of the Roman Magmatic Province","authors":"Vincenza Guarino ,&nbsp;Roberto Solone ,&nbsp;Martina Casalini ,&nbsp;Luigi Franciosi ,&nbsp;Luigi Dallai ,&nbsp;Vincenzo Morra ,&nbsp;Sandro Conticelli ,&nbsp;Leone Melluso","doi":"10.1016/j.chemer.2023.126076","DOIUrl":"10.1016/j.chemer.2023.126076","url":null,"abstract":"<div><p>The lavas of the Mt. Somma volcanic epoch were erupted during the early stage of the Somma-Vesuvius volcanic complex. These lavas are mildly differentiated with the presence of plagioclase-clinopyroxene-olivine- ± leucite-bearing rocks (<em>leucite tephrites, leucite-bearing shoshonites</em>, <em>latites</em>), also characterized by low in MgO, Cr and Ni, with a Sr-Nd-isotope range (⁸⁷Sr/⁸⁶Sr = 0.706865–0.707861; ¹⁴³Nd/¹⁴⁴Nd = 0.51244–0.51258) that overlaps with lavas of the late stage Vesuvius erupted after 1631 CE (late stage of the Somma-Vesuvius volcanic complex). Differentiation is dominated by closed-system processes, with fractional crystallization of clinopyroxene, calcic plagioclase, olivine, magnetite, and leucite. Open-system differentiation processes are subordinate and associated with limited interaction with crustal rocks. Oxygen isotopes on clinopyroxene and olivine phenocrysts (δ¹⁸O = 6.5–7.9 ‰) are higher than typical uncontaminated mantle magmas, suggesting a crustal contribution to the melt. Although open-system assimilation + fractional crystallization certainly took place, this process alone does not adequately reproduce the chemical and isotopic composition of the Mt. Somma ultrapotassic magmas. Therefore, a contribution from a recycled crustal component in the mantle source is required, but probably dominated by sediment-derived fluids and melts. The Mt. Somma lavas are characterized by distinctly different geochemical features compared to the mafic products of the neighboring volcanic areas (i.e., Phlegrean, Procida and Ischia volcanic fields), where the recycled crustal component is less pronounced.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 1","pages":"Article 126076"},"PeriodicalIF":0.0,"publicationDate":"2024-01-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281923001277/pdfft?md5=152ed0cbe09c839f081f5149a995a32b&pid=1-s2.0-S0009281923001277-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139397070","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Geochemical variations in early Islamic glass finds from Bukhara (Uzbekistan)","authors":"Nadine Schibille ,&nbsp;Catherine Klesner ,&nbsp;Daniel R. Neuville ,&nbsp;Sören Stark ,&nbsp;Asan I. Torgoev ,&nbsp;Sirojiddin J. Mirzaakhmedov","doi":"10.1016/j.chemer.2024.126078","DOIUrl":"10.1016/j.chemer.2024.126078","url":null,"abstract":"<div><p>Glass manufacturing processes and recipes changed fundamentally after the 8th century CE. The earlier centralised production system diversified, primary production sites multiplied, and the scale of individual productions contracted. Mineral soda was no longer used and instead replaced by plant ash as the main fluxing agent, affecting the chemical composition and properties of the glass. In this work, LA-ICP-MS and Raman spectroscopy were used to investigate the compositional and structural characteristics of 68 glass fragments recovered during recent excavations at Bukhara in Uzbekistan, dating to the 9th to early 11th centuries CE. This is the most extensive systematically collected and studied glass assemblage from Central Asia to date. The glass can be attributed to different origins, confirming on the one hand the diversification of glass production during the early Islamic period and, on the other hand, regional variations in the chemical compositions and network structure of soda-rich plant ash glasses. As clear archaeological evidence for early Islamic glass production sites in Central Asia is rare, regional production groups are distinguished primarily on relative concentrations of Mg, K, P, Cl, Li and Cs in relation to the plant ash component, while variabilities in Al, Ti, Cr, Y, Zr, Th and REEs and their ratios indicate different silica sources. Raman spectra suggest variations in network connectivity and <em>Q</em>^<em>n</em> speciation that confirm compositional groupings and suggest structural differences between regional productions of plant ash glass. The results demonstrate a clear dominance of local or regional glass groups, while revealing the importation of Mesopotamian glass, notably a high-end colourless glass type from the region around Samarra in Iraq. The new analytical data allow further separation and characterisation of novel early Islamic plant-ash glass types and their production areas.