Rock glaciers in the southern chukchi peninsula

Abstract

About 550 rock glaciers of different types were identified on the basis of remote sensing and field studies in the Southern Part of the Providcnskiy mountain massif (the Chukchi Plateau). The measured occurrence frequency of rock glaciers of about 8 units/km2 is the highest in the North-East Asia. All known morphodynamic types of rock glaciers were found: Tongue-shaped cirque-associated, lobate-shaped slope-associated and complex ones. Rock glaciers were found over the entire elevation range starting from the sea level. The slope-associated multi-lobate rock glaciers of abnormal sizes, as well as the ice-ground dams are the most widespread ones and they concentrate in linear zones along the sides ofneotectonicgrabens and fracture zones. They were distinguished as a particular type offault-associated rock glaciers. A specific feature of rock glaciers of the Providcnce massif is the thawed bed that causes water infiltration under the front generations, which is similar to "warm" glaciers and rock glaciers of Europe and Central Asia, while in the Mountains of Northeast Asia within the continuous permafrost zone rock glaciers have frozen bed, and their temperatures arc significantly below zero. The age of active rock glaciers of Povidcnskiy massif is not more than 2-2.5 kyr. We attribute their formation to the specific features of the Last Glaciation decay under the conditions of Marine Arctic climate. The increasing role of cryogenic mass movement during the Late Glacial Stage promoted the burial of ice and frozen moraine blocks in the glacial cirques and at valley sides and predetermined their subsequent transformation into rock glaciers.