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Lithos
Elsevier Science B.V.
Lithos

Elsevier Science B.V.

0024-4937

Lithos/Journal LithosSCIISTP
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    Corrigendum to “Petrogenesis and geochronology of Paleoproterozoic magmatic rocks in the Kongling complex: Evidence for a collisional orogenic event in the Yangtze craton” [Lithos 342–343 (2019) 513–529] (LITHOS (2019) 342–343 (513–529), (S0024493719301999), (10.1016/j.lithos.2019.05.015))

    Han Q.Peng S.Polat A.Kusky T....
    2页
    查看更多>>摘要：? 2021 Elsevier B.V.The authors regret that the tectonic setting discrimination diagrams (Fig. 12a) in this article have an obvious mistake that the horizontal and vertical axes (Nb and Y contents in ppm) should be exchanged. The corrected Fig. 12 is attached below. [Figure presented] Fig. 12. (a) and (b) Tectonic setting discrimination diagrams of Nb vs. Y and Y + Nb vs. Rb; (c) and (d) subtype classification of A-type granites. Abbreviations: VAG = volcanic arc granites; ORG = ocean ridge granites; WPG = within-plate granites; Syn-COLG and Post-COLG = syn- and post-collisional granites; OIB = oceanic island basalt; IAB = island arc basalt; A1 = granitoids in anorogenic settings; A2 = post-orogenic granites emplaced after a continental collision. Panels (a) and (b) are after Pearce et al. (1984, 1996). A-type granites field in panel (c) is after Whalen et al. (1987), panels (c) and (d) after Eby (1992). Data sources are the same as in Fig. 7. The authors would like to apologise for any inconvenience caused.
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    • NSTL
    • Elsevier

    Qualitative barometry of high P/T rocks with field based NIR spectroscopy of white mica

    Bradley T.W.Ustunisik G.K.Duke E.F.Flores K.E....
    18页
    查看更多>>摘要：? 2021 Elsevier B.V.White micas (muscovite, phengite, paragonite) are widespread in rocks of high-pressure, low-temperature (high P/T) terranes. Metamorphism in these settings occurs over a wide range in pressure and a relatively narrow range in temperature. Pressure increase results in forward progress of the aluminoceladonite exchange (Al-Cel, AlIV + AlVI=SiIV+[Fe2+,Mg]VI) in the muscovite-phengite series, ultimately producing very high Si content in white micas in blueschists and eclogites. Visible to near-infrared spectroscopy (Vis–NIR, 350–2500 nm) provides an effective monitor of the Al-Cel exchange because the substitution of Fe and Mg for Al in the octahedral site shifts the frequency of the Al-OH absorption band near 2200 nm to longer wavelengths. Importantly, Vis–NIR measurements are readily acquired with field spectrometers and similar data can be acquired with airborne and spaceborne imaging spectrometers. Here we present results of a field-based Vis–NIR study into variation of white mica Al-OH wavelength values and the potential to perform qualitative field-based barometry in high P/T terranes. Field spectra and samples were collected in five regions in northwest Turkey in which previous studies documented metamorphism over a wide range of pressure at relatively constant temperature. Spectra were collected from 186 samples and 20 samples were prepared for electron microprobe analysis (EMPA) and scanning electron microscopy energy dispersive spectroscopy (SEM-EDS) to determine mineral assemblages and white mica compositions. To address possible bulk composition effects, different lithologies were evaluated, broadly categorized as metabasite, metacarbonate, and metapelite. The field-based Al-OH wavelength values range from 2190 nm to 2235 nm, which is equal to the full range of published values for metamorphic or hydrothermal white micas. White mica Si contents range from 2.97 a.p.f.u. (on an 11?oxygen basis) in paragonite in retrograded calc-schist to 3.66 a.p.f.u. in lawsonite blueschist. In each high P/T region the field-based Al-OH wavelength values and white mica compositions are highly variable at scales of 100 s of meters to thin section scale. We interpret this to record variable retrograde re-equilibration at pressures lower than the peak pressure. Despite the variability, the maximum Al-OH wavelength values in each region, taken to represent the highest Al-Cel content in white mica and the most pristine high-pressure assemblage, correlate well with estimated peak pressure for the region. The maximum wavelength increases from ~2202 nm at P ≈ 6.5 kbar to ~2228 nm at P ≈ 11 kbar to ~2235 nm at P ≈ 24 kbar. Moreover, different lithologies in each region exhibit similar Al-OH wavelength variability and maximum Al-OH wavelength values. This suggests that bulk composition effects are minor compared to pressure effects on Al-OH wavelength variation. This study shows that field-based Vis–NIR spectroscopy can provide valuable information regarding peak metamorphic pressures in high P/T terranes as well as the extent and distribution of post-peak re-equilibration. This can help identify the most pristine, peak-pressure samples as well as those that may yield important information regarding patterns of hydration and fluid flow along the retrograde P-T path at scales ranging from hundreds of meters to centimeters.
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    • NSTL
    • Elsevier

    Multiple modes of sulphur cycling within a mineralised orogen: A case study from the Fraser Zone, Western Australia

    Walker A.T.Evans K.A.Kirkland C.L.Polito P.A....
    18页
    查看更多>>摘要：? 2021 Elsevier B.V.Sulphur isotope analysis can be used to fingerprint sulphur sources within mineral systems and trace sulphur cycles through geological time. In this work we present petrographic and in-situ sulphur isotope analyses of sulphide minerals from the Zn–Cu–Au–Ag Andromeda volcanogenic massive sulphide (VMS) prospect, Fraser Zone, Albany-Fraser Orogen, Australia. Sulphide mineral assemblages of pyrrhotite, pyrite, chalcopyrite and sphalerite occur within deformed lenses of sulphide breccia at Andromeda, with the presence of sphalerite contrasting with typical magmatic sulphide mineral assemblages recorded elsewhere within the Fraser Zone. The δ34S values of Andromeda sulphides range from 4.50‰ to 6.70‰, characteristic of Archaean and Proterozoic VMS-style deposits worldwide. The Δ33S data show evidence of mass-independent fractionation of sulphur (MIF-S), which indicates that sulphur from Archaean sediments was included within Andromeda sulphides, which formed in close proximity to the Fraser Shear Zone (FSZ). This contrasts with the findings of previous studies of sulphur isotopes within magmatic sulphides elsewhere in the Fraser Zone, which are distal to major shear zones, and in which sulphur derived from Archaean sediments is absent. The absence of a MIF-S signature from the magmatic sulphides is interpreted to reflect cycling of surface-derived sulphur through the ocean prior to incorporation into the magmatic sulphides. The presence of Archaean sedimentary sulphur at Andromeda is attributed to transport from a reservoir of sulphur recording MIF-S within the older Biranup Zone, which is in close proximity to the FSZ, a lithosphere-scale structure. Fluid movement through the FSZ is a viable mechanism that might have transferred sulphur recording MIF-S from Archaean sulphur-bearing pyrite in the Biranup Zone to sulphides at Andromeda. These findings support multiple modes of sulphur cycling within a single Proterozoic mineralised setting and imply that similar polymodal sulphur cycling might have occurred on other Proterozoic continental margins worldwide, with implications for mineralisation and global sulphur cycle systematics.
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    • NSTL
    • Elsevier

    Critical assessment of pressure estimates in volcanic plumbing systems: The case study of Popocatépetl volcano, Mexico

