ABSTRACT: Geomorphic and climatic implications of the sedimentary record in glacier-fed lakes of the Southern Canadian Cordillera

CGRG Bibliography of Canadian Geomorphology
Search Results

Author :

Date :

Title :

Publication :

Issue :

Page(s) :

Abstract

The sedimentary record of 15 glacier-fed lakes in the southern Canadian Cordillera have been investigated to establish the link between observed sediment flux, lake depositional processes and the rates and control of sediment conveyance through the contributing drainage basin. Lakes were selected to represent a range in modern climate types that typically occur in large mountainous regions. This range in climates provides a spatial analogue for climate variability experienced at any one site throughout the Holocene. Results indicate that the rate and style of sediment delivery varies significantly even when glacier coverage may be similar. For several of the lakes, varve sediments form sequences that begin and end abruptly. Intervening periods are characterized by a sedimentary regime that produces massive or diffusely laminated sediment. The distinct boundary is not uniquely linked to a rapidly ameliorating Holocene climate but can be accounted for by an increase in the probability of sediment storage in the upper lake and watershed such as deltas, floodplains and smaller lakes. Glacier extent, erosion potential and the degree of sediment storage together define a critical threshold. For conditions above this threshold the sediment delivery ratios are high enough to accentuate the seasonal contrast in sediment yield leading to well laminated sediments. Sensitivity of the sediment record to either persistent or abrupt climate changes is reduced unless the system at or near the threshold. The implication of these results is that there are important geomorphic factorscontrolling sediment delivery processes that may not be directly linked to climate forcing.

Bibliography of Canadian Geomorphology