Late Quaternary Tephra Layers Along The Cilento Coastline (southern Italy)

摘要

The results of stratigraphic and tephrostratigraphic analyses of several pyroclastic levels, collected along the coastal sector of the Cilento region (southern Italy), are presented. Some of these levels are here described for the fist time, others, already known in literature, were reconsidered in order to better understand their stratigraphic position and to point out the possible volcanic sources. The main outcrops are located along the southern coast of the Campania region (Cilento coast). All pyroclastic layers are interbedded within coastal or continental successions younger than the substage 5e of the Last Interglacial (<130 ka) or cover erosional coastal morphologies belonging to the same period. Only in one site the sampled tephra can be considered older. As a consequence, the age range for their emplacement is constrained to the last 200 ka. The results of SEM-EDS analyses on well preserved glass fragments indicate a composition falling between the trachyte and phonolite fields of the TAS plot, as typical of Phlaegrean Fields products. By comparing their composition with those of the main tephra marker layers recorded in southern Italy, the correlation of the Cilento pyroclastic layers with well known eruptive episodes was hypothesised. In summary, four different eruptions were recognised. The first one is testified by a pyroclastic layer, not correlated with a terrestrial counterpart, covered by a Middle Pleistocene alluvial fan, the second one is the eruptive event emplacing the X-6 marker tephra layer, and dates around 107 ka, the third is the Campanian Ignimbrite eruption (39 ka), and the last one is testified by the layers correlated with the Y-3 tephra (about 30 ka). These pyroclastic layers can be useful tools for stratigraphic correlations of Late Quaternary successions in southern Italy.