Lithos最新文献

{"title":"Influence of H₂O, CO₂, and eclogite on reactions at the subcontinental lithosphere–asthenosphere interface","authors":"Caroline D.K. Tolotti ,&nbsp;Rommulo V. Conceição ,&nbsp;Stephan Klemme ,&nbsp;Marco A.T. Romeiro ,&nbsp;Gláucia N. Queiroga ,&nbsp;Daniela K. Secchi ,&nbsp;Márcio R. Souza ,&nbsp;Susan M. Drago","doi":"10.1016/j.lithos.2026.108433","DOIUrl":"10.1016/j.lithos.2026.108433","url":null,"abstract":"<div><div>This experimental study investigates interactions between the subcontinental lithosphere and an eclogite-rich asthenosphere source under water- and carbon-bearing conditions, simulating processes across variable geothermal gradients and depths. High-pressure experiments conducted at 2.5 and 4.5 GPa and 900–1300 °C yielded mineral assemblages comprising olivine, orthopyroxene, clinopyroxene, garnet, amphibole, and magnesite, with phlogopite occurring as a late-stage phase associated with the glass. These glasses range from ultrabasic to alkaline and silica-rich compositions. Reaction textures indicate significant alkali mobility and C–O–H fluid activity, characterized by the formation of orthopyroxene- and amphibole-enriched domains around 1100 °C. Notably, amphibole exhibits unexpected stability up to ∼1100 °C at both 2.5 and 4.5 GPa. In contrast, carbonate stability is more restricted, with magnesite observed only at 1000 °C and 4.5 GPa. Above 1100 °C, amphibole breakdown enriches the melt in alkalis and H₂O. The residual assemblage at 1200–1300 °C consists of olivine and metasomatic clinopyroxene. The results indicate enhanced amphibole stability in enriched environments and demonstrate that H₂O inhibits CO₂ dissolution in the melt, promoting the generation of silica-enriched melts when both volatiles coexist.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108433"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147399398","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":"Secrets of crust-mantle interaction in continental arc: Accessory minerals tell the tale in East Kunlun orogen, Northern Tibet Plateau","authors":"Dongdong Yan ,&nbsp;Fuhao Xiong ,&nbsp;Marco Brenna ,&nbsp;Changqian Ma ,&nbsp;Mingcai Hou ,&nbsp;Hao Zou ,&nbsp;Hu Huang ,&nbsp;Wei Wang","doi":"10.1016/j.lithos.2026.108410","DOIUrl":"10.1016/j.lithos.2026.108410","url":null,"abstract":"<div><div>Andesitic arc magmas play a fundamental role in constructing continental crust, yet the long-term operation of crystal mush systems often homogenizes their isotopic signatures, obscuring the discrete contributions of mantle- and crust-derived end-members. To overcome this limitation, this study integrates whole-rock geochemistry, zircon U-Pb-Hf isotopes, and in situ apatite trace-element and Sr<img>Nd isotopic analyses to unravel the magmatic evolution of the Nanshankou intrusive complex in the East Kunlun orogen, Northern Tibet Plateau. The complex comprises coeval (ca. 245 Ma) mafic to felsic intrusions, including amphibole gabbro, gabbroic diorite, quartz diorite, mafic microgranular enclaves, granodiorite, and monzogranite. Mafic units record derivation from a depleted mantle wedge metasomatized by sediment-derived melts during Paleo-Tethyan subduction. In contrast, the intermediate to felsic rocks display broad compositional and isotopic ranges in zircon εHf(t), apatite εNd(t), and REE contents, reflecting progressive crust-mantle hybridization, repeated mafic recharge, internal self-mixing, and late fractional crystallization within a long-lived crystal mush. The results show that mixing between juvenile mafic magmas and ancient lower crust produced isotopically less evolved felsic intrusions, illustrating how subduction-driven magma addition rejuvenates continental crust in arc settings. This study demonstrates the exceptional sensitivity of apatite for tracking magma mixing and provides new constraints on the mechanisms governing compositional diversity in arc magmatic systems.