Lithos最新文献

{"title":"Petrogenesis of Triassic crystal-rich and crystal-poor volcanic rocks in the East Kunlun orogenic belt: Evidence from in-situ zircon-apatite-quartz and whole-rock geochemical compositions","authors":"Meng-Yu Zhang ,&nbsp;Bin Liu ,&nbsp;Chang-Qian Ma ,&nbsp;Zhen-Hua Xue ,&nbsp;Yang Sun ,&nbsp;Yan-Qing Li ,&nbsp;Yao-Yao Zhang ,&nbsp;Luan Wu ,&nbsp;Shi-Ze Li","doi":"10.1016/j.lithos.2026.108411","DOIUrl":"10.1016/j.lithos.2026.108411","url":null,"abstract":"<div><div>Coeval crystal-rich and crystal-poor volcanic rocks are widely regarded as natural archives for exploring the disaggregation of mush and the relevant crustal crystal-melt-volatile interactions. However, the formation mechanisms and genetic links of both types of volcanic rocks remain elusive. This study integrated zircon U<img>Pb geochronology and Hf isotopic compositions, in-situ zircon-apatite-quartz compositions, and whole-rock geochemistry for Triassic crystal-rich and crystal-poor volcanic rocks in the Dulan area of the East Kunlun Orogen Belt (EKOB). The results show that these volcanic rocks are dominated by rhyolitic ignimbrites with contrasting crystal proportions. Compared with crystal-poor volcanic rocks, crystal-rich volcanic rocks display relatively lower SiO₂ and total rare earth elements, but higher TiO₂ and MgO. However, both types of volcanic rocks exhibit similar zircon U<img>Pb ages, REE and trace element patterns, and zircon ε_Hf(t) values, indicating derivation from a common magmatic source, most plausibly linked to partial melting of mafic lower-crustal components. Zircon textures and in-situ compositions also indicate that they have a broadly overlapping evolutionary trend, but those crystal-rich volcanic rocks had experienced a longer duration of magmatic evolution. The presence of zircon antecrysts and feldspar glomerocrysts supports a long-lived (∼2 Myr) crystal-rich mush reservoir. Compositional variations of whole-rock, zircon, and apatite further indicate the mush reservoir underwent complex crystal-melt segregations, primarily governed by the fractionation of plagioclase and recorded by co-crystallizing zircon and apatite. Compared with the crystal-poor volcanic rocks, the crystal-rich volcanic rocks contain abundant quartz and apatite that commonly shows reverse zoning, and record relatively high-temperature signatures. Combined with new regional studies, we propose two-stage crystal-melt segregations to generate Triassic crystal-rich and crystal-poor volcanic rocks in the EKOB. Early crystal-melt segregation favored extraction of relatively H₂O-rich, melt-dominated magma to form the crystal-poor volcanic rocks, whereas subsequent injections of hydrous mafic magma recharge rejuvenated the mush and triggered the later segregation, ultimately generating the crystal-rich volcanic rocks.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108411"},"PeriodicalIF":2.5,"publicationDate":"2026-01-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146080519","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":"2026-01-21","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":"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":"2026-01-20","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":"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":"2026-01-20","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":"Temporal variation of water content in the lithospheric mantle beneath the central North China Craton: New evidence from mantle xenocrystic pyroxenes","authors":"Yao Xu ,&nbsp;Hong-Fu Zhang ,&nbsp;A-Bing Lin ,&nbsp;Chao Zhang","doi":"10.1016/j.lithos.2026.108412","DOIUrl":"10.1016/j.lithos.2026.108412","url":null,"abstract":"<div><div>Nominally anhydrous mantle xenocrystic orthopyroxene (Opx) and clinopyroxene (Cpx) hosted by Cenozoic basalts from Xiyang–Pingding in the central North China Craton (NCC) were analyzed for water contents using Fourier transform infrared spectrometry (FTIR). Water contents in high-Mg# (91.9–94.1) Opx (<em>n</em> = 51), low-Mg# (89.9–91.5) Opx (<em>n</em> = 2), and Cpx (Mg# = 93.3–94.5; <em>n</em> = 4) are 25–126 ppm, 37–65 ppm, and 51–90 ppm, respectively. These data suggest that the Cenozoic subcontinental lithospheric mantle (SCLM) beneath Xiyang–Pingding was dominated by a refractory and overall dry cratonic keel, represented by high-Mg# xenocrystic Opx, with a minor contribution from a more fertile yet comparably dry