On crustal composition of the Sardinia-Corsica continental block inferred from receiver functions

Abstract

Abstract. Subduction-related geodynamic processes significantly influence plate tectonics and Earth’s evolution, yet their impact on the continental crust remains poorly understood. We investigated the Sardinia-Corsica continental block, situated in the Mediterranean Sea, which has experienced intense subduction-driven geodynamic events. By analyzing P-wave receiver functions from our LiSard seismic network and publicly available stations, we aimed to understand crustal structure and composition. We inferred the Moho depth and examined the P-wave to S-wave velocity ratio (V_P /V_S ). We interpret our findings considering petrological data, heat flux measurements, and other geophysical information. We found that the Variscan granitoid batholith has the greatest Moho depths in both Sardinia and Corsica. V_P /V_S ratios (ranging from 1.65 to 1.70) are consistent with average crustal values of SiO₂ between 65 % and 70 %. However, in central Corsica, two stations have exceptionally high V_P /V_S values (>1.80), suggesting the possible presence of serpentinite throughout the crust. In Alpine Corsica, a station exhibited similar high V_P /V_S values but a shallower Moho depth of 21 km. The western part of Sardinia, where Cenozoic volcanism occurred, also showed a shallower Moho depth (20–25 km) and high V_P /V_S values. The highest V_P /V_S value (1.91) is recorded in an area where surface-wave dispersion curves from ambient noise identified the lowest average S-wave velocity and where the highest heat flux has been reported, indicating elevated crustal temperatures and possible presence of melt within the crust. Overall, our results indicate that the recent geodynamic processes have left the granitoid batholith almost intact, with minimal alteration to its composition.