Lithos最新文献

{"title":"U-Pb ages and Hf isotopic composition of detrital zircon in western Algarve Triassic sandstone (SW Iberia): Implications for crustal evolution, provenance, and paleogeography","authors":"Manuel Francisco Pereira,&nbsp;Cristina Gama","doi":"10.1016/j.lithos.2024.107871","DOIUrl":"10.1016/j.lithos.2024.107871","url":null,"abstract":"<div><div>The Triassic paleogeographic configuration before the Central Atlantic Ocean's opening and the Pangea's breakup establishes that Iberia was close to North America and North Africa. We present U<img>Pb and Hf isotope data of Triassic siliciclastic rocks of the Western Algarve basin (Southwest Iberia, Portugal) to draw inferences on their provenance to define the crustal evolution of the potential sources. Detrital zircon age populations of five samples of Triassic sandstones (68–80 % Neoproterozoic; 5–23 % Paleoproterozoic; 5–14 % Mesoproterozoic; &lt;5 % Archaen and &lt; 4 % Paleozoic) differ significantly from those of the underlying Carboniferous turbidites of the South Portuguese Zone suggesting provenance from outside present-day SW Iberia. Hf isotope signatures of the zircon grains from the western Algarve Triassic sandstones unravel a complex crustal evolution characterized by successive cycles of input of juvenile magmas and magmas derived from the reworking of older crust. Archean detrital zircon grains with positive εHf(t) values and model ages of 3.1–3 Ga indicate juvenile crust formation (Leonian event), while a grain dated at ca. 2.6 Ga showing negative εHf(t) values and model ages of 3.1 Ga suggests that the Archean crust became reworked later (Liberian event). Zircon grains dated between 2.4 and 2.5 Ga having positive to slightly negative εHf(t) values and model ages of 3.3–2.6 Ga model ages correspond to magmatism older than the Eburnean event known in the Reguibat shield, involving a juvenile component mixed with variable proportions of reworked Archean crust. Younger Paleoproterozoic grains (ca. 2.10 to 2.05 Ga; Eburnean-Birimian event) having positive εHf(t) values and model ages of 2.3–2.1 Ga and negative εHf(t) values and model ages of 3.6–2.6 Ga, also indicate interaction of juvenile sources with mixing of old crust. Mesoproterozoic grains show positive εHf(t) values and model ages of 2.3–2.1 Ga, suggesting juvenile crust formation and reworking of the Eburnean crust. Neoproterozoic (ca. 695–555 Ma) detrital zircon with positive εHf(t) values and model ages of 0.76–0.58 Ga point to juvenile crust formation (i.e. Cadomian/Pan-African and Avalonian arcs). They also have negative εHf(t) values in the range − 21.6 to −11.7 and model ages of 3.2–2.1 Ga, suggesting reworking of older crust. In summary, the εHf(t) values and U<img>Pb age pattern of the zircon grains from the Triassic siliciclastic rocks are similar to NW Africa and North America potential sources. Still, there is a notable gap in juvenile crust production during the Siderian in the peri-Eastern Laurentia, Avalonia, and Ganderia potential sources unknown in NW Africa. The lack of ca. 525–380 Ma and ca. 380–330 Ma detrital zircon in the western Algarve Triassic sandstones makes it challenging to admit an Atlantic margin of North America and SW Iberia provenance.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107871"},"PeriodicalIF":2.9,"publicationDate":"2024-11-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658300","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":"Magmatic differentiation of peralkaline granites: Constraints from iron isotope fractionation between Fe-bearing minerals","authors":"De-Hong Du ,&nbsp;Xiao-Lei Wang ,&nbsp;Hang Xu ,&nbsp;Shuo Wang ,&nbsp;Ying-Ze Zhang ,&nbsp;Weiqiang Li","doi":"10.1016/j.lithos.2024.107863","DOIUrl":"10.1016/j.lithos.2024.107863","url":null,"abstract":"<div><div>Iron isotopes have been found useful in tracing magmatic processes of calc-alkaline granitic magmas, but its application in peralkaline granitic systems is hampered by the lack of information regarding the Fe isotope fractionation factors between alkali-rich ferromagnesian silicate