The late Quaternary tephrostratigraphical record of the San Gregorio Magno Basin (southern Italy)

Twenty-one primary pyroclastic layers were found embedded in the lacustrine sediments of the San Gregorio Magno basin (Southern Apennine). These sand-sized layers were characterized by a noticeable juvenile fragments content and by a sharp basal contact with the underlying clay and silt sediments. The tephra layers have been correlated with terrestrial counterparts reporting to well known eruptive events of the Campanian volcanic area, or with reference layer from deep sea sediment cores and from Monticchio maar sequence. The investigation of the San Gregorio Magno tephra layers made it possible to deduce that lacustrine sedimentation at San Gregorio Magno basin began before 170 ky B.P. and lasted at least until the Neapolitan Yellow Tuff emplacement, occurred about 15 ky B.P. Through the results of tephra layers analysis the fluctuating sedimentation rate of the basin was pointed out. Finally, the presented correlation between lacustrine and marine sequences represents a step forward to the reconstruction of the late Quaternary tephrostratotype for southern Italy.