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108410"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146037217","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":"Magmatic flux influences chemical heterogeneity of the Chaxas volcanic complex, N. Chile","authors":"Chuck Lewis ,&nbsp;Shanaka de Silva ,&nbsp;Alejandro Cisneros de Leon ,&nbsp;Abdullah Alohali","doi":"10.1016/j.lithos.2026.108417","DOIUrl":"10.1016/j.lithos.2026.108417","url":null,"abstract":"<div><div>Geochemical heterogeneity vs homogeneity of ignimbrites in the Altiplano-Puna Volcanic Complex (APVC) is linked to a high vs low-flux stage of volcanism at the Chaxas Volcanic Complex. The early high-flux Pre-Chaxas stage produced the monotonous intermediate Puripicar Ignimbrite with a range in SiO₂ of merely 4.4 wt % despite its large volume of ∼ 500 km³ along with several rhyolitic eruptions. Whole rock geochemistry and isotope ratios indicate the presence of both a Low and High-Sr dacite in the Puripicar reservoir. Diverse plagioclase textures and zoning from An 26 – 89 reveal a complex thermochemical history that resulted in heterogeneity within the reservoir. Amphibole atomic abundances reveal high temperature gradients and more subtle pressure gradients. Nominally high H₂O contents of ∼ 6 wt % enhanced pre-eruptive homogenization of the two Puripicar dacites. The younger low-flux Chaxas Complex stage produced a dacitic dome complex and small volume rhyolitic eruptions. Plagioclase compositions of the block and ash flows are more restricted to a range of An 41 – 53 and have oscillatory textures that attest to a monotonically cooling reservoir. Isotopic ratios of the Chaxas Complex stage also indicate less prolific assimilation. Combined with previously constrained flux estimates, the geochemical characteristics of the two stages is interpreted to be a function of magmatic flux. Volcanic systems along the margins of the APVC tend to have high fluctuation in flux rates and more diverse geochemistry. This regional synthesis supports that volcanic systems marginal to continental magmatic flare-ups have systematically more geochemical heterogeneity.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108417"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080525","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":"2026-03-01","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":"Cambrian post-collisional overprint recorded by detrital rutile: Insights into the late evolution of the Araçuaí Orogen","authors":"Rodrigo Irineu Cerri ,&nbsp;Alex J. Choupina A. Silva ,&nbsp;Leonardo Azevedo de Sá Alkmin ,&nbsp;Fabrício de Andrade Caxito ,&nbsp;Raíssa Santiago ,&nbsp;Caio Vinícius Gabrig Turbay","doi":"10.1016/j.lithos.2026.108419","DOIUrl":"10.1016/j.lithos.2026.108419","url":null,"abstract":"<div><div>Continental to shallow marine sedimentary rocks were deposited along the Brazilian Atlantic margin during the Mesozoic-Cenozoic opening of the South Atlantic Ocean, following the breakup of West Gondwana. Within this context, the Miocene Barreiras Formation provides a key record of sedimentary processes associated with long-term tectono-sedimentary evolution. New detrital rutile U<img>Pb data reveal a distinct Cambrian metamorphic signature at ca. 504 Ma, not previously identified, contrasting with the predominantly Neoproterozoic ages and complex fission-track signatures typically documented in detrital zircon and underscoring the potential of rutile as a complementary provenance and metamorphic tracer. The ca. 504 Ma detrital rutile ages are consistent with the timing of post-collisional collapse in the Araçuaí Orogen (∼500–485 Ma), suggesting that this mountain belt constituted the main sediment source for the Barreiras Formation and that the rutile signature reflects the tectonometamorphic history associated with the Brasiliano Orogeny. Comparable Cambrian metamorphic ages reported from Pan-African belts in Angola and Namibia indicate that this thermal pulse extended beyond the Brazilian margin and was part of a broader transcontinental tectonothermal framework. The preservation of Cambrian ages in rutile is compatible with Pb diffusion and partial resetting of the U<img>Pb system during high-grade metamorphism and subsequent lithospheric thinning in the Araçuaí Orogen, processes that record a phase of post-collisional reworking that mechanically weakened the lithosphere. In this sense, the Barreiras Formation not only documents Neogene sedimentary dynamics along the passive margin but also constitutes an archive of deeper crustal processes, bridging the Cambrian post-collisional collapse of the Brasiliano/Pan-African orogenic systems with the later Cretaceous onset of South Atlantic rifting and continental breakup.