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In-Situ Dating on Mars Using the ID-Kard Technique
Date: Tuesday, June 3, 2014 Time: 4:00pm Location: 125 Steele, Caltech Speaker: Julia Ann Cartwright
KNI / MDL Seminar
Measuring absolute ages of rocks outcropping on the Martian surface is crucial for understanding the planet’s formation and evolution. Unlike the lunar surface, which has been dated using a combination of absolute dating of returned samples and crater counting techniques, the Martian surface lacks multiple age markers: we have no returned samples, and only a single in-situ age determination that was recently obtained by the Curiosity rover. Prior to this measurement, we have relied on crater counting techniques and a Mars/moon cratering ratio, which leads to significant uncertainties in absolute age estimates.
In this seminar, I will describe our novel technique – ID-KArD (Isotope Dilution K-Ar Dating) – intended for in-situ age dating of geological units on Mars. ID-KArD resolves two challenges that have previously hindered in-situ age dating on other planetary bodies: 1) High fusion temperatures are avoided with the use of a lithium-borate flux; and more importantly 2) Sample mass measurement is not required, due to the addition of an isotope dilution doubly-spiked glass. As the glass has a known 39Ar/41K ratio, the need for concentration measurements is removed, and only isotope ratios are required for a K-Ar age determination. This research is still ongoing and proof-of-concept, and includes the design and construction of a unique instrument at Caltech capable of K-Ar dating using ID-KArD. Overall, ID-KArD has the potential to address Mars chronology inaccuracies, and has been incorporated into a mission proposal for consideration on the Mars 2020 rover.