Optically stimulated luminescence dating properties of Martian sediment analogue materials exposed to a simulated Martian solar spectral environment

Abstract

Deciphering the geomorphic, climatic, and hydrologic history of Mars will require an extensive geochronology on numerous time scales from both returned samples and in-situ measurements. Optically stimulated luminescence dating (OSL), or optical dating, is an established terrestrial geochronological method that is being developed as a member of a suite of dating tools for Mars. As part of this development process, we have built an optical system simulating the calculated Martian solar spectral irradiance taking into account seasonal variations due to attenuation of dust and the planet's orbital position and used it to catalogue the UV dosimetric response and optical dating behavior of a group of sediment analogues exposed to a simulated Martian spectral environment (SMSE) for the surface of the planet. Our results suggest that optical dating should not be compromised by the interaction of the enhanced UV radiation in the Martian spectrum with K-feldspar, Ca-feldspar, anhydrite, or hydrous Ca and Mg sulfates on Mars. However, Na-feldspar appears to be capable of acquiring and retaining an OSL signal under SMSE conditions, which could present a challenge for optical dating on Mars in sedimentary deposits containing more than a trace quantity of sodic feldspars.