RELATIVE SEA-LEVEL CHANGE OF THE WHITE SEA IN THE LATE GLACIAL AND HOLOCENE: CASE STUDY OF THE SREDNYAYA TRET’ LAKE, EASTERN COAST OF THE GORLO STRAIT<a href="#FN4">⁴</a>

Abstract

The relative sea-level changes for the time interval of ~12.1–9.1 ka cal BP were reconstructed on the eastern coast of the Gorlo Strait using the results of paleolimnological, GPR and geomorphological analyses conducted in the basin of the Srednyaya Tret’ Lake (7.3 m a.s.l., 66.014009° N, 41.086294° E), as well as UAV surveying of the lake surroundings. Bottom sediments of the lake were studied from the four core sections and correlated with each other according to the results of GPR data interpretation. Lithostratigraphic descriptions of bottom sediment cores, grain-size and diatom analyses, radiocarbon dating (AMS), determination of LOI, Corg content and Corg /Norg ratio were performed. We present the reconstruction of the coastlines at heights of 4–5 and 12–15 m formed by currents and/or wave processes within the lower Ruch’i River valley and Srednyaya Tret’ Lake according to field observations and interpretation of space images. As a result, the position of the relative sea-level and the chronology of the Late Glacial (Younger Dryas) transgression and the early stages of the Holocene (Tapes) transgression were refined. Late glacial transgression finished earlier than ~12.1 ka cal BP, and its relative level was probably no higher than 15 m a.s.l. After a deep regression, the relative sea-level approached the modern again ~9.5 ka cal BP, and at the Tapes transgression maximum (~9.1 ka cal BP) it was near the lake runoff threshold (∼5 m). Though the coastline was near the lake basin, sea waters never entered the lake. Sands, carried by the wind, accumulated in the part of the basin facing the coast. The the Srednyaya Tret’ Lake basin was gradually filled by fresh water according to the results of diatom analysis.