{"title":"Analyses across a mid-ocean ridge give the scale of plume-fed heterogeneity","authors":"Shiki Machida , Kyoko Okino , Kana Ashida , Shigekazu Yoneda , 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 (<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}
LithosPub Date : 2025-07-05DOI: 10.1016/j.lithos.2025.108182
Yi-Yi Zhang , Jun-Sheng Lu , Rui-Ying Zhang , Yu-Ting Li , Xu Kong , Gang Liu , Qiang Feng , Zeng-Yin Duan , Juan-Juan Li
{"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 , Jun-Sheng Lu , Rui-Ying Zhang , Yu-Ting Li , Xu Kong , Gang Liu , Qiang Feng , Zeng-Yin Duan , Juan-Juan Li","doi":"10.1016/j.lithos.2025.108182","DOIUrl":"10.1016/j.lithos.2025.108182","url":null,"abstract":"<div><div>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<sub>2</sub> and Na<sub>2</sub>O concentrations but relatively low K<sub>2</sub>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<sub>Hf</sub>(t) values ranging from −6.6 to +4.7 and T<sub>DM2</sub> 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}
LithosPub Date : 2025-07-05DOI: 10.1016/j.lithos.2025.108174
Rodrigo Fabiano Silva Santos , Davis Carvalho de Oliveira , José de Arimatéia Costa de Almeida , Roberto Dall'Agnol , Bhrenno Marangoanha , Marco Antonio Galarza , Cláudio Nery Lamarão , Fernando Fernandes da Silva
{"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 , Davis Carvalho de Oliveira , José de Arimatéia Costa de Almeida , Roberto Dall'Agnol , Bhrenno Marangoanha , Marco Antonio Galarza , Cláudio Nery Lamarão , 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<sub>Hf(1.88 Ga)</sub> values range from −11 to −18 (hBMzG), while Ɛ<sub>Nd(1.88 Ga)</sub> values vary from −9 to −11. The Hf-T<sub>DM</sub><sup>C</sup> model ages are between 3.2 and 3.6 Ga, whereas the Nd-T<sub>DM</sub><sup>C</sup> 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}
LithosPub Date : 2025-07-04DOI: 10.1016/j.lithos.2025.108171
Javier Rodríguez , Christian Pin , Saioa Suárez , Luis Ángel Ortega , Jean-Louis Paquette , Benito Ábalos , José Ignacio Gil Ibarguchi
{"title":"Hybridization of crustal magmas and direct evidence for two mantle sources during Early-Ordovician magmatism at the NW Gondwana margin","authors":"Javier Rodríguez , Christian Pin , Saioa Suárez , Luis Ángel Ortega , Jean-Louis Paquette , Benito Ábalos , 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<sub>Nd</sub>(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<sub>Nd</sub>(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}
LithosPub Date : 2025-06-30DOI: 10.1016/j.lithos.2025.108172
Ju-Ting Deng , Jing-Jing Zhu , Pete Hollings , Ming-Liang Huang , Zong-Yong Yang , Dian-Zhong Wang
{"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 , Jing-Jing Zhu , Pete Hollings , Ming-Liang Huang , Zong-Yong Yang , 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}
LithosPub Date : 2025-06-30DOI: 10.1016/j.lithos.2025.108173
E. Yalçın Ersoy , İbrahim Uysal , Osman Candan , Dirk Müller
{"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 , İbrahim Uysal , Osman Candan , 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}
LithosPub Date : 2025-06-28DOI: 10.1016/j.lithos.2025.108170
Qiao Zhang , Jinlong Yao , Guochun Zhao , Yigui Han , Hang Yang , Wei Han , Yuxuan Zhang
{"title":"The operation of plate tectonics in Earth's middle age: Constraints from ∼1.4 Ga calc-alkaline arc magmatism in the southern CAOB","authors":"Qiao Zhang , Jinlong Yao , Guochun Zhao , Yigui Han , Hang Yang , Wei Han , Yuxuan Zhang","doi":"10.1016/j.lithos.2025.108170","DOIUrl":"10.1016/j.lithos.2025.108170","url":null,"abstract":"<div><div>The Mesoproterozoic (1.6–1.0 Ga) era recorded the supercontinent transition from Nuna to Rodinia supercontinent. However, the global tectonic style within this age interval remains highly debated (plate tectonics vs lid tectonics), largely due to the occurrence of widespread continental rifting sequences, alkaline and anhydrous magmatism, along with high T/P metamorphism. We here systematically investigated the whole-rock geochemical, geochronological, and Nd-Hf isotopic characters of metamorphosed Mesoproterozoic granodiorite and monzogranite within the Alxa Block in the central segment of the southern CAOB. The field geology and obtained data indicate that they are typical of I-type granitoids emplaced at 1.43–1.40 Ga, with their parental magmas generated by partial melting of preexisted juvenile mafic crusts. These granitoids belong to the calc-alkaline and magnesian series, and are enriched in LREE and LILE. Moreover, their parental magma contains high magmatic H<sub>2</sub>O contents (>7 %). The data patterns, combined with regional geology, indicate these granitoids are continental arc magmatic rocks. Our data, together with those published data in the microcontinental blocks of southern CAOB, argue that the protracted (1.51–1.40 Ga) calc-alkaline granitic magmatism in these blocks was generated in a continental marginal arc. This prolonged continental arc system coincides well with the Great Proterozoic Accretionary Orogen (GPAO) in the Mesoproterozoic and must have been formed outboard the GPAO. Furthermore, a review of global geological and geochemical data patterns favor widespread subduction on the periphery of Nuna and the operation of plate tectonics in the Mesoproterozoic.