High-Nb alkaline mafic dykes in the central Alps witness to the Triassic evolution of the Adria passive margin - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Lithos Année : 2023

High-Nb alkaline mafic dykes in the central Alps witness to the Triassic evolution of the Adria passive margin

Résumé

The Edolo diabase dykes intruded the Variscan basement in the central Southalpine domain. Biotite 40 Ar / 39 Ar dating shows that the emplacement occurred during the final stage of Permian-Triassic lithospheric thinning. In this phase on the Adria passive margin, middle Triassic magmatism with disputed arc affinity is followed by a late Triassic alkaline event associated with continental rifting. The Edolo diabase dykes are Ti-rich and alkaline, with high Nb and Ta contents and ratios in igneous amphibole, biotite, and ilmenite. These features are typical of the late Triassic magmatism. In contrast, the early-crystallized clinopyroxene shows low Nb and Ta contents and ratios and an apparent arc affinity may be thus envisaged in the clinopyroxene parental melt. However, given the coexistence of both features in the same dykes, their composition cannot be interpreted in terms of transition between tectonic environments. Instead, it is likely attributed to the heterogeneity of the Adriatic lithosphere inherited from the Variscan to Permian evolution, which underwent asthenospheric upwelling due to Permian-Triassic extensional tectonics.
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hal-04368725 , version 1 (01-01-2024)

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Marco Filippi, Davide Zanoni, Massimo Tiepolo, Michel Corsini, Gisella Rebay, et al.. High-Nb alkaline mafic dykes in the central Alps witness to the Triassic evolution of the Adria passive margin. Lithos, 2023, 464-465, ⟨10.1016/j.lithos.2023.107435⟩. ⟨hal-04368725⟩
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