    Tommasini S.Bindi L.Savia L.Orlando A....
    15页
    查看更多>>摘要：? 2021 Elsevier B.V.Most geobarometers use chemical compositions of minerals and their host melt to estimate crystallization pressures. Crystal structural parameters such as cell and site volumes are not usually considered despite their known sensitivity to pressure. Here, we compare two clinopyroxene geobarometers based upon electron microprobe analysis alone and coupled with single-crystal X-ray diffraction data. The case study is the plumbing system of Popocatépetl volcano (Mexico), which consists of three distinct magma reservoirs in upper, middle and lower crustal depths, represented by three compositionally and texturally distinct clinopyroxene populations (T1, Mg# core <78, T2, Mg# core >82, and low-Ca with a lower wollastonite component). These clinopyroxenes are augites of limited compositional variability, although yielding a significant increase in cell (V cell) and M1 site (V M1) volumes from low-Ca and T2 core clinopyroxenes to T1 (core and rim) and T2 (rim) clinopyroxenes. This variation is not due to chemical or temperature effects but is linked to their depth of crystallization. The application of the geobarometer based on chemical composition alone is unable to distinguish the three different reservoirs postulated on volcanological and petrological grounds. In contrast, the application of the geobarometer based on both structural parameters and chemical composition yields a remarkable correlation between the calculated cell volume and the estimated depth of crystallization of the different clinopyroxenes, including core to rim differences. These results have twofold implications. First, the determination of the structural parameters of clinopyroxenes is the only method to resolve the actual distribution of Mg, Fe2+, Fe3+ in the M1 and M2 structural sites and, given the sensitivity of cell and site volumes to pressure, permits to improve geobarometric estimates in volcanic plumbing systems. Second, the quantitative determination of the crystallization depth of the different clinopyroxenes has permitted to rescale the depth of the three different reservoirs in the plumbing system of the Popocatépetl Volcanic Complex located from ~30 km b.s.l. (low-Ca clinopyroxene) to ~18 km b.s.l. (T2 clinopyroxene core) and ~10–0 km b.s.l. (T1 clinopyroxene core and rim, T2 clinopyroxene rim) within the crustal structure of the Morelos platform. This provides further support to the complex plumbing system of the Popocatépetl Volcanic Complex consisting of polybaric storage layers of variable interconnected and interacting transient magma reservoirs.
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    • NSTL
    • Elsevier

    Detrital zircon ages and provenance of a Cambrian succession in the Sierra Albarrana Domain (SW Iberian Massif)

    Solis-Alulima B.Abati J.Lopez-Carmona A.Fernandez-Suarez J....
    34页
    查看更多>>摘要：? 2021 Elsevier B.V.This study presents the first U-Pb geochronological data on detrital zircon grains from the metasedimentary successions of the Sierra Albarrana Domain (SW Iberian Massif) obtained by SHRIMP and LA-ICP-MS. We provide new information on the Maximum Depositional Ages (MDA) during the middle Cambrian through a systematic study, together with age comparisons of the successions, using Kernel Density Estimates (KDE) diagrams, Cumulative Age Distributions (CADs) and the Kolmogorov–Smirnov (K-S) test. On the other hand, the U-Pb zircon data presented in this study have been compared with all the existing data from detrital zircon grains in Neoproterozoic and Cambrian rocks of the Iberian Massif (20 samples, 2706 U–Pb zircon ages). For the comparison, in addition to the KDEs, CADs and K-S test, we apply 3D multidimensional scaling techniques (3D-MDS). The results, together with the geochemical and isotopic characterisation from previous studies, suggest that this domain is likely to be part of the autochthonous section of the Central Iberian Zone (CIZ). Zircon age patterns indicate a probable sedimentary provenance from the Saharan Metacraton with, or without, minor input from the Tuareg Shield. The most important local detrital source corresponds to Cadomian magmatism developed during a magmatic event (535–515 Ma) followed by back-arc extension and early Paleozoic rifting (535–460 Ma). The remaining Mesoproterozoic, Paleoproterozoic and Archean zircon grains would have been provided by the Paleoproterozoic basement and/or the older continental crust recycled in the western sections of the Gondwana margin.
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    • NSTL
    • Elsevier

    Geochronology, whole-rock geochemistry, Sr[sbnd]Nd isotopes, and biotite chemistry of the Deh-Bala intrusive rocks, Central Urumieh-Dokhtar Magmatic Arc (Iran): Implications for magmatic processes and copper mineralization

