GSA Annual Meeting in Indianapolis, Indiana, USA - 2018

Paper No. 239-12
Presentation Time: 11:35 AM


FILIBERTO, Justin1, HERD, Christopher D.K.2, BEATY, David W.3, MCSWEEN Jr., Harry Y.4, SEFTON-NASH, Elliot5, CARRIER, Brandi L.3, SCHWENZER, Susanne P.6, GRADY, Monica7 and IMOST, Team, (1)Lunar and Planetary Institute, USRA, 3600 Bay Area Blvd, Houston, TX 77058, (2)Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton, AB, Canada, (3)Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr, Pasadena, CA 91109-8001, (4)Earth and Planetary Sciences, University of Tennessee, Knoxville, TN 37996, (5)ESTEC, European Space Agency, Keplerlaan 1, Noordwijk, 2201AZ, Netherlands, (6)School of Environment, Earth and Ecosystem Sciences, The Open University, Walton Hall, Milton Keynes, MK7 6AA, United Kingdom, (7)Open University, Milton Keynes, United Kingdom

Return of samples from the surface of Mars has been a goal of the international Mars science community for many years. Affirmation by NASA and ESA of the importance of Mars exploration led the agencies to establish the international MSR Objectives and Samples Team (iMOST). The purpose of the iMOST team is to re-evaluate and update the sample-related science and engineering objectives of a Mars Sample Return (MSR) campaign. Here we will present a subset of these goals focusing on the importance of MSR to understanding the Martian interior.

The chemistry and mineralogy of the Martian interior is largely constrained by the type of samples we have of Mars – martian meteorites – with inputs from geophysics, surface rover analyses of igneous rocks, and orbital analyses of the crust. However, comparisons of martian meteorites and igneous rocks analyzed on the surface of Mars show that martian meteorites do not represent average martian crust or magmas. Young Martian meteorites and ancient igneous rocks analyzed in situ by rovers have different elemental compositions, suggesting different source regions – this could be confirmed by radiogenic isotope data and chronology on returned samples; these differences are attributable to a sampling bias inherent the process that delivered the meteorites to Earth. Therefore, a proposed iMOST objective would be to use samples of igneous rocks - either in place or transported - with a range of compositions and an emphasis on older (>3.5 Ga) ages, to help reconstruct the processes that have affected the origin and modification of the interior. Understanding the petrogenesis of igneous rocks sampled from well-documented locations from a well-constrained igneous unit would provide novel insights into the physical properties of martian magmas; the composition(s) of their mantle sources including major, trace, and volatile elements, noble gases, and isotopic characteristics; the conditions of magma genesis; the timing and duration of igneous activity; and subsequent modification by secondary processes.