Chemie Der Erde-Geochemistry最新文献

{"title":"Genesis of the Langwashan Fe deposit, NW China: Constraints from pyrite and magnetite geochemistry, and in-situ Rb-Sr dating","authors":"Yuanlin Chen ,&nbsp;Huan Li ,&nbsp;Wenting Jiang ,&nbsp;Majid Ghaderi ,&nbsp;Adi Maulana ,&nbsp;Liming Ouyang ,&nbsp;Kun Liu","doi":"10.1016/j.chemer.2025.126284","DOIUrl":"10.1016/j.chemer.2025.126284","url":null,"abstract":"<div><div>The Langwashan Fe deposit, with 80 million tons of proven iron ore reserves, is located in the eastern portion of the Tianshan orogenic belt, NW China. Previous research carried out detailed geological, geochemical, and geophysical studies on the deposit, while there are still different views on the ore genesis. In this study, electron probe micro-analysis and laser ablation (multi-collector) inductively coupled plasma mass spectrometry analysis of variable minerals in ore samples were conducted. Based on ore texture, in-situ biotite Rb<img>Sr dating, magnetite and pyrite composition, and mineral assemblage, the Langwashan Fe mineralization has been divided into two metallogenic periods: volcanic hydrothermal metallogenic period (∼344 Ma) and skarn metallogenic period (∼239 Ma). The Early Carboniferous mineralization is characterized by layered ore bodies, a narrow range of δ³⁴S values (+1.37 to +2.77 ‰), and low Co/Ni ratio in early pyrite (Py I), and high Ti, V, Cr, Ni, and Co contents in early magnetite (Mag I), showing single and deep origin for the fluid. In contrast, the Early Triassic mineralization has irregular-shaped ore bodies, higher contents of Si, Al, Mn, Mg, and Ca in late magnetite (Mag II), higher Co, Ni, As, and Cu contents, and a wider range of δ³⁴S values (−0.18 to +3.35 ‰) in late pyrite (Py II), indicating mixed origin for the fluid. Thus, we propose that the Langwashan Fe deposit is formed by the superposition of two types of mineralization. The Early Carboniferous Hongshishan inter-arc oceanic basin subducted beneath the southern Tarim plate, and the iron-bearing magma migrated along the volcanic channel and annular faults, forming the first period of layered Fe ore bodies together with the volcanic rock deposition. During the Early Triassic, a hidden intrusion was generated in an extensional environment in the region, interacting with surrounding rocks through metasomatism, forming superimposed skarn-type Fe ore bodies. The two periods of mineralization determined in Langwashan have great significance for further exploration and prospecting of Fe ore deposits in the Tianshan orogenic belt.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126284"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601372","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deciphering the magmatic evolution of the Hyblean Cretaceous volcanism (SE Sicily, Italy): New geochemical, isotopic and noble gas analyses","authors":"M. Di Bella ,&nbsp;D. Romano ,&nbsp;V. Volpi ,&nbsp;F. Italiano ,&nbsp;A. Correale ,&nbsp;M. Petrelli ,&nbsp;G. De Rosa ,&nbsp;A. Tripodo ,&nbsp;G. Sabatino","doi":"10.1016/j.chemer.2025.126289","DOIUrl":"10.1016/j.chemer.2025.126289","url":null,"abstract":"<div><div>The coupling of helium isotopes in fluid inclusions with conventional geochemical data provided a new perspective on the volcanic processes that took place during the Cretaceous in southern Sicily. Our new investigations reveal that during two distinct volcanic phases in the Late Cretaceous, magmas formed from low degrees of partial melting of a heterogeneous mantle source characterized by spinel lherzolite and varying garnet content. The collected samples, including lava flows, dikes, and sills, exhibit a wide range of rock types, from picritic basalts to hawaiites. Two different magma types were identified: one displaying a bell-shaped pattern akin to ocean island basalts (OIB) and another with an irregular pattern marked by positive spikes in Nb, K, Pb, Sr, Zr, and Ti. Strontium and Neodymium isotope compositions are weakly radiogenic, while the Pb isotope systematics show strong radiogenic values (²⁰⁶Pb/²⁰⁴Pb = 19.64–20.42; ²⁰⁷Pb/²⁰⁴Pb = 15.61–15.70; ²⁰⁸Pb/²⁰⁴ Pb = 39.26–39.98), corresponding to the mantle focal zone (FOZO) component. The observed ³He/⁴He ratios of 3.48 to 6.48 R_c/R_a in pyroxene fluid inclusions reflect the occurrence of pre-eruptive processes such as diffusion-induced fractionation or diffusive exchange taking place during magma residence in the crust. The ³He/⁴He ratios from 7.75 to 9.31 R_c/R_a in olivine crystals are typical of MORB-type basalts, and they likely represent the original signature of the mantle source. The olivine R_c/R_a values may indicate an interaction with recycled (U+Th)-poor lithologies or high ³He/⁴He materials in the upper mantle source. Furthermore, the ³He/⁴He isotope ratios of olivines differ from those determined in the same region for Plio-Pleistocene volcanic products, for which a common origin has been suggested in the majority of previous studies. In light of our findings, the hypothesis that the Hyblean Late Cretaceous and Plio-Pleistocene volcanics are part of a single magmatic suite should be reexamined. Overall, our results indicate that the evolution of those volcanic rocks was influenced by fractional crystallization and accumulation processes providing additional details on the mantle source that may have been overlooked in the past.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126289"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143808325","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Metamorphic evolution of south Indian granulites: New insights from in-situ U-Pb dating and Nd-Hf isotope fingerprinting of zircon, titanite, monazite, and apatite","authors":"J. Amal Dev,&nbsp;J.K. Tomson","doi":"10.1016/j.chemer.2025.126317","DOIUrl":"10.1016/j.chemer.2025.126317","url":null,"abstract":"<div><div>The Precambrian Southern Granulite Terrane (SGT) of south India is well known for the preservation of high to ultrahigh-temperature granulite facies metamorphic rocks, with their formation linked to the assembly of the East Gondwana supercontinent. Although the timing and duration of this Himalayan-scale collisional orogeny is well characterized, the peak to post-peak evolutionary history of these granulitic rocks is poorly understood. This study attempts to characterize the peak to post-peak metamorphic evolutionary history of south Indian granulites using in-situ accessory mineral geochronology and isotopic fingerprinting of a metapyroxenite sample collected from the central part of SGT. U<img>Pb dating of zircon and monazite from the sample constrains the timing of peak metamorphism at 560–550 Ma, while the timing of fluid activity and cooling was characterized using titanite (557 ± 2 Ma) and apatite (410 ± 3 Ma) dating. U<img>Pb ages recovered from available accessory phases, together with temperature estimates from trace element thermometry and closure temperature estimates, suggest variable and slow cooling rates for the studied granulite. On the other hand, Hf<img>Nd isotopic fingerprinting of zircon and titanite points to the involvement of slab-derived materials during peak metamorphism, providing new evidence for melt/fluid-assisted metamorphism in the area.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126317"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144662248","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Melting experiments of an L6 ordinary chondrite: Implications for the formation of alkali-rich achondrites","authors":"S. Iannini Lelarge ,&nbsp;M. Masotta ,&nbsp;L. Folco ,&nbsp;T. Ubide ,&nbsp;M.D. Suttle ,&nbsp;L. Pittarello","doi":"10.1016/j.chemer.2025.126293","DOIUrl":"10.1016/j.chemer.2025.126293","url":null,"abstract":"<div><div>We conducted high-pressure (1 GPa) melting experiments (1100–1400 °C) on the equilibrated ordinary chondrite DAV 01001 (L6) to investigate partial melting scenarios of planetary embryo in the early solar system. At 1100 °C, no melting of the silicate phase is observed, and the initial chondritic texture is preserved, but the metallic-sulphidic phases formed two immiscible Fe–Ni and S-rich liquids. Melting of silicate minerals began at 1200 °C, progressing from plagioclase to high-Ca and low-Ca pyroxene and olivine. As melting advanced, the formation of new olivine and low-Ca pyroxene resulted in the