mantle component. Significant hydrogen loss during xenocryst ascent in the host magma can be largely ruled out, and the measured pyroxenes are inferred to retain their primary mantle H₂O contents, supported by (1) intra-grain homogeneity in H₂O and (2) correlations between H₂O and major-element contents (e.g., Al₂O₃ and CaO in high-Mg# Opx). Together, these observations indicate that the central NCC SCLM was generally dry prior to cratonic destruction, with H₂O variations mainly governed by the extent of partial melting. During the peak destruction stage, the SCLM became more hydrous, yet remained less hydrated than the eastern NCC. In the Cenozoic, it returned to a markedly drier state, plausibly reflecting thermo-chemical modification associated with asthenospheric upwelling. The temporal evolution of SCLM water contents beneath the central NCC implies an early phase of enrichment and hydration linked to flat-slab subduction of the Paleo-Pacific plate, followed by Cenozoic overprinting through refertilization and dehydration driven by asthenospheric upwelling.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108412"},"PeriodicalIF":2.5,"publicationDate":"2026-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034339","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":"2026-01-16","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":"Intracratonic magmatism associated with metallogeny and its magma sources and magmatic fertility: Insights from the Early Cretaceous Laiyuan complex in North China Craton","authors":"Chao Li ,&nbsp;Ju-Quan Zhang ,&nbsp;Degao Zhai ,&nbsp;Bowen Wei ,&nbsp;Cong Li","doi":"10.1016/j.lithos.2026.108409","DOIUrl":"10.1016/j.lithos.2026.108409","url":null,"abstract":"<div><div>Unlike globally prevalent mineralization in cratonic margin, the Hengshan-Wutai-northern Taihang region (HWTR) represents a typical and rare intracratonic Au-polymetallic metallogenic belt, which is situated within the interior North China Craton (NCC), where voluminous Early Cretaceous magmatic suites provide critical insights into intracratonic metallogenic processes associated with magmatism. Here, we present zircon U-Pb geochronology, trace elements, and in-situ Lu-Hf isotopes on various magmatic rocks from the Laiyuan complex, which represents the largest and most compositionally diverse plutonic complex in the HWTR. Our new results, combined with previous whole-rock and zircon geochemical data, suggest that the Early Cretaceous magmatism were emplaced in two episodes: early magmatic event (including ultramafic-mafic rocks, intermediate-felsic granitoids and mafic enclaves) at ∼140–126 Ma, and late mafic diking event at ∼125–111 Ma. Their zircon Hf and whole-rock Sr-Nd isotopic data show different sources for their parent magmas. The early magma was originated predominantly from mafic lower crust, whereas the late magma was mainly derived from enriched lithospheric mantle. The Laiyuan high-K calc-alkaline granitoids exhibit adakitic signatures, e.g., high Sr/Y and low Y. Their trace element systematics, particularly (Sm/Yb)_SN, Yb_SN, and (La/Yb)_N ratios, indicate generation by partial melting of a mafic lower crust under normal thickness (&lt;40 km), rather than from a thickened crust. Besides, the early magmatism is contemporaneous with regional Au-polymetallic mineralization (∼135–129 Ma). Whole-rock fertility indicators (e.g., Nb/Y &gt; 0.3, U/Yb &gt; 0.5, Ba/Zr &gt; 4, V/Y &gt; 2) suggest that the parental melts retained magmatic Au-fertility during magmatic differentiations, with relative hydration states. Further analysis using zircon fertility discriminators (e.g., Eu/Eu* &gt; 0.4, Yb/Dy &gt; 4, 1000*(Eu/Eu*)/Y &gt; 1, (Ce/Nd)Y &gt; 0.01) indicates that the ultramafic-mafic rocks, diorites and monzogranites have a high potential for magmatic Au fertility.