Lithos最新文献

{"title":"Triassic geodynamics of the Korean Peninsula: Insights from petrogenesis of plutonic rocks in the Okcheon Belt and Gyeonggi Massif","authors":"Shahrouz Babazadeh ,&nbsp;Sung Hi Choi ,&nbsp;Hye Won Han","doi":"10.1016/j.lithos.2025.108259","DOIUrl":"10.1016/j.lithos.2025.108259","url":null,"abstract":"<div><div>Triassic magmatism on the Korean Peninsula occurred in response to pre- to post-collisional geodynamic events. The Triassic magmatism on the peninsula has been little studied in terms of its age and radiogenic isotopic compositions. We sampled Triassic igneous rocks in the Okcheon Belt and Gyeonggi Massif, and obtained new whole-rock geochemical and Sr–Nd–Pb isotopic, and zircon U-Pb age and Hf isotope data for the high-K calc-alkaline foliated Daegang and non-foliated Yeongjongdo granites. Zircon U-Pb ages reveal that plutonism occurred during 217–222 and 222–232 Ma in the Daegang and Yeongjongdo regions, respectively. The geochemical features of these granites are similar to those of the upper continental crust, but the former and latter granites are A₂- and A₁-subtype granites, respectively. The Daegang granites have ²⁰⁶Pb/²⁰⁴Pb_(t) = 17.31–17.98, ²⁰⁷Pb/²⁰⁴Pb_(t) = 15.56–15.65, and ²⁰⁸Pb/²⁰⁴Pb_(t) = 37.62–37.98, with εNd_(t) = −18.2 to −15.2. The Daegang zircons have εHf_(t) values of −10.8 to +12.1, with a mean of +1.1 ± 3.5 (1σ). The initial ²⁰⁷Pb/²⁰⁴Pb and ²⁰⁸Pb/²⁰⁴Pb values of the Yeongjongdo granites overlap those of the Daegang samples, and are 15.52–15.58 and 37.40–38.08, respectively, with ²⁰⁶Pb/²⁰⁴Pb_(t) = 16.68–17.68. The Yeongjongdo granites have negative whole-rock εNd_(t) (−17.5 to −15.7), and zircon εHf_(t) values (−20.7 to −2.8). These isotopic data and the high Nb, Rb, and Ta contents of the Yeongjongdo granites are inconsistent with a purely mantle source. We propose that reworking of OIB-like old continental crust, which had a source previously metasomatized by Nb-rich deep-seated melts, along with large degrees of crustal cannibalizing and/or flirting magma with stagnation, are the most plausible explanations for the A₁-type features of the Yeongjongdo granites, rather than extreme differentiation of mantle-derived basaltic magmas.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"516 ","pages":"Article 108259"},"PeriodicalIF":2.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145266344","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":"Partial melting-controlled water concentrations in the non-cratonic continental lithospheric mantle (Tariat region, Mongolia)","authors":"Lisha Zhang ,&nbsp;Hejiu Hui ,&nbsp;Qin Wang ,&nbsp;Dmitri A. Ionov","doi":"10.1016/j.lithos.2025.108258","DOIUrl":"10.1016/j.lithos.2025.108258","url":null,"abstract":"<div><div>Effects of partial melting on water distribution in the lithospheric mantle can be obscured by post-melting metasomatism. Here we report hydrogen concentrations in nominally anhydrous minerals (NAMs) of 16 peridotite xenoliths from the late Cenozoic Shavaryn-Tsaram eruption center in central Mongolia. Extensive previous studies of these samples showed no, or very limited, effects of post-melting processes (e.g., metasomatism). The cores of the NAMs exhibit uniform hydrogen diffusion profiles, which record in situ water contents in their source regions: 0.6–13 ppm (6 ± 4 ppm) in olivine, 41–140 ppm (100 ± 32 ppm) in orthopyroxene, and 80–320 ppm (190 ± 63 ppm) in clinopyroxene. These samples experienced different partial melting degrees (<em>F</em>) and later reached inter-mineral chemical (including water) equilibration at sub-solidus conditions in the lithospheric mantle. The correlations between water concentrations in the NAMs and partial melting indices are evident for less fertile (<em>F</em> &gt; 0.05) samples, but are not conspicuous for more fertile (<em>F</em> &lt; 0.05) samples. Equilibrium melting modeling suggests that the less fertile samples result from melting of the mantle source with initial water content of 330–750 ppm at 3–4 GPa, whereas the more fertile samples are melting residues of the MORB-source mantle with initial water content of 50–200 ppm at ∼1 GPa. Some Shavaryn-Tsaram xenoliths experienced metasomatic Fe-enrichments, which did not disturb their water contents. Hence, we infer that partial melting at different degrees overprinted initially heterogenous water distribution in the mantle, and that the off-cratonic lithospheric mantle in accretionary orogenic belts could be water-poor.