Lithos最新文献

{"title":"Enrichment and hydrothermal remobilization of HREE in the Dabu muscovite granites, South China: Insights from the REE-bearing minerals","authors":"Heng Wang ,&nbsp;Wubin Yang ,&nbsp;Zhiwei Bao ,&nbsp;Hongping He ,&nbsp;Wei Tan ,&nbsp;Xiaoliang Liang ,&nbsp;Jianxi Zhu","doi":"10.1016/j.lithos.2025.108392","DOIUrl":"10.1016/j.lithos.2025.108392","url":null,"abstract":"<div><div>Understanding the enrichment of HREE in granite bedrock is crucial for deciphering the genesis of ion-adsorption HREE deposits. The Dabu muscovite granites that served as the bedrock of an ion-adsorption HREE deposit in South China underwent extreme fractional crystallization and hydrothermal alteration and are significantly enriched in HREE. In this study, we conducted detailed mineralogical and geochemical analyses of REE-bearing minerals from the Dabu muscovite granites to investigate the role of magmatic and hydrothermal processes in HREE enrichment and remobilization. The rock-forming minerals in the Dabu muscovite granites have extremely low REE contents (&lt; 7 ppm), constituting approximately 1% of whole rock REE. Consequently, REE in bedrock is predominantly hosted in REE-bearing accessory minerals. During the early crystallization stage of the Dabu muscovite granites, HREE in highly evolved melts were incorporated into garnet and zircon-I, while LREE were scavenged by monazite. With the evolution of magma, HREE became enriched in volatile-rich residual melts due to the crystallization of large amounts of rock-forming minerals. Thus, abundant HREE-rich minerals, such as samarskite-(Y), xenotime, zircon-II, gadolinite-(Y), thorite, and uraninite, formed in the late stage of magmatic evolution. Extensive hydrothermal activities in the Dabu muscovite granites led to the alteration of some precursor REE-bearing minerals. In addition to the hydrothermal alteration of zircon, monazite also underwent variable alteration in the hydrothermal stage. The released LREE were not transported out from the local alteration systems, and subsequently reprecipitated as synchysite-(Ce) or bastnaesite-(Ce) in contact with the altered monazite. Significantly, abundant xenotime and samarskite-(Y) grains underwent intensive alteration primarily through a fluid-mediated coupled dissolution-reprecipitation process, leading to the leaching of substantial HREE into hydrothermal fluids. A fraction of the released HREE immediately deposited synchysite-(Y) around them, while the remaining HREE were transported over a long distance and eventually precipitated as synchysite-(Y) veinlets and distal HREE-fluorocarbonates. The metasomatic fluids exsolved from the granitic magma were rich in F⁻ and CO₃²⁻, and could alter REE minerals and transport REE. Therefore, hydrothermal alteration not only enriched HREE in granites, but also leached out HREE from refractory HREE minerals to form weathering-prone HREE-fluorocarbonates, which are highly conducive to the formation of ion-adsorption HREE deposits. Our study also provides compelling evidence for the higher mobility of HREE and the relatively limited mobility of LREE during the post-magmatic alteration processes.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108392"},"PeriodicalIF":2.5,"publicationDate":"2025-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840421","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemical and isotopic constraints on Triassic Lujing granites, South China Craton: Implications for petrogenesis and tectonic setting","authors":"Weidong Ren ,&nbsp;Huan Li ,&nbsp;Annan Guan ,&nbsp;Thomas J. Algeo ,&nbsp;Shuang Gao ,&nbsp;Haojie Cao ,&nbsp;Pingning Ouyang ,&nbsp;Qianlin Wang ,&nbsp;Fangchao Yan","doi":"10.1016/j.lithos.2025.108386","DOIUrl":"10.1016/j.lithos.2025.108386","url":null,"abstract":"<div><div>The South China Craton (SCC) hosts numerous W-Sn-U multi-metallic deposits that are related to Mesozoic granitic intrusions, including the Lujing uranium orefield in the central Zhuguangshan Complex. It is uncertain, however, whether the different types of granite in this complex have a common material source and evolutionary history. Hence, zircon U<img>Pb ages, whole-rock geochemistry, and Nd isotopes of the Triassic granites in the Lujing region were analyzed with a view to resolving these issues. Two groups of Triassic granite were identified, both being S-type granites and having overlapping A/CNK (Group 1: 1.07–1.75, Group 2: 1.09–1.88) and Rb/Sr values (Group 1: 5.30–30.00, Group 2: 1.81–6.92). Zircon