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Article

Tectono-Metamorphic Evolution of Serpentinites from Lanzo Valleys Subduction Complex (Piemonte—Sesia-Lanzo Zone Boundary, Western Italian Alps)

1
Dipartimento di Scienze della Terra “A. Desio", Universitá degli Studi di Milano, 20133 Milano, Italy
2
Dipartimento di Scienze della Terra e dell’Ambiente, Universitá degli Studi di Pavia, 27100 Pavia, Italy
*
Author to whom correspondence should be addressed.
Minerals 2020, 10(11), 985; https://doi.org/10.3390/min10110985
Received: 23 September 2020 / Revised: 14 October 2020 / Accepted: 2 November 2020 / Published: 5 November 2020
(This article belongs to the Special Issue Orogenic Metamorphism of Oceanic Lithosphere)
In the upper Tesso Valley the folded contact between Piemonte Zone ophiolites and Sesia-Lanzo Zone continental crust is exposed. Here serpentinites, metabasites, calcschists and fine-grained gneisses are deformed by four ductile superposed groups of structures, associated with different mineral assemblages. Different serpentinite lithologies have been recognized and studied in detail. Mylonitic D2 structures are pervasive and mineral assemblages point to re-equilibration at T of 450 ± 50 C and P of 0.8 ± 0.3 GPa, under blueschist/epidote amphibolite-facies conditions. Pre-D2 structures and mineral assemblages are relics within S2 and indicate a re-equilibration under eclogite-facies conditions, at T of 570 ± 50 C and P > 1.8 GPa. Post-D2 occurs under greenschist-facies conditions. Numerical modeling of a subduction zone allows exploration of the geodynamic context in which such PT path could have developed, and to make hypotheses about the possible timing of such a scenario, in agreement with the timing generally proposed for the Alpine subduction and collision. Model predictions indicate that pre-D2 mineral assemblages may have developed during Paleocene at 60–90 km depth and 115–145 km from the trench, or, alternatively, during lower Eocene at ca. 70–90 km depth, and 135–160 km from the trench. View Full-Text
Keywords: eclogitized serpentinites; Ti-clinohumite; Alpine subduction; multi-scale structural analysis eclogitized serpentinites; Ti-clinohumite; Alpine subduction; multi-scale structural analysis
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MDPI and ACS Style

Assanelli, M.; Luoni, P.; Rebay, G.; Roda, M.; Spalla, M.I. Tectono-Metamorphic Evolution of Serpentinites from Lanzo Valleys Subduction Complex (Piemonte—Sesia-Lanzo Zone Boundary, Western Italian Alps). Minerals 2020, 10, 985. https://doi.org/10.3390/min10110985

AMA Style

Assanelli M, Luoni P, Rebay G, Roda M, Spalla MI. Tectono-Metamorphic Evolution of Serpentinites from Lanzo Valleys Subduction Complex (Piemonte—Sesia-Lanzo Zone Boundary, Western Italian Alps). Minerals. 2020; 10(11):985. https://doi.org/10.3390/min10110985

Chicago/Turabian Style

Assanelli, Matteo, Pietro Luoni, Gisella Rebay, Manuel Roda, and Maria Iole Spalla. 2020. "Tectono-Metamorphic Evolution of Serpentinites from Lanzo Valleys Subduction Complex (Piemonte—Sesia-Lanzo Zone Boundary, Western Italian Alps)" Minerals 10, no. 11: 985. https://doi.org/10.3390/min10110985

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