Lithos最新文献

{"title":"Middle Eocene arc magmatism from Armenia with new insights into tectonic evolution of the Arabia-Eurasia collision zone","authors":"Yu-Chin Lin ,&nbsp;Kwan-Nang Pang ,&nbsp;Ghazar Galoyan ,&nbsp;Rafael Melkonyan ,&nbsp;Hao-Yang Lee ,&nbsp;Ching-Hua Lo ,&nbsp;Jin-Hui Yang ,&nbsp;Sun-Lin Chung","doi":"10.1016/j.lithos.2026.108442","DOIUrl":"10.1016/j.lithos.2026.108442","url":null,"abstract":"<div><div>Eocene magmatism affecting northwestern Armenia, Lesser Caucasus, was distinctive in terms of magmatic distribution, particularly its close spatial association with the Amasia-Sevan-Hakari suture zone, raising the question of whether this activity reflects episodic subduction or a continuous history. Here, we characterize a set of Eocene igneous rocks in northwestern Armenia using radiometric dating and geochemical analysis. Magmatic duration established by zircon U<img>Pb and ⁴⁰Ar/³⁹Ar geochronology ranges from ∼47 Ma to ∼41 Ma. The rocks are characterized by a basalt-andesite-dacite association, calc-alkaline affinity, and arc-like trace element signature. Their whole-rock Sr<img>Nd isotopic compositions are depleted mantle-like (⁸⁷Sr/⁸⁶Sr(i) = 0.70360 to 0.70467, εNd(t) = +6.1 to +2.5), which, together with positive εHf(t) of zircon (+14.3 to +6.1), implies relatively recent derivation from the convecting mantle. Generally, these geochemical traits are consistent with hydrous fractional crystallization of a calc-alkaline basaltic parental magma. In view of recent plate tectonic reconstructions, we propose that the accretion of the South Armenian Block during ∼80–75 Ma triggered a southward subduction jump. This tectonic reorganization resulted in a ∼ 30 Myr magmatic hiatus, which is consistent with the physical jumping time for subduction transference, before establishing an ephemeral Eocene magmatic arc directly upon the suture zone between this microcontinent and the Eurasia margin. The studied calc-alkaline system was subsequently terminated by the arrival of the Anatolide-Tauride Block at ∼41 Ma, which triggered a regional shift towards alkaline magmatism. Collectively, these findings highlight the utility of the magmatic record in reconstructing successive accretions in continental collision zones.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"526 ","pages":"Article 108442"},"PeriodicalIF":2.5,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116581","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":"Tonian crustal melting triggered by subduction along the Rodinia periphery: Evidence from the Liujiaping batholith, NW Yangtze Block, South China","authors":"Yongcheng Li ,&nbsp;Bo Hui ,&nbsp;Yunpeng Dong ,&nbsp;Shengsi Sun ,&nbsp;Zhidong Gu ,&nbsp;Yu Zhu ,&nbsp;Dengfeng He ,&nbsp;Qiwen Dai ,&nbsp;Xin Zhu ,&nbsp;Shuxuan Yan","doi":"10.1016/j.lithos.2026.108445","DOIUrl":"10.1016/j.lithos.2026.108445","url":null,"abstract":"<div><div>Preserving vital insights into deep-crustal processes and the tectonic evolution of the Tonian northwestern Yangtze Block, the Liujiaping intrusive complex remains enigmatic regarding its precise petrogenesis and tectonic context. Herein, we present new data on petrography, zircon –b geochronology, zircon Hf isotopes, whole-rock major and trace elements, whole-rock Sr–Nd isotopes and mineral chemistry of the Xiangfengkou granodiorite, the Maoping granite and the Chenjiagou granite from the Liujiaping batholith. LA–ICP–MS zircon U–Pb dating reveals their crystallization ages at ca. 802–796 Ma in the Tonian. The Xiangfengkou granodiorite is characterized by high A/CNK ratios of 0.90–0.98 and molar (Fe + Mg) values of 0.08–0.11. Zircons exhibit ε_Hf(t) values of −0.39 to +6.79, while the whole rocks have initial ⁸⁷Sr/⁸⁶Sr ratios of 0.708720–0.709944 and ε_Nd(t) values of −1.07 to +0.55. The Maoping and Chenjiagou granites show similar geochemical compositions (A/CNK = 1.00–1.10, molar Fe + Mg = 0.03–0.05), with zircon ε_Hf(t) values ranging from +1.26 to +7.93, initial ⁸⁷Sr/⁸⁶Sr ratios of 0.706810–0.707015, and ε_Nd(t) values of 0.00 to +1.85. All samples display a pronounced negative correlation between A/CNK and Fe + Mg, indicative of the