production of trachy-andesitic melt at 1200 °C, basaltic trachy-andesitic melt at 1300 °C, and andesitic melt at 1400 °C. These silicate melts have chemical similarities with some anomalous achondrites (e.g., GRA 60128/9). At the same time, minerals of new formation resemble those of primitive achondrites (e.g., brachinites, ureilites, IAB silicate inclusions, acapulcoites and lodranites). The rapid mineral-liquid re-equilibration suggests that basaltic liquids can form only above 1400 °C and that relatively high degrees of melting (&gt;20 %) and crystallisation are necessary to explain the observed diversity of achondritic lithologies. These findings suggest that partial melting and recrystallization processes within planetary embryos could have played a critical role in the early solar system, contributing to the early differentiation of planetary bodies and the diversity of achondritic lithologies, including (but not limited to) alkali-rich achondrites.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126293"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143873763","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mineralogical, fluid inclusion, and stable isotope constraints on the genesis of Keban PbZn skarn deposit, southeast Anatolia","authors":"Ece Kırat ,&nbsp;Halim Mutlu","doi":"10.1016/j.chemer.2025.126326","DOIUrl":"10.1016/j.chemer.2025.126326","url":null,"abstract":"<div><div>The Keban Pb<img>Zn deposit is located in the Elazığ district, southeastern Turkey and hosted by the Permo-Triassic/Permo-Carboniferous Keban Metamorphics and the Late Cretaceous-Paleocene Keban Magmatics. Mineralization develops as disseminated, veins and massive types of ore within alkali syenite porphyry, sericite-chlorite banded calc-schist and dolomitic limestone.</div><div>Three paragenetic stages of skarn formation and ore deposition are recognized in the Keban Pb<img>Zn deposit: prograde (stage I), retrograde-sulfide (stage II), and supergene (stage III). The endoskarn forming a narrow zone is composed of grossular (Grt 1), Fe-rich grossular (Grt 2) and andradite (Grt 3) with diopside and plagioclase. The exoskarn comprises grossular (Grt 4), pyroxene and vesuvianite. Ore minerals include galena, sphalerite, chalcopyrite, magnetite, hematite, molybdenite, and pyrite accompanied in small quantities by pyrrhotite, arsenopyrite, manganese oxides, native gold, and sulfosalts. Mineral chemistry of garnets suggests that Grt 1 precipitated under a low water/rock (W/R) ratio and relatively reduced conditions. Grt 2 with strong oscillatory zoning and Grt 3 with high Fe³⁺ contents were formed under infiltration metasomatism with high W/R ratios. When the water–rock intereaction was decreased, Grt 4 and vesuvianite were affected by Al-bearing residual metasomatic fluids that are derived from calc-schist under reduced conditions.</div><div>Depletion of δ¹³C and δ¹⁸O in skarn calcites is largely controlled by hydrothermal fluid infiltration and meteoric water influx. Microthermometric measurements support that magmatic fluids comprising the stage I (473 to 572 °C; 11.9 wt% NaCl eq.) were sequentially mixed with meteoric waters of stage II (230 to 524 °C; 0.8.-6.6 wt% NaCl eq). Based on FI trapping pressures and depths of the boiling system, the mineralization developed after boiling during the retrograde stage in a shallow environment characterized by low to moderate temperatures and low salinities, within the pressure and depth range of ∼100–500 bar and &lt; 1.5 km, respectively. δ³⁴S values of sulfide minerals are between −8.5 and + 2.1 ‰ indicating that ore-forming fluids and metals originated principally from a magmatic-hydrothermal source. High Fe, Mn and Ga contents of sphalerites might point to deposition at low to moderate temperature conditions and trace element concentrations imply that mineralization took place at distal part of the skarn system.