U<img>Pb dating yielded ages of 236.4–233.9 Ma for Group 1 and 236.0–235.2 Ma for Group 2 granites. Group 1 exhibits εNd(t) of −13.0 to −12.5 with T_DM2 ages of 1872–1838 Ma, and εHf(t) of −13.1 to −8.5 with T_DM2 ages of 2099–1813 Ma. The corresponding values for Group 2 are εNd(t) of −13.3 to −11.7 with T_DM2 ages of 1896–1773 Ma, and εHf(t) of −16.5 to −5.9 with T_DM2 ages of 2312–1639 Ma, indicating similar material sources derived from Precambrian clay-rich metapelites in the deep upper crust. Although Group 1 and 2 granites show similar formation ages and material sources, the Group 2 granites exhibit a lesser degree of fractional crystallization, implying that they represent the major intrusion, whereas the Group 1 granites represent a complementary intrusion. Both granite groups are syncollisional granites produced by tectonic amalgamation of the South China and Indochina cratons. The relationship of major and complementary intrusions was previously identified only in Jurassic granites of the SCC, but the results of the present study suggest that this relationship was a common phenomenon across the study region.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108386"},"PeriodicalIF":2.5,"publicationDate":"2025-12-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840422","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Segmented Paleo-Tethys subduction and its role in driving Triassic magmatism within the Elashan Tectonic-Magmatic Belt, northern Tibetan Plateau","authors":"Tengfeng Miao ,&nbsp;Xu Zhao ,&nbsp;Jan Marten Huizenga ,&nbsp;Xiaolong Li ,&nbsp;Lianxin Lai ,&nbsp;Bin Li ,&nbsp;Hongtao Zhu ,&nbsp;Xinxin Zhang ,&nbsp;Hongzhi Zhou ,&nbsp;Junhao Wei","doi":"10.1016/j.lithos.2025.108387","DOIUrl":"10.1016/j.lithos.2025.108387","url":null,"abstract":"<div><div>Segmented subduction redirects mantle flow and melt, controlling orogenic magmatism and deformation. The Elashan Tectonic-Magmatic Belt (ETMB) lies between the East Kunlun (EKOB) and West Qinling (WQOB) orogenic belts, linked to Triassic Paleo-Tethys subduction. We present geological, geochemical, zircon U<img>Pb geochronological, and Hf-Sr-Nd isotopic data from Triassic ETMB granites, supplemented by data from the EKOB and WQOB. The ca. 244 Ma Shiduolong granodiorites display high MgO and enriched ε_Hf (t) (−6.8 to −3.6) values, indicating mixing between crust-derived felsic and mantle-derived mafic melts. The ca. 229 Ma Huda diorites, with low Sr/Y and depleted ε_Hf (t) (−3.0 to -0.7) values, originated from a shallow juvenile lower crust at high-temperature conditions. The Saishitang complex comprises ca. 220 Ma quartz diorite porphyrites and granodiorites, plus ca. 215 Ma diorites. The quartz diorite porphyrites exhibit high-Mg andesite affinities and linear (⁸⁷Sr/⁸⁶Sr)_i-SiO₂ correlation, suggesting partial melting of enriched mantle peridotites with assimilation and fractional crystallization. The granodiorites display high-Mg adakitic characteristics formed by melting of delaminated lower crust. The diorites are geochemically similar to the Huda diorites but exhibit more enriched ε_Hf (t) values (ranging from −9.2 to −4.8), suggesting an older and deeper crustal source. Notably, the 240–230 Ma ETMB granitoids record high ε_Hf (t) values and a depletion trend, which is in contrast with the concurrent enrichment in the adjacent EKOB and WQOB. This implies that, although they were in a contiguous subduction setting, unique dynamics related to the asthenosphere upwelling occurred in the ETMB, related to a slab window between the EKOB and WQOB. The inferred slab window was likely produced by slab tearing, controlled by slab segmentation in response to an along-strike transition from slab rollback in the WQOB to a relatively low-angle subduction regime in the EKOB.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108387"},"PeriodicalIF":2.5,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840418","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"New insights on Madeira-Tore Rise post-Atlantic breakup magmatism: Sr-Nd-Hf-Pb isotopes and 40Ar/39Ar ages of Rugoso, Jo Cousin, and Pico Pia seamounts","authors":"Ana Rita Rosa ,&nbsp;João Mata ,&nbsp;Luísa Pinto Ribeiro ,&nbsp;Hiroshika Sumino ,&nbsp;Vera Assis Fernandes ,&nbsp;Pedro Madureira","doi":"10.1016/j.lithos.2025.108385","DOIUrl":"10.1016/j.lithos.2025.108385","url":null,"abstract":"<div><div>The Central East Atlantic Ocean and its Iberian and Moroccan margins have been affected by intense magmatic activity from