Lithos最新文献

{"title":"Mineral chemistry-perspective of the Kadavur gabbro-anorthosite Complex, Southern Granulite Terrane of the Indian shield: Implications to its petrogenesis in a ridge-subduction setting","authors":"Debaleena Sarkar ,&nbsp;Jyotisankar Ray ,&nbsp;Rohit Pandey ,&nbsp;Moumita Chowdhury ,&nbsp;Christian Koeberl ,&nbsp;Suresh C. Patel ,&nbsp;Desikan Ramakrishnan ,&nbsp;Aantarica Chakraborty ,&nbsp;Simran Dutta","doi":"10.1016/j.lithos.2024.107880","DOIUrl":"10.1016/j.lithos.2024.107880","url":null,"abstract":"<div><div>Mineral chemistry data of constituent silicate and oxide phases are often regarded as a useful tool for assessing the petrogenesis of mafic rocks. In view of this, the chemistry of minerals from the Kadavur gabbro-anorthosite Complex (10°35′N: 78°11′E), a magmatic intrusion in the Southern Granulite Terrane of the Indian shield, has been evaluated using several thermo-barometric methods and tectonic discrimination diagrams. The Complex represents a magmatic intrusion that consists of a highly deformed schistose gabbro-anorthosite type and an undeformed layered gabbro-anorthosite type, with local patches of pegmatoidal gabbro-anorthosite bodies. The constituent minerals in the Complex include clinopyroxene, orthopyroxene, plagioclase, amphibole, and subordinate amounts of ilmenite and magnetite. Pyroxene thermometry (clinopyroxene thermometry, orthopyroxene thermometry and two pyroxene thermometry) gives mean temperatures of ∼1060 °C for the layered gabbro- anorthosite bodies, and ∼ 1124 °C for the pegmatoidal bodies; and ∼ 1130 °C for the schistose gabbro-anorthosite. Hornblende-plagioclase and amphibole thermometry give temperatures of ∼1000–1190 °C. The co-existing oxide (magnetite-ilmenite) thermometry gives a lower temperature of ∼420 °C. The mean clinopyroxene pressure value is 17 kbar for the schistose gabbro-anorthosite, 9 kbar for the layered gabbro-anorthosite, and 11 kbar for the pegmatoid bodies. During the earlier phase of deformation associated with magmatic crystallization (responsible for schistose type), the ambient temperature and pressure of crystallization of the Complex were 955 to 1285°C at ∼17 kbar. The magma equilibrated at shallow to intermediate levels allowing for localized input of H₂O. Consideration of whole-rock geochemical data (especially immobile trace elements) indicates that parent magma was of tholeiitic and alkaline composition and later underwent fractionation. The rare earth element (REE) distribution in the schistose gabbro-anorthosite is broadly similar to that of N-MORB, while the geochemical characteristics of the layered gabbro-anorthosite resemble island arc basalt (IAB). The pegmatoidal gabbro-anorthosite bodies have a transitional affinity between both the N-MORB and IAB. The mineral chemistry and whole-rock geochemistry data suggest that the schistose gabbro-anorthosite mostly corresponds to “non orogenic” and “MORB-type” while layered gabbro-anorthosite and pegmatoid bodies correspond to an ‘orogenic’ and ‘island-arc’ setting, suggesting a clear shift from a MORB setting to an arc-setting suggesting a ridge-subduction event. The Kadavur gabbro-anorthosite Complex is analogous to other well-known Archaean gabbro-anorthosite Complexes around the world.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"494 ","pages":"Article 107880"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143161622","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":"Correlating early Wuchiapingian (early Lopingian/late Permian) biotic and environmental changes with eruptive activity of the Emeishan LIP","authors":"Borhan Bagherpour ,&nbsp;Luis F. De Lena ,&nbsp;Maria Ovtcharova ,&nbsp;Dong-xun Yuan ,&nbsp;Shu-Zhong Shen ,&nbsp;Hugo Bucher ,&nbsp;Urs Schaltegger","doi":"10.1016/j.lithos.2024.107937","DOIUrl":"10.1016/j.lithos.2024.107937","url":null,"abstract":"<div><div>The volcanic activity of the Emeishan Large Igneous Province (LIP) is widely regarded as the main cause of environmental changes and the consequent biodiversity loss around the Guadalupian-Lopingian boundary (GLB). The limited number of high-precision numerical ages, as well as the scarcity of volcanic ash layers interbedded