Lithos最新文献

{"title":"Formation of the Sanchachong skarn W deposit and associated weakly evolved granitoids in South China: Insights from whole-rock and mineral geochemistry","authors":"Tingyi Wang ,&nbsp;Qihai Shu ,&nbsp;Qingfei Wang ,&nbsp;Xiaolin Cui ,&nbsp;Yanning Wang ,&nbsp;Chao Li ,&nbsp;Jun Deng ,&nbsp;Kai Xing ,&nbsp;Tuo Yang ,&nbsp;Chunping Li","doi":"10.1016/j.lithos.2025.108199","DOIUrl":"10.1016/j.lithos.2025.108199","url":null,"abstract":"<div><div>Globally, many tungsten (W) deposits are associated with highly evolved magma systems, but some W deposits are genetically linked with weakly evolved granitoids. Nevertheless, the key factors controlling the W enrichment in such systems remain obscure. The ∼106 Ma Sanchachong W deposit (50 Kt WO₃ at 0.35 %) from the southern Qinzhou–Hangzhou belt of South China is a typical example, with the causative intrusion being a granodiorite. In this contribution, we unravel the magmatic processes, volatile compositions, and ore-forming metal characteristics at Sanchachong, shedding light on the mechanisms driving W mineralization of weakly evolved granitoids. The geochemical characteristics of bulk rocks and key minerals (zircon, apatite, and biotite) jointly denote that the ore-related intrusion is a weakly evolved I-type granitoid. The magmas have experienced the slight-moderate separations of amphibole and biotite, as evident by the elevated Sr/Y ratios and low Rb/Sr and Rb/Ba ratios. Additionally, the low zircon δ¹⁸O of 6.5 to 8.2 ‰ and apatite (⁸⁷Sr/⁸⁶Sr) of 0.7071 to 0.7077, and high apatite ε_Nd(t) of −3.2 to −7.5 indicate derivation from lower continental crustal sources. Distinct from adjacent barren weakly evolved S-type granites, the fertile Sanchachong granodiorites exhibit: (1) elevated magmatic water content, as demonstrated by high zircon H₂O contents (330–490 ppm), amphibole chemistry calculations (∼7.3 wt% H₂O) and apatite Sr/Th ratios (37.8–123); (2) intensive fluid exsolution signatures, reflected in low apatite X_Cl/X_OH ratios of 0.01–0.04 and highly variable X_F/X_Cl ratios of 100–380; and (3) low F and W concentrations in melt, as evidenced by apatite X_F &lt; 0.89, biotite F &lt; 0.85 wt% and W &lt; 0.6 ppm. These characteristics, resembling equivalent granitoids associated with W deposits from the Jiangnan ore belt, reflect that an enrichment in water is more vital to promote W mineralization for weakly evolved granitoids compared with high magmatic W and F contents.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108199"},"PeriodicalIF":2.5,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144781686","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":"Deciphering magma plumbing processes beneath Pako seamount in the West Pacific: constraints from textural and compositional diversities of clinopyroxene phenocrysts","authors":"Xun Wei ,&nbsp;Yi-Gang Xu ,&nbsp;Yan Zhang ,&nbsp;Quan-Shu Yan ,&nbsp;Xue-Fa Shi","doi":"10.1016/j.lithos.2025.108195","DOIUrl":"10.1016/j.lithos.2025.108195","url":null,"abstract":"<div><div>Magma recharge and mixing can result in diversity of magmatic compositions and trigger the eruptions of volcanoes. Such processes can be read through the textural and compositional characterization of minerals in volcanic rocks. Lavas from the Pako guyot in the West Pacific exhibit a large compositional variation and host abundant clinopyroxene phenocrysts, providing a good opportunity to investigate the origin of whole-rock compositional diversities through mineral texture and chemistry. Here we present textural characterization and in-situ major and trace element and Sr isotopic data for clinopyroxene phenocrysts from five lava samples collected from the Pako guyot in the West Pacific. The clinopyroxene phenocrysts commonly show normal and reverse zoning or complex zoning (e.g., combination of normal, reverse and/or patchy zoning). Only a few clinopyroxene phenocrysts are in Fe<img>Mg equilibrium with their respective fine-grained matrix pointing to an autocryst origin. The majority of the clinopyroxene phenocrysts are in disequilibrium with their respective fine-grained