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108419"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146026048","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":"2026-03-01","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":"Time-dependent changes in the origin of aqueous fluids in the shallow mantle wedge: Evidence from noble gas and halogen compositions of the Kamabuseyama serpentinite, Kanto Mnts., Japan","authors":"Koki Aida ,&nbsp;Simon Richard Wallis ,&nbsp;Hirochika Sumino ,&nbsp;Mari Yokota","doi":"10.1016/j.lithos.2026.108400","DOIUrl":"10.1016/j.lithos.2026.108400","url":null,"abstract":"<div><div>Blocks of serpentinite derived from the mantle wedge are widely distributed throughout the Sanbagawa metamorphic belt of SW Japan and the contact domains with surrounding schists represent the paleo subduction zone boundary. This paleo subduction boundary is well exposed in the Kamabuseyama area of the Kanto mountains and originally formed at relatively shallow mantle depths of ∼25 km. The contact zone between the serpentinite and slab-derived schists is characterized by a domain of fluid-mediated metasomatism. Noble gas and halogen analyses of different lithologies from this domain suggest fluid influx occurred in two distinct stages represented by formation of (1) serpentinite and (2) boundary domain metasomatic rocks. Stage (2) metasomatism can be further divided into two substages: (2–1) associated with chlorite rock formation and (2–2) associated with talc rock formation. The origins of the dominant fluids involved in these different stages can be identified as: (1) altered oceanic crust, (2–1) altered oceanic crust + pore fluids in oceanic sediments, and (2–2) pore fluids in oceanic sediments + fluids derived from serpentinized domains of the slab mantle. These results indicate that the origin of the dominant fluid along the paleo subduction boundary changed with time reflecting the development of different fluid pathways. The identification of fluid derived from the dehydration of serpentinite of the slab mantle during the youngest fluid inflow event suggests changes in fluid pathways may be controlled by the progressive development of a boundary shear zone that introduces a permeability anisotropy that allows deep sourced fluids to flow laterally along the subduction boundary.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108400"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080524","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":"An integrated petrochronologic investigation of the ultrahigh temperature metamorphosed granulites of the Vizianagaram-Salur area, Eastern Ghats Province, India: Implications for the evolution of the Rayner-Eastern Ghats orogeny","authors":"Shubhadeep Roy ,&nbsp;Sankar Bose ,&nbsp;Sayantika Ghosh ,&nbsp;Sneha Mukherjee ,&nbsp;Nilanjana Sorcar ,&nbsp;J. Amal Dev","doi":"10.1016/j.lithos.2026.108416","DOIUrl":"10.1016/j.lithos.2026.108416","url":null,"abstract":"<div><div>Aluminous granulite and felsic gneiss from the Vizianagaram-Salur section of the Proterozoic Eastern Ghats Province, India bear evidence of a complex metamorphic history which is recorded in the ultrahigh temperature mineral assemblages and their overprints. Textural, mineral chemical, and phase equilibria modelling of samples from both the areas suggest that the peak (M₁) assemblage of spinel + quartz + Al-orthopyroxene + garnet + ilmenite + plagioclase + K-feldspar + cordierite was stabilized at 7–8 kbar, 950–1000 °C. Subsequent near-isobaric cooling (to ∼800 °C) during retrogression (M_1R) produced multiple coronae involving garnet, orthopyroxene and sillimanite. Breakdown of cordierite to assemblage of orthopyroxene, sillimanite, garnet and quartz indicates a metamorphic reworking (M₂) while the delicate intergrowth involving spinel, cordierite, K-feldspar and quartz in the leucocratic layers suggests near-isothermal decompression (to ∼5.5 kbar) and subsequent cooling (M_2R). Zircon grains in one sample yield concordant ages of 952 ± 8 Ma and 915 ± 7 Ma, while chemical dating of monazite distinctly identifies the ages of the two metamorphic events at ca. 1010–990 Ma (M₁) and ca. 950–890 Ma (M₂), respectively. Subsequent (post-M₂) events are marked by fluid-induced changes as discerned from field evidence and microscopic observation. Based