LACUSTRINE RECORD OF HOLOCENE PALEOENVIRONMENTS FROM SHAININ LAKE, BROOKS RANGE, ARCTIC ALASKA

Placing recent warming in the context of long-term natural climate variability is imperative to understand modern global warming. Quantitative pre-instrumental temperature records are scarce in Alaska, let alone the Arctic. To generate information about past climate, we cored Shainin Lake, situated on the northern margin of the central Brooks Range. In spring 2013, we recovered 17 sediment cores, a total of 15 meters, from water depths ranging from 5-15 m. We generated preliminary age-depth models for our two longest cores based on 12 radiocarbon ages and found basal ages of 10700 ± 64 cal yr BP and 4265 ± 300 cal yr BP. Additional radiocarbon ages are pending. Sediments are brown-colored, clay-rich, highly laminated (not varved), and have no visible macrofossil, tephra layers, or marl deposition. We used a non-destructive high-resolution core-scanning visible reflectance spectroscopy to measure chlorin (chlorophyll and derivatives) content in the sediment cores. Inferred chlorin was recently found to have a high degree of correlation with summer temperature, and used to generate a 5700-yr-long paleotemperature record from Kurupa Lake, situated on the northern side of the Brooks Range 160 km to the west of Shainin Lake. Our goal is to see if the record from Kurupa Lake has any similarities to the chlorin record in Shainin Lake. Generating lacustrine records of environmental change from the Brooks Range will add to longer-term records from this region that place present warming and sea ice reduction in the western Arctic into the context of the Holocene.