matrix both texturally (resorption texture) and chemically (higher Mg# and larger ⁸⁷Sr/⁸⁶Sr variation than that in equilibrium with the respective fine-grained matrix). These clinopyroxene phenocrysts form continuously variable major and trace element concentrations and exhibit nearly identical trace element patterns to the autocrysts, indicating that they are antecrysts that crystallized from co-genetic, progenitor magmas. The clinopyroxene phenocrysts overall display a large variation of Sm/Yb, Dy/Yb and ⁸⁷Sr/⁸⁶Sr (0.7036–0.7061) ratios at a small range of Mg# indicating that they crystallized from multiple batches of melts formed from mixing between focal zone (FOZO)- and enriched mantle 1 (EM1)-derived melts. Clinopyroxene textural and compositional diversities record complex magmatic processes that occurred in the Pako magma reservoir including fractional crystallization, recycling of early formed crystals following dissolution and resorption, and multiple magma replenishment and mixing. Deep (at a depth of ∼20 km near the crust-lithospheric mantle boundary) fractionation of clinopyroxene results in the evolved composition (MgO &lt; 7 wt%) and multiple magma replenishment and mixing generate compositional diversities of the Pako guyot lavas.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108195"},"PeriodicalIF":2.5,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144739177","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":"Analysis of detrital chromian spinel to unravel petrologic character of serpentinite mélange: Example from the Mineoka belt, central Japan","authors":"Shoji Arai ,&nbsp;Terumi Ejima ,&nbsp;Nobuko Ushimura ,&nbsp;Naoki Takahashi","doi":"10.1016/j.lithos.2025.108201","DOIUrl":"10.1016/j.lithos.2025.108201","url":null,"abstract":"<div><div>We propose a new method for petrologic analysis of serpentinite mélange using modern detrital chromian spinel. Serpentinite mélange or strongly sheared serpentinite complexes are composed of hard blocks and softer matrix, where the samples for petrologic examination tend to be taken from the former. The matrix composed of comminuted serpentinite has therefore far less thoroughly sampled than the blocks for petrologic analysis. To test our method, we analyzed detrital chromian spinel from placer-like concentrations on the beach near Mineoka serpentinite mélange of the Miocene, central Japan. The Mineoka serpentinite mélange consists of sheared or comminuted serpentinite which encloses hard serpentinized peridotite blocks of various sizes, which are similar to abyssal peridotites with relatively low Cr# (= Cr/(Cr + Al) atomic ratio; &lt; 0.6) of chromian spinel. In the analyzed detrital spinel grains, high-Cr# (&gt;0.6) spinels are appreciably present, almost equal in amount to the low-Cr# (&lt; 0.6) ones. This means the protolith of the sheared matrix of the mélange, which has been unsampled, was mainly the depleted arc-type peridotites that contain high-Cr# (up to 0.8) spinel. The source peridotite complex for the Mineoka serpentinite mélange was possibly composed of abyssal peridotites and depleted arc-type peridotites before the strong shearing. The latter have been obliged to the shearing because of their preferential serpentinization and mechanical weakness. The serpentinite mélange composed of abyssal peridotite blocks and arc-type peridotite-derived matrix can be therefore produced from a single coherent mantle fragment. Detrital chromian spinel should be used more not only for sedimentological work but also for petrologic work on peridotite or serpentinite complexes.