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126326"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144912510","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenesis and tectonic significance of ∼1.6 Ga and ∼ 0.5 Ga A-type granite magmatism in the Assam-Meghalaya Gneissic Complex (NE India): Insights from geochronology, geochemistry and Sr-Nd isotopes","authors":"Rahul Nag ,&nbsp;H. Hrushikesh ,&nbsp;Nathan Cogné ,&nbsp;Bivin G. George ,&nbsp;Darius J.M. Thabah ,&nbsp;N. Prabhakar","doi":"10.1016/j.chemer.2025.126265","DOIUrl":"10.1016/j.chemer.2025.126265","url":null,"abstract":"<div><div>The widespread granite magmatism in the Assam-Meghalaya Gneissic Complex (AMGC) is crucial for understanding its tectono-magmatic evolution of NE India. This study presents geochemical and Sr-Nd isotopic data along with U-Pb zircon and U-Th-total Pb monazite ages of granites from western, central and eastern parts of the AMGC. Zircon U-Pb dating reveals two distinct episodes of granite magmatism during 1617–1603 Ma and 540–497 Ma. Geochemically, the ∼1.6 Ga and ∼ 0.5 Ga granites exhibit high SiO₂, Na₂O + K₂O, and moderate to low CaO and MgO contents. These granites show high Ga/Al ratios and display enrichment in large-ion lithophile elements (LILEs) relative to high field strength elements (HFSE). The ∼1.6 Ga and ∼ 0.5 Ga granites are classified as A-type granites that were emplaced in post-collisional extensional tectonic setting. The ∼1.6 Ga granites show variable Nd composition [εNd(t) = 0.4 to −3.9] with Nd model ages (T_DM) of 2.6–2.2 Ga, indicating that these granites were derived from the partial melting of juvenile underplated mafic lower crust. In contrast, the ∼0.5 Ga granites show uniform negative εNd(t) values of −10.8 to −12.1 and younger Nd model ages (T_DM) of 2.2–1.7 Ga, suggesting that these granites were derived from the partial melting of the Paleoproterozoic to Mesoproterozoic continental crust beneath the AMGC. The two episodes of A-type granite magmatism in AMGC at ∼1.6 Ga and ∼ 0.5 Ga mark the collisional imprints of Columbia and East Gondwana assemblies, respectively.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126265"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143632046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry, zircon UPb ages and Hf isotopes of Tra Bong granitoid from Kontum massif, central Vietnam, and its petrogenetic significance","authors":"Nguyen Huu Trong ,&nbsp;Pham Trung Hieu ,&nbsp;Pham Minh ,&nbsp;Bui Kim Ngoc ,&nbsp;Nguyen Dinh Luyen ,&nbsp;To Xuan Ban","doi":"10.1016/j.chemer.2025.126295","DOIUrl":"10.1016/j.chemer.2025.126295","url":null,"abstract":"<div><div>Tra Bong granitoid, distributed in the northern area of Kontum, primarily consists of diorite and granodiorite. The main rock-forming minerals contain plagioclase (26–60 %), K-feldspar (8–22 %), quartz (15–33 %), biotite (3–7 %), and hornblende (9–20 %). The accessory minerals are sphene, apatite, zircon, and magnetite. Tra Bong granitoids are characterized by SiO₂ (58.83–65.8 %), total alkali (6.68–8.03 %), and A/CNK (0.80–0.90). They show high-K and relative enrichment of large-ion lithophile elements (Sc, Rb, and K), and the relative depletion of Nb, Ta, and Ti elements. The P₂O₅ content decreases with increasing SiO₂, and Th increases with Rb, a trend typical of I-type granites. All observed petrographic and geochemical characteristics suggested that the Tra Bong granitoid is typical of the I-type granite, formed in a subduction zone. The U<img>Pb crystallization age ranges from 254.5 to 255.0 Ma, coinciding with the Late Permian-Early Triassic magmatic activity, which was previously reported in the Truong Son belt. The ε_Hf(t) value together with the Hf zircon model ages (T_DM2) ranges from 1011 to 1159 Ma. The Tra Bong granitoid is a result of partial melting Mesoproterozoic mafic-intermediate magmatic rocks, with a minor amount of metasedimentary crust remelting. In conjunction with other Permian-Triassic magmatic rocks along Truong Son belt and the Song Ma suture, the Tra Bong granitoid represents magmatic activity related to subduction-collision of the Indochina and South China blocks and closure of Paleo-Tethys Ocean in the Late Permian-Early Triassic, along the Song Ma suture.