SEDIMENTOLOGY OF COLOR LAKE, A NONGLACIAL HIGH ARCTIC LAKE, AXEL-HEIBERG ISLAND, NWT, CANADA

The sedimentary characteristics, both past and present, of a small, nonglacial lake (i.e. a lake that does not presently receive significant quantities of glacial meltwater and sediment) in the Canadian High Arctic were investigated. It is hypothesized that gelifluction (soil movement under periglacial conditions) of soils within the watershed is contributing a significant amount of sediment to the lake through mudflows, and by continuous encroachment of soils towards the lake. Under modern conditions, the annual contribution of lake shore gelifluction to lake sedimentation is estimated at approximately 15 to 30%. The remainder of the modern annual sedimentation rate of 0.2 mm yr(-1) is made up mostly by stream inflow, which also contains geliflucted sediments. Late Holocene environmental change was also traced through study of sediments from sediment cores. During the late Holocene, a river responsible for building an alluvial fan at one end of the lake flowed into the lake (it now flows away from the lake). Throughout this period, the contribution of sediment from inflows was significantly higher than today and the lake drainage area was more than double its present size, which increased the sedimentation rate over the last millennia to 0.7 mm yr(-1). The inflow of the alluvial fan river obscured climatic manifestations in the sediments, but it is believed that lake ice cover extent, interpreted by the alteration of laminated or massive strata, reflects climatic change. Lake ice is the single most important control of sedimentary processes in this lake.