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108201"},"PeriodicalIF":2.9,"publicationDate":"2025-07-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144712996","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":"Geological and geochemical characteristics of intermediate-basic intrusions in Funiushan area, southern margin of the North China Craton: Implications for tectonic environment and mantle properties in the Early Cretaceous","authors":"Wei Zeng ,&nbsp;Feng-Yue Sun ,&nbsp;Cheng-Dong Li ,&nbsp;Zhi-Dan Li ,&nbsp;Yin-Hang Cheng ,&nbsp;Wen-Gang Liu ,&nbsp;Jia-Run Tu ,&nbsp;Chao Zhang ,&nbsp;Xing Liu ,&nbsp;Wei-Zhi Sun","doi":"10.1016/j.lithos.2025.108193","DOIUrl":"10.1016/j.lithos.2025.108193","url":null,"abstract":"<div><div>This study presents new geochronological and geochemical data for Early Cretaceous intermediate–basic rocks located on the southern margin of the North China Craton (SNCC). The petrogenesis and sources of these rocks were analysed, and the tectonic environment and mantle properties of the SNCC were discussed. The examined rocks include Tianqiaogou monzodiorites and quartz monzonites, Hebian gabbros and diorites, and Renjiagou quartz monzodiorites. LA-ICP-MS U<img>Pb dating indicates the crystallization ages of these rocks are 124–116 Ma. The Tianqiaogou monzodiorites show low MgO and Mg^#, low (⁸⁷Sr/⁸⁶Sr)_i ratios (0.706149–0.706388), and high ε_Nd(t) values (−2.36 to −2.68), suggesting that they derived from partial melting of the juvenile basaltic lower crust, which originated from the partial melting of the lithosphere mantle. The uneven composition and unbalanced mineral structure of the quartz monzonites indicate a result of mixing between dioritic magmas and granitic melts. The Hebian gabbros, classified as high-Nb basalt, exhibit significant enrichment in large ion lithophile elements (LILEs) such as Rb, Ba and La, with no negative anomalies for Nb and Ta, as well as high contents of FeO, TiO₂, and total trace elements amount. These characteristics combined with more depleted Nd<img>Hf isotopic compositions, suggest an origin from a lithospheric mantle that has been strongly metasomatized by asthenosphere-derived melts. The Renjiagou quartz monzodiorites, classified as high-Mg diorite, have high Cr and Ni contents, are significantly enriched in LILEs and depleted in Nb, Ta, Ti and P, with enriched Sr-Nd-Hf isotopic compositions, indicating an origin of lithospheric mantle metasomatized by dehydration fluids from the Paleo-Pacific plate. Geochemical and isotopic data reveal that these intrusions formed in a strongly extensional tectonic setting linked to the rollback of the subducting Paleo-Pacific Plate which caused large-scale asthenospheric upwelling and facilitated the melting of the lithospheric mantle. The Early Cretaceous intermediate-basic rocks that appeared along the SNCC directly or indirectly originated from the mantle sources with varying chemical and isotopic compositions, highlighting the heterogeneity of the lithospheric mantle.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108193"},"PeriodicalIF":2.9,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144712997","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":"Secondary rare metal enrichment following biotite alteration in the Umm Naggat granitic pluton, Central Eastern Desert, Egypt","authors":"Mohamed A. Abdelkader ,&nbsp;Yasushi Watanabe ,&nbsp;Maher Dawoud ,&nbsp;Shogo Aoki ,&nbsp;Yoshiaki Kon ,&nbsp;Carmela Tupaz ,&nbsp;Takuya Echigo ,&nbsp;Mai A. El-Lithy ,&nbsp;Hanaa A. El-Dokouny","doi":"10.1016/j.lithos.2025.108191","DOIUrl":"10.1016/j.lithos.2025.108191","url":null,"abstract":"<div><div>Biotite is an essential mineral in regulating Nb<img>Ta fractionation during magma evolution. Post-magmatic, metasomatic biotite alteration may form secondary rare metal (RM)-bearing phases. Nevertheless, the mechanism of biotite alteration remains incompletely elucidated. The Umm Naggat granitic pluton (UMNG) in Egypt comprises RM-bearing amphibole-biotite granite (SBTG) in its southern sector, with biotite being significantly more abundant than amphibole. Amphibole and biotite in the SBTG crystallized from Nb-enriched magma and represent primary high-field strength elements (HFSE) reservoirs. Amphibole contains Nb (280 ppm), Ti (5760 ppm), Y (506 ppm), Zr (87 ppm), and Mn (2801 ppm), while biotite contains significantly higher Nb (1630 ppm), Ta (83 ppm), Sn (392 ppm), Ti (9268 ppm), Rb (2846 ppm), and Li (6331 ppm). The Nb enrichment in biotite mainly depended on its composition (Ti and Fe), enhanced by high formation temperatures.