    Xiao Y.Sarjoughian F.Kazemi K.Modabberi S....
    23页
    查看更多>>摘要：? 2021 Elsevier B.V.The Urumieh-Dokhtar Magmatic Arc (UDMA) of Iran hosts a variety of volcano-plutonic rocks of different composition and age formed by subduction of Neo-Tethyan Ocean beneath Eurasian supercontinent and the subsequent processes of post-subduction magmatism. This study focuses on mineral chemistry of biotite and amphibole, zircon U[sbnd]Pb geochronology, whole-rock geochemistry, and Sr[sbnd]Nd isotopic geochemistry in the Deh-Bala granitoid, in an attempt to investigate the porphyry-epithermal mineralization potential. The Deh-Bala intrusions in the central part of the UDMA consist mainly of granodiorite and minor tonalite, with microgranular enclaves (MEs) of gabbrodiorite, diorite, and monzodiorite composition. In addition, the main ore minerals associated with more altered and mineralized varieties of these intrusions include chalcopyrite, covellite, malachite, and pyrite. The silicic, argillic, phyllic (sericitic), and propylitic facies of alteration occur in parts of the Deh-Bala area; these types of alteration, which are typically considered the most important predictors of porphyry copper?gold and (or) epithermal precious metal mineralization. LA-ICP-MS U[sbnd]Pb dating of zircons reveals that the pluton was emplaced during Middle-Eocene (ca. 39.0 Ma). The Deh-Bala granitoids (DBG) are calc-alkaline in composition (Na2O + K2O: 4.8–7.3 wt%) and display SiO2 contents from ～53 to ～67 wt%. They are enriched in light rare earth elements (LREEs) relative to heavy rare earth elements (HREEs), with marked Eu anomalies. They are also characterized by an enrichment in large-ion lithophile elements (LILEs, such as Rb, K, and U) and a depletion in high-field strength elements (HFSE, such Nb, Y, Ti, and Zr), displaying obviously depletions with Ba, P, and Sc. The DBG shows whole-rock initial 87Sr/86Sr ratios (ISr) of 0.7048–0.7061, εNd(t) values of ?1.79 to +1.64, and Nd two-stage depleted mantle model ages (TDM2) from 747 to 1004 Ma. These isotopic data, combined with the geochemical signatures, indicate that the DBG originated through mixing of mafic and felsic end-members, the former was derived from melting of the lithospheric mantle, and the latter derived from partial melting of Neoproterozoic crustal materials in a continental-arc. Biotite compositions analysed by electron microprobe are consistent with the Deh-Bala magmas being oxidized and chlorine-rich, similar to worldwide porphyry copper?gold systems formed in arc-related settings associated with convergent margin subduction zones. Such a chlorine-rich magmatic-hydrothermal system is known to be effective in scavenging copper and (or) gold from melt and its transfer to shallow levels.
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    • NSTL
    • Elsevier

    Trachyte-phonolite transition at Dunedin Volcano: Fingerprints of magma plumbing system maturity and mush evolution