within sedimentary profiles with bio- and chemostratigraphic controls, has hampered the establishment of a temporal correlation between the Emeishan LIP and environmental and biotic changes. Here, we present new high-precision CA-ID-TIMS U<img>Pb ages and Hf isotope data from ash layers of the paleontologically dated early Wuchiapingian Mapojiao section in southern Guizhou (south China). Our data indicate that the Emeishan volcanic activity continued at least until 258.279 ± 0.065 Ma in the <em>Clarkina transcaucasica</em> conodont zone of the Wuchiapingian Stage. Based on our high-resolution Bayesian age-depth Bchron model, the calculated duration of Wuchiapingian conodont interval zones in this section are the <em>C. transcaucasica</em> Zone: 740 ± 150 kyr, <em>C. guangyuanensis</em> Zone: 195 ± 184 kyr, <em>C. leveni</em> Zone: 221 ± 162 kyr, <em>C. asymmetrica</em> Zone: 285 ± 228 kyr. Moreover, the sedimentation rate of shallow-marine bioclastic thick-bedded limestones and deep-marine radiolarian and sponge spicule-bearing thin-bedded black limestones is estimated at 10 cm/kyr and 3.84 cm/kyr, respectively. Although the GLB is not included in the studied section, our age-depth model implies that the age of the GLB is noticeably older than any currently considered GLB age. The co-occurrence of a base-level fall and drowning event, temperature rise, mantle-sourced volcanism, negative shifts in carbon and strontium isotope records, and thermal fluid activity provide a strong base to suggest two distinct phases of Emeishan volcanic activities in the mid-Capitanian and early Wuchiapingian, respectively.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"494 ","pages":"Article 107937"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143161967","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenesis of Neoproterozoic high-K calc-alkaline granites forming large batholiths in SE Brazil: Clues from trace-element chemistry of apatite, titanite and hornblende","authors":"Valdecir de Assis Janasi,&nbsp;Lucelene Martins,&nbsp;Bárbara Bueno Toledo,&nbsp;Adriana Alves,&nbsp;Silvio Roberto Farias Vlach","doi":"10.1016/j.lithos.2024.107927","DOIUrl":"10.1016/j.lithos.2024.107927","url":null,"abstract":"<div><div>Granites may lose or gain residual melts respectively by compaction and reactive porous flow, and therefore their composition is potentially different from that of the original magmas. Consequently, the chemistry of individual minerals with well-understood textural relationships should be prioritized for inferring magma sources and crystallization conditions. We investigated the major and trace element chemistry of coexisting apatite, titanite and hornblende in thin sections of I-type high-K calc-alkaline (HKCA) granitic rocks forming two voluminous Neoproterozoic batholiths in SE Brazil. Detailed textural studies, major-element analyses by EPMA, and trace-element analyses by LA-ICPMS bring key information on magma genesis and evolution. Titanite is absent or forms thin rims in ferri-ilmenite in granites from Socorro Batholith, resulting from magmatic crystallization at higher temperatures (&gt;800 °C) compared to similar granites from the Agudos Grandes Batholith, where it occurs as large crystals preserving temperature-related zonation, reflected in decreasing LREE and Zr contents. The influence of titanite crystallization is particularly evident in the trace-element chemistry of hornblende and apatite from the Agudos Grandes granites, with one order of magnitude lower REE contents and smaller to suppressed negative Eu anomalies. Systematically higher Sr/Y (and in part also La/Yb) of hornblende, apatite and titanite from Agudos Grandes granites confirms suggestions that they equilibrated at significantly greater depths (and by inference in a thicker crust) as compared to the Socorro granites. Quantitative estimates of Sr/Y in the original melts are hampered by coprecipitation of minerals that accommodate these elements and by potential Sr diffusion, especially in apatite. However, as an early-crystallizing phase in granitic magmas, apatite trace-element composition is a precious source of petrogenetic information; in our study, it reveals that most of the volume of the Agudos Grandes granites crystallized below 800 °C (i.e., after titanite starts to crystallize) and confirms, in agreement with other proxies, that the two batholiths crystallized under oxidizing conditions (e.g., sulfur in apatite up to 800 ppm).