minerals and Fe<img>Ti oxides. To better understand the behavior of Fe isotopes during peralkaline magma differentiation, we carried out high-precision Fe isotope analyses on peralkaline and associated metaluminous high-silica granite rocks and Fe-bearing minerals separated from the rocks in Zhoushan archipelago, southeast China. The Fe-bearing mineral show a large dispersion in Fe isotope compositions, with δ⁵⁶Fe ranging from 0.03 ‰ to 0.70 ‰, following the sequence of K-feldspar ≥ magnetite &gt; aegirine &gt; arfvedsonite &gt; ilmenite. The δ⁵⁶Fe differences between the mineral pairs are relatively consistent. Based on the magmatic temperatures defined by quartz-zircon oxygen isotopic geothermometer, the temperature-dependent equilibrium Fe isotope fractionation functions between following mineral pairs are obtained: Δ⁵⁶Fe_{aegirine-arfvedsonite} = 0.20 (± 0.07) × 10⁶/T², Δ⁵⁶Fe_{magnetite-arfvedsonite} = 0.38 (± 0.06) × 10⁶/T², and Δ⁵⁶Fe_{magnetite-aegirine} = 0.16 (± 0.04) × 10⁶/T². The bulk peralkaline granites have variable but generally high δ⁵⁶Fe values ranging from 0.28 ± 0.03 ‰ to 0.62 ± 0.04 ‰, with a mean of 0.42 ± 0.09 ‰ (1SD), which are higher than those of the associated metaluminous granitic samples (δ⁵⁶Fe = 0.22 ± 0.05 ‰, 1SD). Furthermore, δ⁵⁶Fe values of the peralkaline granites are negatively correlated with Sm/Yb and MnO, consistent with removal of isotopically light Fe-enriched arfvedsonite, implying that peralkaline granites experienced extensive magma differentiation regardless whether they were derived from differentiation of mantle-derived basaltic melts or partial melting of curst sources. Our results highlight a large Fe isotope fractionation between alkali ferromagnesian silicates and oxides, confirming Fe isotopes as a potential tool in tracking the differentiation processes of peralkaline magmas.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107863"},"PeriodicalIF":2.9,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658304","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":"Pressure-Temperature-time paths from metapelites reveal Neoproterozoic continental crust underthrusting related to the West Gondwana amalgamation","authors":"Alice Westin ,&nbsp;Mahyra Tedeschi ,&nbsp;Mario C. Campos Neto ,&nbsp;George L. Luvizotto ,&nbsp;Rafael G. Motta ,&nbsp;Augusto G. Nobre ,&nbsp;Rômulo A. Ando","doi":"10.1016/j.lithos.2024.107865","DOIUrl":"10.1016/j.lithos.2024.107865","url":null,"abstract":"<div><div>In this contribution, we employed a petrochronological approach to investigate the tectonometamorphic evolution of Al-rich garnet-staurolite and garnet-staurolite-kyanite (biotite- and plagioclase-free) metapelites of the southernmost portion of the Neoproterozoic Brasília orogen. We have reconstructed the first prograde to peak pressure-temperature-time (P-T-t) paths reported for metamorphic units of the area, by combining petrographic analyses, quantitative compositional mapping of major elements, phase equilibrium modeling, and EPMA Th–U–Pb monazite chemical dating. The metamorphic reactions involved in the prograde metamorphic evolution are discussed, including the effects of garnet fractionation, exhaustion of reactants, and re-equilibration reactions on the major-element composition of garnet porphyroblasts, and their influence on <em>P-T</em> condition estimates. Raman spectroscopy on carbonaceous material (RSCM) thermometry provided insights into the synkinematic retrograde path. A steep prograde path marked by two stages is recorded by the garnet porphyroblasts of garnet-staurolite-muscovite (±kyanite) schists: (i) 555–585 °C and 0.60–0.90 GPa; (ii) 590–635 °C and 1.0–1.4 GPa. Monazite crystals record the prograde to peak path from <em>ca.</em> 630–625 Ma to <em>ca.</em> 605–595 Ma. Matrix graphite crystals suggest post-peak cooling to 400–500 °C concurrent with the late stages of development of the main foliation. The reconstructed P-T-t paths indicate an intermediate d<em>T</em>/d<em>P</em> metamorphism, and a burial rate of ∼0.55 km/Ma, with garnet compositional zoning suggesting that the high-pressure P-T-t path resulted from a single metamorphic event. The corresponding geothermal gradients, and <em>in-situ</em> ages, combined with regional evidence, suggest that peak metamorphic conditions were attained during collisional underthrusting of the continental crust related to the West Gondwana amalgamation.