Lithos最新文献

{"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":"U-Pb ID-TIMS baddeleyite age and geochemistry of the newly identified ca. 1.94 Ga magmatic event in the Central-Western Bastar craton","authors":"Ankur Ashutosh ,&nbsp;Ulf Söderlund ,&nbsp;Amiya K. Samal ,&nbsp;Gulab C. Gautam ,&nbsp;Rajesh K. Srivastava ,&nbsp;Richard E. Ernst ,&nbsp;Hafida El Bilali","doi":"10.1016/j.lithos.2025.108183","DOIUrl":"10.1016/j.lithos.2025.108183","url":null,"abstract":"<div><div>A NNW-trending mafic dyke from the central-western Bastar craton yields a U<img>Pb ID-TIMS baddeleyite age of 1944 ± 6 Ma. By correlating additional dykes with similar trend and geochemical characteristics, we identify a previously unrecognized dyke swarm, named herein the Pakhanjore swarm. Geochemical evidence suggests that the studied rocks are derived from partial melting of a spinel-rich, shallow lithospheric mantle source, involving 5–15 % partial melting as indicated by the non-modal batch melting model. AFC (Assimilation and fractional crystallization) modelling further reveals that fractional crystallization with moderate crustal assimilation (<em>r</em> = 0.3) contributes to the overall magmatic evolution. The similarity in trend of the ca. 1.94 Ga Pakhanjore swarm with the 1.89–1.88 Ga Bastanar swarm, and the ca. 1.85 Ga Sonakhan swarm of the Bastar craton suggests their emplacement occurred within a shared tectonic regime and/or paleostress field. Although notable geochemical similarities exist between the ca. 1.94 Ga Pakhanjore swarm and the 1.89–1.88 Ga and ca. 1.85 Ga mafic dykes, a direct genetic linkage remains inconclusive. However, based on available geological, geochronological, and geochemical data, the 1.89–1.88 Ga and ca. 1.85 Ga swarms appear to be part of a shared LIP event, whereas the ca. 1.94 Ga event likely represents an independent magmatic episode. The spatial alignment of all three dyke swarms with the NNW-trending Pranhita-Godavari Basin suggests a potential tectonic connection.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108183"},"PeriodicalIF":2.9,"publicationDate":"2025-07-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144662867","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":"Variable onset of magma segregation controls contrasting geochemical patterns of mineral assemblages in fractionating alkaline volcanic systems","authors":"Thomas Binder ,&nbsp;Michael A.W. Marks ,&nbsp;Tobias Fusswinkel ,&nbsp;Benjamin F. Walter ,&nbsp;Gregor Markl","doi":"10.1016/j.lithos.2025.108185","DOIUrl":"10.1016/j.lithos.2025.108185","url":null,"abstract":"<div><div>Three occurrences of primitive, alkaline, SiO₂-undersaturated, volcanic rocks from SW Germany show coarse-grained, mm- to cm-thin veinlets and pockets of differentiated lithologies that are a missing link in an evolutionary trend towards phonolites. (1) In the Hegau region (Hohenstoffeln), melilite-bearing olivine nephelinite contains ijolite pockets with skeletal perovskite, titanomagnetite, and euhedral fluorapatite. (2) Compositionally similar olivine melilitite at Urach (Sternberg) is crosscut by ijolite veinlets with late-magmatic lileyite and wadeite, in which subhedral–euhedral titanomagnetite and perovskite lack a skeletal shape. (3) Nepheline syenitic domains in a phlogopite-nepheline basanite from the Kraichgau region (Steinsberg) contain less clinopyroxene, titanomagnetite, and apatite, but accessory titanite. Differences between the fractionation products partly result from variable host magma compositions. However, the exact starting point of residual melt separation was the key factor explaining the trace element evolution of late mineral phases. Under conditions of advanced clinopyroxene crystallization and perovskite saturation (Urach), massive trace element fractionation led to high Nb/Ta and Zr/Nb, but low LREE/HREE and Zr/Hf ratios in clinopyroxene and perovskite. High F contents contributed to the stabilization of LILE, Zr, and Hf in the enriched residual melt which finally caused crystallization of an agpaitic assemblage. In contrast, melt separation before perovskite saturation (Hegau) resulted in strong, uniform enrichment of LILE, HFSE, and REE in clinopyroxene and perovskite. The nepheline syenite (Kraichgau) underwent a similar evolution with incompatible element enrichment in clinopyroxene and titanite, although its mineral assemblage differs from the ijolites due to higher SiO₂ and H₂O but lower F and P concentrations in the melt.