LATE HOLOCENE GLACIAL-LACUSTRINE VARVE RECORDS FROM TWO PROGLACIAL LAKES IN NORDENSKIÖLDLAND, SVALBARD, NORWEGIAN HIGH ARCTIC

Varved sediments from proglacial lakes provide valuable long-term, high resolution paleoclimate and paleoenvironmental records in regions where instrumental records are commonly short-lived and other proxy-records lack detailed temporal resolution. This study presents preliminary data from two proglacial lakes in Svalbard, Norwegian high arctic: Linnévatnet, situated in the maritime setting in westernmost Spitsbergen and Bodalsvatnet, located in the interior plateau region of Nordenskiöldland. Surface cores (40-50 cm) and modified Nesje percussion cores (1.4 m) were recovered from both lakes in spring 2012.

Linnevatnet is a 4.7 km long basin at 12 m asl fed by an inwash delta 6 km from the margin of Linnebreen, a small polythermal cirque glacier. Sediment cores were recovered from a distal site in the central basin of the lake at 34 m depth. The sediments are finely laminated (mm to sub-mm) dark brown and tan clay-silt couplets that display a decreasing shift in median grain size from the base of the core to the top.

Sediment cores from Bodalsvatnet were recovered in a pilot survey of two small (~1km x 1km) lakes at 400 m asl dammed between two convergent Little Ice Age moraines and the adjacent valley wall. Cores from two sites at 15 and 16 meters depth contain distinct silt-clay varve couplets 2 to 10 mm thick. The composite short and long core record contains approximately 200 varves. The varve sequence is interrupted by fining upward units 10 to 30 mm thick which increase in frequency in the upper 80 to 90 varves.

Detailed analysis of the laminated sediments from both sites is in progress and includes plutonium (^239+240Pu) age determination to validate the annual lamination record, high resolution particle size analysis, and varve measurement from petrographic thin section.