Paleo-thermal and structural indicators for unraveling Burial - Exhumation paths in the Peloritani Mts., NE Sicily, Italy

We used vitrinite reflectance and mixed layered clay minerals to investigate levels of diagenesis of the Oligocene-Miocene basin developed on the nappes of the Alpine orogen in the Peloritani Mts. (NE Sicily). Paleothermal indicators were integrated with stratigraphic-structural analyses and apatite fission-track and (U-Th-Sm)/He ages to define the late evolutionary stages of the Peloritani Mts. The reconstruction of the paleogeothermal gradient in Oligocene-Miocene times was performed to constrain the burial-thermal evolution. In the southern area, thermal parameters increase with depth suggesting that their evolution is ruled by sedimentary burial. They recorded a decrease in paleogeothermal gradients which marked the evolution of the basin from a fore-arc to a thrust-top setting during convergence-collision. In the northern edge of the basin, higher vitrinite reflectance values indicate that thermal evolution was controlled by tectonic burial related to late Langhian-early Serravallian out-of-sequence thrusting. This overburden was removed by extensional tectonics and/or erosion since late Miocene. The short time span at maximum temperature (<2 Ma) elapsing between thrust stack emplacement and the beginning of its removal have allowed only vitrinite reflectance and thermo-chronological indicators to record this compressive reactivation.