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107865"},"PeriodicalIF":2.9,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658369","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":"Tracking HFSE associated with high salinity fluid during HP metamorphism in the Zavkhan Terrane, Western Mongolia","authors":"Manzshir Bayarbold ,&nbsp;Atsushi Okamoto ,&nbsp;Masaoki Uno ,&nbsp;Otgonbayar Dandar ,&nbsp;Mayuko Fukuyama ,&nbsp;Geri Agroli ,&nbsp;Noriyoshi Tsuchiya","doi":"10.1016/j.lithos.2024.107853","DOIUrl":"10.1016/j.lithos.2024.107853","url":null,"abstract":"<div><div>Garnets often exhibit high concentrations of heavy rare-earth elements, which provide crucial insights into element mobility and fluid dynamics during metamorphism. This research reports on the distributions of trace and major elements in garnets from the Khungui eclogite of the Zavkhan Terrane in Western Mongolia. Within the eclogite sample, two types of garnets were identified, featuring dissimilar microstructures and compositional zoning: aggregate-type garnet with asymmetric zoning (Grt1) and euhedral garnet with concentric zoning (Grt2). Previous studies determined that Grt2 formation occurred in the pre-eclogite stage to eclogite facies (2.1–2.2 GPa and 580–610 °C), associated with the infiltration of high-saline fluids. The hexagonal-shaped pseudomorphs of Ti-bearing minerals associated with Grt1 suggest that the nucleation of titanite and garnet was simultaneously accelerated by the destabilization of Ti-augite during pre-eclogite metamorphism. This process could have contributed to the formation of aggregation textures, where Ti-bearing minerals are closely associated with Grt1 in the Khungui eclogite. Based on major divalent elemental composition zoning and trace element characteristics, both Grt1 and Grt2 in the Khungui eclogite are formed simultaneously from the pre-eclogite to eclogite stages. The cores (high Fe + Mg + Mn; Y + REE) of Grt1 and Grt2 are attributed to Rayleigh fractionation or a diffusion-limited uptake process. In contrast, the growth mechanisms of the Grt1 rim and Grt2 rim are distinct during the eclogite stage. The Grt1 rim is explained by a dissolution–reprecipitation, which resulted in the atoll texture observed in Grt1. The Grt2 rim (high Ca; low Y + REE) grew through a mechanism consistent with that of the Grt2 core. The major and trace element zonings of these garnets provide insights into element mobility related to Ti-bearing minerals and infiltration of high salinity fluids at different stages: (1) the mobilization of Ti and V increased under eclogite facies conditions (growth stage of garnet) compared to the pre-eclogite stage, with the mobility of Ti, Nb, Ta elements being pronounced under the exhumation stage (Rt–Ilm–Ttn2), possibly because of the infiltration of high-saline fluids and an increase in temperature, and (2) post-growth compositional modification of Grt1 was induced by a localized transport of Fe, Mg, Mn, and Ca elements in response to the replacement of ilmenite by titanite during decompression (0.1–0.5 GPa and 421–534 °C). The contrasting zoning of garnet in Khungui eclogite indicates dissimilar scales of element mobility under eclogite facies conditions (over a thin-section scale) and during decompression (up to several centimeters or beyond).