SEDIMENTARY AND GEOCHEMICAL PROXIES FOR LITTLE ICE AGE PALEOENVIRONMENTAL RECONSTRUCTIONS, SOUTH MAINLAND SHETLAND

The Old House of Brow, a 17^th century archaeological site, located in South Mainland Shetland was believed to have been inhabited for a short period of time before massive sand blows completely buried the home over a period of a few years. It is currently hypothesized that the massive sand blows may be connected to shifts in the maritime climate that Shetland experiences, associated with the climatic deterioration of the Little Ice Age. Previous investigations indicate deposition of thick sand layers sandwiched between organic sediments in nearby lochs, but the timing and mechanisms of deposition have yet to be determined. Eight cores retrieved from the Loch of Spiggie and the Loch of Brow, both in close proximity to the site were studied using a suite of geochemical, sedimentological, and geochronological analyses that serve as proxies to evaluate environmental shifts through time. Analyses performed include, bulk organic matter stable isotope analysis, biogenic silica, higher plant leaf wax biomarkers, grain size analysis, percent loss on ignition, magnetic susceptibility, and plutonium dating. The objectives of this study are to: (1) compare sedimentary proxies to examine changes in land cover, (2) identify changes in terrestrial production inputs over the last several hundred years B.P, and (3) develop a chronology that will be used to establish the relative age of the minerogenic layer found within the basin of the Loch of Brow. Contiguous coarse-grained sediments can be seen in the middle of most cores. The presence of this minerogenic layer was confirmed in the Loch of Brow through spikes in magnetic susceptibility, an increase in grain size within the unit, and visual identification. Bulk organic stable isotope analysis indicates a relatively stable carbon isotope signal with δ¹³C values ranging between -27‰ and -30‰. Stable nitrogen isotope analysis has indicated δ¹⁵N values of 1-2‰ at the bottom of the core, with an up core enrichment seen where δ¹⁵N values increase up to 5‰. The geochemical and physical dataset to be analyzed over the next few months will be presented in the context of both environmental significance and climatic variability.