the Cretaceous onward. In this study, we present new major and trace element, isotopic (Sr-Nd-Hf-Pb), and geochronological (⁴⁰Ar/³⁹Ar) data for three seamounts (Rugoso, Jo Cousin, and Pico Pia) located on top of the Madeira-Tore Rise (MTR), a major ∼1000 km long physiographic feature in the Central East Atlantic Ocean. The alkaline composition of these volcanoes and their ages (0.07–1.39 Ma) contrast with the mid-ocean ridge basalt (MORB) affinity and the ∼125–130 Ma age of the underlying ridge. This defines the MTR as a complex structure, initially formed during the Atlantic breakup and later overprinted by intraplate magmatism. The reported seamounts are distinct with respect to their degrees of SiO₂-undersaturation (Jo Cousin being the least undersaturated) and magma evolution (reaching phonolitic compositions in Rugoso). Additionally, the studied lavas further increase the range of isotopic signatures previously observed for the post-breakup MTR volcanoes, reflecting their derivation from sources either with more time-integrated depletion (Jo Cousin: ε_Nd up to 10.27 and ²⁰⁶Pb/²⁰⁴Pb down to 18.427) or enrichment (Rugoso and Pico Pia: ε_Nd down to 4.26 and ²⁰⁶Pb/²⁰⁴Pb up to 20.256) in the most incompatible elements. These signatures can be interpreted in terms of the roles of HIMU and DMM mantle components, as well as different proportions of eclogite/pyroxenite and peridotite mantle lithologies in the magma sources. Despite their similar ages and geographic proximity, Rugoso, Jo Cousin, and Pico Pia seamounts exhibit dual isotopic compositions, with Jo Cousin showing affinities with the Madeira Archipelago, and Rugoso and Pico Pia being isotopically comparable to lavas from the Canary Archipelago. However, considering their ages and geographic positions, these volcanic structures cannot be directly attributed to the activity of mantle plumes at the origin of such hotspot provinces. Instead, we propose that they were produced by independent, small-scale, and ephemeral secondary mantle upwellings that sampled compositional domains similar to those feeding the Madeira and Canary provinces within the Central East Atlantic Anomaly (CEAA), located at the topmost lower mantle.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108385"},"PeriodicalIF":2.5,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840423","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Contrasting melt evolution in a pegmatite system: Tourmaline evidence for spodumene vs. lepidolite mineralization in the Boam deposit, South Korea","authors":"Youseong Lee ,&nbsp;Woohyun Choi ,&nbsp;Youn-Joong Jeong ,&nbsp;Changyun Park","doi":"10.1016/j.lithos.2025.108390","DOIUrl":"10.1016/j.lithos.2025.108390","url":null,"abstract":"<div><div>This study examines the micro-texture and geochemistry of tourmalines to understand the differences between spodumene-bearing and lepidolite-bearing pegmatites in the Boam deposit, South Korea. Detailed electron microprobe analysis and laser ablation–inductively coupled plasma–mass spectrometry analysis of tourmalines from the border, wall, and core zones reveal a systematic compositional evolution from a Mg- and Fe-rich to a Li- and Al-rich composition toward the core zone across all orebodies, indicating a common fractionation trend. However, significant differences are observed between the two pegmatite types. Tourmalines from the lepidolite-bearing pegmatites exhibit higher B concentrations throughout all pegmatite zones. Additionally, core zone tourmalines from the lepidolite-bearing pegmatites contain significantly higher concentrations of high field strength elements (Nb, Ta, and Pb). They also exhibit lower Na/(Na + Ca) ratios, contrasting with the continuous increase in this ratio toward the core zone in the spodumene-bearing pegmatite, indicating different crystallization pathways. Texturally, the two pegmatite types show distinct differences, with core zone tourmalines from the lepidolite-bearing pegmatites exhibiting extensive hydrothermal alteration with fluid-origin muscovite and apatite precipitation along the fractures, contrasting with relatively unaltered tourmalines from the spodumene-bearing pegmatite. These textural differences are closely linked to Zn concentration patterns, which suggests that fluid exsolution occurred after core zone tourmaline crystallization in the spodumene-bearing orebody but preceded core zone formation in lepidolite-bearing orebodies, reflecting earlier volatile saturation. The earlier fluid saturation in the lepidolite-bearing pegmatites resulted in increased hydrothermal fluid activity during core zone crystallization, accounting for the extensive alteration textures. These findings demonstrate that the lepidolite-bearing pegmatites crystallized from significantly more evolved and volatile-enriched melts compared to the spodumene-bearing pegmatite. The distinct evolutionary trends observed in these two pegmatite types suggest that they likely formed through episodic extraction from a progressively evolving parental magma.