The Edolo diabase dykes intruded the Variscan basement in the central Southalpine domain. Biotite 40Ar / 39Ar 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.

High-Nb alkaline mafic dykes in the central Alps witness to the Triassic evolution of the Adria passive margin / M. Filippi, D. Zanoni, M. Tiepolo, M. Corsini, G. Rebay, J.M. Lardeaux, M.I. Spalla. - In: LITHOS. - ISSN 0024-4937. - 464-465:(2024 Jan), pp. 107435.1-107435.14. [10.1016/j.lithos.2023.107435]

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

M. Filippi
Primo
;
D. Zanoni
Secondo
;
M. Tiepolo;M.I. Spalla
Ultimo
2024

Abstract

The Edolo diabase dykes intruded the Variscan basement in the central Southalpine domain. Biotite 40Ar / 39Ar 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.
Biotite 40Ar / 39Ar dating; Lithospheric thinning; Pangea break-up; Southalpine domain; Syn-rift magmatism
Settore GEO/03 - Geologia Strutturale
Settore GEO/07 - Petrologia e Petrografia
Settore GEO/08 - Geochimica e Vulcanologia
Settore GEOS-02/C - Geologia strutturale e tettonica
Settore GEOS-01/B - Petrologia
Settore GEOS-01/C - Geochimica e vulcanologia
   Assegnazione Dipartimenti di Eccellenza 2023-2027 - Dipartimento di SCIENZE DELLA TERRA "ARDITO DESIO"
   DECC23_020
   MINISTERO DELL'UNIVERSITA' E DELLA RICERCA
gen-2024
23-nov-2023
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/1097448
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