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"516 ","pages":"Article 108258"},"PeriodicalIF":2.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106369","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":"Complex geochemical structure, age and petrogenesis of the A-type Mesoproterozoic Karlshamn pluton, South Sweden","authors":"Audrius Čečys ,&nbsp;Åke Johansson ,&nbsp;Laurynas Šiliauskas","doi":"10.1016/j.lithos.2025.108262","DOIUrl":"10.1016/j.lithos.2025.108262","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The Karlshamn pluton which intruded at ca. 1.45 Ga in southern Fennoscandia contains two major coeval suites. Both of these have A-type affinity and consist of metaluminous, ferroan, alkali-calcic, and very-high K (shoshonitic) granitic rocks. The two suites are geographically separated within the pluton, and form (semi)parallel trends on Harker-type diagrams. The Eastern suite comprises quartz monzodiorite, quartz monzonite and granite while the Western suite mainly consists of monzogranites. Both suites exhibit similar chondrite-normalized REE patterns with relatively steep LREE and flat HREE. Aluminium-in-hornblende barometric and zircon-saturation thermometric estimates show that both suites were crystallized at relatively high temperatures of 850 - 900 °C and low pressures of 0.33– 0.43 GPa.&lt;/div&gt;&lt;div&gt;Ion microprobe zircon dating from a monzonite of the Eastern suite yielded concordant to nearly concordant U-Pb isotopic compositions. The weighted average &lt;sup&gt;207&lt;/sup&gt;Pb/&lt;sup&gt;206&lt;/sup&gt;Pb age is 1445 ± 11 Ma (2σ, MSWD 1.2), interpreted to date magmatic crystallization. The complex zircons from a monzogranite in the Western suite showed somewhat more scatter and slightly younger ages, however, there are no signs of older inherited materials and no significant age differences between the core-like domains and the overgrowths. The cores yielded a weighted average &lt;sup&gt;207&lt;/sup&gt;Pb/&lt;sup&gt;206&lt;/sup&gt;Pb age of 1431 ± 20 Ma (2σ, MSWD 1.5) and the rims an age of 1424 ± 19 Ma (2σ, MSWD 4.2). The overall age of the zircons from the Western suite is 1426 ± 11 Ma (2σ, MSWD 2.6).&lt;/div&gt;&lt;div&gt;The two major suites as well as related leucogranites and mafic enclaves that are present mainly in the Western suite have indistinguishable initial ε&lt;sub&gt;Nd&lt;/sub&gt; values of −2.2 to −2.7.The Rb- Sr system shows some disturbances, however, initial &lt;sup&gt;87&lt;/sup&gt;Sr/&lt;sup&gt;86&lt;/sup&gt;Sr ratios of undisturbed samples from the two major suites vary between 0.703 and 0.706. Both suites originated either by partial melting of pre-existing mafic rocks within the lower crust or by mixing of mantle-derived magma with crustal melts derived from partial melting of older country rocks.&lt;/div&gt;&lt;div&gt;The mafic enclaves are interpreted as cumulates formed along the walls of the feeder conduits by fractional crystallization caused by the temperature gradient across the feeder walls. The presence of these mafic enclaves in the Western but not the Eastern suite may indicate that they were formed from the Eastern suite magma and subsequently were picked up and engulfed in the later Western suite magma, using the same magma conduits.&lt;/div&gt;&lt;div&gt;Major element geochemical modeling indicate that the Eastern suite intruded first (in accordance with age determinations) and that the remaining magma experienced around 20 % of plagioclase fractionation before it intruded to form the Western suite. The vicinity of the Karlskrona deformation zone may have influenced the intrusion of the pluton.&lt;/div&gt;&lt;/di","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"516 ","pages":"Article 108262"},"PeriodicalIF":2.