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108409"},"PeriodicalIF":2.5,"publicationDate":"2026-01-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146006814","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":"Refining the timing and genesis of NbTa Mufushan–Lianyunshan Orefield pegmatites (South China) using muscovite","authors":"Nurkanati Madayipu ,&nbsp;Huan Li ,&nbsp;Thomas J. Algeo ,&nbsp;Nuo Li ,&nbsp;Wen-Bo Sun ,&nbsp;Alessandro Petroccia ,&nbsp;Biao Liu ,&nbsp;Safiyanu Muhammad Elatikpo ,&nbsp;Han Zheng","doi":"10.1016/j.lithos.2026.108407","DOIUrl":"10.1016/j.lithos.2026.108407","url":null,"abstract":"<div><div>Pegmatites of the Mufushan–Lianyunshan orefield in South China represent one of the most evolved and preserved expressions of late Yanshanian crustal magmatism. Despite its importance, the duration and geochemical evolution of these systems remain debated due to scattered geochronological ages and incomplete integration of mineral-scale records. We combine muscovite major and trace element variation integrated with in-situ ⁴⁰Ar<img>³⁹Ar step-heating analyses, providing a chronological and geochemical constraints allowing to link melt evolution, volatile release, and high field strength elements enrichment. Major elements show limited variability, whereas trace elements such as Li, Be, Nb, Ta, Cs, Rb and Sn display systematic enrichments indicating advanced fractionation of peraluminous melts. Muscovite results reveal that Mufushan pegmatites experienced a higher degree of magmatic fractionation and are more favorable for Na–Ta–(Li–Be–Cs) mineralization, whereas Lianyunshan pegmatites show relative Sn enrichment. Muscovite in-situ ⁴⁰Ar<img>³⁹Ar plateau ages form a narrow cluster of 129.8–128.6 Ma in Mufushan and 128.5–126.0 Ma in Lianyunshan, outlining a ∼ 4 Myr interval corresponding to the final magmatic–hydrothermal stage. When integrated with existing ages that span ∼142–121 Ma, a coherent multi-stage evolution emerges in which early high-temperature magmatism was followed by progressive melt fractionation and pegmatite generation, culminating in high field strength elements-rich muscovite crystallization. Beyond the importance of the obtained results in refining the timing and evolution of Nb<img>Ta pegmatites in South China, our results confirm the importance of muscovite for characterizing rare-metal systems and guiding exploration strategies.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108407"},"PeriodicalIF":2.5,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976974","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":"Monazite petrochronology and Nd isotopes deciphering dynamic magma sources in the genesis of the Himalayan leucogranites","authors":"Hui-Chan Huang ,&nbsp;Peng Gao ,&nbsp;Zhang-Jian Wu ,&nbsp;Yan Wang ,&nbsp;Zi-Fu Zhao ,&nbsp;Changqing Yin","doi":"10.1016/j.lithos.2026.108414","DOIUrl":"10.1016/j.lithos.2026.108414","url":null,"abstract":"&lt;div&gt;&lt;div&gt;Deciphering the magmatic evolution of S-type granites through zircon petrochronology presents significant challenges due to the textural complexities observed in this mineral, particularly so for the Himalayan leucogranites in which zircon is characterized by large relict cores but narrow overgrowth rims. Conventional whole-rock geochemical approaches often fail to adequately resolve dynamically varied magmatic sources and processes. In this study, we utilize integrated in-situ monazite U–Th–Pb geochronology, and trace element and Nd isotope geochemistry of the Cuonadong granitic suite, which includes two-mica granite, muscovite granite, and pegmatite, located in the eastern Tethyan Himalaya, to constrain the timing, duration and evolution process during magma crystallization. Our monazite data collectively reveal a crystallization history lasting ca. 5.2 Myr and three distinct magmatic pulses occurring at ca. 20, 18, and 16 Ma, respectively, characterized by progressively decreasing ε&lt;sub&gt;Nd&lt;/sub&gt;(t) values (from −8.7 to −15.4) and varying rare earth element (REE) compositions, collectively documenting evolving melt sources and discrete or cogenetic crystallization processes. The earliest phase (∼19–20 Ma), consisting of all three lithologies, have ε&lt;sub&gt;Nd&lt;/sub&gt;(t) values ranging from −12.5 to −8.7, featuring pegmatites with the most depleted ε&lt;sub&gt;Nd&lt;/sub&gt;(t) values and the earliest crystallization initiation relative to two-mica and muscovite granites. This challenges the general fractionation crystallization model, but suggests that the pegmatitic melts originate from volatile-rich sources within Higher Himalayan Crystalline Sequence (HHCS) metapelites under extensional decompression of South Tibet Detachment System (STDS). Subsequent pulse (∼17–18 Ma) also includes the three lithologies and displays comparable Nd isotope compositions (ε&lt;sub&gt;Nd&lt;/sub&gt;(t) = −13.5 to −9.4) alongside systematic REE variations that reflect concomitant fractional crystallization of monazite and feldspar. In the latest pulse, the