</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"494 ","pages":"Article 107927"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162155","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":"Multi-stage evolution of the lithospheric mantle beneath the Hessian Depression (Germany): Peridotite xenoliths from Stöpfling","authors":"Jacek Puziewicz ,&nbsp;Sonja Aulbach ,&nbsp;Mary-Alix Kaczmarek ,&nbsp;Theodoros Ntaflos ,&nbsp;Magdalena Matusiak-Małek ,&nbsp;Małgorzata Ziobro-Mikrut ,&nbsp;Axel Gerdes","doi":"10.1016/j.lithos.2024.107908","DOIUrl":"10.1016/j.lithos.2024.107908","url":null,"abstract":"<div><div>The Hessian Depression in Germany is the northern continuation of the Upper Rhine Graben, from which it is separated by the Vogelsberg volcanic region. Abundant Cenozoic basaltic eruptions locally brought mantle xenoliths to the surface. The legacy suite of 15 ultramafic xenoliths from the Stöpfling quarry has been studied in detail to decipher nature and evolution of this fragment of European mantle lithosphere.</div><div>The xenolith suite comprises harzburgites, clinopyroxene-poor lherzolites and clinopyroxene-rich lherzolites. One of the xenoliths is a harzburgite hosting a centimetric olivine websterite layer. Olivine contains 90.1–91.5 % forsterite, 0.39–0.43 wt%. NiO, 120–500 μg/g Ca. Orthopyroxene (0.10–0.18 atoms of Al per formula unit, pfu), has Mg/(Mg + Fe), Mg#, of 0.90–0.92, similar to that of olivine. Clinopyroxene (0.12–0.25 atoms Al pfu; Mg# 0.90–0.95). Rare Earth Elements (REE) and trace-element patterns are highly variable, but all are enriched in light REE relative to medium/heavy REE. Spinel Cr/(Cr + Al) varies from 17 to 46. The ⁸⁷Sr/⁸⁶Sr ratios measured in situ in clinopyroxene vary from 0.703969(± 37 1σ) to 0.708615(± 149 1σ) and are in part heterogenous at the scale of individual samples and grains.</div><div>The peridotites typically have well defined olivine-orthopyroxene or olivine-only crystal preferred orientation, whereas clinopyroxene (or clinopyroxene and orthopyroxene) is oriented independently in most of the rocks. This is taken to reflect secondary clinopyroxene addition to an originally refractory harzburgite protolith. The latter is still preserved in two harzburgites with highly depleted compositions and low clinopyroxene modal abundances. Melt depletion recorded in the most depleted harzburgites was followed by carbonatitic metasomatism, whereas other harzburgites and clinopyroxene-poor lherzolites were metasomatized by carbonated silicate or alkaline silicate melts. The clinopyroxene-rich lherzolites preserved relics of MORB-like refertilization, overprinted by alkaline metasomatism analogous to that affecting the rest of the rocks.</div><div>The two-pyroxene equilibration temperatures (940–1050 °C) mostly show excellent agreement between Fe<img>Mg and REE-based thermometers. This suggests chemical and thermal equilibration after clinopyroxene addition and shows that Stöpfling xenoliths sample a rather narrow ∼8 km depth interval of the mantle lithosphere. The Stöpfling mantle profile probably records two-stage tectono-metasomatic evolution, comprising (1) mantle lithosphere upwelling and melting during flattening of the Variscan orogen root due to late orogenic collapse followed by thermal re-equilibration, and (2) further local lithosphere thinning during Alpine rifting, accompanied by multiple local chromatographic-style metasomatic episodes that culminated in volcanism as well as xenolith entrainment and transport to the surface.