DETRITAL MODES AND PROVENANCE OF MIOCENE SANDSTONES AND MODERN SANDS OF THE SOUTHERN APENNINES THRUST-TOP BASINS (ITALY)

The Cilento Group (Lower-Middle Miocene), the Monte Sacro Conglomerate (Upper Miocene), the Gorgoglione Formation (Upper Miocene), and the Crati submarine fan (Holocene) are four turbidite sequences deposited in northwest-southeast-trending thrust-top basins of the southern Apennines (Italy) foreland region. The Corigliano basin is a part of the modern Taranto Gulf foredeep basin that developed since the late Pleistocene. Sandstone detrital modes of the Miocene turbidite units are quartzofeldspathic (Petrofacies 1, 2a, 4, 5, 8; Q(62)F(25)L(13)), quartzolithic (Petrofacies 2b; Q(60)F(16)L(24)), and arkosic (Petrofacies 7; Q(50)F(45)L(5)), reflecting a collisional orogenic provenance. Volcanolithic sandstones (Petrofacies 3, Q(23)F(11)L(66)) suggest an important contribution also from a volcanic source area related to the convergent-continental-margin volcanism connected with the collisional tectonic regime that affected the western Mediterranean (e.g., Sardinia volcanic are). Individual carbonatoclastic beds (hybrid arenite, biocalcarenite, and mudstone) are interbedded with sandstone units of the Cilento Group. They have siliciclastic content of about 35% and are quartzofeldspathic (Petrofacies 6; Q(53)F(23)L(24)), These beds (0.10-65 m thick) record impulsive gravitational collapses of the carbonate-platform passive margin to the east and southeast. The petrologic parameters show a temporal evolution from metasedimentary to granitic-gneissic provenance ascribed to different tectonostratigraphic units of the Calabrian are Nine Miocene petrofacies suggest dynamic evolution of the source terranes from Langhian to Tortonian time. Facies, dispersal patterns, and petrologic parameters of the Miocene sandstones suggest a provenance from the northern and western margins of the basins. Comparison between the Holocene Crati Fan (Petrofacies 9; Q(54)F(24)L(22)) and Miocene detrital modes suggests that the sandstones of the Cilento Group, the Monte Sacro Conglomerate, and the Gorgoglione Formation were derived from unroofing of the thrusted basement block, transported by torrential-type, fluvio-deltaic systems and then funneled into a major turbidite dispersal system, analogous to the modern Crati submarine fan of the Corigliano thrust-top basin.