New information from 'old' seismic lines: an updated geological interpretation from the re-processing of the CROP line M-2A/I (Bonifacio Straits) at shallow depths

Abstract

The shallowest part (about 3 sec two-way traveltime) of theCROP line M-2A/I, acquired during 1991 in the Bonifacio Strait(between Corsica and Sardinia), has been reprocessed to improveits geological interpretation. The original target of the M-2A/I profilewas the entire crust and therefore the shallowest part was onlypartially interpreted. In this context, the re-processing procedure wascarried out to improve the signal-to-noise ratio and the resolutionof the M-2A/I seismic profile at shallow depth. The geologicalinterpretation of the reprocessed data aimed at the reconstructionof the sedimentary succession and the contact with the underlyingHercynian basement.The M-2A/I seismic profile has been interpreted identifyingdiverse seismic facies, interpreted considering the geological unitsoutcropping to the north (in Corsica) and to the south (in Sardinia)of the seismic profile. The study supports the existence of a thickMesozoic succession, onlapping the Hercynian basement, preservedbelow the Cenozoic succession in the Asinara Gulf, suggesting that theNurra succession continues northward below the sea. The Mesozoic succession is bordered by a major, east-dipping normal fault, east the Asinara Island ridge. The faults recognized in the seismic profile indicate a prevailing strike slip/transtensional tectonics, questioning the role of compressional tectonics suggested in a previousinterpretation. The obtained results also indicate the potential of reprocessing of existing seismic profiles, whose interpretation can be significantly updated thanks to the development of new processing procedures and to the continuous upgrade of the regional geological knowledge.