on textural and mineral chemical data, the fluid composition has been considered as a mixture of Na₂SiO₅, CO₂, and H₂O. This fluid has caused alteration in monazite grains, producing convolute structure and late patches on pre-900 Ma monazite micro-domains. Spot data from such monazite domains vary in the range ca. 570–540 Ma with well-defined probability density peaks in both the samples. This pervasive fluid infiltration event within the heartland of the province was presumably aided by structural pathways generated by far-field stress during the Kuunga orogeny. Our study presents a comprehensive geological evolution of the Eastern Ghats Province during ca. 1000–500 Ma which is comparable to the Rayner Province of East Antarctica.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108416"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080520","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":"Titanite fingerprint of SiO2-oversaturated to -undersaturated plutons: Insights into petrogenesis, passive rifting and Neo-Tethys opening on the NE Gondwanan margin","authors":"Musa Khan ,&nbsp;Huan Li ,&nbsp;Thomas J. Algeo ,&nbsp;Lian-Xun Wang ,&nbsp;Asad Khan","doi":"10.1016/j.lithos.2026.108434","DOIUrl":"10.1016/j.lithos.2026.108434","url":null,"abstract":"<div><div>The Early Permian pre-Himalayan plutonic rocks situated on the northern Indian Plate margin record a key tectono-magmatic event in the breakup of NE Gondwana. The Ambela Granitic Batholith (AGB) in NW Pakistan hosts several of these plutonic rock bodies, but details of their petrogenesis and the regional geodynamic forces (e.g., mantle-plume versus slab-pull) that contributed to their formation remain poorly understood. In this contribution, we present petrographic observations, major- and trace-element concentrations, Sm<img>Nd isotopes, and U<img>Pb geochronology for titanite as well as trace-element data for zircons from SiO₂-oversaturated (granite), SiO₂-saturated (monzonite and quartz syenite), and SiO₂-undersaturated (nepheline syenite) plutonic rocks from the AGB. The titanite shows typical euhedral to subhedral morphologies, homogeneous textures and core-to-rim zonation. All titanite grains have high Th/U, low Lu/Hf, and high total rare earth element contents (ƩREE; range ∼ 2870 to 31,500 ppm, mean ∼ 13,000 ppm), suggesting a magmatic origin. The titanite U<img>Pb geochronology reveals two magmatic events, i.e., an early-stage event that generated SiO₂-oversaturated magmas (i.e., granitic in composition; crystallized at ∼293 Ma) and a late-stage event that generated SiO₂-saturated-undersaturated magmas (i.e. monzonitic-syenitic-alkali syenitic in composition; crystallized at ∼278–276 Ma). Based on Ti-in-zircon thermometry, we obtained mean crystallization temperatures of 668 ± 32 °C for the early-stage magma and 657 ± 87 °C for the late-stage magma. In addition, the titanite grains show variable trace-element and Sm<img>Nd isotopic compositions, i.e., εNd(t) = −0.2 to +0.8 for the early-stage magma and + 1.6 to +3.8 for the late-stage magma, indicating that the parent melts of the former were created through crustal anatexis of the metasedimentary lower-crust under granulite-facies conditions, whereas the latter was produced through partial melting of metasomatized ultramafic lithospheric mantle. The early-stage magma formed in a dehydrated system that was dominated by strong plagioclase crystallization, unlike the late-stage magma, which formed under hydrated conditions and was dominated by amphibole crystallization. Two-stage model age data (TDM₂) signify that the parent materials of the early- and late-stage magmas were respectively Mesoproterozoic-Neoproterozoic and Neoproterozoic in age, demonstrating that the former was relatively older than the latter. These two episodes of Early Permian magmatism were linked to initial rifting of the Neo-Tethys Ocean basin. These features are consistent with a model of far-field passive rifting triggered by subduction of the Paleo-Tethys Plate under the southern margin of the Eurasian continent, triggering breakup of NE Gondwana.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108434"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147399396","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":"2026-03-01","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}