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126295"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143895853","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Positive Matrix Factorization (PMF) based on geochemical data for revising geological map in semi-desert covered terrains: A case study from a map sheer of Urat Rear Banner, Inner Mongolia, China","authors":"Yanling Sun,&nbsp;Xueqiu Wang,&nbsp;Hanliang Liu,&nbsp;Jian Zhou,&nbsp;Mingjun Xie","doi":"10.1016/j.chemer.2025.126299","DOIUrl":"10.1016/j.chemer.2025.126299","url":null,"abstract":"<div><div>There is a significant deficiency for geological mapping in the Gobi Desert terrain covered by wind-blown sands with limited exposure of bedrock. Major and minor element data of stream sediments using Positive Matrix Factorization (PMF) analysis were employed to interpret the geological signatures from the Urat Rear Banner, a representative area of the Gobi Desert terrains. Six primary geochemical factors (M1, M2, M3, T1, T2, T3), corresponding to geological units were extracted from 8 major elements and 18 minor elements. Notably, the SiO₂-Al₂O₃-K₂O-and Pb-Ba-Th-Be-Y-Li-U combinations (primarily M1 and T1) are associated with felsic intrusive rocks, complex metamorphic rocks, and sandstones. The MgO-Fe₂O₃-TiO₂, Cu-Mn-Zn-Co combinations (primarily M2 and T2) indicate basic intrusive rocks, complexes. The Al₂O₃-Na₂O-CaO, Sr-Co-Mn-P-Cu-Zn-Ba (primarily M3 and T3) are related to neutral intrusive bodies (or complexes) and marble (or limestone). Additionally, the study utilizes standardized M1, M2, and M3 factor scores to refine the delineation of lithological boundaries of magmatic rocks. The findings highlight the effectiveness of the PMF method coupled with stream sediment geochemistry, as a powerful tool for extracting geological signatures. This approach offers valuable insights into geological information extraction in Gobi Desert terrains, particularly for identifying and delineating lithological boundaries within magmatic rock formations.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126299"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143911632","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenetic and dynamic links between felsic and mafic magmas: Insights from the Devonian post-collisional magmatism in the North Qaidam terrane, western China","authors":"Denghui Chen ,&nbsp;Hao Wu ,&nbsp;Dongdong Yan ,&nbsp;Chengxiang Li ,&nbsp;Huajun Wen ,&nbsp;Fuhao Xiong","doi":"10.1016/j.chemer.2025.126298","DOIUrl":"10.1016/j.chemer.2025.126298","url":null,"abstract":"<div><div>Felsic-mafic magmatism in post-collisional settings provides valuable insights into the growth and evolution of continental crust, but the interaction processes between felsic and mafic magmatism and their implications for the diversity of igneous rocks remain controversial. This study presents petrological, geochronological, geochemical, and Sr-Nd-Hf isotopic analyses of the Mohe felsic-mafic complex, a rare post-collisional composite pluton in the North Qaidam terrane (western China), to investigate the petrogenetic and dynamic links between felsic and mafic magmas. The results reveal that the Mohe complex, consisting of granite, granodiorite, diorite, and appinites, is genetically related and formed between ca. 408–400 Ma. The granites and granodiorites are classified as I-type and are characterized by enriched isotopic signatures, including whole-rock (⁸⁷Sr/⁸⁶Sr)ᵢ values of 0.714584–0.728765, εNd_{(400 Ma)} values of −7.75 to −5.56, and zircon εHf(t) values of −3.04 to −0.28. These rocks were primarily derived from partial melting of Mesoproterozoic to Paleoproterozoic crustal materials, with minor input from a mantle source. The appinites display depleted zircon Hf isotopic compositions (εHf(t) = +4.10 to +5.71), indicating derivation from an OIB-like depleted mantle source that was metasomatized by subducted slab-derived melts. The diorites show weakly enriched isotopes ((⁸⁷Sr/⁸⁶Sr)_<em>i</em> = 0.709358–0.713210, εNd_{(400 Ma)} = −2.99 to −2.73, εHf(t) = −1.35 to +3.54), and were formed by the mixing of 80–90 % appinitic magma with 10–20 % crustal-derived granitic magma. Our findings suggest that the Early Devonian magmatism in the North Qaidam terrane was likely driven by slab break-off-related geodynamic processes, where crust-mantle magma mixing, along with mineral accumulation and fractional crystallization, played a key role in the petrological diversity of the continental crust in a post-collisional extensional setting.