Volume 18 (2001)
PALAEOGEOGRAPHY OF LATE GLACIAL
AND LOWER HOLOCENE LAKES IN THE POMERANIAN BAY ON THE BASIS OF
MALACOFAUNA AND OSTRACODS AND SEISMOACOUSTIC DATA
Jarmila Krzymińska, Piotr Przezdziecki
Within a small (2.5 x 2.5 km) test field, located in the
eastern part of the Pomeranian Bay, the geological structure was
investigated in detail using seismoacoustic profiling and coring. In
the cores, mineral grain size and micro- and macrofauna were analysed.
Basing on seismoacoustic records, three main seismostratigraphic units
were distinguished. The lowest unit is built of sand and muddy sand.
Higher up lies the unit of sandy mud, in some places – of clay.
Fauna assemblages indicate cold climate conditions, and clearly point
to an existence of lacustrine reservoir of oligotrophic character.
Analysis of cores shows that sedimentation began in bog conditions. The
lakes in the area existed till the Atlantic period, when due to sea
transgression they became filled with sandy sediments. The third unit
is built mainly of fine sand, locally medium sand, even with addition
of gravel. Basing on the presence of marine fauna, this unit is
classified as marine sand.
Pomeranian Bay, malacofauna, ostracods, seismoacoustic data