IN-SITU GEOCHRONOLOGY FOR MARTIAN DUNES: A REVIEW OF OPTICAL DATING CONCEPTS AND EXPERIMENTS WITH ANALOG MATERIALS. K. Lepper. Optical Dating and Dosime-

Introduction: Eolian dunes are a direct geomorphic expression of the dynamic interaction between the atmosphere and the lithosphere of planets. The timing, frequency and spatial extent of dune mobility reflect changing climatic conditions. However, one of the greatest challenges to deciphering the record of climate variability on Mars will be the need for absolute dating techniques, particularly those techniques applicable to the timeframes and materials involved in Mars surface processes [1]. Lepper and McKeever [2-4] have proposed developing optical dating (a.k.a. OSL), an established terrestrial Quaternary dating method based on principles of solid-state physics, for remote in-situ application to Martian sediments. Eolian transport provides the optimal conditions for successful optical dating and the technique has been used successfully to make absolute age determinations for numerous terrestrial eolian deposits (reviewed in [5, 6]). The MER rovers and the orbital instruments OMEGA and CRISM have identified sulfate minerals as important constituents of Mars surface deposits. Orbital observations also suggest that sulfates may be concentrated by eolian processes and may occur as primary components of dunes (Fig. 1). The goals of this presentation are to introduce optical dating to the community of planetary scientists that are conducting research on dunes and to review nearly a decade of OSL experimental work with terrestrial analogs of Mars surface sediments focusing on our recent work with sulfate minerals.