Shallow burial and exhumation of the Peloritani Mts. (NE Sicily, Italy): Insight from paleo-thermal and structural indicators

We used vitrinite reflectance and mixed layered clay minerals to investigate levels of diagenesis of the Oligocene-Miocene basindeveloped on the nappes of the Alpine orogen exposed in the Peloritani Mountains(NE Sicily). Paleothermal indicators were integrated with stratigraphic and structuralanalyses and published apatite fission-track and (U-Th-Sm)/He ages to define the lateevolutionary stages of the Peloritani Mountains.This multimethod approach allowed us to reconstruct the paleogeothermal gradientof the basin in Oligocene-Miocene times, toconstrain its burial evolution, and discriminatebetween areas where it has been affectedby sedimentary and/or tectonic load. In the southern area of the basin, organic and inorganicthermal parameters increase as function of depth, suggesting that their evolutionwas ruled by sedimentary burial. They recorda decrease in paleogeothermal gradient values marking the evolution of the basinfrom a forearc to a thrust-top setting duringthe convergence-collision process betweenthe Calabria-Peloritani Arc and the African plate. On the other hand, in the northernedge of the basin, vitrinite refl ectance values(0.46%–0.58%) indicate that the thermalevolution of this area was controlled by tectonicburial related to late Langhian–earlySerravallian out-of-sequence thrust tectonics.The tectonic overburden has been totallyremoved by extensional tectonics and/or erosionsince the late Miocene. The short timespan at maximum temperature (<2 m.y.)elapsing between thrust stack emplacementand the beginning of tectonic overburdenremoval has allowed only vitrinite reflectanceand thermochronological indicators torecord this compressive reactivation.