FERDYNANDOVIAN INTERGLACIAL CLIMATE RECONSTRUCTIONS FROM POLLEN SUCCESSIONS, STABLE-ISOTOPE COMPOSITION AND MAGNETIC-SUSCEPTIBILITY

The Ferdynandovian Interglacial is one of the most controversial Quate rnary stratigraphic horizons in Europe. This study concentrates on pal aeoclimatic reconstruction of this interglacial based on pollen succes sion, isotope composition and magnetic susceptibility. The section inv estigated is located in the open cast mine at Belchatow, central Polan d. The lacustrine sequence contains laminated diatomite at the base, w hich was deposited in deep, meromictic lake, and massive diatomite to calcareous gyttja in its upper part. The latter were deposited in a ho lomictic lake, which became progressively more shallow. The gradual in crease of delta(18)O values and simultaneous decrease of susceptibilit y in the lower part of the Ferdynandovian sequence at Belchatow corres pond well with climatic amelioration documented by pollen analysis. Si multaneous increase of precipitation of carbonates and its delta(13)C values correspond well with the increase in biological activity in the lake. Results obtained by isotope investigations showed an increase i n the mean annual temperature to a maximum of 7.5 degrees C from the b eginning of the interglacial to the first appearance of thermophilous, deciduous trees. The oxygen-isotope curve does not show any short-ter m climatic oscillations. Susceptibility oscillations are somewhat more distinct, but because the main magnetic carrier is greigite deposited on spores of unicellular organisms, they are linked to the concentrat ion of these spores lather than with the climatic oscillations. Twelve secular cycles or their fragments have been recorded in the interglac ial sequence by palaeomagnetic investigations, suggesting c. 9600 year s of deposition. This corresponds well with the 10 000 years of deposi tion calculated for the same sequence based on annually laminated diat omites.