</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107853"},"PeriodicalIF":2.9,"publicationDate":"2024-11-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658368","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":"Triassic–Jurassic alkaline magmatism in the Ivrea-Verbano Zone, Southern Alps: A zircon perspective on mantle sources and geodynamic significance","authors":"Mattia Bonazzi ,&nbsp;Abimbola C. Ogunyele ,&nbsp;Tommaso Giovanardi ,&nbsp;Maurizio Mazzucchelli ,&nbsp;Alessandro Decarlis ,&nbsp;Alessio Sanfilippo ,&nbsp;Alberto Zanetti","doi":"10.1016/j.lithos.2024.107854","DOIUrl":"10.1016/j.lithos.2024.107854","url":null,"abstract":"<div><div>The Ivrea-Verbano Zone (IVZ; western Southern Alps) consists of a distinctive sequence of the lower continental crust of the Adriatic plate, extending down to the subcontinental lithospheric mantle. It is characterized by a large variety of intrusive bodies of variable geochemical composition and age, offering a unique insight into the evolution of mantle-derived magmatism in post-collisional and extensional geodynamic settings. In this study, we characterize a suite of alkaline dykes intruding a mantle massif – the Finero Phlogopite Peridotite in northern IVZ. These dykes include zircon-bearing diorites and anorthosites, mainly composed by HFSE-rich amphibole and phlogopite, albite (&gt;90 vol% in anorthosites) and apatite. Zircon, monazite, ilmenite, titanite, Nb-rich oxides, and carbonates are common accessory minerals. Additionally, a “composite” diorite dyke containing both HFSE-rich and HFSE-poor amphiboles was investigated. The study is aimed at providing new trace element, U-Pb geochronological and Lu-Hf isotopes dataset on zircon from these alkaline dykes, to refine the understanding of their mantle source characteristics, emplacement age and geodynamic implications. The trace element composition of zircons from the studied dykes points to segregation from melts with alkaline to ultra-alkaline affinity. Concordia U-Pb ages of zircon from the alkaline diorite dykes span from 221 to 191 Ma, which are interpreted as the result of multiple crystallization/recrystallization stages related to different magmatic pulses. Conversely, zircon from anorthosite and composite diorite dykes yield a narrow time range of 198–202 Ma, highlighting the occurrence of a magmatic pulse around ca. 200 Ma. The εHf_(t) values (+13.4 to +5.7) of zircon from the alkaline diorite dykes are significantly more positive compared to the values in those from anorthosite and composite diorite dykes (+4.2 to −0.4), suggesting that the parental melts were derived from heterogeneous asthenospheric mantle sources with low to moderate amount of recycled continental crust components. Our data and reappraisal of the literature indicate that the IVZ experienced a protracted period of alkaline magmatism from ca. 235 Ma to 185 Ma. The melts migrated along mantle shear zones during the Triassic-Jurassic lithospheric extension. Different pulses of alkaline magmatism were associated with relevant extensional tectonic stages recorded by the continental crust, presumably triggering a passive uplift of heterogenous asthenospheric reservoirs over a front of at least 500 km. This tectono-magmatic cycle is a precursor to the focused rifting stage which caused the opening of the Jurassic Alpine Tethys, enhancing Pangea fragmentation.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107854"},"PeriodicalIF":2.9,"publicationDate":"2024-11-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658302","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":"Paleoproterozoic sediment-derived magmas reveal a late orogenic stage in the southern São Francisco Craton, Brazil: Evidence from petrogenesis of the 2.0 Ga Cupim Pluton leucogranites","authors":"Syro Lacerda ,&nbsp;Martin Guitreau ,&nbsp;Leonardo Gonçalves ,&nbsp;Hugo Moreira ,&nbsp;Cristiane C. Gonçalves ,&nbsp;Marco Aurélio Pinheiro ,&nbsp;Cassiano Costa e Castro ,&nbsp;Régis Doucelance","doi":"10.1016/j.lithos.2024.107852","DOIUrl":"10.1016/j.lithos.2024.107852","url":null,"abstract":"<div><div>Sediment-derived granites (S-type) can provide detailed information about continental crust reworking processes and tectonic regimes through time. Their compositions reflect the nature of sedimentary rocks that melted to form them. Inherited accessory minerals in these granites can provide information regarding the age and nature of the crustal rocks that contributed to the formation of their sedimentary source rock. In addition, S-type