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108390"},"PeriodicalIF":2.5,"publicationDate":"2025-12-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840420","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ambient pyroxenite mantle melting in the origin of Panjal-Qiangtang continental flood basalts: Implications for Early Permian Gondwana rifting and the birth of the Neo-Tethys","authors":"Ashutosh Pandey ,&nbsp;T. Pon Gayathri ,&nbsp;Irfan M. Bhat","doi":"10.1016/j.lithos.2025.108378","DOIUrl":"10.1016/j.lithos.2025.108378","url":null,"abstract":"<div><div>Understanding the source of basalt and the conditions under which magma is generated provides fundamental insight into the composition and thermal history of the Earth's mantle, crust-mantle interactions and the origin of mantle heterogeneities. The source lithology of continental flood basalts remains a contentious issue. We evaluate a compilation of geochemical data on the Early Permian (ca. 290 Ma) Panjal-Qiangtang continental flood basalts (PQ-CFB) to constrain their source lithology and estimate the temperature and pressure conditions during magma generation. Primitive basalts and mafic dykes (MgO &gt; 7.5 wt%) from the PQ-CFB exhibit low CaO content but elevated FeO/MnO and Zn/Fe ratios at equivalent MgO contents compared to the peridotite-derived melts. Their major element chemistry is consistent with experimental pyroxenite-derived melts, distinguishing them from melts of a peridotitic source. We propose that mantle pyroxenite significantly contributed to the origin of the Early Permian PQ-CFB, like the Late Permian Emeishan and the Early Jurassic Karoo continental flood basalts. Melting temperature and pressure estimates from this study indicate that the PQ-CFB were generated under ambient mantle conditions comparable to those at which mid-ocean ridge basalts form. This raises doubts in invoking a mantle plume origin for this magmatic province. We propose that the passive continental margin of northern Gondwana underwent extension due to tensional stresses under ambient mantle conditions, leading to voluminous flood basalt eruptions sourced from readily fusible pyroxenites. Our observations support the non-plume model for the break-up of the northern Gondwana margin and opening of the Neo-Tethys Ocean during the Early Permian.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108378"},"PeriodicalIF":2.5,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145880722","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Experimental melting of tin-enriched sedimentary protoliths: Implications for the formation of tin-specialized granites","authors":"Yongchao Liu ,&nbsp;Rolf L. Romer ,&nbsp;Christian Schmidt ,&nbsp;Bernd Wunder ,&nbsp;Christina Günter ,&nbsp;Jiankang Li ,&nbsp;Zhenyu Chen ,&nbsp;Fangyue Wang ,&nbsp;Jessica A. Stammeier ,&nbsp;Melanie J. Sieber","doi":"10.1016/j.lithos.2025.108384","DOIUrl":"10.1016/j.lithos.2025.108384","url":null,"abstract":"<div><div>Endogenic tin (Sn) mineralization is associated with peraluminous granites that are derived from partial melting of metasedimentary rocks. These melts commonly experienced extensive fractional crystallization. There is increasing evidence that the nature of the protoliths is essential for the formation of Sn-specialized granites. Whether a Sn-rich protolith can produce a Sn-specialized granite at a minor extent of fractionation or from a small source volume, however, remains a matter of debate. We performed fluid-absent melting experiments at 750–950 °C, 300 and 900 MPa, and at oxygen fugacity of ∼FMQ − 1.4 to ∼FMQ + 2.9 on a Sn-rich, feldspar-poor metasedimentary schist. Our experimental results show that feldspar-poor schists produce larger proportions of melt than feldspar-bearing metasedimentary rocks under similar <em>P</em>–<em>T</em> conditions. Because of the Sn-rich nature of the studied protolith, these melts have high Sn contents (&gt;2500 ppm), which implies that depending on Sn enrichment in the source even small intrusions may produce major mineralization. Apart from the Sn contents in the protoliths, the concentrations of Sn in melts are primarily a function of temperature, suggesting that efficient Sn mobilization requires high-temperature melting, which requires input of heat from the mantle. Our findings offer new insights into the origin of Sn-specialized granites and suggest a potential paradigm shift from “fractionation only” to “protolith is essential”. This change may also be relevant for the understanding of the genesis of other granite-related ore systems.