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

The sedimentary characteristics, both past and present, of a small, no nglacial lake (i.e. a lake that does not presently receive significant quantities of glacial meltwater and sediment) in the Canadian High Ar ctic were investigated. It is hypothesized that gelifluction (soil mov ement under periglacial conditions) of soils within the watershed is c ontributing a significant amount of sediment to the lake through mudfl ows, and by continuous encroachment of soils towards the lake. Under m odern conditions, the annual contribution of lake shore gelifluction t o lake sedimentation is estimated at approximately 15 to 30%. The rema inder 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 respo nsible 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, t he contribution of sediment from inflows was significantly higher than today and the lake drainage area was more than double its present siz e, which increased the sedimentation rate over the last millennia to 0 .7 mm yr(-1). The inflow of the alluvial fan river obscured climatic m anifestations 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 contr ol of sedimentary processes in this lake.