</div><div>In the SBTG, hydrothermal alteration is divided into the metasomatic and aqueous stages. The metasomatic fluid was enriched in Na-F-Nb-Ta-Zr, causing albitization and precipitation of metasomatic fluorite, columbite-(Fe), and zircon. Biotite is extensively altered during the aqueous stage, mainly to muscovite and chlorite, through a coupled dissolution-precipitation mechanism. The replacement textures of primary biotite imply that the hydrothermal fluids were acidic and fluorine-bearing, with considerable Y and REE amounts. During the alteration, Ti, Fe, Sn, Ta, and Nb were liberated from the biotite into the fluid as Ta-Nb-F complexes. The continuous consumption of H⁺ and F⁻ resulted in their depletion, making the Ta-Nb-F complexes unstable, reducing their solubility, and leading to the precipitation of secondary Ta-Nb-Sn-Y-REE-Fe-Ti-bearing oxides near or within muscovite and chlorite. The former alteration-precipitated oxides, including niobian rutile, Nb-ilmenite, columbite-(Fe), and euxenite-(Y), are significantly enriched in Nb, Ta, and Sn compared to their primary equivalents (primary niobian rutile, Nb-ilmenite, columbite-(Fe), and fergusonite-(Y)). The spatial distribution of biotite alteration byproducts within the SBTG reveals distinct variations where the northern sector of the SBTG includes muscovite, niobian rutile, columbite-(Fe), and euxenite-(Y), while the southern sector includes muscovite, chlorite, niobian rutile, columbite-(Fe), and Nb-ilmenite with the dominancy of Fe cations in the fluid increasing over Ti cations toward the south. The hydrothermal fluid likely evolved into a more acidic character as the fluid temperature dropped with the alteration advancing toward the south of the SBTG. Considering its distinctive petrography, mineralogy, and textural variations, the alteration-formed Nb-Ta-Sn-enriched mineralization may delineate a new potential style and source for RMs in Egypt and worldwide.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108191"},"PeriodicalIF":2.9,"publicationDate":"2025-07-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144704330","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":"Geochronological and Sr-Pb-C-O isotope constraints on the genesis of carbonatites from the polychronous Mundwara alkaline complex (north western India)","authors":"Sudipa Bhunia ,&nbsp;N.V. Chalapathi Rao ,&nbsp;Andrea Giuliani ,&nbsp;Lorenzo Tavazzani ,&nbsp;Debojit Talukdar ,&nbsp;Rohit Pandey ,&nbsp;Alok Kumar ,&nbsp;Sirajuddin Ansari ,&nbsp;Bernd Lehmann","doi":"10.1016/j.lithos.2025.108194","DOIUrl":"10.1016/j.lithos.2025.108194","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The genesis of carbonatites is commonly related to either direct melting of carbonate-bearing mantle rocks or derivation from CO&lt;sub&gt;2&lt;/sub&gt;-rich silicate melts via either igneous fractionation or liquid immiscibility. Testing these hypotheses requires accurate geochronological and isotopic constraints on carbonatite and silicate rocks from the same igneous complex. The polychronous Mundwara alkaline complex offers an excellent setting to examine the origin of carbonatites because it contains a range of silicate rocks (including alkali-gabbros, syenites and other alkaline lithologies) and their ages (110–68.5 Ma) and radiogenic isotopic compositions have been previously constrained. However, the age and isotopic composition of the Mundwara carbonatites are currently unknown. To further our understanding of carbonatite magmatism at Mundwara, new apatite U-Pb ages are combined with petrographic observations, bulk‑carbonate C-O isotope analyses and in-situ determinations of trace element contents and Sr-Pb isotopic ratios for calcite and apatite. The Mundwara carbonatite dykes consist of calcite cumulates along with accessory apatite, pyrochlore, alkali feldspar, Fe-oxides and biotite. A range of REE-bearing phases including bastnäsite, parisite, and monazite is also present, although in accessory amounts. Cumulitic and seriate texture along with high Sr contents (&gt;1 wt%), attest to the primary igneous nature of the calcites. The apatites are magmatic as