Surficial mapping of the Cape Espenberg-Devil Mountain region and lake-core analyses from North Killeak Lake, Bering Land Bridge National Preserve, Western Alaska
University of Massachusetts at Amherst
The landscape of the Cape Espenberg-Devil Mountain (CEDM) region, located in the northern portion of Seward Peninsula, western Alaska, has been the site of multiple maar eruptions during the Quaternary. These volcanic eruptions, characterized by widespread deposition of basaltic tephra on the landscape, have been hypothesized to have erupted explosively when rising magma came in contact with the permafrost underlying the CEDM region. Surficial mapping of the region, including field reconnaissance visits during the summer of 1992, indicate that basaltic tephra originating from the maar eruptions is a dominant sediment component within many CEDM surficial deposit units. Long continuous records of environmental change in the CEDM region are difficult to decipher from the thermokarst lacustrine sediments dominating the surficial geology due to the relatively brief timespan of individual basins on the landscape, Conversely, five lakes which have formed within basins created by maar eruptions provide a unique opportunity for recovery of long sedimentary records from the CEDM region. These lakes, listed in order of decreasing depth and increasing age, are South and North Devil Mountain Lake (contemporaneous formation), South Killeak Lake, North Killeak Lake and Whitefish Lake. As a precursor to coring of North Killeak Lake, bathymetric measurements were made during the summer of 1992. From the bathymetric data, the deep basin in North Killeak Lake was identified and subsequently cored during the spring of 1993. Two cores, NK-2 (5.96 m in length) and NK-3 (6.84 m), were retrieved from the central basin of the lake. The cores were analyzed for wet density, water content, loss on ignition (LOI), biogenic silica content, magnetic susceptibility and grainsize. Additional samples for diatoms, pollen and organic geochemistry were sampled for analyses by collaborating researchers. Based on the results of the above analyses, the sedimentation history of North...
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