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 1","pages":"Article 126078"},"PeriodicalIF":0.0,"publicationDate":"2024-01-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281924000023/pdfft?md5=99f57b534b7498ae9b54cd62433a0fb0&pid=1-s2.0-S0009281924000023-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139375359","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Multiple mineralization events recorded in the Dahenglu CuCo deposit, eastern North China Craton: Constraints from ReOs and UPb geochronology","authors":"Yong Zhang ,&nbsp;Yande Tai ,&nbsp;Lixing Li ,&nbsp;Chao Li ,&nbsp;Yingli Zhang ,&nbsp;Quanheng Song ,&nbsp;Siyu Liu","doi":"10.1016/j.chemer.2023.126075","DOIUrl":"10.1016/j.chemer.2023.126075","url":null,"abstract":"<div><p>The formation of sediment-hosted Cu<img>Co deposits remains controversial, in part due to the lack of a precise age for Cu<img>Co mineralization. The Dahenglu deposit is located in the eastern part of the Jiao–Liao–Ji Belt (JLJB), one of the famous sedimentary–metamorphic-type Cu<img>Co deposits in China, that is mainly hosted within Palaeoproterozoic epimetamorphic rocks. The orebodies occur as stratoid, lenticular and veined forms in conformity with the carbonaceous sericite phyllite. In this study, we present new Re<img>Os and monazite U<img>Pb geochronological data for carbonaceous sericite phyllite, and zircon U<img>Pb geochronological data for diorite porphyry associated with the deposit. The Re<img>Os geochronology on carbonaceous rocks from the Dalizi Formation provides a direct and reliable depositional age of 1967 ± 23 Ma. The U<img>Pb analyses of metamorphic monazite intergrown with cobaltite yield an age of 1812 ± 8 Ma. Magmatic zircon U<img>Pb dating from ore-bearing diorite porphyry yields a weighted mean age of 121.8 ± 0.8 Ma. These results constrain three periods of mineralization in the Dahenglu deposit. Syngenetic sedimentary mineralization and metamorphic mineralization occurred during the Palaeoproterozoic, and magmatic–hydrothermal mineralization occurred during the Early Cretaceous. We suggest that Re<img>Os and U<img>Pb geochronology on carbonaceous-bearing epimetamorphic rock and metamorphic monazite can serve as robust chronometers to establish the age and temporal evolution of sedimentary hosted Cu<img>Co mineralization.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 1","pages":"Article 126075"},"PeriodicalIF":0.0,"publicationDate":"2024-01-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281923001265/pdfft?md5=c48a0f2565c2e3c54f8e70da60fc00c3&pid=1-s2.0-S0009281923001265-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139092330","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"A record of overpressure and Sevier tectonics within beef calcite of the Heath Formation, Central Montana Trough","authors":"Alex M. Washburn ,&nbsp;Paul J. Sylvester ,&nbsp;Kathryn E. Snell","doi":"10.1016/j.chemer.2023.126073","DOIUrl":"10.1016/j.chemer.2023.126073","url":null,"abstract":"<div><p>The Central Montana Trough is an important sedimentary basin for petroleum resources and as a record of North American tectonism. The thermal, overpressure, and tectonic histories of the trough are investigated through a study of beef calcite veins taken from the Heath Formation, the primary hydrocarbon source rock of the basin. Results from beef calcite analysis include petrographic characterization, U-Pb geochronology via LA-ICP-MS, clumped isotope thermometry, and conventional carbon and oxygen stable isotopes. U-Pb ages and clumped isotope temperatures are 121.8 ± 19.2 Ma at 43.1 ± 2.3 °C; 96.2 ± 25.9 Ma at 52.1 ± 3.7 °C; and 101.6 ± 24.2 Ma at 50.2 ± 2.4 °C. Large errors on U-Pb ages result from very low U contents (&lt;0.03 ppm). Ages and temperatures indicate staged vein precipitation at burial depths between 600 m to 1.3 km during the major burial event of the basin and a normal geothermal gradient of 25 °C/km. Beef calcite emplacement and basin burial are the direct result of regional tectonism of the Sevier Orogeny. Calculated fluid δ¹⁸O using clumped isotope temperatures revealed δ¹⁸O values of 3–7 ‰ (SMOW), indicating beef calcite precipitation from connate formation brine. Analysis of median-symmetrical beef carbonate δ¹⁸O and δ¹³C values indicates precipitating fluids were diagenetically modified by bacterial sulfate reduction and methanogenesis of organic matter. A thin (0.1 mm) second generation of growth is found on the outermost vein margin by a sharp chemical boundary and a trail of inclusions. This second growth stage could not be dated separately, but significantly lower δ¹⁸O and δ¹³C values of −2 ‰ and −5.5 ‰, respectively, indicate precipitating fluids were hotter and further diagenetically altered by thermal organic matter breakdown.