Emplacement of the Arzachena Pluton (Corsica–Sardinia Batholith) and the geodynamics of incoming Pangaea

Structural map of Variscan northern Sardinia (Italy)

“…The final convergence between the continental blocks was characterized by the development of a wide network of lithospheric strike-slip shear zones, which accommodated the northeastward displacement of Laurussia and Avalonia relative to stable Gondwana from late Visean to Early Permian (Faure, Lardeaux, & Ledru, 2009;Gutiérrez-Alonso et al, 2008;Muttoni, Kent, & Channell, 1996). The pre-Mesozoic basement of north Sardinia is a section of the Variscan orogen equivalent to the Moldanubian domain ( Figure 1) of central Europe (Edel et al, 2013;Matte, 2001;Rossi, Oggiano, & Cocherie, 2009 (Buzzi, Gaggero, & Oggiano, 2008;Casini et al, 2012;Oggiano, Gaggero, Funedda, Buzzi, & Tiepolo, 2010), and a Lower Metamorphic Complex (LMC), made of paragneisses, micaschists, quartzites and subordinate amphibolite boudins (Cappelli et al, 1991;Carmignani et al, 1994).The Visean collisional evolution is testified by exhumation of HP rocks and southward thrusting of UMC onto LMC. The phase of shortening is associated with nearisothermal decompression and partial melting of UMC in the kyanite stability field (Ferrara, Ricci, & Rita, 1978;Giacomini, Bomparola, & Ghezzo, 2005).…”

“…The oldest magmatic complexes in the Sardinian part of C-SB are indicated in the map as Barrabisa (BBR) and Isola di S. Maria (ISM) plutons. They consist of dyke-shaped, S-to I-type, strongly foliated peraluminous monzogranites and granodiorites emplaced between 15 -20 km of depth within E-W and NW-SE ductile shear zones rooted in a granulitic lower crust (Casini, 2012;Casini et al, 2012Casini et al, , 2013. The early U2 plutons show systematically moderate to absent grain-size reduction towards the migmatitic host rock and preserve a well-developed magmatic foliation almost parallel to the fabric of migmatites ( Figure 3).…”

“…This recognized structural control motivated geologists to improve their knowledge about the geometry and timing of different plutons in relation to major orogenic events. Work has included detailed structural maps of Variscan batholiths that have been coupled to high-resolution geochronological studies in the French Massif Central (Faure, Cocherie, Mézème, Charles, & Rossi, 2010;Gébelin et al, 2009), External Crystalline Massifs on the western Alps (Rubatto, Ferrando, Compagnoni, & Lombardo, 2010), the Pyrenean region (Liesa et al, 2011;Vilà et al, 2010) and the Corsica-Sardinia block (Casini, Cuccuru, Maino, Oggiano, & Tiepolo, 2012;Gattacceca et al, 2004;Gébelin et al, 2009;Rossi & Cocherie, 1991). However, recent work on the Sardinian part of the Corsica-Sardinia Batholith have focused on petrological aspects related to the origin of melts (Cruciani, Franceschelli, Jung, Puxeddu, & Utzeri, 2008;Ferré & Leake, 2001;Gaggero, Oggiano, Buzzi, Slejko, & Cortesogno, 2007;Macera, Di Pisa, & Gasperini, 2011).…”

Uranium distribution in the Variscan Basement of Northeastern Sardinia

“…12,000 km 2 area, constitutes one of the largest batholiths in south-western Europe, emplaced at approximately 40 Ma (Late Mississippian Pennsylvanian-Early Permian). Three main magmatic suites can be recognized: a magnesium-potassium complex exposed only in northern Corsica, a peraluminous calc-alkaline complex (Casini et al, 2012;Rossi & Cocherie, 1991) and finally, a late to postorogenic alkaline suite in the VBNS (Bonin, 2007). The 2100 km 2 of the VBNS (Figure 1) are characterized by several calc-alkaline plutons and a few minor alkaline complexes emplaced within migmatites and amphibolite-facies of metamorphic rocks (Casini, Cuccuru, Maino, et al, 2015).…”

“…The eU distribution is discussed in the geodynamic framework proposed by , taking into account the petrological features of the C-SB, the compositional variation and the emplacement timing of Variscan granitoids. Finally, we focus on the eU distribution measured in the granitoids of the Arzachena pluton, linking it to the emplacement mechanism proposed by Casini, Cuccuru, Maino, Oggiano, and Tiepolo (2012).…”