New findings of the Etnean Lateglacial tephra in Central Italy

Abstract

This work discusses the results of the characterisation study of two Lateglacial air-fall tephra layers found in long palaeoclimatic records from the volcanic lakes of Vico and Mezzano, in the northern Lazio region. Both tephra layers are about 0.5 cm thick; they are mostly made up of vesicular pumice pyroclasts and contain feldspar and black pyroxene. From the chemical point of view, both can be classified as benmoreites (sodic trachy-andesites). The available radiocarbon datings on the bracketing sediments indicate that both tephra layers were deposited about 14 ka BP. Because of the similarity of their macroscopic, microscopic and geochemical features and of the same chronological framework, the two layers can be correlated to each other. They are attributed to the tephra marker from Etna that has been found in marine and continental sediments of the Central Mediterranean. It formed during the final polyphasic eruption of the Eliittico volcano, that occurred 15-14 ka BP and represents a major explosive event in the evolution of Etna. This work enables to confirm the chronological framework of the two studied lacustrine sequences and allows to correlate them with other palaeoclimatic records, for more complete Late Quaternary climatic and environmental recontructions. The recovery of the Etnean Lateglacial tephra in the northern Lazio region extends its areal distribution towards the NNW and may contribute towards revised estimations of the volume of ejecta produced during the Etnean eruption. By integrating the available findings a distribution map has been constructed according which this tephra was deposited in two main fans so far recognized up to 600 km from the source: One extending to the SE and another extending to the N.