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April 21, 2017: A Young K-Ar Age of Jarosite in the Mojave 2 Sample at Gale Crater, Mars

Posted on Mar 31, 2017 in Seminars

Peter Martin (Caltech)

Talk Title: A Young K-Ar Age of Jarosite in the Mojave 2 Sample at Gale Crater, Mars

Abstract: Although the relative timing of surface processes on Mars is relatively well constrained, the absolute timing of these events remains uncertain due to the inherent limitations of crater counting geochronology. The Curiosity rover has the demonstrated ability to measure the bulk K-Ar ages of rocks; an age of 4.21±0.35 Ga was measured early in the mission. A recent sample collected by Curiosity contains a relatively large proportion of jarosite, so a two-step heating experiment was conceived to allow separate measurement of the plagioclase (detrital) and jarosite (authigenic) ages. The low-temperature step (authigenic) yields a bulk age of 1.72 [+0.34, -0.30] Ga, while the high temperate step revealed a plagioclase age of 3.5 [+0.8, -0.6] Ga. The unexpectedly young age of the authigenic materials suggests relatively recent fluid flow in Gale Crater.