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"494 ","pages":"Article 107908"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143161959","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Revisiting the high temperature Darongshan-Shiwandashan granitoids in the South China: A response to slab tearing associated with diachronous collision between Indochina and South China blocks","authors":"Yu-Fan Yue ,&nbsp;Xiao-Ping Xia ,&nbsp;Pengfei Li ,&nbsp;Bin He ,&nbsp;Touping Peng ,&nbsp;Min Sun ,&nbsp;Jian Xu ,&nbsp;M.P. Manu Prasanth","doi":"10.1016/j.lithos.2024.107898","DOIUrl":"10.1016/j.lithos.2024.107898","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Darongshan-Shiwandashan granite belt (DSGB) is composed of S-type granites and granodiorite intrusions, which are characterized by high- or ultrahigh-temperature cordierite, orthopyroxene, and granulite xenoliths. The petrogenesis of these plutons is a subject of debate, and a thorough overview of regional tectonic evolution and geochemistry is still absent despite the numerous research conducted in this granite belt. This study is a comprehensive overview of geochronology, whole-rock major-trace elements, Sr&lt;img&gt;Nd isotopes, and zircon Hf&lt;img&gt;O isotopes in the DSGB, focusing on their petrogenesis and tectonic setting of formation. The geochronological data indicates that DSGB granitoids emplaced at ca. 250 Ma, with a southwestward-younging trend. Moreover, mineral assemblages of cordierite + orthopyroxene suggest that the DSGB was formed in a high-temperature (∼850 °C) and low-pressure (3.7–6 kbar) tectonic setting. Three main plutons (Darongshan, Jiuzhou, and Taima) of the DSGB exhibit distinctly different compositions. The Darongshan and Taima granitoids display high silica (SiO&lt;sub&gt;2&lt;/sub&gt; = 68.65–78.10 wt%), low-maficity (FeO + MgO = 1.97–7.28 wt%), along with negative whole-rock ε&lt;sub&gt;Nd&lt;/sub&gt;(t) values (−13.9 to −9.7) and elevated initial &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr values (0.71638 to 0.73165). The Jiuzhou granitoids, on the other hand, exhibit relatively low silica (SiO&lt;sub&gt;2&lt;/sub&gt; = 63.90–72.72 wt%) and high maficity (FeO + MgO = 3.03–9.88 wt%), with largely overlapping but relatively high ε&lt;sub&gt;Nd&lt;/sub&gt;(t) values ranging from −12.9 to −9.9 and lower initial &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr values from 0.71453 to 0.72401. Two-component mixing model results indicate these different compositions represent varying degrees of mixing between crust- and mantle-derived magmas, with 0–10 %, 0–20 % and 20–40 % basaltic melts involved for Taima, Darongshan and Jiuzhou plutons, respectively. The subducting slab tearing, induced by the diachronous collision between the South China Block (SCB) and Indochina Block (ICB), provide the most feasible interpretation for the petrogenesis and spatio-temporal geochemical pattern of the granitic rocks in the DSGB. The onset of the diachronous collision initiated at the Hainan-Yunkai massif, southwest of SCB, while the Tethys Ocean still existed in the northwest (Nanpanjiang area), causing notable disparities in the convergence velocities of the subducting ocean slab. The heterogeneous stresses resulting from the different subduction rates were accommodated by bending and tearing of the subducting slab. Then, ultrahigh-temperature basaltic melts derived from the decompression melting of the lithospheric mantle facilitated the melting of metasedimentary rocks, which resulted in the formation of high-temperature S-type granitoids. The Jiuzhou pluton, located at the center of slab tearing, received more mantle contributions than the Darongshan and the Taima plutons, which are emplaced away from th","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"494 ","pages":"Article 107898"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143161055","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":"Identification of ca. 470 Ma continental margin arc volcanism in the Cathaysia Block interior: Constrains on the geodynamic process of the early Paleozoic orogeny in South China","authors":"Longming Li ,&nbsp;Fan Xiao ,&nbsp;Xilin Zhao ,&nbsp;Guangfu Xing ,&nbsp;Yan Zhou","doi":"10.1016/j.lithos.2024.107928","DOIUrl":"10.1016/j.lithos.2024.107928","url":null,"abstract":"<div><div>Due to the lack of evidence related to oceanic subduction, it has been debated whether the early Paleozoic orogeny in South China Block belongs to an intracontinental orogeny or a subduction-collision orogeny. To better understand the nature and geodynamic