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108185"},"PeriodicalIF":2.9,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144656796","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":"Subduction initiation of the Neotethyan Ocean recorded in chromite deposits: A case study of the Kızıldağ ophiolite, southern Türkiye","authors":"Ibrahim Uysal ,&nbsp;Recep Melih Akmaz ,&nbsp;Ben-Xun Su ,&nbsp;Yılmaz Demir ,&nbsp;Ahmet Dündar Şen","doi":"10.1016/j.lithos.2025.108184","DOIUrl":"10.1016/j.lithos.2025.108184","url":null,"abstract":"<div><div>The chromitites of the Kızıldağ ophiolite (KO) are primarily characterized by massive and disseminated textures within refractory mantle peridotites, predominantly harzburgite and dunite, with occasional occurrences of banded and nodular chromitites. Based on chromite composition, these chromitites can be classified into two groups exhibiting a broad compositional range: intermediate (0.55 ≤ Cr# &lt; 0.70, TiO₂ = 0.08–0.51 wt%) and high-Cr (0.70 ≤ Cr# ≤ 0.77, TiO₂ = 0.05–0.28 wt%). The compositions of minor and trace elements align consistently with variations in Cr#. Total PGE (Os, Ir, Ru, Rh, Pt, Pd) contents in these chromitites are generally less than 500 ppb, with many samples showing enrichment of IPGE (Os, Ir, Ru) relative to PPGE (Rh, Pt, Pd). However, certain samples from both groups display elevated PGE concentrations (ƩPGE_intermediate = 718 ppb, ƩPGE_High-Cr = 866 ppb) compared to other samples. The dominant platinum group mineral inclusions in chromite are Ru-rich laurite [(Ru, Os)S₂], with a single osmiridium (Os-Ir alloy) grain also observed suggesting formation under high-temperature and low ƒS₂ conditions. Primary base metal mineral inclusions include millerite and pentlandite. Additionally, some chromite crystals contain single or multi-phase silicate inclusions, such as clinopyroxene, orthopyroxene, olivine, and amphibole. Parental melt compositions, calculated from Al₂O₃ and TiO₂ contents of chromites, indicate that most high-Cr chromitites originated from boninitic melts, whereas intermediate chromitites and some high-Cr samples derived from melts with intermediate compositions. Trace element compositions of amphibole and clinopyroxene inclusions in the chromite crystals from the intermediate group further support crystallization from hydrous intermediate melts. It is proposed that the intermediate chromitite group formed from partial melts influenced by fluids from the subducted oceanic crust during the early stages of subduction initiation, while high-Cr chromitites originated from hydrous melts derived from a more depleted mantle wedge in later stages.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108184"},"PeriodicalIF":2.9,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144631285","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":"Analyses across a mid-ocean ridge give the scale of plume-fed heterogeneity","authors":"Shiki Machida ,&nbsp;Kyoko Okino ,&nbsp;Kana Ashida ,&nbsp;Shigekazu Yoneda ,&nbsp;Yasuhiro Kato","doi":"10.1016/j.lithos.2025.108175","DOIUrl":"10.1016/j.lithos.2025.108175","url":null,"abstract":"<div><div>The primary spatial scale of heterogeneity in the Earth's upper mantle, introduced from plume sources thousands of kilometres in scale at the base of the mantle, is critical for understanding mantle convection but is poorly constrained. Here, we demonstrate a geochemical shift in a set of lava samples collected from sites spaced approximately 10 km apart perpendicular to the Central Indian Ridge, which shows the length scale for