    Pontesilli A.Mollo S.Nazzari M.Scarlato P....
    17页
    查看更多>>摘要：? 2021 Elsevier B.V.Phonolite-trachyte associations are a common feature of alkaline volcanoes in intraplate settings, and their coexistence challenges closed-system magmatic differentiation scenarios. Here we have investigated the mineralogical and petrochemical features of dikes, lavas, pyroclastic deposits, and comagmatic crystal-rich enclaves outcropping at Dunedin Volcano (Otago region, southern New Zealand). These alkaline magmatic products show both highly and mildly alkaline affinities, trending towards phonolitic and trachytic end-members, respectively. Intermediate rocks are phonotephrites + tephriphonolites (highly alkaline series) and mugearites + benmoreites (mildly alkaline series) with a phenocryst assemblage of clinopyroxene + plagioclase ± amphibole formed at low to mid-crustal levels (i.e., ~29–16 km). Phonolites are porphyritic rocks characterized by alkali feldspar ± amphibole ± clinopyroxene. Their whole-rock compositions are highly enriched in incompatible elements, with variable Ba + Sr contents. A weak negative to slightly positive Eu anomaly is also associated with 87Sr/86Sr ratios of 0.7028–0.7031, which are comparable to those of parental magmas. Geochemical models indicate that phonolites originate as interstitial melts that are generated via abundant alkali feldspar crystallization from a shallow crystalline mush (i.e., ~14–5 km). Strong melt differentiation and extraction is testified by crystal-rich enclaves, as remnants of the mush region. On the other hand, trachytes are phenocryst-poor products strongly depleted in Ba + Sr and with a marked negative Eu anomaly. Trachytes are characterized by 87Sr/86Sr ratios of 0.7040–0.7060, which are different from intermediate rocks and phonolites, and trend towards crustal isotopic compositions. Integrated mass balance, trace element, and energy-constrained modeling confirm that trachytes originate from mildly alkaline magmas interacting with the country rock during feldspar fractionation. We interpret the transition from trachyte to phonolite formation and eruption resulting from the maturation of the plumbing system through accumulation, cooling, and degassing of both highly and mildly alkaline magmas.
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    • NSTL
    • Elsevier

    Geochemistry of tourmaline of elbaite-dravite series from sapphire bearing pegmatites, proterozoic higher Himalayan Crystalline Complex Jammu and Kashmir, India: Implication for evolution of pegmatite melt

    Srivastava P.K.Singh P.
    21页
    查看更多>>摘要：? 2021 Elsevier B.V.Tourmaline of rare elbaite-dravite series has been reported for the first time from the sapphire bearing pegmatite from the Paddar area, Kishtwar District (Jammu and Kashmir), India. The sapphire-bearing pegmatites are hosted by ultramafic rocks of the Higher Himalayan Crystalline metamorphic complex. These pegmatites are dominantly composed of sodic-plagioclase, perthite, tourmaline, and sapphire, whereas microcline, biotite, and muscovite make up the minor phases. The tourmaline from these pegmatites contains high Mg, Ca, Na, and F content as well as low K, Fe, and Cr content. They are classified as alkali tourmaline, characterized by higher Mg/Mg + Fe and Na/Na + Ca ratios. They display complex substitution mechanisms during the crystallization (Li + Al?Mg, Fe?Mg, Na?Ca, B + Al?Si) and post crystallization alteration by the hydrothermal fluids. The geochemistry of tourmaline suggests that the tourmaline is crystallized from peraluminous, silicious pegmatitic melt (enriched in Al, Li, B, and H2O). This melt was most likely formed through partial melting of the metasediments of Higher Himalaya Crystalline during the M2 phase of regional metamorphism. The pegmatitic melt was injected in the ultramafics, resulting in bimtasomatism reaction evidenced by the development of systematic alteration zones next to the contact. Bimetasomatism results in the diffusion of the Ca and Mg from host rock to pegmatitic melt, and removal of silica from the pegmatitic melt, which leads to the increase of Al in pegmatitic melt. Finally, a saturation of the Al in the melt with a high Mg influx from host rock results in the favourable environment for crystallization of Mg-rich tourmaline and sapphire.
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    • NSTL
    • Elsevier

    Magmatic and hydrothermal evolution of mafic pegmatites and their host basalts, Paraná Large Igneous Province, Brazil