</p><p><strong>Supplemental data</strong>: <span>https://osf.io/39znd/</span><svg><path></path></svg>.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 1","pages":"Article 126073"},"PeriodicalIF":0.0,"publicationDate":"2023-12-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281923001241/pdfft?md5=0a4d4d817f6409f7f41d91d775e65494&pid=1-s2.0-S0009281923001241-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139071825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"What do we know about the natural sources, transport and sinks of antimony in the environment?","authors":"Juraj Majzlan ,&nbsp;Montserrat Filella","doi":"10.1016/j.chemer.2023.126072","DOIUrl":"10.1016/j.chemer.2023.126072","url":null,"abstract":"<div><p>Limited attention has been given to antimony present in detrital form in the different environmental compartments except for highly polluted systems related in some way to ore deposits. In highly polluted systems, the ultimate sinks of Sb may be the minerals tripuhyite (FeSbO₄) or perhaps schafarzikite (FeSb₂O₄) but how about Sb dynamics in the much more abundant, weakly polluted or ‘non-polluted’ systems? This deficiency in our knowledge is probably related to the perception that the element is mostly present ‘dissolved’ in waters and to a focus on the role of its binding to iron oxyhydroxides in solid phases. Here we evaluate the state of our knowledge in the Sb journey from geological matrices to detrital forms in soils and waters and identify key aspects that require further investigation. In high-temperature environments, Sb demonstrated its striking incompatibility by fractionation into aqueous fluids or sulfide/metallic melts, or by uptake in a few common minerals that accept this element (e.g., rutile or pyrite). In low-temperature environments, Sb enters the structures of minerals with different formation rates and solubilities, creating a confusing impression of being mobile and immobile at the same time. The estimates of Sb concentration in the upper continental crust are scattered and the Sb-bearing mineral(s) there have not yet been identified. Given that sedimentary rocks are consistently enriched in Sb, the carriers could be the clay minerals. In surface water bodies, Sb could be carried predominantly in the particulate fraction, despite the popular belief of the opposite. An important point to consider is the transport of Sb within the suspended particulate matter, not on its surface. In soils, many studies employed sequential extractions to show that Sb accumulates in the ‘residual’ fraction, without ever asking what the nature of this fraction is. Based on these facts (i.e., knowns), we have identified the unknowns regarding detrital Sb on our planet that should preferentially be addressed by future projects if our understanding is to improve.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 1","pages":"Article 126072"},"PeriodicalIF":0.0,"publicationDate":"2023-12-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S000928192300123X/pdfft?md5=5b374c85c88f0d7921a4375b8bbd3dcf&pid=1-s2.0-S000928192300123X-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139012846","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Zircon UPb and Hf isotope insights into the Mesoproterozoic breakup of supercontinent Columbia from the Sausar Belt, Central Indian Tectonic Zone","authors":"Swayoma Bose ,&nbsp;R. Anand ,&nbsp;Joseph D'Souza ,&nbsp;Michael Hartnady ,&nbsp;Chris Kirkland ,&nbsp;Ellen Kooijman","doi":"10.1016/j.chemer.2023.126054","DOIUrl":"10.1016/j.chemer.2023.126054","url":null,"abstract":"<div><p>Credible records of rifting and associated sedimentation and granitoid magmatism coinciding with the Columbia breakup event are not common in the Precambrian Indian continent. We report a 1322 ± 3 Ma concordia age for magmatic zircons from the granitoid rocks of the Sausar mobile belt, Central Indian Tectonic Zone (CITZ). The rocks exhibit geochemical characteristics of A-type granitoid rocks and were generated by the dehydration melting of shallow crust in an extensional tectonic setting. The predominantly negative ε_Hf(t) values and partial melting modelling imply their origin