a cross-section of concentric asthenospheric flow through the Réunion plume. This conclusion is derived from a mixing model that incorporates all expected mantle endmembers and common mantle components to reconstruct Sr–Nd–Pb isotopes and trace element profiles of lavas. The mixing model revealed that more than 95 % of the geochemical fingerprints of lavas are dictated by interactions between depleted mid-ocean ridge basalt mantle (DMM) and the prevalent mantle component of the plume (PREMA). The remaining, more specific features are contributed by varying proportions of enriched mantle components for each volcanic stage, reflecting the proposed archetypal chemical structure of the plume source at the base of the mantle. The latter additional components are concentrated in the core of the asthenospheric plume flow, which provides the primary short-length-scale (&lt;10 km) heterogeneity in the upper mantle. Material transport from the lower mantle to the upper mantle thus occurs on a scale one order of magnitude smaller than that of seismic detection. This result provides a high-resolution constraint on solid-Earth convection models.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108175"},"PeriodicalIF":2.9,"publicationDate":"2025-07-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144631286","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":"Discovery of ca. 2.33–2.22 Ga magmatic activities in the Longshan Complex bordering the southwestern margin of the North China Craton: Implications for tectonic transformation","authors":"Yi-Yi Zhang ,&nbsp;Jun-Sheng Lu ,&nbsp;Rui-Ying Zhang ,&nbsp;Yu-Ting Li ,&nbsp;Xu Kong ,&nbsp;Gang Liu ,&nbsp;Qiang Feng ,&nbsp;Zeng-Yin Duan ,&nbsp;Juan-Juan Li","doi":"10.1016/j.lithos.2025.108182","DOIUrl":"10.1016/j.lithos.2025.108182","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The 2.45–2.20 Ga in the early Paleoproterozoic, known as the tectono-magmatic lull, was marked by a decline in global continental magmatism and orogenic activity. This study is the first to identify ca. 2.33–2.30 Ga tonalite–trondhjemite–granodiorite (TTG) gneisses (2325 ± 23 Ma, 2296 ± 22 Ma) and ca. 2.25–2.22 Ga TTG gneisses (2246 ± 19 Ma, 2242 ± 23 Ma, 2217 ± 24 Ma) in the Zhangjiachuan area of the Longshan Complex, located along the southwestern margin of the North China Craton (NCC). All TTG gneisses exhibit high SiO&lt;sub&gt;2&lt;/sub&gt; and Na&lt;sub&gt;2&lt;/sub&gt;O concentrations but relatively low K&lt;sub&gt;2&lt;/sub&gt;O and MgO concentrations. The ca. 2.33–2.30 Ga TTG gneisses have medium to high Yb (0.78–2.94 ppm) and Y (11.16–28.01 ppm) concentrations, along with flat heavy rare-earth element patterns, suggesting that amphibole and/or garnet were the residual phases during partial melting under medium-pressure conditions. Their moderate Sr (225–437 ppm) concentrations and predominantly negative Eu anomalies (δEu = 0.61–0.93) further imply the presence of plagioclase in the residue. Alternatively, the ca. 2.25–2.22 Ga TTG gneisses exhibit low Yb (0.27–1.06 ppm) and Y (3.84–12.31 ppm) concentrations, positive or negligible Eu anomalies (δEu = 0.96–1.55), and higher Sr (333–1095 ppm) concentrations, indicating garnet and amphibole as the residual phases under high-pressure conditions. The lower Mg# (28–44), Cr (3.04–34.70 ppm), and Ni (2.83–5.45 ppm) concentrations suggest that the ca. 2.33–2.30 Ga TTG gneisses formed through the partial melting of the lower continental crust. Conversely, the higher Mg# (46–52) but lower Cr (6.03–16.67 ppm) and Ni (6.22–15.97 ppm) concentrations in the ca. 2.25–2.22 Ga TTG gneisses may indicate interaction with mafic melts from the mantle. The ca. 2.33–2.22 Ga TTG gneisses display ε&lt;sub&gt;Hf&lt;/sub&gt;(t) values ranging from −6.6 to +4.7 and T&lt;sub&gt;DM2&lt;/sub&gt; ages of 3.29 to 2.55 Ga, closely resembling those of the ca. 2.30 Ga TTG gneisses found in the southern NCC, suggesting that the ca. 2.33–2.22 Ga TTG gneisses originally formed in the southern NCC. Crust thickness calculations indicate a gradual