Ophiolite‐bearing mélanges in southern Italy

Abstract

In southern Italy two ophiolite-bearing belts, respectively involved in the Adria-verging southern Apennines and in the Europeverging thrust belt of the northern Calabrian Arc, represent the southward extension of the northern Apennines and of 'Alpine Corsica' ophiolitic units, respectively. They form two distinct suture zones, which are characterized by different age of emplacement and opposite sense of tectonic transport. The ophiolite-bearing units of the southern Apennines are represented by broken formation and tectonic mélange associated with remnants of a well-developed accretionary wedge emplaced on top of the Adria continental margin, with an overall NE direction of tectonic transport. These units consist of a Cretaceous-Oligocene matrix, which includes blocks of continental-type rocks and ophiolites with remnants of their original Upper Jurassic to Lower Cretaceous pelagic cover. The innermost portion of the accretionary wedge is represented by a polymetamorphosed and polydeformed tectonic units that underwent a Late Oligocene high pressure/low temperature (HP/LT) metamorphism. The northern Calabria ophiolitic-belt is indeed composed of west-verging tectonic slices of oceanic rocks which, embedded between platform carbonate units of a western continental margin at the bottom and the basement crystalline nappes of the Calabrian Arc at the top, are affected by a Late Eocene-Early Oligocene HP/LT metamorphism. The main tectonic features of these two suture zones suggest that they can be interpreted as the result of the closure of two branches of the western Neotethys separated by a continental block that includes the crystalline basement rocks of the Calabrian Arc. We thus suggest that the north-east verging southern Apennine suture constituted by a well-developed accretionary wedge is the result of the closure of a large Late JurassicEarly Cretaceous oceanic domain (the Ligurian Ocean) located between the African (the Adria Block) and European continental margins. The northern Calabria suture derives indeed from the deformation of a very narrow oceanic-floored basin developed during the Mesozoic rifting stages within the European margin separating a small continental ribbon (Calabrian Block) from the main continent.

The Tell-Rif orogenic system (Morocco, Algeria, Tunisia) and the structural heritage of the southern Tethys margin

“…In the Alpine Tethys, Manatschal and Müntener (2009) propose 166 Ma for the onset of accretion and separation between Europe and Apulia. Equivalent ages for oceanic accretion characterize the Ligurian Tethys (Puga et al, 2011;Tortorici et al, 2009). Following different authors (Andrieux, 1971;Carminati et al, 2012;Doglioni et al, 1997;Guerrera et al, 1993;Handy et al, 2010;Puga et al, 2011;Vitale-Brovarone et al, 2013), it is pertinent to distinguish two branches in the Ligurian oceanic realm with the intervening AlKaPeCa continental domain (Fig.…”

Mineralogical Asbestos Assessment in the Southern Apennines (Italy): A Review

“…According to several authors [22][23][24][25], the Frido Unit forms the uppermost thrust sheet of southern Apennines and tectonically overlies the North Calabrian Units, which in turn are split in different thrust sheets [25]. The Frido Unit is characterized by HP/LT metamorphic sequences developed between Upper Jurassic to the Upper Oligocene [26][27][28][29] and references therein. The ophiolitic rocks in the Frido Unit, from the bottom to the top, consist of tectonized serpentinite [30][31][32][33][34][35], metabasalt [36], metagabbro, metapillow lavas [37], dismembered metadoleritic and rodingite dykes [28,[38][39][40], and sedimentary cover [41].…”

The First Occurrence of Asbestiform Magnesio-Riebeckite in Schists in the Frido Unit (Pollino Unesco Global Geopark, Southern Italy)

“…From bottom to top, it consists of the blueschist Frido Unit, the Episcopia-San Severino Mélange, and non-metamorphic North Calabrian Unit [2,14,15] ( Figure 1b). The Frido Unit represents the uppermost unit of the ophiolite-bearing terranes [16], and mainly consists of polydeformed sequence, including blocks of oceanic and continental type rocks, and metasediments [13,[17][18][19][20][21][22]. The ophiolite sequence from the Frido Unit consists of basalts and tectonized serpentinites containing blocks of metabasites, and rodingites [7,17,21,[23][24][25][26][27][28][29], foliated metabasites [30], and metapillow lava [31].…”