granites typically form during collisional stages in modern orogens, and their Precambrian records can provide clues about ancient tectonics. In this contribution, we present a detailed petrogenesis of the Cupim Pluton, located in the Paleoproterozoic Mineiro Belt (Brazil). The Cupim pluton is composed of two-mica and garnet-bearing leucogranites that are strongly peraluminous (ASI &gt; 1.1), high-K (K₂O/Na₂O &gt; 1), low MgO + FeO + TiO₂ (&lt;2 wt%). Its composition is similar to that of melts experimentally produced by muscovite/biotite dehydration melting reactions. Rb/Sr and Rb/Ba ratios suggest that these leucogranites are formed by the melting of heterogeneous sedimentary source(s). Zircon crystals from the Cupim Pluton unveil a protracted crustal melting period (2.01–1.98 Ga) hitherto unknown in the Mineiro Belt, which itself discloses a late collisional orogenic stage in southern São Francisco Craton. Igneous zircon crystals exhibit εHf_(t) between −16.4 and − 0.6, and δ³⁰Si between −1.16 and − 0.26 ‰, which is typical for zircon from sediment-derived granites. Hafnium isotope variations reflect mixing between at least two crustal sources, which is in line with inherited zircon cores that evidence major Archean and minor Paleoproterozoic sediment contributions. The emplacement of the Cupim Pluton leucogranites ends a subduction-collision cycle, following a long period of TTG-sanukitoid magma production, and promoted the stabilization of the southern São Francisco Craton.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107852"},"PeriodicalIF":2.9,"publicationDate":"2024-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658301","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":"Mesozoic lithospheric mantle evolution in South China: Evidence from Ar-Ar dating, geochemistry and Sr-Nd-Pb isotopes of lamprophyres","authors":"Lei Wang ,&nbsp;Hua Huang ,&nbsp;Xinbiao Jin ,&nbsp;Xiujuan Bai ,&nbsp;Xinyu Wang ,&nbsp;Xiangke Wu","doi":"10.1016/j.lithos.2024.107851","DOIUrl":"10.1016/j.lithos.2024.107851","url":null,"abstract":"<div><div>Understanding the Mesozoic lithospheric mantle beneath South China is challenging, primarily because mantle-derived magmatic rocks are rare, whereas granitic magmatism is far more abundant. In this study, we present new ⁴⁰Ar/³⁹Ar geochronology, major and trace elemental composition, and Sr-Nd-Pb isotopic data for lamprophyres from northern and central Guangxi Province, South China. Our results reveal two intrusion phases: an earlier phase at 207.7 ± 1.2 Ma, and a later phase between 95.6 ± 0.6 Ma and 102.3 ± 0.7 Ma. The earlier phase, represented by the Danyang lamprophyres, is marked by low Cr (330–355 ppm) and Ni (241–258 ppm) contents and strongly fractionated REE patterns with (La/Yb)n ratios of 57.5 to 62.8. The later phase, represented by the Leidong, Nongchang, and Longchang lamprophyres, shows higher Cr (490–781 ppm) and Ni (237–377 ppm) contents, with less fractionated REE patterns and (La/Yb)n ratios of 20.2 to 27.8. Despite their temporal differences, the lamprophyres share similar isotopic characteristics, including high initial ⁸⁷Sr/⁸⁶Sr (0.707940–0.721310), negative ε_Nd(t) (−9.19 to −5.31), and radiogenic Pb isotopic compositions (²⁰⁶Pb/²⁰⁴Pb: 18.200–18.331, ²⁰⁷Pb/²⁰⁴Pb: 15.62–15.72, ²⁰⁸Pb/²⁰⁴Pb: 38.53–38.84). These features suggest derivation from low-degree partial melting of a phlogopite-bearing, refractory peridotite lithospheric mantle, modified by olivine and clinopyroxene fractionation. This refractory mantle was metasomatically enriched by Proterozoic subduction processes beneath the Yangtze Craton. By synthesizing published Sr-Nd-Pb isotopic data, we propose that the lithospheric mantle beneath South China shifted from enriched to depleted mantle between ∼220 Ma and ∼ 100 Ma, possibly due to extension associated with the subduction and rollback of the Paleo-Pacific Plate.