Revision of the Italian Magnetic Database for the Albegna basin (South Tuscany, Italy)

A comparison between ground level total magnetic field intensity anomaly map (F) of Italy and the total intensity aeromagnetic map by ENI/AGIP, had shown that an anomaly pattern for the Albegna basin (South Tuscany), quite evident from ground measurements, doesn’t show in the aeromagnetic map. Ligurian units, made of ophiolite blocks (metagabbros, basalts, serpentinites), intrusives and subordinate volcanic products, all able to trigger a strong magnetic signal, could not be excluded in the area, and for this reason the magnetic anomaly estimated by ground level measurements was not considered unreasonable. In this paper the result of a magnetic survey finalized to verify the authentic existence of such a large magnetic total intensity anomaly in the Albegna basin, is reported. On the basis of the new result, the suspected ground level total intensity anomaly in the Albegna basin, was demonstrated to be non-existent and then the Italian Magnetic Database corrected accordingly. Measurements and procedures that brought to the magnetic elements elaboration and new anomaly maps for Albegna basin, are shown here.