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108384"},"PeriodicalIF":2.5,"publicationDate":"2025-12-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840419","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mantle depletion and melt-rock reaction revealed by olivine in Gakkel Ridge abyssal peridotites","authors":"Yang Xu ,&nbsp;Chuan-Zhou Liu ,&nbsp;Yin-Zheng Lin","doi":"10.1016/j.lithos.2025.108379","DOIUrl":"10.1016/j.lithos.2025.108379","url":null,"abstract":"<div><div>This study presents a comprehensive geochemical investigation of olivine from thirty abyssal peridotites from the Gakkel Ridge (Arctic Ocean) and five forearc peridotites from the New Caledonia ophiolite. By analyzing a suite of trace elements (Ca, Sc, Ti, Cr, Co, Ni, Zn, Y, Er, Tm, Yb, Lu) using high-precision LA-ICP-MS, we constrain the histories of partial melting, melt-rock reaction and subsolidus cooling recorded in these mantle residues. Olivines in New Caledonia forearc peridotites are depleted in HREE, Y, and Ti and have higher Ca/Ti ratios. In contrast, Gakkel Ridge abyssal peridotite olivines show the opposite signatures, consistent with their lower partial melting degrees. Elevated Ti and Yb contents coupled with low Ni/Co ratios in some olivines suggest modification by melt-rock reactions in both tectonic settings. Furthermore, closure temperatures recorded by both pyroxene-based and olivine-based thermometers are higher in Gakkel Ridge peridotites. These distinct geochemical fingerprints between abyssal peridotites and forearc peridotites not only highlight the different melting and metasomatic histories in mid-ocean ridge versus forearc settings but also establish olivine composition as a robust tracer for unequivocally discriminating the tectonic origins of ophiolitic peridotites.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108379"},"PeriodicalIF":2.5,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Lower Jurassic heterogeneous arc magmatism sheds light on the early stages of Neotethyan subduction in the Zagros orogenic belt (Esfandaghe area, SE Iran)","authors":"Mahbubeh Arabzade Baniasadi ,&nbsp;Habibollah Ghasemi ,&nbsp;Clothilde Minnaert ,&nbsp;Samuel Angiboust ,&nbsp;Aitor Cambeses ,&nbsp;Mehdi Rezaei Kahkhaei ,&nbsp;Johannes Glodny ,&nbsp;Lambrini Papadopoulou","doi":"10.1016/j.lithos.2025.108382","DOIUrl":"10.1016/j.lithos.2025.108382","url":null,"abstract":"<div><div>Lower Jurassic Abshour gabbro (178.3 ± 2.3 Ma and 187.2 ± 4.7 Ma) and Gowd-e-Howz granitoid (180.3 ± 1.3 and 178.9 ± 1.2 Ma) intrusions are exposed in the Esfandaghe area, Kerman province, SE Iran, as part of the southern Sannandaj-Sirjan metamorphic-magmatic zone (SSMMZ). These igneous bodies intruded into Upper Paleozoic-Triassic metamorphic rocks. The Gowd-e-Howz granitoid stock primarily consists of coarse to medium-grained granodiorite, with subordinate diorite, quartz diorite, quartz monzonite, granite, and aplitic-pegmatitic alkali granitic veins, accompanied by a small amount of gabbro and cut by middle Jurassic quartz monzonitic dykes. Mafic microgranular/microgranitoid enclaves (MMEs) of various sizes are present in the stock. The granitoid rocks exhibit a low to medium-K calc-alkaline nature, with enrichment in large ionic lithophile elements (LILEs) such as Rb, Ba, K, and Ce, alongside a depletion in high field strength elements (HFSEs) like Ti, Y, Nb, and Zr. The REE patterns display relatively parallel, smooth LREE-enriched chondrite normalized trends, indicating the influence of fractional crystallization, along with contamination, assimilation, and magma mixing/mingling processes in magma evolution. The type of lithologic association (gabbro, diorite, granodiorite, granite), the presence of MMEs, the prevalence of Fe-Mg silicate minerals (Cpx, Amph. Bt), and the plots of the geochemical data on various whole rock and mineral chemistry discriminant diagrams suggest that the Gowd-e-Howz