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107851"},"PeriodicalIF":2.9,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658305","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":"Restite entrainment in S-type granites: A systematic review","authors":"M. García-Arias","doi":"10.1016/j.lithos.2024.107850","DOIUrl":"10.1016/j.lithos.2024.107850","url":null,"abstract":"<div><div>S-type granites show linear correlations for major elements and some trace elements in bivariate diagrams against maficity (FeO_t + MgO), with negative trends for major incompatible elements and positive trends for major compatible elements, extending beyond the usual composition of experimental and anatectic melts. Although several petrogenetic processes have been suggested, restite entrainment has been prominently proposed to explain that compositional feature. Restite entrainment implies that melt leaves the partially melted source rocks containing variable amounts of the solid phases present in the melting volume, which are generally Ca-Fe-Mg-Ti-richer and Si-Na-K-poorer than the melt. The entrainment of these phases will consequently produce the described compositional trends. In this manuscript I provide a review of this process based on my personal experience with thermodynamic modelling of the partial melting of metasedimentary sources and on conclusions published by other authors. In particular, I review what constitutes restite, the factors that control the entrainment of minerals, the proposed types of restite entrainment, the evidence in favor of (or against) this process, and other related aspects.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107850"},"PeriodicalIF":2.9,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658303","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":"Givetian-Frasnian rift-related volcanism of the Shipunikha Depression, NW Rudny Altai, Central Asia: Tectono-magmatic significance and new constraints on whole-rock geochemistry, Nd-isotopic data and UPb ages","authors":"M.L. Kuibida ,&nbsp;N.N. Kruk ,&nbsp;I.V. Vikentiev ,&nbsp;O.V. Murzin ,&nbsp;N.M. Murzina ,&nbsp;V.A. Yakovlev ,&nbsp;Ya Yu Shelepov ,&nbsp;A.V. Chugaev ,&nbsp;M.A. Mizernaya ,&nbsp;R.A. Shelepaev ,&nbsp;P.D. Kotler ,&nbsp;E.I. Mikheev ,&nbsp;I.V. Nikolaeva ,&nbsp;S.V. Palesskiy ,&nbsp;D.V. Semenova ,&nbsp;N.G. Soloshenko ,&nbsp;A.P. Pyatkova ,&nbsp;G.F. Karmanov","doi":"10.1016/j.lithos.2024.107849","DOIUrl":"10.1016/j.lithos.2024.107849","url":null,"abstract":"&lt;div&gt;&lt;div&gt;The paper presents new original data on the Devonian rift-related volcanism from the Rudny Altai, a marginal terrane of the Siberian continent (Altai-Sayan Fold Belt, western Central Asian Orogenic Belt). The extensional regime in relation to tectono-magmatic reactivation of the continental margin was accompanied by an intense flare up of bimodal-type shallow-marine volcanism and injection of subvolcanic intrusions. On the first stage basic magmatism evolved from (i) injection of “More LREE- and HFSE-enriched” dolerite (&lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Nd&lt;/sub&gt;(t) = +5.1) to (ii) eruption of their effusive analogues (&lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Nd&lt;/sub&gt;(t) = +1.4), and following “Less LREE- and HFSE-enriched” basalt (&lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Nd&lt;/sub&gt;(t) = +6.1). This stage reflects initial opening of the rift. On the second stage, volcanism evolved from (iii) “LREE- and HFSE-depleted” (&lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Nd&lt;/sub&gt;(t) = +5.4) to (iv) “LREE-enriched and HFSE-depleted” (&lt;em&gt;ε&lt;/em&gt;&lt;sub&gt;Nd&lt;/sub&gt;(t) = +4.1 to +4.7) types. This stage correspond to the prolonged opening of the pull-apart basin, as there is no geological evidence for island-arc uplift during this period. Variations in indicator HFSE ratios (Th/Yb, Nb/Yb and Zr/Y), enrichment of Nb relative to La and Th in combination with moderate Nd isotopic values resemble those for basalts from the behind-arc region with close spatial-temporal relation to rifting. The trace element variation indicates a change in the partial melting degree of the mantle source, from lower to higher, consistent with progressive rifting. The petrogenesis of magmas has been interpreted as shallow melting of a lithospheric mantle, metosomatised by a previous subduction event, and inherited geochemical signatures of relict mantle. The voluminous felsic magmatism was formed by crustal melting during lithospheric extension when basic magmas reached high crustal levels. The dacites yield zircon U&lt;img&gt;Pb ages of ca. 375 Ma, reflecting the peak of volcanic activity. The tectonic record bear evidence of strike-slip deformation, which could been induced by translation of arc and back-arc lithospheric plates.