processes of this orogeny, we conducted geochronological, geochemical, and isotopic studies on pyroclastic rocks, including crystal tuffs and sedimentary volcanic breccias, which outcrop in the Zhenghe area of the Cathaysia Block. The crystal tuffs have experienced strong chloritization and have high FeO^t (25–31.3 wt%) and high Cr (60.7–143 ppm) and Ni (33.8–93.6 ppm) contents. Immobile elements indicate that the crystal tuffs are products of basic-intermediate volcanism. SIMS and LA-ICP-MS U<img>Pb dating show that the crystal tuffs were erupted during 471–465 Ma. The crystal tuffs exhibit positive zircon <em>ε</em>_Hf(t) (+7.8 to +14.2) and low δ¹⁸O values (5.05 to 5.89 ‰), suggesting that they were derived from depleted mantle. They exhibit subduction-related geochemical signatures, with enrichment in Th but depletion in Nb and Ta. Additionally, high U/Yb and low Nb/Yb values of the zircons suggest that the crystal tuffs were generated in a continental arc environment. The interlayered sedimentary volcanic breccias are products of intermediate-acidic volcanism. They share similar geochemical characteristics with the crystal tuffs, including zircon U<img>Pb ages (<em>ca.</em> 467 Ma), whole-rock trace element patterns, zircon CL images, zircon <em>ε</em>_Hf(t) values (+ 9.9 to +13.3) and zircon trace element ratios, implying that the two types of volcanic rocks originated from similar sources or were genetically related. Notably, the presence of few continental clastic materials in these pyroclastic rocks provides evidence that the volcanic arc was situated offshore from the continent. The identification of the <em>ca.</em> 470 Ma continental margin arc volcanism in the Zhenghe-Dapu fault, along with the previously discovered <em>ca.</em> 520 Ma MOR-type ophiolite in the same fault, and the widespread presence of late-Ordovician to early-Devonian igneous activities and Silurian high-grade metamorphism in the Cathaysia Block, supports that the early Paleozoic orogeny in South China was a subduction-collision orogeny, with the Zhenghe-Dapu fault serving as a suture zone. Consequently, it is believed that this orogeny resulted from the collision between the West Cathaysia Block and either the East Cathaysia Block or the northern margin of Gondwana. The geodynamic process involved the initiation of oceanic plate subduction during the middle Ordovician, transitioning to continent-continent collision by the middle Silurian, and concluding with post-orogenic collapse from the late Silurian to early Devonian.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"494 ","pages":"Article 107928"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143161966","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":"Recycling of terrigenous sediments recorded in late Permian-early Triassic Fe-rich intrusions from Yunkai Massif, South China","authors":"Yaqian Wen ,&nbsp;Feng Guo ,&nbsp;Liang Zhao ,&nbsp;Feng Zhang ,&nbsp;Xin Huang ,&nbsp;Melesse Alemayehu","doi":"10.1016/j.lithos.2024.107809","DOIUrl":"10.1016/j.lithos.2024.107809","url":null,"abstract":"<div><div>The origin of Fe-rich intrusion remains debatable regarding the respective role of magmatic evolution and Fe enrichment in the source. Here, we report detailed mineral and bulk-rock geochemistry of Permian-Triassic (251–250 Ma) mafic intrusions from the Tengxian area in Yunkai Massif, South China. These rocks consist of hornblende norites, show Fe-rich affinities with high FeO*(FeO* = FeOt / (FeOt + MgO) in weight ratio, &gt;0.8, based on total iron oxide in the rock), and exhibit significant enrichment in large ion lithophile elements (LILEs) and light rare earth elements (LREEs) but depletion in Sr and high field strength elements (HFSEs), resembling subduction-related magmas. In addition, they show remarkable features that include very high δ¹⁸O values in zircon (δ¹⁸O = 8.8–10.6 ‰) and apatite (δ¹⁸O = 8.7–10.8 ‰), and extremely enriched Sr<img>Pb [e.g. ⁸⁷Sr/⁸⁶Sr(i) = 0.7181–0.7196, ²⁰⁷Pb/²⁰⁴Pb(i) = 15.77–15.78, ²⁰⁸Pb/²⁰⁴Pb(i) = 38.95–39.05] and nonradiogenic Nd<img>Hf isotopic compositions [e.g. ε_Nd(t) = −11.1 ∼ − 10.1, ε_Hf(t) = −8.8 ∼ −7.3] in bulk rocks. These characteristics distinguish the Tengxian