Magmatism and Geodynamics in the Tyrrhenian Sea Region
The Tyrrhenian Sea region is the site of widespread Cenozoic igneous activity that shows extreme compositional variations in space and time, highlighting complex evolution history for magmas and their sources. Based on ages and volcanological-petrological
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Abstract
The Tyrrhenian Sea region is the site of widespread Cenozoic igneous activity that shows extreme compositional variations in space and time, highlighting complex evolution history for magmas and their sources. Based on ages and volcanological-petrological-geochemical characteristics of mafic rocks, several magmatic provinces are distinguished, which are related to compositionally distinct sectors of the upper mantle beneath the Tyrrhenian Sea region. Rocks with MORB- and OIB-type geochemical signatures (i.e. low LILE/HFSE ratios, and EM1, FOZO, DMM isotopic compositions) originated from mantle rocks that were not affected by young subduction events. FOZO- and DMM-type magmas are best represented by the Sicily volcanics and may derive from an ascending plume head or from a metasomatised lithosphere-asthenosphere permeated by deep asthenospheric fluids. EM1-type rocks crop out in Sardinia and are unique in Europe. They could derive either from a mantle plume or from an ancient metasomatised lithosphere. The petrogenesis of arc-type magmas is related to contamination of various mantle rocks (MORB to OIB-type) by subducted upper crustal components. Four main types of subduction-related mantle metasomatic events are recognised in the Tyrrhenian Sea area, with a role of upper crustal components (sediments) increasing from Sardinia and the southern Tyrrhenian Sea to Central Italy. Metasomatism beneath Tuscany was Alpine in age, whereas mantle contamination beneath the Roman Province was provided by Miocene-Quaternary subduction of the Adriatic continental plate beneath the Northern Apennines. In contrast, subduction of the Ionian oceanic plate plus some sediments generated metasomatism and magmatism in Campania and the central-southern Tyrrhenian Sea.
© Springer International Publishing AG 2017 A. Peccerillo, Cenozoic Volcanism in the Tyrrhenian Sea Region, Advances in Volcanology, DOI 10.1007/978-3-319-42491-0_13
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Keywords
Magmatism and Geodynamics in the Tyrrhenian Sea Region
Tyrrhenian Sea Magmatism Geodynamics MORB OIB Arc-type magmas Mantle metasomatism Subduction Sediment subduction Adriatic plate Ionian plate
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Introduction
The magmatic provinces discussed in the previous chapters exhibit exceedingly large compositional variations that almost entirely cover the range of magmatic rocks occurring worldwide. Except for a few crustal anatectic rocks, mostly occurring in Tuscany, the bulk of magmatism is of ultimate mantle origin. Many of the observed compositional characteristics are related to magma evolution processes, which, however, are unable to explain the first-order geochemical and petrological variations, especially for mafic rocks. It has been, therefore, unanimously concluded that the wide variety of magmas occurring in the Tyrrhenian Sea region reveals extremely heterogeneous mantle sources. These are the result of a long and complex evolution history suffered by the Tyrrhenian Sea and Western Mediterranean, from Paleozoic until the present day. In thi
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