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Unravelling the Crustal Architecture of Cape Verde from the Seamount Xenolith Record.
Barker, Abigail K., Hansteen, Thor and Nilsson, David (2019) Unravelling the Crustal Architecture of Cape Verde from the Seamount Xenolith Record. Minerals, 9 (2, Article 90). DOI 10.3390/min9020090.
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Abstract
The Cape Verde oceanic plateau hosts 10 islands and 11 seamounts and provides an extensive suite of alkaline lavas and pyroclastic rocks. The volcanic rocks host a range of crustal and mantle xenoliths. These xenoliths provide a spectrum of lithologies available to interact with magma during transport through the lithospheric mantle and crust. We explore the origin and depth of formation of crustal xenoliths to develop a framework of magma-crust interaction and a model for the crustal architecture beneath the Cape Verde oceanic plateau. The host lavas are phononephelinites to phonolites and the crustal xenoliths are mostly mafic plutonic assemblages with one sedimentary xenolith. REE profiles of clinopyroxene in the host lavas are light rare-earth element (LREE) enriched whereas clinopyoxene from the plutonic xenoliths are LREE depleted. Modelling of REE melt compositions indicates the plutonic xenoliths are derived from mid-ocean ridge basalt (MORB)-type ocean crust. Thermobarometry indicates that clinopyroxene in the host lavas formed at depths of 17 to 46 km, whereas those in the xenoliths formed at 5 to 20 km. This places the depth of origin of the plutonic xenoliths in the oceanic crust. Therefore, the xenoliths trace magma-crust interaction to the MORB oceanic crust and overlying sediments located beneath the Cape Verde oceanic plateau.
Document Type: | Article |
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Keywords: | alkaline volcanics; crustal xenoliths; thermobarometry; magma-crust interaction; Cape Verde |
Research affiliation: | OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS |
Refereed: | Yes |
Open Access Journal?: | Yes |
Publisher: | MDPI |
Expeditions/Models/Experiments: | |
Date Deposited: | 05 Feb 2019 11:16 |
Last Modified: | 31 Jan 2022 09:18 |
URI: | https://oceanrep.geomar.de/id/eprint/45275 |
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