typical high-mafic I-type granitoid characteristics. Combined mineralogical and geochemical data suggest that these granitoids were mainly generated by the partial melting of a newly formed mafic lower crust. The notably high Fe, Mg, Ti and Ca contents further imply the entrainment of Fe-Mg-Ti-Ca-rich minerals during melt segregation. Strong positive correlations between Ti and Ca contents with maficity, as well as a negative correlation between A/CNK and maficity, indicate that a peritectic assemblage entrainment process involving transitional minerals (e.g., clinopyroxene, plagioclase and ilmenite) occurred during biotite-hornblende coupled melting. The geochemical, isotopic and mineralogical evidence collectively support the view that the Liujiaping granitoids formed in a subduction-related active continental margin setting. Together with previous studies, these results further demonstrate that the northwestern to western margin of the Yangtze Block was part of a long-lived subduction-related active continental margin, consistent with its tectonic position along the periphery of the Rodinia supercontinent.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"526 ","pages":"Article 108445"},"PeriodicalIF":2.5,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116654","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":"Crustal structure of Lanzarote and magma ascent path for the Timanfaya 1730 to 1736 eruption recorded by mineralogy and fluid inclusions of lower crustal xenoliths","authors":"Leon Kausch ,&nbsp;Thor H. Hansteen ,&nbsp;Romain Bousquet","doi":"10.1016/j.lithos.2026.108441","DOIUrl":"10.1016/j.lithos.2026.108441","url":null,"abstract":"<div><div>The Timanfaya eruption on Lanzarote (1730 to 1736) was among the largest historic eruptions on any ocean island, and understanding their eruption dynamics can help to enhance hazard mitigation measures. Gabbroic xenoliths with MORB-type mineral compositions, interpreted as fragments of the Jurassic ocean crust, were transported to the surface during the eruption. The xenoliths have to variable extents been affected by heating, causing formation of intergranular reaction rims, and also partial melting reflected by melt-filled veins. Two-pyroxene thermobarometry using the abundant orthopyroxene exsolution lamellae in clinopyroxene give average formation temperatures of 865 °C. CO₂-dominated fluid inclusions in plagioclase, olivine and clinopyroxene show two density modes, the main mode at 0.62 ± 0.11 g/cm³ with a skewed distribution towards higher densities up to 0.80 g/cm³, and a less prominent mode at 0.28 ± 0.10 g/cm³, respectively. The primary fluid inclusions are contained in the main mode. Coexistence of secondary CO₂-dominated fluid inclusions with melt inclusions demonstrate late-stage magmatic temperatures in the xenoliths. We suggest that the xenoliths originated as magma chamber wall rocks, and were entrained in the Timanfaya magmas at pressures of about 315 ± 95 MPa. Heating of the xenoliths to magmatic temperatures during limited magma stagnation in the lower crust led to isobaric re-equilibration of the primary fluid inclusions. Some xenoliths record an additional transient stagnation level at 100 ± 45 MPa, which corresponds to the shallowest level of <em>syn</em>-eruption magma stagnation. This ascent history is strikingly similar to the events recorded during the 2021 La Palma eruption, and to those of mafic magmas on ocean islands worldwide, suggesting that such lower crustal magma stagnation beneath ocean islands is the rule rather than the exception.