Contemporary Sedimentary Environments on Baffin Island, N.W.T., Canada: Reconnaissance of Lakes on Cumberland Peninsula

Abstract

Studies were made of four lakes receiving significant quantities of glacial sediment, and of five lakes receiving no glacial sediment. All waters contain less than 10 mg L^-1 dissolved sediment, with highest values in the glacial lakes where ion scavenging can occur from fine suspended sediment. Zooplankton abundance and total carbon content of sediments are an order of magnitude higher in the nonglacial lakes.

Shallow box cores were taken in order to study the recent sediments. Two depositional environments can be recognized, one dominated by physical processes with higher rates of clastic sedimentation, and one dominated by chemical processes, especially iron/manganese concentration. In the former, which occurs in both glacial and nonglacial lakes, periodic high sediment inflow associated with glacial or nival melt, or with summer precipitation, produces distinct laminae. Although they contain less than 10% sand, grading and load structures indicate that these beds were probably deposited from underflows or interflows in the lake. Iron bands containing up to 39% by weight iron form where sedimentation occurs slowly and continuously under redox conditions which change as deposition occurs. Despite a very pronounced difference between winter and summer inflow to the lakes, varves could not be recognized in any of the sediments.