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Crust-mantle interaction during syn-collisional magmatism – Evidence from the Oamikaub diorite and Neikhoes metagabbro (Damara orogen, Namibia)

Identifikátory výsledku

  • Kód výsledku v IS VaVaI

    <a href="https://www.isvavai.cz/riv?ss=detail&h=RIV%2F26722445%3A90120%2F20%3AN0000105" target="_blank" >RIV/26722445:90120/20:N0000105 - isvavai.cz</a>

  • Výsledek na webu

    <a href="https://www.sciencedirect.com/science/article/abs/pii/S0301926820305441" target="_blank" >https://www.sciencedirect.com/science/article/abs/pii/S0301926820305441</a>

  • DOI - Digital Object Identifier

    <a href="http://dx.doi.org/10.1016/j.precamres.2020.105955" target="_blank" >10.1016/j.precamres.2020.105955</a>

Alternativní jazyky

  • Jazyk výsledku

    angličtina

  • Název v původním jazyce

    Crust-mantle interaction during syn-collisional magmatism – Evidence from the Oamikaub diorite and Neikhoes metagabbro (Damara orogen, Namibia)

  • Popis výsledku v původním jazyce

    The early-syntectonic 563.7 +/- 6.1 Ma old Oamikaub diorite (Damara orogen, Namibia) consists of metaluminous, magnesian, calc-alkalic to calcic diorites, granodiorites and granites. Associated gabbro-diorites and gabbros belong to the Neikhoes metagabbro. Linear major and trace element variations imply that the rock suite evolved through fractional crystallization processes involving amphibole, biotite, Fe-Ti oxides, zircon and apatite. Initial Sr (Sr-87/Sr-86: 0.7058-0.7123) and Nd (epsilon Nd: -2.1 to -18.8) isotopic compositions are highly variable and negatively correlated indicating that assimilation of crustal components occurred. Unradiogenic initial (206)pb/(204)pb (16.23-17.23) and Pb-207/Pb-204 ratios (15.50-15.57) suggest derivation from or interaction with ancient crust with low U/Pb. Two gabbro-diorites have MgO, Ni and Cr abundances that are compatible with derivation of these rocks from upper mantle lithologies. Their initial epsilon Nd values (-2.1 and - 7.4) and Sr-87/Sr-86 ratios (0.7058 and 0.7076) imply derivation from an aged metasomatized lithospheric mantle. Other mafic samples have MgO abundances and compatible element concentrations that exceed the values commonly accepted for primary mafic melts implying some accumulation of clinopyroxene and amphibole. The granodiorites form a homogenous group in which the isotope data (initial epsilon Nd: -12.4 to -14.1; initial Sr-87/Sr-86: 0.7083-0.7096) imply a lower crustal source. The granites are also magnesian and calc-alkaline but two of them are strongly peraluminous. Their isotope data (initial epsilon Nd: -13.2 to -18.8; initial Sr-87/ Sr-86: 0.7099 to 0.7123) imply derivation from more ancient sources, alternatively these samples gained their isotope systematics through extensive AFC processes from parental granodiorites. A common subduction zone environment as suggested from negative Nb-Ta anomalies in multi-element diagrams seems unlikely for all samples because of a lack of isotopically depleted signatures. The data from the Oamikaub diorite and other mafic complexes are better explained by a "flat" subduction model involving mainly continental mantle lithosphere and crust with limited, if any, melting of asthenospheric mantle.

  • Název v anglickém jazyce

    Crust-mantle interaction during syn-collisional magmatism – Evidence from the Oamikaub diorite and Neikhoes metagabbro (Damara orogen, Namibia)

  • Popis výsledku anglicky

    The early-syntectonic 563.7 +/- 6.1 Ma old Oamikaub diorite (Damara orogen, Namibia) consists of metaluminous, magnesian, calc-alkalic to calcic diorites, granodiorites and granites. Associated gabbro-diorites and gabbros belong to the Neikhoes metagabbro. Linear major and trace element variations imply that the rock suite evolved through fractional crystallization processes involving amphibole, biotite, Fe-Ti oxides, zircon and apatite. Initial Sr (Sr-87/Sr-86: 0.7058-0.7123) and Nd (epsilon Nd: -2.1 to -18.8) isotopic compositions are highly variable and negatively correlated indicating that assimilation of crustal components occurred. Unradiogenic initial (206)pb/(204)pb (16.23-17.23) and Pb-207/Pb-204 ratios (15.50-15.57) suggest derivation from or interaction with ancient crust with low U/Pb. Two gabbro-diorites have MgO, Ni and Cr abundances that are compatible with derivation of these rocks from upper mantle lithologies. Their initial epsilon Nd values (-2.1 and - 7.4) and Sr-87/Sr-86 ratios (0.7058 and 0.7076) imply derivation from an aged metasomatized lithospheric mantle. Other mafic samples have MgO abundances and compatible element concentrations that exceed the values commonly accepted for primary mafic melts implying some accumulation of clinopyroxene and amphibole. The granodiorites form a homogenous group in which the isotope data (initial epsilon Nd: -12.4 to -14.1; initial Sr-87/Sr-86: 0.7083-0.7096) imply a lower crustal source. The granites are also magnesian and calc-alkaline but two of them are strongly peraluminous. Their isotope data (initial epsilon Nd: -13.2 to -18.8; initial Sr-87/ Sr-86: 0.7099 to 0.7123) imply derivation from more ancient sources, alternatively these samples gained their isotope systematics through extensive AFC processes from parental granodiorites. A common subduction zone environment as suggested from negative Nb-Ta anomalies in multi-element diagrams seems unlikely for all samples because of a lack of isotopically depleted signatures. The data from the Oamikaub diorite and other mafic complexes are better explained by a "flat" subduction model involving mainly continental mantle lithosphere and crust with limited, if any, melting of asthenospheric mantle.

Klasifikace

  • Druh

    J<sub>imp</sub> - Článek v periodiku v databázi Web of Science

  • CEP obor

  • OECD FORD obor

    10505 - Geology

Návaznosti výsledku

  • Projekt

  • Návaznosti

Ostatní

  • Rok uplatnění

    2020

  • Kód důvěrnosti údajů

    S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů

Údaje specifické pro druh výsledku

  • Název periodika

    Precambrian research

  • ISSN

    0301-9268

  • e-ISSN

    1872-7433

  • Svazek periodika

    351

  • Číslo periodika v rámci svazku

    December

  • Stát vydavatele periodika

    NL - Nizozemsko

  • Počet stran výsledku

    22

  • Strana od-do

    1-22

  • Kód UT WoS článku

    000595149400011

  • EID výsledku v databázi Scopus

    2-s2.0-85094608801