Crust-mantle interaction during syn-collisional magmatism – Evidence from the Oamikaub diorite and Neikhoes metagabbro (Damara orogen, Namibia)
The result's identifiers
Result code in 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>
Result on the web
<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>
Alternative languages
Result language
angličtina
Original language name
Crust-mantle interaction during syn-collisional magmatism – Evidence from the Oamikaub diorite and Neikhoes metagabbro (Damara orogen, Namibia)
Original language description
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.
Czech name
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Czech description
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Classification
Type
J<sub>imp</sub> - Article in a specialist periodical, which is included in the Web of Science database
CEP classification
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OECD FORD branch
10505 - Geology
Result continuities
Project
—
Continuities
—
Others
Publication year
2020
Confidentiality
S - Úplné a pravdivé údaje o projektu nepodléhají ochraně podle zvláštních právních předpisů
Data specific for result type
Name of the periodical
Precambrian research
ISSN
0301-9268
e-ISSN
1872-7433
Volume of the periodical
351
Issue of the periodical within the volume
December
Country of publishing house
NL - THE KINGDOM OF THE NETHERLANDS
Number of pages
22
Pages from-to
1-22
UT code for WoS article
000595149400011
EID of the result in the Scopus database
2-s2.0-85094608801