Composition and provenance of Late Carboniferous to Permian sandstones within the Circum-Mediterranean region.

Late Carboniferous to Permian sandstone suites within the Circum-Mediterranean region occur both in subsurface (Puglia 1 well) and are exposed in Sardinia and Sicily. These clastic wedges record the most critical and dramatic restocking of Pangaea supercontinent. In this contest, the circum-Mediterranean region was experiencing particular tectonic and climatic environment, imprinted in siliciclastic strata. Here are discussed compositional data of Permian strata of the Apulia Unit, the Permian San Calogero Formation in Sicily, the Late Carboniferous-early Permian Rio Su Luda Formation and the Permian Mulargia Formation in central Sardinia. The Apulia Unit is crucial in the Mediterranean paleogeographical contest because, for its position, it received a great Permian sedimentary load. These strata are intersected in Puglia 1 well, between 7070 m to 6110 m in depth, for 960 m in thickness, with sandstone, mudstone and breccia strata. The Permian succession in Sicily is strongly tectonized (Lercara complex), outcropping around the Roccapalumba-Lercara area and the Sosio Valley (Northwestern Sicily). It consists of rock packages of different facies among which deep-water turbidites. Also, Carboniferous-to Permian sandstones (Gerrei basin, Central Sardinia) of the Rio Su Luda and Mulargia formations display a quite succession made of conglomerate, sandstone, mudrock and episodically interbedded volcaniclastic breccia and sandstones. Sandstones of the Puglia 1 Well are quartzolithic, with abundant quartz and metasedimentary lithic fragments (mainly phyllite and schist), while feldspars are minor. Sandstones of the Lercara complex are variable in composition and suffer the marine imprinting. Here, quartz-rich sandstones, hybrid arenites and calclithite include abundant extrabasinal carbonate fragments, metasedimentary lithic fragments, and intrabasinal carbonate grains. Primary volcanic and volcaniclastic layers are interbedded with sandstone. Sandstones of the Rio Su Luda and Mulargia formations display a more variable composition range, from quartzolithic to lithic with diverse amount of volcanic and metamorphic lithic fragments. Metasedimentary lithic fragments are abundant and derived from schist and phyllite basement rocks occurred in Sardinia and Corsica, whereas abundant volcanic lithic fragments are mainly derived from active Late Paleozoic volcanism widespread in Sardinia. Permian sandstone detrital modes of the three key areas within the central Mediterranean region, are typical of quartzolithic to lithic, hybrid arenite and calclithite, that should be related to the erosion of the recycled orogenic section of Cambrian-Carboniferous rocks, with most of metasedimentary and sedimentary rocks occurring in Calabria-Peloritani, southern Alps, Sardinia-Corsica and in internal domains of the Circum- Mediterranean orogens. Furthermore, volcanic signature in the Sardinian basins demonstrate an active volcanic activity during late early Permian.