demonstrated by their pill shape, low Sr content and strongly fractionated chondrite-normalized REE patterns, which clearly distinguishes them from typical hydrothermal apatite elsewhere. The apatite grains yield a weighted mean &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr of 0.70447 ± 0.00003 (&lt;em&gt;n&lt;/em&gt; = 24), indistinguishable from those of the carbonates analyzed in the same samples (&lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr = 0.70446 ± 0.00001; &lt;em&gt;n&lt;/em&gt; = 54). Lead (&lt;sup&gt;207&lt;/sup&gt;Pb/&lt;sup&gt;206&lt;/sup&gt;Pb = 0.820–0.829; &lt;sup&gt;208&lt;/sup&gt;Pb/&lt;sup&gt;206&lt;/sup&gt;Pb = 2.065–2.088) and Sr isotopic compositions of the calcites are broadly intermediate between enriched mantle (EM) and HIMU (high &lt;sup&gt;238&lt;/sup&gt;U/&lt;sup&gt;204&lt;/sup&gt;Pb) compositions. The bulk‑carbonate δ&lt;sup&gt;13&lt;/sup&gt;C and δ&lt;sup&gt;18&lt;/sup&gt;O data of the Mundwara carbonatites have a narrow range from −6.2 ‰ to −6.8 ‰ and from +6.3 ‰ to +7.3 ‰ respectively, showing typical mantle values and excluding significant contamination or post-magmatic alteration as well as contribution by subducted carbon. Apatite defines an accurate, although imprecise U-Pb age of 100 ± 20 Ma, which closely matches the 110–102 Ma Ar-Ar ages of nepheline syenites from this complex. This observation coupled with overlapping Sr-Pb isotope compositions of the carbonatites and alkaline mafic rocks from Mundwara implies a close genetic link between carbonatites and silicate melts, which is best explained by either liquid immiscibility or differentiation of CO&lt;sub&gt;2&lt;/sub&gt;-bearing ultramafic melts. The ","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108194"},"PeriodicalIF":2.5,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144781689","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 the synorogenic alkaline Doros intrusion: Insights into geodynamic processes and lithospheric mantle heterogeneity beneath the Damara belt, Namibia","authors":"E.M. Hars ,&nbsp;S. Jung ,&nbsp;R.L. Romer","doi":"10.1016/j.lithos.2025.108192","DOIUrl":"10.1016/j.lithos.2025.108192","url":null,"abstract":"<div><div>The ∼530 Ma synorogenic alkaline Doros intrusion is characterized by a wide range of SiO₂ contents (48.5–75.3 wt%) and includes nepheline-normative monzodiorites to quartz-normative syenites, monzonites and granites. The K₂O + Na₂O contents are high and the MgO contents are low to moderate. Incompatible elements of the alkaline rocks are enriched (LILE: Sr and Ba up to 3460 and 4290 ppm, respectively) and Rare Earth Element patterns are strongly fractionated ([La/Yb]_N: 22–64) with no or minor Eu anomalies. Strontium and Nd isotopic compositions are moderately evolved (initial ⁸⁷Sr/⁸⁶Sr: 0.7049–0.7068, initial εNd: −2.7 to −4.9) and the Pb isotope ratios are moderately radiogenic (²⁰⁶Pb/²⁰⁴Pb: 17.48–18.62, ²⁰⁷Pb/²⁰⁴Pb: 15.58–15.67, ²⁰⁸Pb/²⁰⁴Pb: 37.41–37.93). The magma of the Doros intrusion evolved by combined AFC processes. Relative depletions of Ba and Sr with increasing differentiation imply fractionation of K-feldspar and plagioclase. Zr/Hf and Nb/Ta ratios are superchondritic in the primitive samples and decrease with increasing SiO₂ mainly as a result of amphibole and biotite fractionation coupled to some crustal assimilation. Systematic isotopic variations indicate 10–20 % assimilation of highly evolved basement material. The Doros intrusion likely resulted from partial melting of metasomatized lithospheric mantle material that had been enriched in a subduction zone environment, as is evident from relative depletions of Rb, Nb<img>Ta, K, Pb, P, Zr<img>Hf and Ti (primitive mantle-normalized multi-element diagram) in less evolved rocks. Metasomatic enrichment could have occurred in the Palaeoproterozoic (∼1.7–1.9 Ga) during subduction of juvenile crustal material or during subduction of evolved crustal material shortly before alkaline melt generation. Distinct differences in the Sr, Nd and Pb isotope signatures of the synorogenic alkaline intrusions of the Damara orogen (Doros, Voetspoer, Otjimbingwe alkaline complex) reflect large-scale heterogeneity of the lithospheric mantle beneath the Damara belt during Pan-African times as a result of spatial variations in the nature of the subducted material. Transtensional reactivation of shear zones in the Ugab Zone during the Damara orogeny facilitated melting of the lithospheric mantle and magma ascent for the Doros and Voetspoer intrusions.