STRATIGRAPHY AND SEDIMENTOLOGY OF THE MURRAY FORMATION, AS OBSERVED USING THE MARS SCIENCE LABORATORY CURIOSITY ROVER

Since landing in Gale crater, the Mars Science Laboratory Curiosity rover has investigated more than 350 m of stratigraphy, revealing a rich array of clastic sedimentary rocks. Gale is a 154 km diameter impact crater located on fluvially-dissected, cratered highlands bedrock along the martian dichotomy. For more than 1200 sols, the rover has been used to explore the Murray formation, which represents more than 300 m of stratigraphy and forms the lowermost stratal package of the crater’s central mound, Aeolis Mons. The Murray formation is a diverse package of sedimentary facies, interpreted to consist predominantly of mudstones deposited in a lacustrine setting. Most recently, the rover team has been exploring a prominent geomorphic and spectrally distinctive landform known as Vera Rubin Ridge (VRR), searching for changes in composition and depositional environment. The majority of the strata explored on VRR are characterized by a fine-grained facies (grain sizes of very fine sand and smaller) exhibiting continuous planar lamination. Individual laminae are generally ~0.6-0.7 mm thick and can be traced laterally for several meters. Outcrops at the base of the section are crosscut by abundant fine fractures and curvi-planar calcium sulfate veins. At higher elevations along the ridge, there is a distinct boundary that marks a transition to more variable facies with notable color differences. A few isolated outcrops reveal decimeter to meter-scale inclined strata that dip in multiple directions, which hint at possible slumping and deformation (still under investigation). Minor outcrops of low-angle stratification suggest possible interruption by eolian or subaqueous transport processes in what was otherwise a continuous record of lacustrine sedimentation. This is consistent with prior observations of the Murray formation, and the strata in the ridge appear to be a continuation of the Murray formation with no significant observable gaps in the stratigraphic record. Collectively, the rocks exposed at VRR provide additional evidence for a long-lived lacustrine environment, recording the progressive infilling of the Gale crater basin.