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145155484","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Petrogenesis of a post-collisional, shallow crustal mafic complex: A case study of the Yıldız Dağı gabbroic intrusion (Northern Türkiye)","authors":"Gönenç Göçmengil ,&nbsp;Othmar Müntener ,&nbsp;Zekiye Karacık ,&nbsp;Ş. Can Genç ,&nbsp;Alexey Ulianov ,&nbsp;Namık Aysal","doi":"10.1016/j.lithos.2025.108260","DOIUrl":"10.1016/j.lithos.2025.108260","url":null,"abstract":"<div><div>The Yıldız Dağı gabbroic intrusion and associated dykes intruded the southern part of the Pontides, along the İzmir-Ankara-Erzincan suture zone (central-northern-Türkiye). The intrusion has an elongated shape and is exposed over 2 km². It consists of melagabbro, leucogabbro, troctolitic enclaves, hornblende gabbro, and pegmatite. Melagabbro is the most common rock type and displays complex internal structures such as crossbedding and faint layering. Leucogabbro is situated at the upper level of the intrusion. Whole-rock geochemical data suggest that the gabbroic units of the pluton are cumulates primarily controlled by the fractionation of ferro-magnesian minerals such as olivine, clinopyroxene, and magnetite. All rocks display negative Nb<img>Ta and Hf<img>Zr anomalies, LILE enrichment, and slightly elevated potassium contents similar to those of other post-collisional early Cenozoic magmatic units in northern Türkiye. The leucogabbro (44.1 ± 3.2 Ma) and hornblende gabbro (42.9 ± 0.2 Ma) have Eocene U<img>Pb zircon and Ar<img>Ar hornblende ages. Whole rock Sr<img>Nd isotopic data are clustered within the mantle array, which is typical of primitive Eocene post-collisional igneous rocks of northern Türkiye. Olivine, clinopyroxene, high-An plagioclase, and magnetite are early cumulus minerals, while brown hornblende, low-An plagioclase, biotite, ilmenite, apatite, and quartz crystallized from the intercumulus liquid. Simulated trapped melt fractions range from 10 to 12 %, resulting in a tenfold increase of REE contents in clinopyroxene from core to rims. High anorthite plagioclase (up to 90) and widespread interstitial amphibole indicate moderately hydrous source regions for the gabbros. P-T calculations based on different mineral pairs and single clinopyroxene geothermobarometry indicate upper-crustal intrusive conditions. As a well-preserved example of small-scale post-collisional gabbroic magmatism within the İzmir–Ankara–Erzincan suture zone, the Yıldız Dağı gabbroic intrusion serves as a valuable analogue for mafic intrusions in similar tectonic settings worldwide and exemplifies the diversification of shallow-level differentiated plutons across the Alpine–Himalayan orogenic belt.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"516 ","pages":"Article 108260"},"PeriodicalIF":2.5,"publicationDate":"2025-09-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145154844","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":"1.4 Ga metabasites in the South China block: Insights into its mesoproterozoic geological evolution","authors":"Yongfeng Cai ,&nbsp;Jie Gao ,&nbsp;Zuohai Feng ,&nbsp;Zhenglin Li ,&nbsp;Hongxing Song ,&nbsp;Yun Zhou","doi":"10.1016/j.lithos.2025.108255","DOIUrl":"10.1016/j.lithos.2025.108255","url":null,"abstract":"<div><div>The paleogeographic reconstruction of the Paleo-Mesoproterozoic Nuna/Columbia supercontinent is less well constrained compared to that of younger supercontinents (e.g., Rodinia, Gondwana, Pangea). For instance, the precise paleoposition of the Cathaysia Block within Nuna remains uncertain. This challenge is partly due to the scarcity of relative paleontological and precise paleomagnetic data, along with limited geological records extending into deep time. Here, we identified a suite of Mesoproterozoic metabasites on the Hainan Island in the southern margin of Cathaysia Block. Zircon U<img>Pb dating constrains the studied rocks formed at ∼1.43 Ga, with distribution patterns of rare earth elements resembling enriched mid-ocean ridge basalt and significantly negative Nb<img>Ta anomalies in the spider diagram. Additionally, Mesoproterozoic metabasites were characterized by radiogenic zircon Hf (ε_Hf(t) &gt; 0) and whole-rock Nd (ε_Nd(t)) &gt; 0) isotopes, indicating that they originated from a depleted mantle source. Given that these metabasites concurrently occurred with A-type granitic rocks in the studied region, we propose that they were most likely produced in an intraplate rift setting, corresponding to the breakup of the Nuna supercontinent. Furthermore, we compiled zircon U<img>Pb isotopic data from Mesoproterozoic sedimentary rocks across other cratonic blocks. Provenance statistical analysis of this data showed that the Cathaysia Block shares a positional affinity with Mawson and Laurentia.