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108192"},"PeriodicalIF":2.5,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144722974","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":"Age and geology of granitoids in northeast Palmer Land, Antarctic Peninsula","authors":"Ryan North ,&nbsp;Lloyd T. White ,&nbsp;Teal R. Riley ,&nbsp;Dominique Tanner ,&nbsp;Timothy T. Barrows","doi":"10.1016/j.lithos.2025.108188","DOIUrl":"10.1016/j.lithos.2025.108188","url":null,"abstract":"<div><div>The Antarctic Peninsula preserves a long history of Late Paleozoic and Mesozoic magmatism that reflects dynamic processes along the southwestern Gondwanan convergent margin. Granitoid magmatism is widespread across the Peninsula and records a complex history of subduction, massive silicic volcanism, and metamorphism. However, direct field observations are rare due to the inaccessibility of many remote outcrops, particularly in the central sector of the Antarctic Peninsula. Robust petrochronological data are even more scarce, limiting the ability to connect rock exposures across large ice-covered areas. Plutonic rocks across parts of the southern Antarctic Peninsula (northeast Palmer Land) lack detailed characterisation and geochronological constraints. Here, U<img>Pb isotopes and trace elements (e.g., Ti, P, Ce, Eu, and other REEs) are analysed in zircon (<em>n</em> = 1148) from archived samples from Mount Faith, Mount Sullivan, and Engel Peaks to calculate the timing and nature of magmatic and metamorphic events. These data are supplemented with in situ and whole-rock geochemistry. The resulting magmatic crystallisation ages are Early Jurassic (188–179 Ma) for calc-alkaline, peraluminous, weakly S-type granitoids at all three locations. This novel age constraint for the Mount Faith Granite: (1) indicates it is distinct from all three granitoid emplacement phases at Mount Charity immediately south, and (2) provides an upper age limit on cross-cutting tholeiitic mafic dykes. Deformation of the Mount Faith Granite could reflect either post-crystallisation strain or <em>syn</em>-emplacement strain that deformed granitoids of the Subcordilleran Plutonic Belt. Early Cretaceous (116–120 Ma) recrystallisation of Early Jurassic zircon provide evidence of the first phases of the Palmer Land Event on the central Peninsula. New data presented here provide a detailed geochronology of granitoids in northeast Palmer Land that can be used for Mesozoic tectonic reconstructions.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108188"},"PeriodicalIF":2.9,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144656795","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":"Duration and final closure of the Changning–Menglian Paleo-Tethys Ocean in the Southeastern Tibetan Plateau","authors":"Dongbing Wang ,&nbsp;Keqing Zong ,&nbsp;Liang Luo ,&nbsp;Yuan Tang ,&nbsp;Baodi Wang","doi":"10.1016/j.lithos.2025.108187","DOIUrl":"10.1016/j.lithos.2025.108187","url":null,"abstract":"<div><div>The timescales for the duration and final closure of the Paleo-Tethys Ocean (PTO) remain controversial. To address these issues, this study reports the geochronological and geochemical data of two newly identified retrograded eclogites in the southeastern Tibetan Plateau. These eclogites outcropped in the Genhen and Mangna regions within the Changning–Menglian suture that represents the extinct site of the PTO. Geochemically, the protoliths of the Genhen and Mangna samples are arc-related and oceanic crust-related mafic rocks, respectively. Zircon cores that exhibit oscillatory zoning, high Th/U ratios, and enriched heavy rare earth element (HREE) patterns yield U<img>Pb ages of 250 ± 1 Ma and 429 ± 3 Ma, which are interpreted