The geodynamic evolution of the Southern European Variscides: constraints from the U/Pb geochronology and geochemistry of the lower Palaeozoic magmatic-sedimentary sequences of Sardinia (Italy)

Deformation during exhumation of medium‐ and high‐grade metamorphic rocks in the Variscan chain in northern Sardinia (Italy)

“…The increase in the thickness and size of S2-parallel pegmatitic veins (related to partial melting) traced eastwards on the high-grade metamorphic rocks on the east side of phyllonitic belt is in agreement with a gradual transition from the MGMC to the HGMC in the northern sector of the study area (Figure 2). In addition, it is worth noting that recent petrographical, geochronological and geochemical studies Helbing and Tiepolo 2004;Giacomini et al 2005Giacomini et al , 2006 seriously question the presence of two different continental margins and, by extension, the presence of an oceanic palaeosuture in the eastern transect of the PAL (Baronie region).…”

“…Carosi and Palmeri (2002), Carosi and Oggiano (2002), Carosi et al (2005) and Iacopini et al (2008) documented the presence of a wide dextral transpressional belt (the Posada-Asinara Line, PAL: Cappelli et al 1992) active around 315-320 Ma (Di . Moreover, we document in the strongly foliated boudins of metabasite have been documented, which generally preserved a complex metamorphic evolution from eclogitic, granulitic, amphibolitic to greenschist facies (Ricci and Sabatini 1978;Ghezzo et al 1979;Cappelli et al 1992;Oggiano and Di Pisa 1992;Franceschelli et al 1982Franceschelli et al , 2005 with references therein; Cortesogno et al 2004;Palmeri et al 2004;Giacomini et al 2005Giacomini et al , 2006.…”

“…Recent structural, geochronological (Helbing and Tiepolo 2003;Frassi 2006;Giacomini et al 2005Giacomini et al , 2006) and geochemical (Giacomini et al 2005(Giacomini et al , 2006) data throw new doubts on the presence of an oceanic suture in Sardinia. In addition, Giacomini et al (2006) have suggested a possible ensialic evolution between the Hun terrane and the northern margin of Gondwana as a consequence of the early closure of Palaeotethys before spreading.…”

A balanced foreland–hinterland deformation model for the Southern Variscan belt of Sardinia, Italy

“…On the map-scale, it is possible to distinguish an unmetamorphosed to a weakly metamorphosed foreland in the southwest, a low-grade metamorphic nappe zone in central and southeast Sardinia, and an inner zone with medium to high-grade metamorphism in northern Sardinia and Corsica (for a recent review of regional metamorphic zoneography, see Franceschelli et al, 2005). The high-grade metamorphic complex, which mainly consists of migmatites, orthogneisses, mafic granulites and eclogitic bodies, represent the orogenic roots (Giacomini et al, 2005(Giacomini et al, , 2006. This crystalline massif is rooted in the inferred suture zone, possibly marked by the Mg-K suite of Corsica, and comes into contact with the medium-grade metasedimentary complex along the PosadaAsinara Line (PAL).…”

The birth of the Rheic Ocean — Early Palaeozoic subsidence patterns and subsequent tectonic plate scenarios

“…Since our comprehensive discussion on Ordovician granitoids von Raumer et al, 2003) and their narrow relation to Ordovician subduction and subsequent crustal extension, new data are at disposal from different Alpine realms (Bertrand et al, 2000;Guillot et al, 2002;Schulz and Bombach, 2003), from the Carpathian mountains (Gaab et al, 2005), from Sardinia (Helbing 2003;Helbing and Tiepolo 2005;Giacomini et al, 2006), from Sicily (Trombetta et al, 2004), from the Pyrenees and from the Bohemian Massif (Bavarian Forest, Teipel et al, 2004).…”