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"516 ","pages":"Article 108255"},"PeriodicalIF":2.5,"publicationDate":"2025-09-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106372","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":"Mixing, mingling and metasomatism: Magmatic and hydro-carbothermal processes in an Angolan subvolcanic alkaline silicate complex","authors":"A.M. Borst ,&nbsp;A.A. Finch ,&nbsp;P.R. Siegfried ,&nbsp;B.D. Heredia ,&nbsp;T.B. Thomsen ,&nbsp;E. Vassilieva ,&nbsp;A. Bambi","doi":"10.1016/j.lithos.2025.108253","DOIUrl":"10.1016/j.lithos.2025.108253","url":null,"abstract":"<div><div>The Angola Alkaline Province hosts 35 alkaline igneous complexes that offer valuable insights into rift-related alkaline‑carbonatite magmatism and their potential for strategic critical metal resources such as rare earth elements (REE) and niobium (Nb). This study presents the first detailed investigation of the Nejoio Alkaline Complex, including field observations, petrography, whole rock and mineral chemistry, and U-Pb age data. Nejoio forms a subvolcanic ring complex composed mainly of pyroxene-biotite ijolite and feldspathoidal syenite. Its circular inner zone features heterogeneous ijolite-syenite hybrids rich in pyroxene, biotite, amphibole, apatite and titanite, formed from melanocratic ijolite melts mixed with meso- to leucocratic syenitic crystal mushes. These hybrids exhibit large phenocrysts of alkali feldspar and aegirine-augite with diopside-hedenbergite cores, set in a fine-grained matrix dominated by aegirine, biotite, titanite, apatite, and minor amphibole and fluorite. Interstitial melt pockets in the ijolite contain zircon and Na-Zr-Ti-Nb silicates such as wöhlerite, hiortdahlite, rosenbuschite, and catapleiite, recording a late-magmatic transition from miaskitic to agpaitic mineral assemblages. The inner zone is surrounded by an outer ring of feldspathoidal syenites with abundant alkali feldspar, nepheline, sodalite and cancrinite. These contain accessory magnetite, zircon, and pyrochlore and host late-stage veins with needles of rosenbuschite. Hydro- and carbothermal fluids overprinted both units, replacing primary Mg-Ca rich aegirine-augite with aegirine, and secondary assemblages with dolomite, dawsonite, calcite, cancrinite, pyrite, magnetite and REE-Sr‑carbonates, as well as analcime, natrolite, fluorite, cryolite, paragonite-pyrophyllite and catapleiite. U-Pb dating of primary titanite and apatite indicates that Nejoio was emplaced during the late Cretaceous (107–101 Ma), well after the Atlantic Ocean's opening, reflecting continued magmatism in a failed rift arm following Gondwana's breakup. Nejoio serves as a representative analogue for understanding alkaline magmatism across the Angolan province, emphasizing its economic and geotectonic significance.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"516 ","pages":"Article 108253"},"PeriodicalIF":2.5,"publicationDate":"2025-09-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106371","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":"Cogenetic origin of mafic and felsic enclaves in the Tarnița Complex, Ditrău Alkaline Massif (Eastern Carpathians, Romania): Insights from structural, textural, and geochemical features","authors":"Elemér Pál-Molnár ,&nbsp;Luca Kiri ,&nbsp;Adrián Heincz,&nbsp;Anikó Batki,&nbsp;Máté Szemerédi","doi":"10.1016/j.lithos.2025.108254","DOIUrl":"10.1016/j.lithos.2025.108254","url":null,"abstract":"<div><div>Enclaves in plutonic and volcanic rocks serve as pivotal indicators of magmatic processes and magma dynamics, offering valuable insights into the evolution of igneous systems. This study investigates the structural, textural, and geochemical characteristics of mafic and felsic enclaves in the Triassic, continental rift-related Ditrău Alkaline Massif (Eastern Carpathians, Romania), aiming to elucidate their origin and relationship with the host rock which belongs to the Tarnița Complex. Overlapping whole-rock geochemical as well as amphibole and plagioclase compositions strongly suggest the cognate origin of the different lithologies. The mafic enclaves are characterised by sharp contacts and fine-grained igneous textures, implying rapid crystallisation along the margins of the magma batches. Side-wall cumulates were fragmented, transported and dispersed in the partially solidified host magma by convective currents. Felsic enclaves represent fragments of previously crystallised felsic roof cumulates and felsic rock fragments as well as loosely packed crystal mush fragments. The study emphasises the dynamic nature of the studied magma reservoir in the Ditrău Alkaline Massif, where convective magma flow and injections of replenishing magma batches played a crucial role in the formation and distribution of the enclaves.