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 C rati submarine fan (Holocene) are four turbidite sequences deposited i n northwest-southeast-trending thrust-top basins of the southern Apenn ines (Italy) foreland region. The Corigliano basin is a part of the mo dern Taranto Gulf foredeep basin that developed since the late Pleisto cene. Sandstone detrital modes of the Miocene turbidite units are quar tzofeldspathic (Petrofacies 1, 2a, 4, 5, 8; Q(62)F(25)L(13)), quartzol ithic (Petrofacies 2b; Q(60)F(16)L(24)), and arkosic (Petrofacies 7; Q (50)F(45)L(5)), reflecting a collisional orogenic provenance. Volcanol ithic sandstones (Petrofacies 3, Q(23)F(11)L(66)) suggest an important contribution also from a volcanic source area related to the converge nt-continental-margin volcanism connected with the collisional tectoni c regime that affected the western Mediterranean (e.g., Sardinia volca nic are). Individual carbonatoclastic beds (hybrid arenite, biocalcare nite, and mudstone) are interbedded with sandstone units of the Cilent o Group. They have siliciclastic content of about 35% and are quartzof eldspathic (Petrofacies 6; Q(53)F(23)L(24)), These beds (0.10-65 m thi ck) record impulsive gravitational collapses of the carbonate-platform passive margin to the east and southeast. The petrologic parameters s how a temporal evolution from metasedimentary to granitic-gneissic pro venance ascribed to different tectonostratigraphic units of the Calabr ian are Nine Miocene petrofacies suggest dynamic evolution of the sour ce terranes from Langhian to Tortonian time. Facies, dispersal pattern s, and petrologic parameters of the Miocene sandstones suggest a prove nance from the northern and western margins of the basins. Comparison between the Holocene Crati Fan (Petrofacies 9; Q(54)F(24)L(22)) and Mi ocene detrital modes suggests that the sandstones of the Cilento Group , the Monte Sacro Conglomerate, and the Gorgoglione Formation were der ived from unroofing of the thrusted basement block, transported by tor rential-type, fluvio-deltaic systems and then funneled into a major tu rbidite dispersal system, analogous to the modern Crati submarine fan of the Corigliano thrust-top basin.