Abstract

Low marine terrace sequence of Kunashiri Island includes Atlantic, Subboreal and Subatlantic terraces, reflected sea level oscillations during Middle-Late Holocene. The section of Atlantic terrace (5-6m elevation) exposes storm ridge deposits, covered lacustric silts and peat. Pollen and diatom fossils and 14C-dates (5, 450-6, 070yrs BP) correspond to development of large barrier forms with lakes in the Holocene Optimum. The paleostraits existed in the place modern Sernovodsky and Kruglovsky Isthmuses. Ocean level rose to 2.5-3m a. m. s. l. A minor regression took place during Atlantic-Subboreal cooling. Drainage of inshore zone led to development of large dunes. Subboreal deposits record two high sea level positions: about 4, 010-3, 400yrs BP and 2, 950-2, 620yrs BP. Small estuarian lagoons and inlets developed in that time. The cooling and ocean level lowering at Subboreal-Subatlantic boundary accompanied by formation of dune fields and swamping of the lagoon coasts (2, 220±80yrs BP, 1, 440±60yrs BP, GIN-7895, GIN-7262). Subatlantic terrace (2.5m) formed during ocean level rise to 1m about 1, 170-820yrs BP. Dunes were formed during Little Ice Age regression. The terrace study indicates their weak tectonic deformation.

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