The carbonate profile of two recent Ionian Sea cores: Evidence that the sedimentation rate is constant over the last millennia

Abstract

We confirm and extend the results previously reported on the carbonate profile of the GT14 Ionian Sea core [Cini Castagnoli et al., 1990]. A second, much longer core (2.81 meters), named GT89/3, has been taken about 1 km apart from the previous one. The carbonate profiles of the two cores are impressively similar; the details of the CaCO₃ variations in the two sediments match on the scale of the sampling interval Δd = 2.5 mm used for both cores. We show that Δd corresponds to the mud deposited in a time interval Δt = 3.87±0.04 years, a value which is constant throughout the entire length of the cores. This precision is achieved by the tephroanalysis of the two cores. In this approach the markers of well‐known historical eruptions in the Vesuvius area are recognized (Pompei, AD 79, Pollena, AD 472, Ischia, AD 1301), providing a precise dating which accurately tunes that obtained by the radiometric method. The correlation between the carbonate profile of the GT14 core and the tree‐ring radiocarbon record has been discussed in [Cini Castagnoli et al., 1990]; here we extend these results and show that the same correlation holds at least up to 1690 BC. Due to the longer length of the GT89/3 time series, we also show that three periodic components at about 206 yr, 228 yr and 179 yr may now be resolved in the carbonate series, in close agreement with the results already found for the radiocarbon record.