Magnetostratigraphy-based astronomical tuning of the early Pliocene
lacustrine sediments of Ptolemais (NW Greece) and bed-to-bed
correlation with the marine record
Continental deposits from the early Pliocene lacustrine Ptolemais basin in NW Greece display rhythmical alternations
of lignite and marl beds. Three parallel sections from this area are studied using magnetostratigraphy and cyclostratigraphy.
The presence of the greater part of the Gilbert Chron enables the recognition of astronomical periodicities in the
succession. Especially the precessional influence is evident, as it determines the lithological cycles. The continental
Ptolemais composite section is correlated to the most recent astronomical time scale and thus to the marine reference
section: the Rossello composite from Sicily [C.G. Langereis, F.J. Hilgen, The Rossello composite: a Mediterranean and
global reference section for the Early to early Late Pliocene, Earth Planet. Sci. Lett. 104 (1991) 211-225] on a
bed-to-bed scale. It is concluded that lignite corresponds to an insolation minimum (beige layer in the Rossello composite),
and marl to an insolation maximum (grey layer in the Rossello composite). This implies a precipitation increase during
insolation maxima in early Pliocene continental Greece. Ó 1998 Elsevier Science B.V. All rights reserved