Vetygala Exposure: the problem of the lower boundary of Pleistocene

Abstract

The presented results of palaeomagnetic and lithological investigations of the Vetygala Exposure are one more attempt to solve the problem of the lower boundary of the Pleistocene in Eastern Lithuania. Five lithological complexes distinguished in the deposit sequence of the Vetygala Exposure of up to 22 metres height were studied by means of lithology and palaeomagnetism. Carbonate analysis undertaken showed that the amount of carbonates is increasing only in the uppermost part of outcrop, but some carbonate content in the lower part suggests that the sediments in the Vetygala Exposure could have formed at the beginning of the Pleistocene. Results of measurements of the magnetic susceptibility of sediments and the determination of the anisotropy of magnetic susceptibility and remanent magnetisation for orientated samples from clayey silt interlayers demonstrate that changes of Earth’s magnetic field polarity were frequent during the sediments deposition and maintain about a relatively long period of sedimentation. The results of recent lithological and palaeomagnetic studies do not give a straight answer about the stratigraphical identity of investigated sediments. Thus, the stratigraphical subdivision of sediments in the Vetygala Exposure and their correlation with neighbouring geological sections are still open to variable interpretation.