Isostatic adjustments in a full glacial sea

Abstract

During the last glaciation an ice-free corridor existed between the northeastern Ellesmere Island and northwestern Greenland ice sheets. This corridor constituted a peripheral depression in which the marine limit marks the uppermost extent of a full glacial sea. The full glacial sea is characterized by 14C dates on in situ marine shells that predate initial emergence (unloading) followed by synchronous emergence from the marine limit throughout the peripheral depression. Relative sea-level curves from the full glacial sea confirm previous morphostratigraphic and glacioisostatic evidence for limited ice extent during the last glaciation. These curves also document the history of glacial unloading and the form of the relative sea-level curve that one would theoretically expect in the peripheral depression. The form of the curves presented here is unlike any other published emergence curves from arctic Canada or from Fennoscandia. The relative sea-level curves for northeastern Ellesmere Island show 3 segments: an interval of stable relative sea level (isostatic equilibrium) at the marine limit between at least 11,000 and 8000 B.P.; an interval of slow emergence from 8000-6200 B.P. during which northeastern Ellesmere Island ice slowly retreated; and an interval of rapid emergence, caused by rapid glacial unloading, after 6200 B.P. when a prominent amelioration was in progress. These relative sea-level curves are discussed in relation to other paleoclimatic changes and the deglacial history of northwestern Greenland. These curves are of regional importance in that they provide a new means of distinguishing between areas that were ice covered and ice free during the last glaciation.