Thermal and Thermo-chronological Constraints to the Southern Apennines Evolution, Italy

Abstract

A multidisciplinary approach for thermo-baric data acquisition is proposed along the southern Appennines, a key region of the Alpine orogen in the central Mediterranean area, including the remnants of a Cretaceous to Palaeogene accretionary complex. Ophiolite-bearing HP-LT tectonic units occur on top of the thrust pile. The underlying outcropping thrust sheets consist of Mesozoic and Cenozoic rocks derived from the sedimentary cover of the foreland plate (Apennine carbonate platform and Lagonegro pelagic units). These latter suffered, in some parts, HT-LT metamorphic conditions. We integrated independent thermal and thermo-chronological methods such as XRD analyses of clay mineral assemblages, fluid inclusion micro-thermometry, apatite fission tracks and vitrinite reflectance analyses, sampling both metamorphic and non methamorphic low-temperature successions. Our results indicate that a significant part of the sedimentary rocks exposed in the southern Apennines experienced substantial tectonic burial (locally in excess of 5 km), and confirm that, besides kinetics factors, a combination of methods allow to define thermo-cronological and, subordinately, pressure characteristics also for the HP-LT successions. Finally, in the northern sector of the area (Lucania), a break in thermal maturity from the Apennine carbonate platform and Lagonegro pelagic derived units has been documented, and along-strike variations of thermal maturity also emerged.