Improving the Precision and Extending the Age Range of Luminescence Dating of Pleistocene Sediment

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9809354 Berger There is a dearth of accurate and precise numeric dating techniques for Pleistocene terrestrial sediment older than 40-50 ka, the usual limit of radiocarbon dating. Luminescence dating methods for unheated sediment have the potential (based on kinetics studies) to directly date detrital- feldspar burial time to well beyond 1 ma, a time period embracing at least half the Pleistocene and therefore many glacial-interglacial cycles. This award supports high- precision measurements on loess samples using the new, more precise, infra-red- stimulated-luminescence (IRSL) dating procedure. Use of this method is expected to improve luminescence- dating precision for loess by more than a factor of two, in the established time range for IRSL dating (400Ka). Companion termoluminescence (TL) measurements will be made on several samples to validate previous TL results and to improve their precision using more recent TL experimental protocols. Furthermore, both TL and IRSL measurements will be made on new loess samples to be collected from sites in Alaska and the Yukon Territory (Canada). These sites have newly documented independent numerical ages up to 2 Ma, based on paleomagnetic polarity-reversal boundaries and fission track ages of volcanic ash beds. Improved luminescence dating of Pleistocene terrestrial feldspars should benefit global efforts to extract time-series data from much of the Pleistocene land record.