granitoid stock possesses characteristics of metaluminous to slightly peraluminous, calc-alkaline, magnetite series, I-type granitoids typical of continental volcanic arc settings formed from partial melting of a subducting oceanic slab and lower crust (C_I-type granite) in an active continental margin subduction zone. In this model, the initiation of NE-dipping subduction of the Zagros Neotethyan oceanic lithosphere beneath the Central Iran continental lithosphere during the Late Triassic-Early Jurassic (≈180 Ma) may have accounted for the generation of mafic and felsic magmas in the Andean-type arc magmatism of the SSMMZ, where gabbroic and granitoid plutons formed and intruded in metamorphic country rocks. Thermobarometric calculations indicate that magma storage, plumbing, and fractionation occurred at three levels (40–45, 14–16, and 5–7 km) in the base, middle, and upper continental crust, respectively.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108382"},"PeriodicalIF":2.5,"publicationDate":"2025-12-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145840426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Geochemistry and UPb zircon ages of Early Devonian volcanic rocks in the NW Altai: Implications for passive margin breakup and back-arc extension","authors":"M.L. Kuibida ,&nbsp;V.I. Timkin ,&nbsp;O.M. Popova ,&nbsp;V.I. Krupchatnikov ,&nbsp;V.A. Krivchikov ,&nbsp;N.N. Kruk ,&nbsp;M. Sun ,&nbsp;J. Wong ,&nbsp;P.D. Kotler ,&nbsp;V.A. Yakovlev ,&nbsp;R.A. Shelepaev ,&nbsp;M. Cherdanceva ,&nbsp;Ya.Yu. Shelepov ,&nbsp;A.V. Lavrenchuk ,&nbsp;E.I. Mikheev ,&nbsp;G.F. Karmanov","doi":"10.1016/j.lithos.2025.108376","DOIUrl":"10.1016/j.lithos.2025.108376","url":null,"abstract":"<div><div>The Devonian tectono-magmatic activation of the Siberian terrane–orogenic margin remains controversial, especially along the southwestern belt facing the Paleo-Asian Ocean. Based on existing data, a spatio-temporal migration of the magmatic front from the continent to the ocean was occurred during Devonian period. This study investigates Early Devonian volcanic sequences in the NW Altai-Mongolian sector of the Altai Orogen, including parts of the Russian and Kazakhstan Altai. New zircon LA-ICP-MS U<img>Pb data from volcanic rocks yield weighted mean ages of ca. 415–410 Ma, corresponding to the end of the first and the beginning of the second episode of tectono-magmatic event. Based on TiO₂ content, the rocks are subdivided into low-, medium-, and high-Ti types. Seven geochemical types are distinguished: (i–iv) calc-alkaline middle- and low-Ti basaltic andesite to dacite flows resembling Andean-type suites but enriched in HFSE, similar to enriched back-arc basin basalt; (v) A₂-type dacite flows; (vi) low-Ti basaltic andesite similar to continental rift tholeiite, and (vii) subvolcanic high-Ti basaltic andesites, that do not have HMAAs comagmatic pair. Comparative analysis shows, the geodynamic setting, producing similar volcanic series, have associative features with rifting of the Late Cenozoic Eastern-Asian continental margin pre-opening stage of the Japan Sea. We propose a Devonian geodynamic scenario from a destruction of the passive margin to back-arc extension, driven by asthenospheric upwelling and/or thermally weakened lithosphere associated with slab rollback.</div></div><div><h3>Summary</h3><div>The Devonian evolution of the NW Altai convergent margin of the Siberian continent was accompanied by the generation of basaltic andesite – andesite – dacitic andesite – dacite volcanism (∼415–410 Ma). Based on volcanic phase sequences and geochemical variations within the temporal range, three stages are distinguished that correspond to initial, prolonged, and late extension tectonics. The petrogenesis of mafic magmas is interpreted as the shallow melting of a refertilised lithospheric mantle of the DM type, which was enriched by a subduction component operating over varying timescales. A comparative analysis shows that the geodynamic environment producing similar volcanic series exhibits features associated with the destruction of the Late Cenozoic Eastern Asian continental margin. These features include the pre-opening stage of the Japan Sea and prolonged lithospheric thinning in a distal setting relative to the retreating subduction zone.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108376"},"PeriodicalIF":2.5,"publicationDate":"2025-12-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145748390","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}