Tephrochronological study in the quaternary Val d'Agri intermontane basin (Southern Apennines, Italy)

摘要

In the south-eastern depocentre of the Val d'Agri basin (Southern Apennines), a volcanic ash layer crops out interbedded within poorly structured alluvial fan deposits of Late Pleistocene age. Textural, depositional and pedological features of this weathered layer suggest a primary deposition from a pyroclastic fall-out of volcanic ash. Chemical analyses of feldspars show an alkali trachytic composition and accessory minerals association allow to correlate this tephra layer with the regionally dispersed Y-7 marine tephra layer (Tufo Verde Epomeo eruption, Ischia volcano), dated at 56 ± 4 ka. The Val d'Agri tephra here described for the first time was deposited during MIS Stage 3. Its recovery and characterization permit to contribute to regional correlation of the Mediterranean climatic and volcanic events from marine to continental successions and to describe landscape evolution of the Southern Apennines during glacial-interglacial cycles.