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"526 ","pages":"Article 108441"},"PeriodicalIF":2.5,"publicationDate":"2026-02-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116580","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":"Corrigendum to “Mantle evolution of the nascent oceanic basin subsequent to continental breakup constrained by Mo–Sr–Nd–Hf isotopes in MORBs from the northern margin of the South China Sea” [Lithos 512–513(2025) 108151]","authors":"Yu-Xin Cai ,&nbsp;Xiao-Long Huang ,&nbsp;Fan Yang ,&nbsp;Yang Yu ,&nbsp;Jie Li ,&nbsp;Zhen-Min Ge","doi":"10.1016/j.lithos.2026.108406","DOIUrl":"10.1016/j.lithos.2026.108406","url":null,"abstract":"","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108406"},"PeriodicalIF":2.5,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146077848","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":"The hidden role of Mg–Si–COH fluids on mantle wedge metasomatism","authors":"Carla Tiraboschi ,&nbsp;Dimitri Sverjensky ,&nbsp;Carmen Sanchez-Valle","doi":"10.1016/j.lithos.2026.108436","DOIUrl":"10.1016/j.lithos.2026.108436","url":null,"abstract":"<div><div>COH fluids have long been thought to play a key role in subduction zone processes as their release from the subducting slab drives metasomatic alteration in the overlying mantle wedge. Among these, graphite-saturated COH fluids derived from a model peridotitic assemblage exhibit high solute concentrations of Mg and Si, compared to COH- and H₂O-only fluids: up to 17 wt% at 1 GPa and 900 °C, making them potentially efficient metasomatic agents. Probing experimentally the metasomatic effect of these fluids is however limited by the inability to recover the fluid phase with its solute load upon quenching, to further test the interaction with relevant graphite-free mantle wedge lithologies. To overcome this challenge, we employ thermodynamic modeling to both reproduce the solute load observed in experiments and subsequently simulate fluid–rock interactions at controlled conditions.</div><div>Here we use EQ3/6 coupled with the Deep Earth Water model to investigate the metasomatic effects of COH fluids generated by the dissolution of forsterite and enstatite in graphite-saturated COH fluids, interacting with graphite-free lherzolite, harzburgite, and dunite at 1 GPa and 700–900 °C, over a range of fluid/rock ratios. For comparison, we also simulate metasomatism by a H₂O-only fluid at identical conditions.</div><div>Our results confirm that Mg–Si–COH fluids drive significant compositional changes in the host rocks. While H₂O-only fluids primarily stabilize clinochlore up to 800 °C, graphite-saturated COH fluids promote orthopyroxene formation, doubling its mineral proportions for high fluid/rock ratios. These results highlight the enhanced metasomatic potential of carbon-bearing fluids, which, in the model, can generate orthopyroxene-rich assemblages and silica-enriched mantle domains comparable to those observed in natural subduction settings. They also expose a paradox: carbon is essential to produce the solute-rich fluid, yet no carbon-bearing phases remain in the final rock assemblage. This implies that carbon-bearing fluids may have been more influential in subduction zone metasomatism than previously recognized, despite leaving no direct mineralogical evidence in the exhumed rock record.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"526 ","pages":"Article 108436"},"PeriodicalIF":2.5,"publicationDate":"2026-01-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146116579","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":"Rare preservation of epithermal Cu–Au–Pb–Zn mineralization associated with mesoproterozoic arc magmatism in the Bastar Craton, Central India","authors":"M Lachhana Dora ,&nbsp;V. Kumaravel ,&nbsp;D.B.K. Khuntia ,&nbsp;Subhasree Lenka ,&nbsp;M.P. Manu Prasanth ,&nbsp;Vivek P. Malviya ,&nbsp;Mrinal Kanti Mukherjee ,&nbsp;Tushar Meshram ,&nbsp;S.R. Baswani ,&nbsp;Raghuram ,&nbsp;K. Randive","doi":"10.1016/j.lithos.2026.108415","DOIUrl":"10.1016/j.lithos.2026.108415","url":null,"abstract":"<div><div>Epithermal base- and precious-metal deposits are rare in the Precambrian rock record, and their detailed documentation of characteristics and genetic processes is limited. The Cu–Pb–Zn–Au mineralization in the Denwari-Minjhari-Bamhani belt of Western Bastar Craton, Central India, is associated with Paleo-Mesoproterozoic I-type calc-alkaline granitoids. The polymetallic mineralization is structurally controlled by NW-trending brittle shear zones and is hosted within quartz veins, accompanied by pervasive silicification and hydrothermal alteration. Hydrothermal alteration, characterized by silicification, argillic, and propylitization, is