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