Kimberlite-like metasomatism and "garnet signature" in spinel-peridotite xenoliths from Sal, Cape Verde Archipelago; relics of a subcontinental mantle domain within the Atlantic oceanic lithosphere?

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doi: 10.1093/petrology/egi061
Authors:Bonadiman, C.; Beccaluva, L.; Coltorti, M.; Siena, F.
Author Affiliations:Primary:
University of Ferrara, Earth Science Department, Ferrara, Italy
Volume Title:Journal of Petrology
Source:Journal of Petrology, 46(12), p.2465-2493. Publisher: Oxford University Press, Oxford, United Kingdom. ISSN: 0022-3530
Publication Date:2005
Note:In English. 102 refs.; illus., incl. 6 tables, sketch map
Summary:Major, trace and REE analyses of rocks, olivines, clinopyroxenes, orthopyroxenes, spinels, K-feldspars and glasses from a Late Tertiary mantle xenolith suite of spinel lherzolites and harzburgites with secondary metasomatism are listed. The lherzolites have suffered low-degree (∼4%) partial melting of a primitive mantle-like garnet lherzolite followed by partial re-equilibration of the melt residue from the garnet to the spinel stability field, in agreement with the PT estimates (975 to 1210°C; 1.3 to 2.1 GPa) which cluster around the spinel-garnet boundary in the peridotite system. The harzburgites could be residues after MORB extraction melting processes. All the peridotites suffered secondary metasomatism giving new ortho- and clino-pyroxenes and high K2O glasses (up to 8.78 wt%) with K-feldspar, due to infiltration of a kimberlite-like metasomatizing agent derived from subcontinental mantle lithospheric relicts left behind by the drifting of the African Plate during the opening of the Atlantic Ocean. [B.E.L.]
Subsections:Igneous petrology
Subjects:Chemical ratios; Garnet peridotite; Geochemistry; Igneous rocks; Inclusions; Kimberlite; Lithogeochemistry; Lithosphere; Mantle; Mantle plumes; Oceanic lithosphere; Peridotites; Plutonic rocks; Spinel peridotite; Ultramafics; Xenoliths; Africa; Atlantic Ocean; Atlantic Ocean Islands; Cape Verde Islands; Sal Island
Coordinates:N150000 N170000 W0240000 W0260000
Abstract Numbers:05M/4185
Record ID:2006036348
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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