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Earths Cryosphere

2022 year, number 2

CLIMATE, SEA LEVEL AND GLACIATION CHANGES IN THE MARGINAL ZONE OF ANTARCTICA DURING THE LAST 50 000 YEARS

S.R. Verkulich
Arctic and Antarctic Research Institute, Bering str. 38, St. Petersburg, 199397, Russia
Keywords: marginal zone of Antarctica, climate, sea level, glaciation, interstadial, last glacial maximum, Holocene, relief, Quaternary deposits, paleogeographic reconstruction

Abstract

The article integrates the results of half a century studies of Late Pleistocene-Holocene changes in climate, sea level and glaciation in the marginal zone of Antarctica in order to identify the chronology, parameters, mechanisms of these changes under the influence of global, regional and local factors. During the interstadial (MIS 3), the natural conditions here resembled modern ones, and the sea level in some areas exceeded modern marks. The development of glaciation of the marginal zone from about 26 000 years BP went on when the temperature fell and the sea level dropped by 30-50 m. The growth of glaciation on the shelf outpaced the growth of ice on the outskirts of the continent, leading to a moisture deficit in the interior regions. During the LGM, there was a thin (less than 300 m) glaciation of coastal and mountainous land areas, and a thick (more than 1000 m) glaciation on the shelf. Deglaciation of the marginal zone began about 17 000 years BP due to rising sea level and global warming. Holocene climate changes in most areas had a general trend: warming in the early Holocene to about 8000 years BP and 4000-2000 years BP, cooling 2000-1500 years BP, but also had local differences. The relative sea level rose in the regions from the early Holocene to the period 8000-6000 years BP; then it fell with a decrease in speed and even with a possible rise of the level 2500-1300 years BP; local differences in the amplitudes and course of the level were determined by local tectonics and dynamics of deglaciation. Deglaciation rates were high from the early Holocene to about 7500 years BP due to warming and marine transgression; then the speed dropped. The advance of outlet and shelf glaciers 6500 and 4500 years BP was associated with a decrease in sea level and cooling. In the period 4000-1000 years BP, outlet and shelf glaciers could also respond to changes in sea level, and ice domes expanded according to the warming-increasing humidity-increasing snow and ice accumulation pattern. During the Little Ice Age, moraines were created in some areas, registering a slight increase in glaciers due to cooling.