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"516 ","pages":"Article 108254"},"PeriodicalIF":2.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145106370","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":"A mantle source for water in the Greendale (appinite) Complex: Implications for genesis of granitoid batholiths and crustal growth in magmatic arcs","authors":"J.B. Murphy ,&nbsp;D.B. Archibald ,&nbsp;C.J. Spencer ,&nbsp;W.J. Collins ,&nbsp;E. LeDuc ,&nbsp;E. Scanlan ,&nbsp;A. Debosz ,&nbsp;I.P. Cawood","doi":"10.1016/j.lithos.2025.108256","DOIUrl":"10.1016/j.lithos.2025.108256","url":null,"abstract":"<div><div>Appinite complexes are small (∼1–5 km wide) hornblende-rich, predominantly mafic plutons that crystallized from anomalously water-rich mafic magma. The Neoproterozoic Greendale Complex, Nova Scotia, exemplifies these complexes, occurring as a small pluton, emplaced at ∼10–15 km depth, adjacent to a major fault along the periphery of granitoid plutons intruded in the waning stages of subduction. Stable isotopic data from hornblende in the complex yield −61 to −72 ‰ δD and + 3.7 to +7.0 ‰ δ¹⁸O values, indicating water in the appinite magma was dominantly mantle-derived. These data suggest appinites may represent aliquots of hydrous basaltic magma that segregated from a crystallizing mafic underplate before emplacement at higher crustal levels. Some amphiboles crystallized in situ; others crystallized at ∼12–20 km depth, cooled from ∼950-870 °C, and were entrained as the magma ascended.</div><div>Transfer of mantle-derived fluids and heat into the lower crust during mafic underplating triggered partial melting and generation of coeval granitoid magmas. These granitoids were emplaced at shallow levels (∼3–5 kbar) and formed the upper part of a plumbing system that created rheological barriers, impeding the ascent of coeval mafic magmas except along the deep crustal Hollow Fault, which bounded the plutonic system and along which the Greendale Complex was emplaced. More generally, these relationships imply feedback between active faulting and emplacement of overpressured hydrous mafic magmas, facilitating rapid ascent and high degrees of undercooling, and disequilibrium textures characteristic of water saturation. Appinite magmas may provide a direct window into the fluid conditions of the crystallizing mafic underplate and Deep Crustal Hot Zone. Therefore, appinite complexes provide deep insights into the processes that generate granitoid batholiths and crustal growth in arc systems.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"516 ","pages":"Article 108256"},"PeriodicalIF":2.5,"publicationDate":"2025-09-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145046770","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":"Depositional environment and evolution of the upper Ediacaran to lower Cambrian transition black rock series in Northern Guizhou Province, China","authors":"Liangwei Xu ,&nbsp;Kun Zhang ,&nbsp;Yi Jin ,&nbsp;Zhenxue Jiang ,&nbsp;Luofu Liu ,&nbsp;Xiaokai Xu ,&nbsp;Zhazha Hu ,&nbsp;Xiaowei Huang ,&nbsp;Zengli Guo ,&nbsp;Lei Chen","doi":"10.1016/j.lithos.2025.108252","DOIUrl":"10.1016/j.lithos.2025.108252","url":null,"abstract":"<div><div>The black rock series in northern Guizhou within the Yangtze plate is a benchmark deposit in South China and spans the Neoproterozoic to early Palaeozoic transition period. This period was associated with many major global geological events and the Cambrian Explosion, as well as the formation of a metal-rich layer containing Ni, Mo, platinum group element (PGE) and shale gas resources. However, the evolution of the sedimentary characteristics and palaeoenvironmental conditions of this black rock series remain unclear, and the corresponding enrichment mechanism and organic matter model must be established. Our research revealed that the black rock series formed mainly in a continental or