Evidence of Permian magmatism in the Alpi Apuane metamorphic complex (Northern Apennines, Italy): New hints for the geological evolution of the basement of the Adria plate

Permian Hydrothermal Alteration Preserved in Polymetamorphic Basement and Constraints for Ore-genesis (Alpi Apuane, Italy)

“…The Massa Unit consists of a Paleozoic metasedimentary and metavolcanics basement and an upper Permian-Upper Triassic metasilicoclastic succession (Figure 1; e.g., [16,17]). The Apuane Unit includes a litho-stratigraphic sequence made up of a Paleozoic basement (e.g., [18]) intruded by post-Variscan magmatic rocks (Fornovolasco Metarhyolite Fm; [19][20][21]), unconformably overlain by an Upper Triassic-Oligocene metasedimentary succession (Figures 1 and 2; e.g., [16]).…”

“…The Fornovolasco Metarhyolite Fm is formed by fine-grained massive subvolcanic rocks with a granular to porphyritic texture, locally showing the widespread occurrence of cm-sized tourmaline + quartz orbicules [19,20]. On the basis of LA-ICP-MS U-Pb zircon dating, Vezzoni et al [20] dated this formation to Permian (c.a. 270 Ma).…”

“…The pyrite, baryte, and Fe-oxides ores are an example of metamorphosed orebodies (following the definition reported in e.g., [8,39]) in which the primary mineralogy and texture were modified by the Alpine metamorphism and associated polyphasic deformation (e.g., [40] and references therein). Previous authors debated the origin and age of the ores (e.g., [41] and references therein), and recently, a magmatic-hydrothermal origin, likely Permian age, was suggested [20] on the basis of the following observations: i.…”

“…the discovery of tourmaline-bearing Permian felsic shallow-intrusive rocks (Fornovolasco Metarhyolite Fm) [19,20] spatially associated with the orebodies; ii.…”

Disproving the Presence of Paleozoic‐Triassic Metamorphic Rocks on the Island of Zannone (Central Italy): Implications for the Early Stages of the Tyrrhenian‐Apennines Tectonic Evolution

“…The early orogenic history of the Apennine fold‐and‐thrust belt in Italy is poorly known as the innermost (westernmost) portion of the chain was dismantled, downfaulted, and overprinted by the opening of the Tyrrhenian back‐arc basin, which developed since Middle Miocene time at the rear of the eastward migrating compressional front of the orogenic wedge (e.g., Carmignani et al, 2004; Carminati et al, 2010; Faccenna et al, 1997; Malinverno & Ryan, 1986). The rare and scattered metamorphic rocks along the western inner margin of the belt have provided essential information to unravel part of the early stages of the Apennine tectonic building (e.g., Faccenna et al, 2001; Jolivet et al, 1998, 2003; Papeschi et al, 2020; Rossetti et al, 1999; Vezzoni et al, 2018; Vignaroli et al, 2009). The metamorphic complexes of the Apennine belt consist of three main lithotectonic systems: (i) European‐derived continental units (e.g., Beaudoin et al, 2017; Di Rosa et al, 2020; Di Vincenzo et al, 2016; Jolivet et al, 2003; Molli & Malavieille, 2011; Rossetti et al, 2015; Vitale Brovarone et al, 2013; Figure 1); (ii) ocean‐derived (Tethys) units (e.g., Carmignani et al, 1994; Rossetti, Faccenna, Goffé, et al, 2001; Rossetti et al, 2004; Vai, 2001; Vignaroli et al, 2009; Vitale Brovarone et al, 2013; Figure 1), and (iii) Adria‐derived continental units (e.g., Jolivet et al, 1998; Molli et al, 2018; Rossetti et al, 1999).…”