by the reworking of pre-existing granitoid crust. T_DM2 (Hf) model ages for these rocks range from 2856 Ma to 1885 Ma suggesting a prolonged period of crustal evolution and reworking of Archean to Paleoproterozoic basement rocks. The temperature for magma generation, determined from the calculated zircon saturation temperature of 874.2 °C is suggestive of melting of a thinned crust that was heated by the upwelling asthenosphere in an extensional tectonic setting. The obtained ages provide evidence for the existence of an extensional event during mid-Mesoproterozoic coinciding with the Columbia breakup event. The extension could also be argued as a local event related to far-field stresses generated due to the ca. 1.6 to 1.5 Ga subduction-collision event at the plate margin farther to the north of the studied region of the CITZ. The recrystallized margins of zircon grains yield ²⁰⁷Pb/²⁰⁶Pb ages between 0.95 Ga and 1.0 Ga implying their alteration during a metamorphic event that can be identified with the final amalgamation and stabilization of the northern and southern Indian blocks along the CITZ, coinciding with the Rodinia assembly, during which the regional structural fabric developed.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 1","pages":"Article 126054"},"PeriodicalIF":0.0,"publicationDate":"2023-12-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281923001058/pdfft?md5=28b86ea30b03c44b3bf4f8c22b1e157e&pid=1-s2.0-S0009281923001058-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139027699","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Chemical and boron isotope composition of tourmaline from Koktokay pegmatite, Altay Orogenic Belt, Northwest China: Implications for metallogenic mechanism and prospecting indicator for rare-metal pegmatites","authors":"Beiqi Zheng ,&nbsp;Meihua Chen ,&nbsp;Yuyang Zhang","doi":"10.1016/j.chemer.2023.126071","DOIUrl":"10.1016/j.chemer.2023.126071","url":null,"abstract":"<div><p>The metallogenesis of Li-rich pegmatites remains contentious and an innovative approach for exploring such deposits is needed. The well-known Koktokay pegmatites in the Altay Orogenic Belt exhibit various mineralization degrees and patterns. In this study, we conducted systematic elemental and boron isotope analyses on five tourmaline samples to decipher the metallogenic mechanism and prospecting indicators of rare metal pegmatites. KKTH2 and KKTH3 were collected directly from the magmatic stage and magmatic–hydrothermal stage of the No. 3 pegmatite, KKTH1 was collected from the Aikoz mine pit, and KKTH4 and KKTH5 were collected from a small operational mine near the No. 3 pegmatite. Unlike the No. 3 pegmatite, this mine produces gem crystals but lacks Li mineralization. All tourmalines belong to the alkali group, whereby KKTH1 and KKTH2 are classified as fluor-elbaite, whereas KKTH3 and KKTH4 are schorl. The tourmaline in KKTH5 shows high Al content (up to 45.30 wt%), classifying as mostly rossmanite–elbaite series, with minor amounts of olenite and liddicoatite.</p><p>A Rayleigh fractionation model yields a shift in △¹¹B value of 4.8‰ between Zone IV and VI involved more than just magma, as B-isotope fractionation between tourmaline and melt would be &lt;1‰ when temperature drop from 650 °C to 500 °C. It further indicates that different parts of No. 3 pegmatite may have originated from diverse sources.</p><p>After comparing the δ¹¹B values of tourmaline in this study with other fertile and barren pegmatite globally, we suggest that δ¹¹B values of tourmaline higher than −10‰ is a potentially useful indicator for Li-rich pegmatites because of the likely relationship with marine evaporite or carbonate rocks in the source. Furthermore, we propose that tourmaline with a V/Sc value lower than 1 and a Li/Sr value higher than 100 can be used as indicators for Li exploration. The extent of Li migration from magma into the hydrothermal stage and mineralized in the residual melt correlates with the salinity of magma, which may reasonably explain the less intense wallrock alteration near the No.3 pegmatite. This finding provides new insight into the use of trace elements and boron isotope composition as a guide for exploring Li-rich pegmatites.</p></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 1","pages":"Article 126071"},"PeriodicalIF":0.0,"publicationDate":"2023-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281923001228/pdfft?md5=cea5f383c9116d22d2be54d596ba4672&pid=1-s2.0-S0009281923001228-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138685066","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"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":"Fluid evolution and genesis of the Zhuanghuhe Au–Sb mineralization in the Duobaoshan orefield, Northeast China: Evidence from fluid inclusions and H–O–C isotopes","authors":"Han-wen Xue ,&nbsp;Ke-yong Wang ,&nbsp;Jian-zhen Geng ,&nbsp;Si-wen Fan ,&nbsp;Jun-chi Chen ,&nbsp;Xue Wang","doi":"10.1016/j.chemer.2023.126048","DOIUrl":"10.1016/j.chemer.2023.126048","url":null,"abstract":"&lt;div&gt;&lt;p&gt;The newly discovered Zhuanghuhe Au–Sb occurrence is located 20 km north of the famous Duobaoshan Cu–Mo deposit, it is the first gold–antimony deposit discovered in the Duobaoshan orefield. The hydrothermal quartz vein-type orebodies occur in the Middle Ordovician Duobaoshan Formation and are controlled by NNW and ENE compressional faults. Four mineralization stages are identified: stage I quartz + pyrite + arsenopyrite, stage II quartz + polymetallic sulfides, stage III quartz + stibnite, and stage IV quartz + calcite. Fluid inclusions (FIs) in quartz and calcite veins include six types: types I (two-phase aqueous), IIa (aqueous–carbonic; the volume of the carbon phase &lt;50 %), IIb (aqueous–carbonic; the volume of the carbon phase &gt;50 %, with more CO&lt;sub&gt;2&lt;/sub&gt; than CH&lt;sub&gt;4&lt;/sub&gt;), IIc (aqueous–carbonic; the volume of the carbon phase &gt;50 %, with more CH&lt;sub&gt;4&lt;/sub&gt; than CO&lt;sub&gt;2&lt;/sub&gt;), IIIa (carbonic, with more CO&lt;sub&gt;2&lt;/sub&gt; than CH&lt;sub&gt;4&lt;/sub&gt;) and IIIb (carbonic, with more CH&lt;sub&gt;4&lt;/sub&gt; than CO&lt;sub&gt;2&lt;/sub&gt;). FIs of stage I are types I, IIa, IIb and IIIa, with homogenization temperatures of 279–311 °C and salinities of 4.87–11.84 wt%, indicating a medium-temperature low-salinity immiscible NaCl–H&lt;sub&gt;2&lt;/sub&gt;O–CO&lt;sub&gt;2&lt;/sub&gt; fluid system. Stage II contains all FI types with final homogenization temperatures of 233–288 °C and salinities of 4.94–8.67 wt%, indicating a medium- to low-temperature low-salinity NaCl–H&lt;sub&gt;2&lt;/sub&gt;O–CO&lt;sub&gt;2&lt;/sub&gt;–CH&lt;sub&gt;4&lt;/sub&gt; system. FIs of stage III contain types I and IIa with homogenization temperatures of 193–240 °C and salinities of 3.85–6.63 wt%, belong to a low-temperature low-salinity NaCl–H&lt;sub&gt;2&lt;/sub&gt;O–CO&lt;sub&gt;2&lt;/sub&gt; ± CH&lt;sub&gt;4&lt;/sub&gt; system. FIs of stage IV contain only type I with homogenization temperatures of 158–212 °C and salinities of 2.56–4.01 wt%, indicating a NaCl–H&lt;sub&gt;2&lt;/sub&gt;O system. The H–O–C isotope data show that the NaCl–H&lt;sub&gt;2&lt;/sub&gt;O–CO&lt;sub&gt;2&lt;/sub&gt; fluids of stage I (δD = −98 to −105.7 ‰, δO&lt;sub&gt;H&lt;/sub&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;sub&gt;O&lt;/sub&gt; = 5.7 to 6.9 ‰, δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;CO&lt;/sub&gt;&lt;sub&gt;2&lt;/sub&gt; = −11.9 to −11.1 ‰) were derived from a magmatic system, the fluids of stage II (δD = −85.7 ‰, δO&lt;sub&gt;H&lt;/sub&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;sub&gt;O&lt;/sub&gt; = 2.8 ‰, δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;CO&lt;/sub&gt;&lt;sub&gt;2&lt;/sub&gt; = −14.2 ‰, δ&lt;sup&gt;13&lt;/sup&gt;C&lt;sub&gt;CH&lt;/sub&gt;&lt;sub&gt;4&lt;/sub&gt; = −32.5 to −31.9 ‰) were characterized by the addition of CH&lt;sub&gt;4,&lt;/sub&gt; which might have come from the reaction between the original ore-forming fluids and carbonaceous slate of the Duobaoshan Formation. The fluids in stage III (δD = −90.2 to −89.6 ‰, δO&lt;sub&gt;H&lt;/sub&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;sub&gt;O&lt;/sub&gt; = −9.1 to −6.1 ‰) and stage IV (δD = −110.6 to −96.3 ‰, δO&lt;sub&gt;H&lt;/sub&gt;&lt;sub&gt;2&lt;/sub&gt;&lt;sub&gt;O&lt;/sub&gt; = −13.0 to −12.6 ‰) were characterized by mixing of meteoric water. According to the geology, fluid inclusion and H-O-C stable isotope evidences, the initial magma-derived NaCl-H&lt;sub&gt;2&lt;/sub&gt;O-CO&lt;sub&gt;2&lt;/sub&gt; fluids were immiscible in stage I and then the process of mixing with CH","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"84 1","pages":"Article 126048"},"PeriodicalIF":0.0,"publicationDate":"2023-11-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0009281923000995/pdfft?md5=d8489e193925928a67b36ceba40c7655&pid=1-s2.0-S0009281923000995-main.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138520603","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}