thickening from 2.35 to 2.30 Ga, followed by a gradual decrease after 2.30/2.26 Ga in the southern NCC. This region experienced mafic–granitic magmatism during the early Paleoproterozoic, likely triggered by magmatic underplating—a process that facilitated mafic material injection into the lower crust, leading to progressive crustal thickening. Concurrently, the migration of intermediate-felsic magmas may have contributed to crustal densification. The combined effects of crustal thickening and densification could have induced lower crustal delamination, potentially explaining the observed post 2.30/2.26 Ga crustal thinning. The ca. 2.25–2.22 Ga TTG gneisses also exhibit geochemical characteristics indicative of interaction with mafic melts from the mantle. Thus, the southern NCC experienced a tectonic transition during the early Paleop","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108182"},"PeriodicalIF":2.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144580726","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 and emplacement of the Paleoproterozoic A-type Marajoara granite in the Carajás province, southeastern Amazonian craton: Constraints from geochemistry, zircon geochronology, NdHf isotopes, coexistence of reduced and oxidized magmas and new insights from a composite dike","authors":"Rodrigo Fabiano Silva Santos ,&nbsp;Davis Carvalho de Oliveira ,&nbsp;José de Arimatéia Costa de Almeida ,&nbsp;Roberto Dall'Agnol ,&nbsp;Bhrenno Marangoanha ,&nbsp;Marco Antonio Galarza ,&nbsp;Cláudio Nery Lamarão ,&nbsp;Fernando Fernandes da Silva","doi":"10.1016/j.lithos.2025.108174","DOIUrl":"10.1016/j.lithos.2025.108174","url":null,"abstract":"<div><div>The Marajoara granite is a Paleoproterozoic A-type stock that intruded into Mesoarchean tonalitic granitoids in the Rio Maria domain. It is composed of two compositionally and texturally distinct facies: equigranular (eBMzG) and heterogranular (hBMzG) biotite monzogranites. A rapakivi texture and the occurrence of microgranular enclaves (ME) and porphyritic ME (pME) are restricted to the hBMzG facies. The magnetic susceptibility values and the presence of magnetite indicate that the hBMzG facies is akin to granites from the magnetite series, whereas the eBMzG variety shows affinity with the granites of ilmenite series. These granites are high-silica, peraluminous and similar to ferroan granites. The hBMzG and pME show affinities with oxidized and the eBMzG with reduced A-type granites in the Jamon and Velho Guilherme suites, respectively. The ME have affinities with magnesian granites and the calc-alkaline series. U<img>Pb zircon analyses (SHRIMP) yield a crystallization age of 1884 ± 11 Ma for the hBMzG. Lu<img>Hf and Sm<img>Nd isotope data Ɛ_{Hf(1.88 Ga)} values range from −11 to −18 (hBMzG), while Ɛ_{Nd(1.88 Ga)} values vary from −9 to −11. The Hf-T_DM^C model ages are between 3.2 and 3.6 Ga, whereas the Nd-T_DM^C ages range from 2.9 to 3.6 Ga, indicating that the Marajoara granite-forming magma originated from a Meso- to Paleoarchean crustal source. Whole-rock geochemical data reveal compositional gaps, in terms of major and trace elements, between the two varieties that constitute the Marajoara granite, supporting the interpretation that they are not cogenetic. Geochemical modeling indicates that the original magmas were generated from partial melting of tonalitic rocks, with assimilation of metasedimentary rocks in the case of eBMzG. The contrasting redox states and modeling outcomes support distinct petrogenetic paths for the two facies. Felsic–mafic magma mixing played an important role in the crystallization history of the granite. The enclaves represent a basic magma from the lithospheric mantle that was injected into the magma chamber during underplating, where it interacted with the Marajoara pluton. This hypothesis is reinforced by the occurrence of a 1.88 Ga porphyritic granite–diabase composite dike in the Rio Maria area, provides independent evidence of bimodal magmatism. Microgranular and porphyritic enclaves formed due to the mixing of the felsic and mafic magmas. The results presented in this work highlight the importance of the Archean crust for the origin of Paleoproterozoic granites, whose emplacement at shallow crustal levels occurred through a dike feeder system resulting from extensional tectonics.