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":"2026-04-01","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":"2026-04-01","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":"2026-04-01","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":"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":"2026-04-01","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":"Tibetan Oligocene adakitic granites sourced from metasedimentary rocks in thickened lower crust","authors":"Jin Luan ,&nbsp;Huixia Ding ,&nbsp;Matthew J. Kohn ,&nbsp;Zeming Zhang ,&nbsp;Mingming Guo ,&nbsp;Chengyuan Zhang ,&nbsp;Shuangpeng Wu","doi":"10.1016/j.lithos.2026.108435","DOIUrl":"10.1016/j.lithos.2026.108435","url":null,"abstract":"<div><div>Widespread Late Cenozoic granites in the southern Tibetan Plateau mostly show adakite-like geochemical signatures and have been commonly considered to derive from partial melting of mafic rocks in thickened juvenile lower crust. Here, we show that Late Oligocene adakitic granites from the eastern Gangdese arc, southeastern Tibet, contain an unequivocal metasedimentary source. The studied granites are characteristically adakitic, with variable but high SiO₂, K₂O and Sr (222–802 ppm), and high Sr/Y (16.1–195.2) and La/Yb (6.7–89.7). Most importantly, zircon with Late Oligocene (∼26 Ma) magmatic rims has inherited detrital cores with major age peaks at ∼1600, ∼1100, ∼550, and ∼ 300 Ma. Isotope compositions have high (⁸⁷Sr/⁸⁶Sr)_i (0.70588–0.71058) and low ε_Nd(t) (−5.8 to −2.3). These characteristics, together with phase equilibrium and radiogenic heating modeling results, indicate derivation of adakitic granites from partial melting of Carboniferous metasedimentary rocks in the thickened lower crust. Crustal thickening and associated radioactive heating during Cenozoic collisional orogeny triggered extensive partial melting of thickened lower crust. We suggest that the Late Cenozoic adakitic granites in southern Tibet were derived from diverse lower crustal sources, and have significantly distinct chemical compositions and metallogenic potentials. The coexistence of adakitic granites sourced both from metaigneous and metasedimentary rocks is a key indicator of Tibetan Plateau-like collisional orogens.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"524 ","pages":"Article 108435"},"PeriodicalIF":2.5,"publicationDate":"2026-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"147399430","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":"2026-03-01","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":"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":"2026-03-01","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":"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":"2026-03-01","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":"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":"2026-03-01","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":"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}