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108170"},"PeriodicalIF":2.9,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144522066","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}
LithosPub Date : 2025-06-28DOI: 10.1016/j.lithos.2025.108166
Yang Yu , Xiao-Long Huang , Fan Yang , Yu Wang , Yi-Gang Xu , Iwan Setiawan , Sun-Lin Chung , Le Zhang , Guan-Hong Zhu
{"title":"Mg-Fe isotopic constraint on the role of the lithosphere mantle in arc magmatism","authors":"Yang Yu , Xiao-Long Huang , Fan Yang , Yu Wang , Yi-Gang Xu , Iwan Setiawan , Sun-Lin Chung , Le Zhang , Guan-Hong Zhu","doi":"10.1016/j.lithos.2025.108166","DOIUrl":"10.1016/j.lithos.2025.108166","url":null,"abstract":"<div><div>Arc magmatism is commonly envisaged as generation through a two-endmember petrogenetic process involving the subducted components and asthenospheric mantle wedge. The contribution of sub-arc lithospheric mantle, as a key chemical reservoir in subduction zone, to arc magmas remains poorly constrained. Here we present, for the first time, a systematic dataset of Mg<img>Fe isotopes on continental arc basalts (CABs) from the Sunda Arc for deciphering the role of sub-arc lithospheric mantle in arc magmatism. The Sunda CABs show significant variations in δ<sup>26</sup>Mg (−0.28 ‰ to −0.05 ‰) and δ<sup>56</sup>Fe values (−0.19 ‰ to 0.14 ‰), with mean values of −0.17 ‰ and 0.02 ‰, respectively, resembling those of global arc magmas. These samples mainly display low TiO<sub>2</sub>/Yb (0.3–0.5) and Fe/Mn (30–60) ratios, indicating their derivation from peridotite melting within the depleted asthenospheric mantle wedge. The weak correlations of Mg and Fe isotopes with ε<sub>Nd</sub> suggest that subduction-related metasomatism has not significantly influenced the Mg and Fe isotopic compositions of the asthenospheric mantle wedge. The majority of Sunda CABs exhibit a negative correlation between δ<sup>26</sup>Mg and Fe/Mn, as well as a positive correlation between δ<sup>56</sup>Fe and Fe/Mn, both also observed in global arc magmas. These significant variations in Mg<img>Fe isotopes and Fe/Mn ratios within arc magmas likely result from their intensive interactions with the sub-arc lithospheric mantle through incorporations of the low Fe/Mn (30–50) pyroxenite and high Fe/Mn (50–70) peridotite in different proportions. The interactions may have also elevated the oxygen fugacity as evidenced by the co-variations of Mg<img>Fe isotopes and V/Sc ratios for the Sunda CABs and global arc basalts. We therefore conclude the crucial role played by the sub-arc lithospheric mantle in global arc magmatism, which has long been overlooked in popular petrogenetic models for subduction zone magmatism.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"512 ","pages":"Article 108166"},"PeriodicalIF":2.9,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518473","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}
LithosPub Date : 2025-06-28DOI: 10.1016/j.lithos.2025.108167
Zhihao Sun , Bin Zhang , Jing Wu , Zeyang Zhu , Chunqing Sun , Zhengfu Guo , Jiaqi Liu
{"title":"Magmatic genesis, magmatic plumbing system, and geodynamic mechanism of Changbaishan volcanoes: New evidence from mineralogical, geochemical, and geothermobarometric data","authors":"Zhihao Sun , Bin Zhang , Jing Wu , Zeyang Zhu , Chunqing Sun , Zhengfu Guo , Jiaqi Liu","doi":"10.1016/j.lithos.2025.108167","DOIUrl":"10.1016/j.lithos.2025.108167","url":null,"abstract":"<div><div>The Changbaishan volcanic field (mainly comprising Tianchi, Wangtian'e, Namphothe, and Tumen River volcanoes), located in the intraplate domain of the eastern Eurasian plate, has exhibited vigorous Cenozoic volcanism. However, the magmatic system and deep geodynamic mechanisms related to the volcanic activity underlying this active region remain controversial; namely, whether the magma originates from the mantle or subducted Pacific slab; whether the magma reservoir is multi- or single-layered with a large scale; and the source of the driving force of volcanic activity. In this study, we present an integrated analysis of newly acquired geochemical and geochronological data spanning all eruptive phases since the Pliocene, combined with existing datasets, and reconstruct the volcanic evolution of