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108174"},"PeriodicalIF":2.9,"publicationDate":"2025-07-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144587649","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":"Hybridization of crustal magmas and direct evidence for two mantle sources during Early-Ordovician magmatism at the NW Gondwana margin","authors":"Javier Rodríguez ,&nbsp;Christian Pin ,&nbsp;Saioa Suárez ,&nbsp;Luis Ángel Ortega ,&nbsp;Jean-Louis Paquette ,&nbsp;Benito Ábalos ,&nbsp;José Ignacio Gil Ibarguchi","doi":"10.1016/j.lithos.2025.108171","DOIUrl":"10.1016/j.lithos.2025.108171","url":null,"abstract":"<div><div>In the Malpica-Tui Complex, granitic gneisses, metagranodiorite and eclogite-facies gneisses represent a former subalkaline association of hypersolvus granite, granodiorite and tonalite. Besides, peralkaline gneisses, ferropargasite-bearing gneisses and alaskitic gneisses derive from an alkaline association of subsolvus alkali-feldspar granites and quartz alkali-feldspar syenites. The subalkaline association formed by open-system processes: anatectic granitoids contain comagmatic, subalkaline basic enclaves from a depleted mantle source [Y/Nb = 3–10; ε_Nd(475) = −0.8 to +5.3]. Also, the presence of HFSE-rich granodiorite with ferropargasite-bearing trondhjemite enclaves points to hybridization with a subordinate alkaline source. In the alkaline association, peraluminous alkali-feldspar granites (alaskites) contain the same basic enclaves as the subalkaline association, but also comagmatic, alkaline mafic rocks [Y/Nb = 0.5–1.1; ε_Nd(475) = +1.3 to +3.6]. Peralkaline granite, metaluminous alkali-feldspar granite and quartz alkali-feldspar syenite evolved from alkaline mantle melts through fractional crystallisation, with minor crustal assimilation. The two igneous associations developed in a regional context of continental rifting in Late Cambrian - Early Ordovician. In this setting, heat and mass transfer from rising mantle materials induced crustal anatexis and hybridization of the resulting partial melts with mantle-derived subalkaline magmas, presumably in the Late Cambrian. Subsequently, minor amounts of alkaline melts were also involved in the generation of subalkaline granitoids in the Early Ordovician (481 ± 1 Ma). The increasing relative contribution of alkaline melts progressively changed the composition of the acid magmas, leading to the emplacement of peraluminous alkali-feldspar granites, and finally, of mantle-derived, peralkaline and metaluminous granitoids at 472 ± 1 Ma.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108171"},"PeriodicalIF":2.9,"publicationDate":"2025-07-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144596013","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":"Superimposed Triassic and Oligocene W mineralization in the Yangla deposit, Southwest China: Evidence from scheelite geochemistry and U-Pb geochronology","authors":"Ju-Ting Deng ,&nbsp;Jing-Jing Zhu ,&nbsp;Pete Hollings ,&nbsp;Ming-Liang Huang ,&nbsp;Zong-Yong Yang ,&nbsp;Dian-Zhong Wang","doi":"10.1016/j.lithos.2025.108172","DOIUrl":"10.1016/j.lithos.2025.108172","url":null,"abstract":"<div><div>The Sanjiang region in southwestern China, located within the eastern Tethyan metallogenic domain, hosts the Yangla Cu deposit, a large-scale skarn system associated with Triassic granitoids. This study integrates mineral assemblages, U-Pb geochronology, and trace element compositions of scheelite to identify two discrete W mineralization events at Yangla. Three scheelite groups have been identified: (1) S-group scheelite, hosted in skarn ores, is coeval with chalcopyrite and pyrite, indicating its association with Triassic skarn Cu mineralization. Geochemically, it