Optical Dating Studies of southeastern Patagonian Sand Wedges in Chile and Argentina

The purpose of this study was to establish a suitable single aliquot regenerative dose (SAR) optical dating protocol for K-feldspar sediments in southeast Patagonia using radiocarbon-dated Holocene dune sediments at Lago Arturo. The established protocol was then applied to sand wedge sediments found in the region in order to date periods of permafrost and to provide limiting ages on glaciation. The suitable SAR protocol incorporates a 200oC/10 s preheat for both the additive-dose and test dose measurements, a hot (290oC) bleach step at the end of each SAR cycle to reduce recuperation, and measurement of the stimulated luminescence at 50oC. A select number of sand wedges found throughout the region were dated using the established protocol. Those that yielded reliable ages date to the last glaciation. Some sand wedges provided older optical ages, however, more testing is required to determine if these ages are accurate.