norites from modern arc basalts and subduction-related magmas in the Paleo-Pacific Tectonic Domain. Instead, they are isotopically similar to Cenozoic Tibetan and Mediterranean potassic to ultrapotassic rocks in the Tethys Tectonic Domain. Regardless of variable influence by orthopyroxene and plagioclase accumulation, the intrinsically low SiO₂ and high FeOt and Fe/Mn ratios in these rocks were likely attributed to significant contribution of a Fe-rich mantle component such as Si-poor pyroxenite, which might have formed through crystal accumulation of mafic magmas at mantle conditions. The highly evolved Sr-Nd-Pb-Hf isotopic signatures and very high δ¹⁸O values in zircon and apatite required substantial (10–20 %) involvement of recycled crust in the mantle source. The combined mineral and bulk-rock geochemical data suggest that the parental magmas for the Tengxian norites originated from a metasomatized mantle wedge through addition of terrigenous sediment-derived melt following the subduction of Paleo-Tethys Ocean beneath the Yunkai Massif.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"494 ","pages":"Article 107809"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162021","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":"Remnants of a Jurassic marginal sea plate in the Meso-Tethyan Ocean revealed by multi-stage magmatism in the Lagkorco ophiolite, Central Tibet","authors":"Wei-Qi Zhang ,&nbsp;Chuan-Zhou Liu ,&nbsp;Tong Liu ,&nbsp;Chang Zhang ,&nbsp;Xiao-Ni Li ,&nbsp;Zhen-Yu Zhang ,&nbsp;Zhen Zhang ,&nbsp;Yin-Zheng Lin","doi":"10.1016/j.lithos.2024.107895","DOIUrl":"10.1016/j.lithos.2024.107895","url":null,"abstract":"<div><div>The formation of marginal sea plate, through multi-stage arc rupture and back-arc spreading, is a fundamental process in mature intra-ocean convergent plate margins. Identifying remnants of ancient marginal sea microplates within suture zones is crucial for unraveling the evolution of ancient ocean basins, although it presents significant challenges. In this study, we present new zircon and titanite U<img>Pb ages, along with Sr-Nd-Fe isotopic compositions, for a suite of well-characterized cumulates from the Lagkorco ophiolite which represents remnants of the Bangong-Nujiang Meso-Tethyan oceanic lithosphere. Our integrated dataset, combined with previous findings, reveals three distinct magmatic phases within the Lagkorco ophiolite: i) Unit A: early Jurassic (∼184 Ma) amphibolite-facies mafic-felsic complex, ii) Unit B1: early Jurassic (187–192 Ma) oceanic lithosphere, and iii) Unit B2: middle Jurassic (160–170 Ma) oceanic lithosphere. Geochemical data from Unit B1 cumulates indicate a damp (∼1 % H₂O) but arc-like parental magma. These cumulates exhibit more enriched Sr<img>Nd isotopes compared to mid-ocean ridge basalts and typical island arc basalts. Unit B1 cumulates exhibit clinopyroxene Fe isotopes (δ⁵⁶Fe = −0.06 − +0.01) lighter than mid-ocean ridge cumulate clinopyroxene (δ⁵⁶Fe = +0.02 − +0.05). These data indicate that the Unit B1 cumulates originated from a subduction-modified depleted mantle mixed with minor sediments. Combining our results with previously published data, we propose that the parental magmas for both Unit B1 and Unit B2 were damp but arc-like, which aligns with the repeated re-melting of previously depleted sub-arc mantle during episodic back-arc spreading. Our interpretation suggests two-stage back-arc spreading (Unit B1 and Unit B2) and at least one episode of arc magmatism (Unit A) between 192 and 160 Ma. These results imply the existence of a Jurassic marginal sea plate, akin to the present-day Philippine Sea plate, within the Meso-Tethyan Ocean, which was likely later subducted beneath the Qiangtang continent.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"494 ","pages":"Article 107895"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143161070","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":"Sources of alkaline and tholeiitic basaltic magmas of Changbaishan volcanic area (Northeastern China)","authors":"O.A. Andreeva ,&nbsp;V.M. Savatenkov ,&nbsp;V.V. Yarmolyuk ,&nbsp;I.A. Andreeva ,&nbsp;J.