oceanic island arc environment and was influenced by hydrothermal activity to varying degrees. Sediment was supplied from terrestrial sources and supplemented with marine hydrothermal material. An anoxic environment occurred in the research area, with a moderately stratified water column. Hence, deposition occurred in a transitional redox environment with relatively smooth circulation. Moreover, the degree of water restriction in northern Guizhou fluctuated between intense and moderate. The pyrite particle size distribution suggests that the formation environment transitioned from sulfidic to anoxic to hypoxic, with early sulfidic-to-suboxic transition and a gradual oxidizing trend from the bottom up. From the lower dolomite to upper black shale, the overall water exchange power decreased, and the salinity index suddenly decreased, indicating that the sedimentary process was impacted by a rapid increase in the relative sea level and deepening of the sedimentary environment. The chemical index of alteration (CIA) and chemical index of weathering (CIW) demonstrate that dolomite and phosphorite formed in dry and hot climates, while black shale and siliceous rocks formed in warm and wet climates. This study revealed the process of organic matter deposition under reducing, anoxic, and sulfidic conditions, clarified the palaeoenvironment and depositional processes, and provided an enrichment model for organic matter in this black rock series.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"516 ","pages":"Article 108252"},"PeriodicalIF":2.5,"publicationDate":"2025-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145119394","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":"Cambrian intermediate-felsic rocks in Central Pamir: Insights into source heterogeneity and subduction initiation in the Proto-Tethys Ocean","authors":"Sharifjon Odinaev ,&nbsp;Jovid Aminov ,&nbsp;Gennadiy Kallistov ,&nbsp;Xin Ma ,&nbsp;Guo-Rong Tang ,&nbsp;Murodov Azamdzhon ,&nbsp;Aleksandr S. Stepanov ,&nbsp;Ilhomjon Oimuhammadzoda ,&nbsp;Mustafo Gadoev ,&nbsp;Sohibnazar Ashuraliev ,&nbsp;Wei Dan ,&nbsp;Gong-Jian Tang","doi":"10.1016/j.lithos.2025.108251","DOIUrl":"10.1016/j.lithos.2025.108251","url":null,"abstract":"<div><div>The Early Paleozoic magmatic rocks in the Central Pamir provide insights into the tectonic evolution of the Proto-Tethys Ocean. This study integrates zircon U<img>Pb ages, in situ Hf<img>O isotopes, whole-rock elemental and Sr<img>Nd isotopic data of the intermediate and felsic rocks from the Zorburulyuk, Panghazjilga, and Taxkorgan complexes in the eastern segment of the Central Pamir to constrain their magma sources and tectonic implications. Zircon U<img>Pb ages reveal these magmatic rocks formed at Early Cambrian (pegmatite: 527.0 ± 5.4 Ma; gneiss-granite: 524.3 ± 3.6 Ma; monzodiorite mafic microgranular enclaves (MMEs): 524.1 ± 1.6 Ma; quartz diorite: 517.3 ± 1.1 and 520.3 ± 2.2 Ma and biotite granite: 512.1 ± 3.5 Ma). The intermediate rocks exhibit enriched isotopic compositions (ε_Hf(t) = −5.78 to +6.93; ε_Nd(t) = −5.56 to −4.02; ⁸⁷Sr/⁸⁶Sr = 0.70212–0.70844), indicating mainly derivation from a metasomatized subcontinental lithospheric mantle source that was enriched by subduction-derived sediments, and involved magma fractionation of mantle-derived mafic melts to produce intermediate rocks. The felsic rocks exhibit variable isotopic compositions: pegmatites (ε_Hf(t) = −2.41 to +0.95; ε_Nd(t) = −4.02 to −5.15), biotite granites (ε_Nd(t) = −1.54 to −0.94; δ¹⁸O = 7.87–9.17 ‰), which are similar to coeval mafic-intermediate rocks, indicating that they were derived from melting of hybrid lower crustal sources represented by the latter. Our results propose that the Cambrian intermediate-felsic rocks record the early stages of southward subduction of the Proto-Tethys Ocean with arc magmatism peaking in the Early Cambrian (ca. 524–527 Ma). In this process, slab rollback facilitated magma underplating and crustal hybridization, leading to the formation of intermediate-felsic rocks through melting of metasomatized subcontinental lithospheric mantle and lower crustal sources.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"516 ","pages":"Article 108251"},"PeriodicalIF":2.5,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145061211","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}