muscovite granites crystallized earlier (16.8–16.3 Ma) than the two-mica granites (16.2–15.6 Ma) and have higher ε&lt;sub&gt;Nd&lt;/sub&gt;(t) values than the latter (−13.8 to −12.3 vs −15.4 to −13.3). Therefore, the apparently systematic variations in REE compositions do not testify fractional crystallization-controlled process but only illustrate respective crystallization processes of two melt batches. Importantly, the progressively lowering ε&lt;sub&gt;Nd&lt;/sub&gt;(t) values with crystallization ages suggest an increasing incorporation of ancient Lesser Himalayan Sequence (LHS) material since 20 Ma, probably driven by the movement along the Main Central Thrust (MCT). These findings fundamentally challenge the recently proposed fractionation crystallization model regarding the relationship between the three lithologies of interest, rejecting the simplistic differentiation trends from two-mica granite through muscovite granite to pegmatite. Instead,","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108414"},"PeriodicalIF":2.5,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146034340","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":"Petrogenesis of Early Cretaceous granitoids in the northern Lhasa margin, Tibet: Implications for the southward subduction of the Bangong-Nujiang Meso-Tethys Ocean","authors":"Wei Chen ,&nbsp;Miao Sun ,&nbsp;Xudong Ma ,&nbsp;Yang Song ,&nbsp;Zhi Zhang ,&nbsp;Jiajia Yu ,&nbsp;Mengxiang Di ,&nbsp;Chang Liu ,&nbsp;Shuhao Zhang ,&nbsp;Juxing Tang","doi":"10.1016/j.lithos.2026.108413","DOIUrl":"10.1016/j.lithos.2026.108413","url":null,"abstract":"<div><div>Debates persist over the tectonic evolution of the Bangong-Nujiang Meso-Tethys Ocean (BNTO), especially the hypothesis about its southward subduction. There is a lack of evidence for its southward subduction beneath the northern Lhasa terrane due to the presence of sedimentary cover and ambiguous geodynamic interpretations. To address this issue, this study investigated the Early Cretaceous granitoids (116–108 Ma) in the Xiongmei-Bange area located along the northern margin of the Lhasa terrane. The results indicate that the granitoids consist of two distinct suites: peraluminous and metaluminous granitoids. Among these, the peraluminous granitoids exhibit A/CNK ratios ranging from 1.03 to 1.47 and moderate enrichment in isotopic signatures, with ε_Hf(t) and ε_Nd(t) values varying from −5.1 to +2.4 and from −10.7 to −5.9, respectively. These granitoids were derived from the amphibolitic lower crust metasomatized by subducted sediments. In contrast, the metaluminous granitoids manifest A/CNK ratios ranging from 0.99 to 1.06, high enrichment in Nd<img>Hf isotopes, with ε_Hf(t) and ε_Nd(t) values ranging from −8.7 to −0.9 and from −11.2 to −8.0, respectively, and elevated Mg# values varying from 50 to 63. They originated from the partial melting of the ancient lower crust, with significant mantle-derived contributions, a source composition indicated by their metaluminous character, enriched Nd<img>Hf isotopes, and elevated Mg#, which collectively reflect limited influence from subducted sediments compared to the peraluminous suite. The results suggest that the southward subduction of the BNTO may have commenced during the Middle Jurassic, with slab rollback at about 130 Ma and subsequent slab breakoff at around 115 Ma potentially triggering asthenospheric upwelling. This process could have induced lithospheric mantle melting and crustal anatexis, leading to the formation of the two granitoid suites. Slab rollback and breakoff are interpreted to have destabilized the overriding plate, causing the lithospheric subsidence in the northern Lhasa terrane during the Early Cretaceous. This subsidence likely induced a major marine transgression (Langshan Formation, 115–98 Ma). Consequently, the Jurassic - Early Cretaceous magmatic arc was covered by shallow-marine carbonates, effectively masking direct evidence of southward subduction. By integrating slab dynamics (i.e., possible rollback and subsequent breakoff) with the burial history, this study proposes a model that addressed the long-standing debate over the apparent absence of an arc-trench system.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"522 ","pages":"Article 108413"},"PeriodicalIF":2.5,"publicationDate":"2026-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145976975","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}