-Q. Ji ,&nbsp;X. Zhou ,&nbsp;J. Zhou","doi":"10.1016/j.lithos.2024.107940","DOIUrl":"10.1016/j.lithos.2024.107940","url":null,"abstract":"<div><div>Changbaishan volcanic area (China-North Korea) is located on the margin of the Eurasian continent within the large Cenozoic intraplate province of Central and Eastern Asia. Two large volcanoes Wangtian'e and Changbaishan of the area are situated 30 km from each other in Northeastern China. Basalts of Wangtian'e volcano belong to the tholeiitic rock series as well as basalts of Changbaishan volcano belong to the alkaline one. In this paper we use data on chemical and isotopic (Pb, Sr, Nd) composition of tholeiitic and alkaline basalts to reconstruct magmatic sources that participated in the tholeiitic and alkaline rock formation. Isotopic and geochemical features of tholeiitic and alkaline basalts of the Changbaishan volcanic area indicate the participation of three different sources in their formation. The formation of tholeiitic and alkaline melts of the Changbaishan volcanic area occurred within the mechanical asthenosphere-lithosphere boundary layer at a depth of 30–75 km in two stages. The first stage corresponds to the melting of supra-subduction peridotite of the lithospheric mantle and eclogite lenses resulted in the formation of tholeiitic melts that formed Wangtian'e volcano. As the eclogite was exhausted, the resulting tholeiitic melt reacted with fertilized mantle peridotite producting pyroxenite source. The second stage corresponds to the partial melting of pyroxenite together with peridotite of the asthenospheric mantle, which led to the appearance of alkali-basaltic melts that participated in the formation of Changbaishan volcano.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"494 ","pages":"Article 107940"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143161969","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":"Boron isotopic characterization of ophiolitic serpentinites from Atlin terrane, Canadian Cordillera","authors":"Adina Bogatu ,&nbsp;Loïc Labrousse ,&nbsp;Céline Martin ,&nbsp;Alexandre Zagorevski ,&nbsp;Jean H. Bédard ,&nbsp;Alain Tremblay","doi":"10.1016/j.lithos.2024.107922","DOIUrl":"10.1016/j.lithos.2024.107922","url":null,"abstract":"<div><div>Atlin terrane ophiolites (Canadian Cordillera) exhibit non-Penrose pseudostratigraphy, with extensive serpentinites at the interface between upper crust and mantle. Petrography, Raman spectroscopy, electron probe microanalyzer (EPMA) and in-situ boron (δ¹¹B) isotopic analysis of serpentinites from Squanga Lake and Union Mt. ophiolites of Atlin terrane, identified four distinct phases of serpentine growth. Phase I (δ¹¹B = +1.6 ± 1 ‰ to +12.9 ± 1.3 ‰) and Ia (δ¹¹B = −5.7 ± 1.1 ‰ to +1.8 ± 1.1 ‰) serpentines have δ¹¹B signatures suggestive of seawater input, possibly along a detachment during oceanic core complex formation. These have up to 9 wt% FeO_tot concentrations, suggestive of primary mesh and bastite after ultramafic minerals. Phase I δ¹¹B values are typical of serpentinized ophiolite (−5.7 ‰ to +25 ‰). Phase II antigorite (δ¹¹B = −13.5 ± 0.8 ‰ to −6.3 ± 1.9 ‰; with propagated 1 S.E. error) and phase III fibrous chrysotile (δ¹¹B = −10.0 ± 2.5 ‰ to −2.7 ± 0.7 ‰) have strong negative δ¹¹B values distinct from phase I/Ia values. Phase II and III serpentines formed during listvenite alteration, coeval with Jurassic thrust imbrication of ophiolitic units and post-obduction plutonism and might be resulted from sediment-derived fluids. While δ¹¹B values of phase II antigorite align perfectly with those obtained from Dalayee Lake sediment (−14.6 ± 0.6 ‰ to −7.7 ± 2.1 ‰), the less negative δ¹¹B values of phase III chrysotile might indicate fluid evolution during exhumation. Phase IV antigorite flakes (δ¹¹B = −1.9 ± 1.4 ‰ to +1.5 ± 0.9 ‰) overprint phase II &amp; III serpentines and might be related to post-obduction plutonism. These have lowest FeO_tot values (&lt;2.3 wt%), compatible with multiple re-crystallisation pulses of Union Mt. antigorite.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"494 ","pages":"Article 107922"},"PeriodicalIF":2.9,"publicationDate":"2025-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143162011","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}