Tephrochronology of core C from Lago Grande di Monticchio

Abstract

Tephrochronological studies of sediment from Lago Grande di Monticchio have begun with detailed electron microprobe analyses of two thickest tephra layers found in Core C. A total of 76 analyses of both layers reveals them to be of trachytic composition, of the type erupted from the Campi Flegrei during the last 35,000 years. LGM C41, the lower layer, is a co-ignimbrite ash-fall deposit and is tentatively correlated with the Campanian Ignimbrite which was erupted about 35,000 BP. The Yellow Neapolitan Tuff (12,000 BP) is suggested as a possible correlation for the upper layer, LGM C33. Some geochemical differences exist within units in LGM C33 but there appears to be none within LGM C41. Conflicting geochemical and palaeomagnetic work on the lake sediments suggests that these two layers may be 80,000 years older and possible correlations are also made with three trachytic tephra layers ranging in age between 90,000 and 120,000 BP. The 51 metre deep profile obtained in Core D provides the possibility of a tephrochronological record stretching back into the Eemian and the glacial cycle before that.