closely associated with the deposition of base metals (Cu, Pb, Zn). Cathodoluminescence imaging of quartz reveals euhedral concentric growth zones and colloform banding, indicative of an epithermal origin in an open hydrothermal system. The Minjhari deposit is characterized by vuggy silica, clay alteration, and Cu mineralization, whereas the Bamhani–Denwari prospects display comb textures and open-space filling veins, associated with Pb-Zn. These features indicate a high-sulfidation (HS) Cu-Au-Fe system at Minjhari, overprinted by a later intermediate-sulfidation (IS) Pb-Zn-Cu-Ag mineralization stage at Bamhani-Denwari. The In-situ pyrite geochemistry from Minjhari further indicates evolving high-sulfidation (HS) conditions, whereas low-iron sphalerite (0.01–3.7 mol% FeS) from Bamhani–Denwari is characteristic of an intermediate-sulfidation environment (IS). The host granites exhibit a subduction-related geochemical signature and are categorized as continental arc granites. Magma generation is inferred at deeper crustal to upper mantle levels based on bulk-rock geochemistry, including enrichment in LILE (K, Rb, Ba); HREE depletion (Nb, Ta, Ti), high (La/Yb) and (Gd/Yb) ratios, and mild Eu anomalies, indicating melting within the garnet stability field. These signatures are comparable to fertile, hydrous arc magmas from convergent margin settings worldwide and support a deep-seated arc magma source for the Minjhari system. This study presents robust evidence for a rare, remarkably well-preserved Precambrian HS–IS epithermal system. The recognition of epithermal mineralization at Minjhari-Bamhani likely represents the uppermost expression of a larger, possibly concealed Porphyry or/and IOCG mineral system (?), highlighting significant Cu-Au exploration potential along the western margin of the Bastar Craton.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108415"},"PeriodicalIF":2.5,"publicationDate":"2026-01-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080523","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":"Neoproterozoic juvenile continental crust formation in the Arabian Shield (Khamal intrusive complex, Western Arabia)","authors":"Davide Berno ,&nbsp;Alessio Sanfilippo ,&nbsp;Mattia Bonazzi ,&nbsp;Avanzinelli Riccardo ,&nbsp;Jakub Fedorik ,&nbsp;Abdulkader M. Afifi","doi":"10.1016/j.lithos.2026.108420","DOIUrl":"10.1016/j.lithos.2026.108420","url":null,"abstract":"<div><div>The Arabian–Nubian Shield (ANS) is one of the largest Neoproterozoic juvenile crustal provinces on Earth, providing insights into crustal growth, mantle dynamics, and continental assembly. The Wadi Khamal Complex, in the northwestern Arabian Shield, is a mafic intrusive body comprising a central anorthositic core and marginal gabbronorites, with subordinate granites and younger felsic to basaltic dykes. This study integrates petrography, whole-rock and mineral geochemistry, Sr–Nd–Pb isotopes, zircon U<img>Pb geochronology, and equilibrium-melt modeling from minerals to reconstruct the origin, age, and conditions of emplacement of this anorthosite complex.</div><div>In the complex, the anorthosites are dominated by cumulate plagioclase (An₈₁–₃₆) with interstitial pyroxenes, whereas gabbronorites exhibit modal layering and magmatic foliation defined by plagioclase–pyroxene (± olivine). The granites are in primary contact with anorthosite. The anorthosite–gabbronorite–granite association is crosscut by multiple generations of felsic dykes; additional basaltic dykes are attributed, by field relations and chemistry, to Cenozoic alkaline magmatism coeval with Red Sea rifting. The complex intrudes older arc-related lithologies—including amphibolitized mélanges and a voluminous diorite–tonalite–granodiorite batholith—that are structurally important but not petrogenetically related to Wadi Khamal.