Changbaishan volcanic field. Geochemical results reveal homogeneous trace element patterns and Sr-Nd-Pb isotopic compositions across the Tianchi, Wangtian'e, and Tumen volcanic centers, indicating that the magma originated from an enriched mantle source formed by the mechanical mixing and fluid-melt metasomatism between the asthenosphere mantle and subducted Pacific slab components. Fractional crystallization is identified as the dominant magma differentiation mechanism. Mineral thermobarometers reveal a multi-tiered magma storage system, with shallow (ca. 3–5 km), intermediate (ca. 8–18 km), and deep-seated (ca. 25–36 km) reservoirs beneath Tianchi volcanoes. Moreover, the magma reservoirs of Wangtian'e volcano are located at depths of 8–15 and 25–36 km, contrasting with deeper magma sources (ca. 26–50 km) beneath the Tumen River volcano. These findings demonstrate that the stagnant Pacific slab in the mantle transition zone exerts fundamental control over regional volcanism through both material contributions and dynamic forces and resolves the genetic connections between surface volcanism and deep mantle processes. Furthermore, we also reconcile previous controversies regarding the origin of magma from the mantle and subducted Pacific slab with a multi-layered magma reservoir.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108167"},"PeriodicalIF":2.9,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144518018","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}
LithosPub Date : 2025-06-28DOI: 10.1016/j.lithos.2025.108168
L. Boschetti , C. Boullerne , Y. Rolland , S. Schwartz , G. Milesi , D. Bienveignant , E. Macret , D. Charpentier , P. Münch , J. Mercadier , A. Iemmolo , P. Lanari , M. Rossi , F. Mouthereau
{"title":"Shear zone memory revealed by in-situ Rb-Sr and 40Ar/39Ar dating of Pyrenean and Alpine tectonic phases in the external Alps","authors":"L. Boschetti , C. Boullerne , Y. Rolland , S. Schwartz , G. Milesi , D. Bienveignant , E. Macret , D. Charpentier , P. Münch , J. Mercadier , A. Iemmolo , P. Lanari , M. Rossi , F. Mouthereau","doi":"10.1016/j.lithos.2025.108168","DOIUrl":"10.1016/j.lithos.2025.108168","url":null,"abstract":"<div><div>The combination of Rb-Sr and <sup>40</sup>Ar/<sup>39</sup>Ar dating methods with high-resolution mineralogical investigation allows deciphering the multiphase history of shear zones and serves as a tool for tectonic reconstructions. However, the interpretation of dates obtained by these two methods in relation to cooling, fluid circulation or to deformation-induced (re)crystallization remains controversial. Here, we apply the in situ <sup>87</sup>Rb/<sup>87</sup>Sr and <sup>40</sup>Ar/<sup>39</sup>Ar dating methods to shear zone minerals used together with step heating <sup>40</sup>Ar/<sup>39</sup>Ar dating in several case studies with contrasting structural and metamorphic histories along the External Crystalline Massifs (ECMs) of the SW Alps. Our results emphasize polyphase deformation and highlight a variable behaviour of Rb-Sr and K-Ar systems in shear zones. This study provides new constraints about the timing, conditions and mechanisms of deformation in the southern ECMs of the Western Alps. The inherited crustal-scale Variscan shear zones have been reactivated several times in a thick-skin mode since the Late Cretaceous. An early N-S compressional phase impacted the SW Alps mainly at around ∼80–70 and ∼40 Ma in the Argentera and Pelvoux shear zones, but this signal is not documented further north. This signal is better preserved in the southern Pelvoux massif, with a Rb-Sr age of 79.7 ± 3.7 Ma. There is also a significant compressional deformation on the W-Alpine scale at 34–32 Ma, associated with underthrusting beneath the Penninic Frontal Thrust (PFT). Two compressional deformation pulses occur at 26 and 22–20 Ma in the southern Argentera Massif, corresponding to the onset of transpressive deformation induced by the anti-clockwise rotation of the Adriatic Plate. Finally, the last phase of deformation around 18–15 Ma concerns only the NW Alps, in the Beaufortain massif, which was buried under the Mont-Blanc massif, during the propagation of deformation leading to the development of the frontal fold and thrust belt of the SW Alps. Our results also show that the southern Pelvoux massif already reached a temperature around 300 °C at a depth of 10–15 km depth during the Late Cretaceous. This range of temperature and pressure conditions is broadly similar to that reached in the ECMs during the Cenozoic deformation stages.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"514 ","pages":"Article 108168"},"PeriodicalIF":2.9,"publicationDate":"2025-06-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144548452","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}