</div></div>","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126298"},"PeriodicalIF":2.6,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143911631","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neotethyan Jurassic supra-subduction ophiolitic complex with Triassic subducted sole: Mineral chemistry, sole P–T estimates, and U/Pb geochronology of an intra-oceanic domain (Central Dinarides, Bosnia and Herzegovina)","authors":"Marián Putiš ,&nbsp;Ondrej Nemec ,&nbsp;Samir Ustalić ,&nbsp;Dražen Balen ,&nbsp;Jiří Sláma ,&nbsp;Elvir Babajić ,&nbsp;Ján Soták ,&nbsp;Peter Ružička ,&nbsp;Sergii Kurylo ,&nbsp;Petar Katanić","doi":"10.1016/j.chemer.2025.126263","DOIUrl":"10.1016/j.chemer.2025.126263","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The ophiolitic blocks in the Cretaceous mélanges of the Central Dinaridic Ozren and Borja–Mahnjača massifs revealed two different evolutionary periods of the Neotethys Ocean: (1) A pre-subduction Middle Triassic to Early Jurassic spreading, and (2) Late Early Jurassic (Toarcian) intra-oceanic subduction and the formation of late Early to Middle Jurassic supra-subduction ophiolitic complex. The goal of this paper is to report the rebuilding of the upper oceanic plate mid-ocean ridge (MOR) abyssal to supra-subduction zone (SSZ) ophiolites. This process is indicated by an increase of Cr# in spinel (Spl) from ~0.1 to 0.6, exceptionally to 0.75 in peridotite, the Mg# decrease in orthopyroxene1 (Opx1) from ~89–91.5 in abyssal to ~86–88 in SSZ types of peridotites, as well as with overall Al and Ti decrease in pyroxene1. However, refertilization was rarely detected in newly formed Cpx, Opx, and Spl (2, 3) generations. A relatively thin, amphibole (Amp)-rich gabbro-dolerite layer of this Jurassic Ozren–Borja–Mahnjača ophiolitic complex may have formed in a nascent fore-arc, slow-spreading ridge. Remnants of Middle Triassic oceanic crust was dated at 242 ± 1 Ma from a relic zircon population in a trondhjemite (remelted plagiogranitic) dyke of the sole eclogite by LA–ICP–MS U–Pb method, whereas its main zircon population of 176 ± 2 Ma constrains the metamorphic-anatectic recrystallization age of the dyke in eclogite. Another trondhjemitic dyke gave a magmatic crystallization zircon age of 216 ± 6 Ma with rare inherited Middle Triassic (240–230 Ma) zircon. The clinopyroxene (Cpx)–garnet (Grt)–rutile (Rt) eclogites indicate the intra-oceanic subduction of the Triassic oceanic crust to about 50 km, which was estimated from Perple_X modelling of 1.5–1.6 GPa and 860–870 °C. However, a sole skarn achieved 950 °C at 0.5 GPa. Metamorphic zircon of a sole eclogite yielded 173 ± 2 Ma (D1 subduction event at ~180–175 Ma). Partial melting of the subducted slab and the mantle wedge initiated the transition of MOR to SSZ type ophiolites. The late Early Jurassic lower oceanic crust was dated on a gabbro (178 ± 1 Ma, zircon) and plagiogranite (177 ± 1 Ma, zircon). The Spl lherzolite, harzburgite, and dunite are crosscut by early Middle Jurassic Cpx–plagioclase (Pl) and Amp–Cpx–Pl gabbro, gabbro-pegmatite, leuco-gabbro (174 ± 1 Ma, zircon), and dolerite (174 ± 5 Ma, apatite) dykes, all suggesting an advanced evolutional stage and a shallower level of ophiolites due to extension and the deeper mantle melting in the SSZ setting. Inferred slab roll-back enhanced the sole exhumation (D2) between ~175–171 Ma followed by obduction of the upper plate, hot mantle rocks over the exhuming sole (the zircon age of 171 ± 0.5 Ma at D3 ~171–168 Ma from the sole Grt–pargasite–ilmenite skarn). The outboard-directed compression led to the formation of the rear fore-arc basin upper oceanic crust basalt–radiolarite section (~170–164 Ma) sited on the upper plate lower oceanic crust. ","PeriodicalId":55973,"journal":{"name":"Chemie Der Erde-Geochemistry","volume":"85 3","pages":"Article 126263"},"PeriodicalIF":2.9,"publicationDate":"2025-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145060177","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}