</div><div>Bulk-rock and mineral systematics define trends consistent with assembly of cumulate anorthosite and gabbronorite from tholeiitic parental melts; because the data are cumulate-dominated, bulk trends need not follow liquid lines of descent. Equilibrium-melt proxies indicate LREE-enriched tholeiitic melts lacking arc-type Nb<img>Ta troughs, consistent with small to moderate degrees of partial melting of a juvenile (depleted to slightly enriched) mantle. Nd–Sr–Pb isotope signatures (εNd(i) = +4.5 to +6.1; ⁸⁷Sr/⁸⁶Sr(i) = 0.70256–0.70277; ²⁰⁶Pb/²⁰⁴Pb(i) = 17.3–17.9; ²⁰⁷Pb/²⁰⁴Pb(i) = 15.4–15.5; ²⁰⁸Pb/²⁰⁴Pb(i) = 36.2–37.2) indicate juvenile, non-arc mantle with limited crustal input. New zircon U<img>Pb dating yields an emplacement age of 614 ± 3.4 Ma.</div><div>We conclude that the Wadi Khamal Complex represents a small-scale, late Ediacaran massif-type anorthosite assembled as a crystal-mush from juvenile tholeiitic melts during post-collisional extension. The isotopic contrast between the intrusion and later basaltic dykes underscores a long-term shift from juvenile asthenosphere-dominated sources to enriched, SCLM-influenced sources during Red Sea rifting.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108420"},"PeriodicalIF":2.5,"publicationDate":"2026-01-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080521","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":"From FeLi rich micas to lepidolite and muscovite: The magmatic to hydrothermal evolution of phyllosilicates in the apical zone of the Beauvoir granite (French Massif Central)","authors":"Zia Steven Kahou ,&nbsp;Michel Cathelineau ,&nbsp;Marie-Christine Boiron ,&nbsp;Andreï Lecomte ,&nbsp;Chantal Peiffert ,&nbsp;Patrick Fullenwarth","doi":"10.1016/j.lithos.2026.108418","DOIUrl":"10.1016/j.lithos.2026.108418","url":null,"abstract":"<div><div>The albite–lepidolite–topaz Beauvoir granite (western European Variscan belt) represents an extreme example of late-stage peraluminous magmatic differentiation associated with enrichment in Li, Sn, Nb, Ta and Be. This study investigates the textures and chemistry of micas from the highly evolved B1 unit to constrain the final stages of magmatic evolution and to evaluate the impact of post-magmatic fluid–rock interaction. Magmatic mica assemblages are dominated by lepidolite, whereas Fe<img>Li micas are rare and preserved only locally; both display high Li contents (28,000–32,000 ppm) and record late-stage Rb<img>Cs enrichment. Hydrothermal alteration is expressed by the development of fine-grained dioctahedral muscovite along fracture-controlled alteration corridors, where albite and lepidolite are progressively replaced. Hydrothermal muscovite is nearly Li-free (∼90 ppm), and its formation leads to a pronounced decrease in the modal abundance of lepidolite (from ∼20% to 5–10%), resulting in significant Li depletion at the whole-rock scale despite limited Li loss from residual lepidolite crystals. Muscovitisation is also associated with the depletion of Nb, Ta and W, whereas Sn is partly redistributed and incorporated into muscovite (up to 1400 ppm). The absence of transitional compositions toward Li-rich muscovite or phengite indicates that this alteration stage is decoupled from magmatic differentiation and reflects a structurally controlled hydrothermal event. These results highlight the key role of post-magmatic hydrothermal processes in rare-metal redistribution and in reducing the lithium endowment of highly fractionated granites.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108418"},"PeriodicalIF":2.5,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080402","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":"Electrical conductivity of zoisite at high temperature and pressure and its implications on high electrical conductivity anomalies","authors":"Zhiqing Zhang ,&nbsp;Duojun Wang ,&nbsp;Kewei Shen ,&nbsp;Rui Zhang","doi":"10.1016/j.lithos.2026.108431","DOIUrl":"10.1016/j.lithos.2026.108431","url":null,"abstract":"<div><div>Geophysical surveys reveal high electrical conductivity anomalies in mantle wedges, which provide insights into the Earth's interior features and dynamics. These anomalies are commonly attributed to the dehydration of hydrous minerals. Hence, understanding the property changes of hydrous minerals during dehydration is essential for explaining the geophysical observations. Compared with other hydrous minerals such as amphibole, zoisite can remain stable at higher pressures