The Corno Alto complex (Adamello batholith): A modern analogue of the high Ba/K sanukitoids
Articolo
Data di Pubblicazione:
2024
Citazione:
The Corno Alto complex (Adamello batholith): A modern analogue of the high Ba/K sanukitoids / A. Mosconi, E. Cannaò, F. Farina, M.G. Malusà, S. Zanchetta, M. Tiepolo. - In: LITHOS. - ISSN 0024-4937. - 470-471:(2024), pp. 107522.1-107522.18. [Epub ahead of print] [10.1016/j.lithos.2024.107522]
Abstract:
The Corno Alto complex represents the onset of the intrusive igneous activity during the Alpine Orogen and for
this reason has particular importance in the interpretation of the geodynamic evolution of the Alps. Whole-rock
chemistry of the granitoid rocks of the Corno Alto complex reveals peculiar features with respect to the other
units of the Adamello batholith, and to typical I-type and S-type granitoids. In particular, the Corno Alto rocks are
enriched in Ba, Sr and La/Yb at any given SiO2 content. U–Pb geochronology on zircon suggests an incremental
assembly of the Corno Alto complex by multiple and possibly discrete magma injections in a time span of about 5
Myr starting from 44 Ma. The different zircon domains have significantly distinct Hf isotopic signature (up to 18
εHf units of variation) with some values trending towards the isotopic composition of the depleted mantle (DM).
Bulk major and trace element geochemistry together with in-situ Hf isotope composition of zircon allow to
distinguish at least two geochemically components in the Corno Alto rocks: i) a high Ba component characterized
by high Sr and La/Yb ratios, likely derived from melting of carbonate sediments of slab origin; ii) a juvenile
component with Hf isotopic signature close to the DM and capable to crystallize plagioclase with An90, which is
interpreted as the primitive mantle signal. This work constrains for the first time the occurrence of a slab derived
carbonate input in the mantle-derived melts during the onset of the Alpine magmatism (dated at 44 Ma). The
anomalously high thermal conditions required to induced carbonate melting may reflect the rise of astheno-
spheric material near the torn edge of the European slab where the Corno alto is located. Remarkably, these high
thermal conditions parallel those at the Archean-Proterozoic transition and the Corno Alto complex could thus
represent a kind of modern analogues of the high Ba/K sanukitoids.
Tipologia IRIS:
01 - Articolo su periodico
Keywords:
Corno Alto; Alpine orogen; Adamello batholith; High Ba–Sr granitoids
Elenco autori:
A. Mosconi, E. Cannaò, F. Farina, M.G. Malusà, S. Zanchetta, M. Tiepolo
Link alla scheda completa: