Fission-track analysis and provenance studies in Calabrian Are sedimentary rocks, southern Italy

Abstract

Fission track analysis has been applied to the Stilo–Capo d'Orlando Formation of southern Italy. This is a terrigenous syn-orogenic sedimentary deposit of Oligo-Miocene age that accumulated during a phase of accelerated denudation that affected the nearby crystalline basement rocks of the Calabrian Arc between c. 30 and 15 Ma. Seven conglomerate clasts and two sandstone samples from the base of the formation have produced eight apatite fission-track ages, nine zircon fission-track ages and six apatite confined-track length analyses. The zircon fission-track data confirm that detritus was derived from local Hercynian igneous and metamorphic rocks. In addition, apatite fission-track results from the two sandstone samples reveal that the basal part of the Stilo–Capo d'Orlando Formation was exposed to maximum palaeotemperatures in excess of 70°C after deposition. Despite this, apatite fission track ages much older than those obtained from the in situ crystalline basement source rocks of the Calabrian Are have been acquired. These ages are interpreted as being derived from ‘lost cover’, that is, rocks originating from the structurally highest levels of the basement complex that have now been completely removed by erosion. Fission track analysis demonstrates that erosion, in addition to previously identified extensional tectonism, was a major factor during accelerated denudation of the Calabrian Are basement rocks during the late Oligocene and early Miocene.