Origin, Morphology, and Chronology of Sublacustrine Moraines, Generator Lake Baffin Island, Northwest Territories, Canada

Abstract

The morphology and chronology of exposed sublacustrine moraines is discussed. These are shown to have been formed in a sublacustrine environment. The moraines are characterized by their occurrence in large numbers within a former ice dammed lake basin and by their asymmetric cross section. Using moraine volume estimates combined with the time control, a till depositional rate is calculated.A radiocarbon chronology for the Generator Lake area over the last 4500 years is presented.Hydrological relationships are established which are shown to influence the formation of sublacustrine moraines. The relationships are physically connected and are not empirical. Current studies of the calving ice front at Generator Lake show that moraines must be forming under the tapered ice ramps which flow into the lake. Measurements of debris content within the ice combined with ice flow rate measurements show that the present till supply rates are consistent with those calculated from the exposed moraine field.A model is set up which connects the lake hydrology with the existence or destruction of the ice ramps, as controlled by bending induced by buoyancy forces. The time of existence and subsequent behavior of the ramps is shown to influence the geometry and indirectly the spacing of the sublacustrine moraines.