and may be capable of transporting water to greater depths in the Earth's interior, making it a plausible contributor to the deep high electrical conductivity anomalies in mantle wedges. In this study, the electrical conductivity of zoisite was measured at pressures of 1.0, 3.0, and 4.5 GPa and temperatures ranging from 723 to 1573 K. The results show that the electrical conductivity of zoisite increases with increasing temperature and pressure. Under the experimental pressures, zoisite dehydrated at 1073–1123 K, and its conductivity exceeded 0.1 S/m upon dehydration. The increase in conductivity associated with a high activation energy of 223–428 kJ/mol was attributed to an inhomogeneous dehydration model involving Al³⁺ cation migration. The dehydration products of zoisite vary with pressure and may include garnet, kyanite, corundum, and coesite. A comparison of the geophysically imaged electrical structure with our conductivity data indicates that zoisite likely contributes to the high electrical conductivity of the mantle wedge at 110–160 km depth in central Cascadia and at 150–240 km depth in the central Chile gap.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108431"},"PeriodicalIF":2.5,"publicationDate":"2026-01-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080403","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":"Petrological and volcanological evolution of the Gandhi Tekdi vitrophyre: A late-stage silicic lava dome in the western Deccan continental flood basalt province","authors":"Arunodaya Shekhar ,&nbsp;Hetu Sheth ,&nbsp;B. Astha ,&nbsp;Anmol Naik ,&nbsp;Waliur Rahaman ,&nbsp;Subham Kumar","doi":"10.1016/j.lithos.2026.108421","DOIUrl":"10.1016/j.lithos.2026.108421","url":null,"abstract":"<div><div>The Mumbai area in the western Deccan continental flood basalt (CFB) province is well known for large-scale, compositionally diverse, Danian-age (post-K/Pg boundary) Deccan magmatism, coinciding with or slightly postdating the 62.5 Ma India-Seychelles continental breakup. The late-Deccan Mumbai magmatic suite contains subaerial tholeiitic lavas, subaqueous spilitic pillow lavas, “intertrappean” sediments (with substantial volcanic ash input), rhyolitic lavas and tuffs, a tholeiitic dyke swarm, gabbro-granophyre intrusions, and trachyte intrusions containing alkali basalt enclaves. We present new geological and compositional data on the vitrophyre forming the hillock of Gandhi Tekdi, in the Sanjay Gandhi National Park and forest reserve, in Mumbai City. The vitrophyre is traversed throughout by a polyhedral fracture network, and has an upper surface covered with loose primary blocks reflecting active crustal brecciation. The vitrophyre is texturally extremely uniform, containing abundant crystal aggregates and phenocrysts of andesine to oligoclase feldspar and augite, with minor Fe-Ti oxides, in a glassy groundmass rich in anorthoclase microlites. In major element composition it varies from (mainly) rhyolite to trachyte and trachydacite, all of metaluminous character, due to slightly variable crystal cargoes. In trace element (including rare earth element) composition it bridges the Mumbai trachytes and rhyolites, indicating a compositional continuum. Its relatively low (⁸⁷Sr/⁸⁶Sr)_t ratios (0.70516–0.70596) and moderately low ε_Ndt values (−3.1 to −3.3) indicate considerable isotopic homogeneity, and likely derivation from closed-system fractional crystallisation of known isotopically matched Mumbai tholeiites. The rhyolitic groundmass (glass + microlites) of the vitrophyre represents the residual liquid extracted from a dioritic cumulate mush, which is represented by the vitrophyre's crystal cargo. Based on its major outcrop features we interpret the Gandhi Tekdi vitrophyre as a lava dome, the first identified silicic lava dome in the entire Deccan Traps, which expands the varied styles of silicic magmatism recognised in this continental flood basalt province.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108421"},"PeriodicalIF":2.5,"publicationDate":"2026-01-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080522","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}