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Summary&lt;/h3&gt;&lt;div&gt;The Devonian evolution of the Altai Convergent Margin (NW Rudny Altai) of the Siberian continent was accompanied by the generation of basalt-dacite volcanism (∼380-375 Ma). Based on the sequence of volcanic phases and their geochemical variations in the time range, two stages corresponding to the initial and long-term opening of the pull-apart basin are distinguished. The petrogenesis of the magmas is interpreted as shallow melting of lithospheric mantle metasomatised by a previous subduction event and inheriting geochemical signatures of the relict mantle. The initial and subsequent magmatic phases can be reproduced by varying the degree of partial melting of the magma source from lower to higher, consistent with the evolution of the pull-apart basin. Rift-related magmatism is caused by arc and back-arc plate translation, wi","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107849"},"PeriodicalIF":2.9,"publicationDate":"2024-11-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142658365","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":"First-principles calculations of equilibrium inter-mineral nickel isotope fractionation in the mantle","authors":"Zhuang Ma ,&nbsp;Wenzhong Wang ,&nbsp;Shui-Jiong Wang","doi":"10.1016/j.lithos.2024.107848","DOIUrl":"10.1016/j.lithos.2024.107848","url":null,"abstract":"<div><div>The nickel (Ni) isotopic systematics has been increasingly utilized to understand the processes governing planetary differentiation. However, there is a lack of fundamental knowledge regarding equilibrium Ni isotope fractionation among mantle minerals, which hampered further applications of Ni isotopes in this domain. In this study, we conducted first-principles calculations to determine the reduced partition function ratios of ⁶⁰Ni/⁵⁸Ni (10³lnβ₆₀_–₅₈) in major Ni-doped mantle minerals, including olivine, orthopyroxene, clinopyroxene, pyrope and spinel. Our calculations reveal that the 10³lnβ₆₀_–₅₈ is insensitive to the Ni concentration within the mineral Ni concentration ranges investigated here, and the 10³lnβ₆₀_–₅₈ increases in the order of pyrope &lt; clinopyroxene &lt; orthopyroxene &lt; olivine &lt; spinel. Moreover, the 10³lnβ₆₀_–₅₈ demonstrates a predominantly linear relationship with the average force constant (&lt; F &gt;) of Ni that is mainly influenced by the average Ni<img>O bond length. By comparing the measured inter-mineral Ni isotopic differences in mantle rocks with our predicted results, we find that olivine, spinel and orthopyroxene in most peridotitic samples have attained Ni isotopic equilibrium. Conversely, clinopyroxene appears to fall out of equilibrium with other mineral phases, likely attributed to its metasomatic origin. Furthermore, in conjunction with the melt-olivine Ni isotope fractionation factor obtained from theoretical calculation and laboratory experiment, we demonstrate that mantle silicate melting produces melts with a heavier Ni isotopic signature compared to the source. Consequently, the systematically lighter Ni isotopic compositions observed in global basalts cannot be purely attributed to silicate melting-induced Ni isotope fractionation. An additional process, perhaps sulfide dissolution, must be invoked.</div></div>","PeriodicalId":18070,"journal":{"name":"Lithos","volume":"490 ","pages":"Article 107848"},"PeriodicalIF":2.9,"publicationDate":"2024-11-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142586047","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}