as the formation ages of their protoliths. Combined with other early Paleozoic magmatic and metamorphic records in this suture, we propose that the PTO may have existed for over 200 Myr in the southeastern Tibetan Plateau. By contrast, zircon rims characterized by low Th/U ratios and flat HREE patterns yield U<img>Pb ages of 230 ± 4 Ma and 231 ± 2 Ma, which are consistent with the ⁴⁰Ar/³⁹Ar plateau age (232.6 ± 2.2 Ma) of phengites from the country-rock schist. In addition, given that phengite inclusions have been found in zircon rims, we propose that these eclogites with varying protolith ages simultaneously experienced retrograde metamorphism at ∼230 Ma, which might be associated with slab break off and exhumation after continental collision. Our data reconstruct the timelines for the development of the PTO in the southeastern Tibetan Plateau, including its persistence from the early to late Paleozoic and final closure prior to the high-pressure metamorphism at ∼230 Ma but not earlier than the youngest protolith ages (∼250 Ma) of retrograded eclogites. These approaches and results have general implications for understanding the tectonic evolution of the Paleo-Tethys Ocean.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108187"},"PeriodicalIF":2.9,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686473","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 Late Cretaceous andesitic porphyrites in the Zhongcang area: Implications for early uplift and tectonic evolution of the central Tibetan Plateau","authors":"Yongpeng Lin ,&nbsp;Feng Huang ,&nbsp;Jifeng Xu ,&nbsp;Yunchuan Zeng","doi":"10.1016/j.lithos.2025.108186","DOIUrl":"10.1016/j.lithos.2025.108186","url":null,"abstract":"<div><div>The central Tibetan Plateau is widely recognized to have undergone significant surface uplift during the Late Cretaceous; however, the deep-seated geodynamic processes driving this uplift remain debated. Magmatic rocks, as direct records of lithospheric processes, provide critical constraints on the nature and evolution of the deep crust and mantle. This study presents a comprehensive petrographic, zircon U-Pb geochronological, geochemical, and Sr-Nd-Hf isotopic investigation of Late Cretaceous andesitic porphyrites from the Zhongcang area in the northern Lhasa Terrane, central Tibetan Plateau. Geochronological results indicate that the Zhongcang andesitic porphyrites crystallized at ∼90 Ma. These rocks are characterized by relatively high SiO₂ (62.00–62.96 wt%) and moderate K₂O (0.96–1.14 wt%) contents, elevated Mg# values (51.6–53.7), high Sr (369–399 ppm) and low Y (10.2–10.9 ppm) concentrations, and high Sr/Y ratios (34.49–38.25), geochemically resembling high-Mg# adakitic rocks. They exhibit enrichment in large-ion lithophile elements and depletion in high-field-strength elements, with Th/U (3.82–4.42) and Nb/Ta (12.5–14.9) ratios comparable to those of continental crust. The heterogeneous zircon Hf isotopic compositions (ε_Hf(t) = −7.7 to +10.7) indicates involvement of both juvenile and ancient crustal components, whereas whole-rock Sr-Nd isotopic compositions (⁸⁷Sr/⁸⁶Sr_i = 0.704716–0.705051, ε_Nd(t) = +0.23 to +0.59) suggest a mainly juvenial crustal source. Pressure estimates from whole-rock and zircon trace element barometry indicate that the crustal thickness of the northern Lhasa Terrane reached ∼70 km during the early Late Cretaceous. Given that this period corresponds to the post-collisional setting of the Qiangtang-Lhasa terrane convergence, we propose that the Zhongcang andesitic porphyrites were derived from magmas generated by the delamination of the thickened juvenile lower crust with locally ancient components, which subsequently interacted with mantle materials during ascent. This lower crustal delamination not only contributed to surface uplift in the central Tibetan Plateau but may have also facilitated lithospheric thinning following crustal thickening.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108186"},"PeriodicalIF":2.9,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144686472","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}