exhibits high Nb + Ta contents, low Sr/Mo ratios, and pronounced negative Eu anomalies, consistent with scheelite from granite-related W deposits. (2) B- and M-group scheelite, hosted in hydrothermal breccia and marble ores, respectively, formed during the Oligocene (M-group scheelite U-Pb ages: 28.1–30.0 Ma) and coeval with stibnite and calcite. They display distinct geochemical signatures, including low Nb + Ta contents, high Sr/Mo ratios, and slightly positive Eu anomalies, supporting a non-magmatic fluid origin. A comparison of the Yangla Triassic intrusions with other W polymetallic, Cu- and W-related granites in the Sanjiang region reveals significant similarities in both magmatic source and fractionation degree to those of granites associated with W polymetallic deposits. These granites exhibit mixed crust-mantle source and moderate to high degree of magmatic fractionation, which may be a critical control on the formation of W polymetallic deposits. The identification of Triassic skarn scheelite challenges the traditional view of Yangla as a solely Cenozoic W deposit, providing critical insights for regional exploration strategies targeting concealed W orebodies.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108172"},"PeriodicalIF":2.9,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144557030","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":"Coeval calcalkaline, adakitic, and ultrapotassic Eocene magmatism in Central-Eastern Anatolia: Implications for the syn- to post-collisional tectonics in the region","authors":"E. Yalçın Ersoy ,&nbsp;İbrahim Uysal ,&nbsp;Osman Candan ,&nbsp;Dirk Müller","doi":"10.1016/j.lithos.2025.108173","DOIUrl":"10.1016/j.lithos.2025.108173","url":null,"abstract":"<div><div>The central-eastern Anatolian region includes a wide range of <em>syn</em>- to post-collisional Paleocene to Eocene magmatic rocks. On a regional scale, these rocks are here grouped as (1) the post-collisional Eocene magmatic rocks that occur along the Pontides, (2) the <em>syn</em>- to post-collisional Paleocene-Eocene magmatic rocks associated with the foreland basins developed along the İzmir-Ankara and Inner Tauride suture zones, (3) the Eocene magmatic rocks associated with the Maden Basin to the southeast, (4) the small outcrops of Eocene granitoid plutons and volcanic rocks developed in an N-S trend along the Sivas and Malatya regions which is the main scope of this study. In this study, we focused on the (2) and (4) group rocks.</div><div>The Eocene magmatic rocks between the Sivas and Malatya comprise (1) basaltic volcanics and gabbroic to dioritic plutons derived from subduction-modified mantle sources, (2) andesitic rocks that have differentiated from the basaltic magmas via crystal fractionation and mixing processes, (3) adakitic rhyolites produced by the melting of lower crustal lithologies possibly in response tobasic underplating. The basaltic rocks were derived from the shallow melting of depleted lithospheric mantle sources, which were metasomatised by subduction-related components. This N-S trending Eocene magmatism may have originated from a zone of weakness inherited from the transform fault-related deformations in the upper plate, which was related to the Subduction-Transform Edge Propagator (STEP) faulting at the western margin of the Late Cretaceous Baskil-Hınıs arc.</div><div>The Eocene ultrapotassic rocks exposed in the Ulukışla and Sivas basins along the Inner Tauride suture zone, however, were derived from more fertile and deeper mantle sources with contributions from the asthenosphere, which have been highly contaminated by subduction-related processes, possibly by the Late Cretaceous continental subduction. This magmatic activity was related to slab-break-off processes developed shortly after the latest Cretaceous collision.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108173"},"PeriodicalIF":2.9,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144557035","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}