PALEOCLIMATE RECONSTRUCTION USING LAMINATED SEDIMENTS FROM A HIGH ARCTIC ISOLATION BASIN: DEPOT POINT LAKE, CORNWALLIS ISLAND, NUNAVUT, CANADA

Annually laminated sediments from high arctic coastal lakes may provide valuable high-resolution records of Holocene paleoenvironmental change. The coastal lakes, or isolation basins, have evolved from marine inlets and fiords due to postglacial isostatic uplift and subsequent trapping of seawater in the basins. Anoxia in the bottom waters favors preservation of finely laminated sediments by precluding bottom fauna. High arctic lakes have distinctly seasonal sediment inputs primarily from snow and glacier-melt runoff in the summer melt season.

In this study (in progress), two vibracores up to 4.96m in length from Depot Point Lake are investigated. The lake is located on southeastern Cornwallis Island (75º45'N, 93º39'W) and is presently at 12m ASL; it is a freshwater lake or isolation basin. The sediment cores contain up to 2.83m of finely laminated sediments overlying massive marine mud. AMS 14C ages on mollusk valves in the marine mud range from ca. 5760+ 40 B.P. near the top of the massive mud to 9120 + 40 B.P. near the base of the cores. Variations in lamination structure and thickness, organic matter content (%LOI) and sediment particle size are proxies examined in this study to determine past environmental changes that may be controlled by changes in temperature and precipitation through the Holocene.