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Journal Articles Terra Nova Year : 2019

Geochemical characteristics of basalts related to incipient oceanization: The example from the Alpine‐Tethys OCTs

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Abstract

Basalts exposed in the Platta and Tasna nappes (SE Switzerland) derive from the Alpine-Tethys Ocean-Continent Transitions (OCT) and overlie SubContinental Lithospheric Mantle (SCLM). We show that the trace element signatures of these basalts differ from Mid-Ocean Ridge Basalts (MORB). Two types of basalts occur in the OCT: a type-1 showing a "garnet signature" that can be modeled by the partial melting of the SCLM in the spinel stability field and a type-2 characterized by an enrichment in incompatible elements that can be explained by the mixing between garnet-pyroxenite-derived melts and the melting of either a depleted MORB mantle or a refertilized SCLM. Based on geological and geochemical observations we propose that the basalts from the Alpine-Tethys OCTs result from a poly-phase magmatic system that carry an inherited SCLM signature. These basalts should therefore be referred to as OCT-basalts rather than as MOR-basalts.
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insu-02456734 , version 1 (30-11-2020)

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Méderic Amann, Marc Ulrich, Gianreto Manatschal, Eric Pelt, Marie‐eva Epin, et al.. Geochemical characteristics of basalts related to incipient oceanization: The example from the Alpine‐Tethys OCTs. Terra Nova, 2019, 32 (1), pp.75-88. ⟨10.1111/ter.12438⟩. ⟨insu-02456734⟩
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