    Gomes A.S.Vasconcelos P.M.Ubide T.Vasconcellos E.M.G....
    22页
    查看更多>>摘要：? 2021 Elsevier B.V.The high-Ti Paranapanema sequence in the Paraná Large Igneous Province consists of a succession of pahoehoe lava flows. Some of these flows host mafic segregation structures, such as horizontal pegmatitic sheet layers and vesicular cylinders. Geochronology, whole-rock and mineral chemistry of two pegmatite occurrences and their host basalts permit characterizing crystal-melt segregation processes that occur during magmatic differentiation after lava flow emplacement. The mineralogy of the pegmatites is similar to that of the host basalts, and it includes plagioclase, pyroxene and titanomagnetite-ilmenite crystals; the only observable difference is the coarser grain size of primary phases and an increase in the volume fraction of clay minerals derived from glass devitrification and vesicle infilling in the pegmatites (~15 vol% clay in the pegmatites vs. ~6 vol% clay in the basalts). The pegmatites from both sites are more fractionated than the enclosing lavas and are enriched in TiO2, FeOtotal, K2O, P2O5 and incompatible trace elements (e.g., Ba, Rb, Nb, Hf, Y, Zr, La, Ce, Yb). Thermodynamic modeling of whole-rock compositional data suggests that the Barrac?o pegmatites were formed after ~8–27 wt% fractional crystallization of the host basalt, whereas the Capanema pegmatites formed after ~38–43 wt% fractional crystallization of the host basalt. 40Ar/39Ar geochronology indicates slight yet significant age differences between plagioclase phenocrysts from the pegmatites and whole-rock fragments from the enclosing lavas (Capanema: 133.56 ± 0.52 pegmatite vs. 134.30 ± 0.46 Ma enclosing lava; Barrac?o: 133.23 ± 0.88 pegmatite vs. 134.49 ± 0.31 Ma enclosing lava). These age differences likely result from hydrothermal alteration of the plagioclase phenocrysts (e.g., secondary albite and K-feldspar), and they are not due to resolvable differences in crystallization age. Smectite-celadonite aggregates recovered from the Capanema basalt suggest that hydrothermalism occurred at 123.18 ± 0.61 Ma, approximately ten million years after rock crystallization.
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    • NSTL
    • Elsevier

    Boron release and transfer induced by phengite breakdown in subducted impure metacarbonates

    Guo S.Su B.Tang P.Chen Y....
    21页
    查看更多>>摘要：? 2021 Elsevier B.V.White mica is an important reservoir of boron (B) in subducted metasedimentary rocks. To quantify the effect of phengite breakdown on B release and transfer, we investigated the replacement processes of phengitic mica and associated element redistribution in exhumed ultra-high pressure (UHP) impure marbles from the Dabie terrane, China. Three types of microstructures, which are related to the liberation, transport, and precipitation of B, are recognized: (1) Type-I is the pseudomorphic replacement of phengite by the assemblage of biotite + plagioclase ± quartz ± epidote. The assemblage maintains a flaky shape of pre-existing phengite, which only rarely occurs as a relict phase in the product assemblages. Phase equilibria modelling indicates that the conditions of replacement reactions are 1.2–1.3 GPa at ~600 °C, with a relatively low XCO2 of 0.04–0.16. (2) Type-II is characterized by the local occurrence of fine-grained tourmaline (Tur-F) along the outer margin of Type-I texture domains, which represents the in situ precipitation of B released by the replacement reactions. (3) Type-III texture involves the irregularly shaped intergrowth of tourmaline (Tur-In) + quartz in the calcite matrix, isolated from the Type-I and Type-II texture domains. The Type-III minerals are in equilibrium with diopside and plagioclase and most likely represent the precipitation from a “transported”, B-bearing fluid. Mineral trace element analyses indicate that relict phengite in Type-I texture has significantly higher B contents (284–464 μg/g) than all of the product minerals (2–26 μg/g). A mass balance estimate indicates that the majority (>90%) of B in the reactants is lost during the process of phengite replacement. The calculations in terms of mineral-fluid partition indicate that the fluid involved in the replacement reactions has B contents of 1893–6858 μg/g. In situ B isotopic analyses indicate that Tur-F and Tur-In have a similar variation range of δ11B (+4 ~ +7‰). Both types of low-pressure tourmaline have lower δ11B values than the previously reported eclogite-facies tourmaline (reaching +15‰) from phengite-bearing marbles in the same study area. This result indicates two episodes of tourmaline growth and B transfer. Thus, a two-stage model of B loss from phengite during slab exhumation is proposed. Our results reveal that the breakdown of white mica in exhumed metasedimentary rocks can cause a strong release of B, which would largely influence the B budget at convergent plate margins.
      原文链接:
    • NSTL
    • Elsevier