Chemistry of sedimentary rocks at Gale crater, Mars: Alpha Particle X-ray Spectrometer (APXS) constraints.

Lucy M Thompson1, Ralf Gellert2, Mariek E Schmidt3, Jeff A. Berger4, Nick Boyd2, Beverley E. Elliott5, Betina Pavri6, Glynis M Perrett2, John G Spray5, Scott Van Bommel2 and Albert Yen6, (1)University of New Brunswick, Fredericton, NB, Canada, (2)University of Guelph, Guelph, ON, Canada, (3)Brock University, St Catharines, ON, Canada, (4)University of Western Ontario, London, ON, Canada, (5)University of New Brunswick, Planetary and Space Science Centre, Fredericton, NB, Canada, (6)NASA Jet Propulsion Laboratory, Pasadena, CA, United States

Contact First Author: Lucy M Thompson; lthompso@unb.ca

Abstract ID#: 34422

 

English Abstract:
Since landing within Gale crater, the MSL Curiosity rover has encountered a variety of sedimentary rocks as it traversed the crater floor, and since arriving at the base of Mount Sharp. Curiosity initially drove towards the Yellowknife Bay (YKB) area before driving towards Mount Sharp. Three waypoint locations: Darwin, Cooperstown, and the Kimberly were selected for more in-depth exploration by the rover along the route to Mount Sharp. Specifically, Curiosity’s APXS instrument has acquired 138 rock and soil analyses since landing and embarking along the traverse to Mount Sharp, recording a diversity of rock compositions. A further 37 APXS analyses of the Murray Formation at the base of Mount Sharp have also been obtained. This has enabled the classification of sedimentary rocks into several primary compositional classes:
  • The basaltic John Klein class, typified by the mudstones and siltstones encountered in YKB, as well as one sedimentary rock target at the base of Mount Sharp
  • The basaltic, high Cr2O3 (~0.8 %) Shaler class, typified by cross-stratified sandstones encountered as Curiosity exited YKB, as well as one sedimentary rock target at the base of Mount Sharp
  • The K2O (~3 %), MgO (9-13 %), MnO (~0.5 %), and Zn (1200-4000 ppm) rich, Bathurst class typified by sandstones encountered at a number of different locations along the traverse, including on Bradbury Rise, and at the Cooperstown and Kimberley waypoints
  • The moderate SiO2 (~50 %) and alkali (~4.8%) content Darwin class, typified by coarse grained to pebbly sandstones at the Darwin waypoint and several other conglomeratic outcrops
  • The low MgO (~5 %) and CaO (~4.1 %) Pahrump class, typified by mudstones and sandstones encountered within the Murray Formation at the base of Mount Sharp

We will examine how these classes, and comparisons to other, more likely igneous compositional classes, can be used to investigate provenance, as well as the diagenetic and alteration history of Gale crater sedimentary rocks.

Back to: Fluvial Landforms and Sedimentary Deposits on Planetary Surfaces