CPSX Research Forum - How old is old on Mars?

How old is old on Mars? Finding a Martian isochron

Radu Dan Capitan, Ph.D. Researcher, Al I Cuza University, Romania

Abstract:

In-situ analysis of rocks, mapping, and orbital observations are used together to establish a planet’s surface history. At Gale crater, Mars, the K/Ar dating set a 4.21  0.35 billion years (Ga) ago for Bedded Fractured (BF) formation, with an end-member of 1.6 Ga ago, depending on the potassium concentration in the detrital fraction. Evidence that surface deposits at Yellowknife Bay were removed by erosion that also affected at a larger scale the entire northern Gale’s crater floor and beyond the depth of most current small-sized craters provides however hints on craters formation and evolution that can be traced and computed at different scales. This work addresses the dating of martian surfaces by combining morphometrical characteristics of craters and their accumulation statistics in a single age model. We establish that modifications of craters morphometry are concordant for craters at different successive spatial scales, and propose a parameter to quantify this concordance. We found that northern Gale crater floor formed 1691 0.014 Ga ago, in agreement with the isotope dating, and has been affected by resurfacing up to 88.34 0.716 Ma ago. We can thus confirm an Earth-like evolution of the Martian surface at the regional scale, and set premises to refine its geochronology.