The hercynian chain in Sardinia (Italy)

The Middle Jurassic Alpine Tethyan Unconformity and the Eastern Sardinia - Corsica Jurassic High: A sedimentary and regional analysis

“…The E Sardinia Variscan basement consists of several superposed tectonic units (Carmignani et al, 1994;2001) with a metamorphic grade that grows from S to N from the greenschists facies to the amphibolite facies. According to the most recent findings (Funedda, pers.…”

“…This cover tectonically undisturbed rests over an unconformity that is Bajocian in age and forms the base of the Middle Jurassic succession (Dieni et al, 1983). This unconformity, named the "Alpine Tethyan unconformity" herein, tops Variscan Cambrian to Early Carboniferous metamorphic rocks (Carmignani et al, 1994(Carmignani et al, , 2001, and less commonly Triassic (Costamagna and Barca, 2002) and Permian (Cassinis and Ronchi, 2002) sedimentary deposits. The age and causes of this unconformity is coeval to the Jurassic opening of the Alpine Tethys in the W Mediterranean area (Abbate et al, 1986;Bernoulli and Jenkyns, 1974;Stampfli, 2000) an thus can be considered related to it.…”

Structural map of Variscan northern Sardinia (Italy)

“…Therefore, in the absence of high-resolution geochronologic constraints, faulting is inferred to be Late-Carboniferous to Early Permian and possibly related to the large clockwise rotation of the Corsica-Sardinia block in late Variscan times (Edel, Casini, Oggiano, Rossi, & Schulmann, 2014). The faults characterized by sinistral kinematic and NE to ENE direction entangle the Mesozoic-Cenozoic sedimentary and volcanic sequences, generating either positive flower structures or strike-slip basins corresponding to restraining or releasing bends respectively (Carmignani et al, 1994). The age of syntectonic sediments indicates that most of these late Variscan faults were reactivated in Oligocene to Miocene times (Carmignani et al, 1995), during the collision between the Corsica-Sardinia block and Adria (Carmignani, Funedda, Oggiano, & Pasci, 2004;Oggiano, Funedda, Carmignani, & Pasci, 2009).…”

“…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).…”

Geomorphosites in Granitic Environments: An Example from Northern Sardinia (Italy)

“…The structure of Sardinia is characterized by a Paleozoic basement of metamorphic formations intruded by pluton units with granitoid composition. This basement is a fragment of the South-European Hercynian chain, originating from the collision between the Armorican and Gondwana continental margins [1]. This basement is characterized by a marked increase in the metamorphic degree from SW to NE [2,3].…”