COASTAL MORPHO- DYNAMICS OF THE NORTH-WESTERN ONEZHSKY PENINSULA, WHITE SEA IN THE HOLOCENE. KONYUKHOV BAY

Abstract

Data from geomorphological surveys of the Konyukhov Bay coast (north-western part of Onezhsky Peninsula), radiocarbon dating of organogenic sediments, echo sounding of water areas of the bay and lakes (water lines at 15.8-26.1 m a. s. l.) performed during thevoyage of the research vessel "Ecolog" in July 2014 were used to reconstruct the history of the landform development in the Holocene. The morphodynamics of the coast is considered as a result of interactions between coastal processes and the underlying litho- genic structure against the background of postglacial movements and climate change. Two geomorphological levels were distinguished and dated, which differ in the scope of transformation of ice-marginal formations of the Neva stage of the last glaciation by the sea and correspond to the main stages of post-glacial development of the relief: 1) paleo- straits and bays in depressions between moraine ridges at altitudes of 17.5-30 m a. s. l., filled in during the post-glacial transgression; the basinal stage of their development ended no later than 8540 ± 50 - 7610 ± 70 14C (~9500-8400 cal.) BP; 2) marine terraces at altitudes below 15-17 m a. s. l., formed in the middle-late Holocene in the environments similar to modern ones. The abrasion coastline (14-17.5 m) formed during the sea level stabilization stage with its high wave activity, which took place during the Tapes transgression, was revealed. Bays at the upper level, with a threshold runoff below ~ 17.5 m a. s. l., were at that time re-filled with sea water. The relative uplift rate of the Konyukhov Bay coast was estimated according to the ages of the lower horizon of lacustrine and palus- trine sediments at 2-2.2 mm/year.

Keywords

• white sea
• coast
• morphodynamics
• morainic kettle hole lakes
• chronology
• vertical movements
• sea level
• holocene