title: The stratigraphy and evolution of lower Mount Sharp from spectral, morphological, and thermophysical orbital data sets.
abstract: We have developed a refined geologic map and stratigraphy for lower Mount Sharp using coordinated analyses of new spectral, thermophysical, and morphologic orbital data products. The Mount Sharp group consists of seven relatively planar units delineated by differences in texture, mineralogy, and thermophysical properties. These units are (1-3) three spatially adjacent units in the Murray formation which contain a variety of secondary phases and are distinguishable by thermal inertia and albedo differences, (4) a phyllosilicate-bearing unit, (5) a hematite-capped ridge unit, (6) a unit associated with material having a strongly sloped spectral signature at visible near-infrared wavelengths, and (7) a layered sulfate unit. The Siccar Point group consists of the Stimson formation and two additional units that unconformably overlie the Mount Sharp group. All Siccar Point group units are distinguished by higher thermal inertia values and record a period of substantial deposition and exhumation that followed the deposition and exhumation of the Mount Sharp group. Several spatially extensive silica deposits associated with veins and fractures show that late-stage silica enrichment within lower Mount Sharp was pervasive. At least two laterally extensive hematitic deposits are present at different stratigraphic intervals, and both are geometrically conformable with lower Mount Sharp strata. The occurrence of hematite at multiple stratigraphic horizons suggests redox interfaces were widespread in space and/or in time, and future measurements by the Mars Science Laboratory Curiosity rover will provide further insights into the depositional settings of these and other mineral phases.
authors.affiliation: Jet Propulsion Laboratory California Institute of Technology Pasadena California USA.
authors.forename: A A
authors.initials: AA
authors.lastname: Fraeman
authors.affiliation: Jet Propulsion Laboratory California Institute of Technology Pasadena California USA; Division of Geological and Planetary Sciences California Institute of Technology Pasadena California USA.
authors.forename: B L
authors.initials: BL
authors.lastname: Ehlmann
authors.affiliation: Department of Earth and Planetary Sciences Washington University in St. Louis St. Louis Missouri USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Arvidson
authors.affiliation: United States Geological Survey Flagstaff Arizona USA; Department of Physics and Astronomy Northern Arizona University Flagstaff Arizona USA.
authors.forename: C S
authors.initials: CS
authors.lastname: Edwards
authors.affiliation: Division of Geological and Planetary Sciences California Institute of Technology Pasadena California USA.
authors.forename: J P
authors.initials: JP
authors.lastname: Grotzinger
authors.affiliation: Department of Earth, Environmental and Planetary Sciences Brown University Providence Rhode Island USA.
authors.forename: R E
authors.initials: RE
authors.lastname: Milliken
authors.affiliation: Division of Geological and Planetary Sciences California Institute of Technology Pasadena California USA.
authors.forename: D P
authors.initials: DP
authors.lastname: Quinn
authors.affiliation: Geology Department, Physics and Astronomy Department Western Washington University Bellingham Washington USA.
authors.forename: M S
authors.initials: MS
authors.lastname: Rice
keywords: Mount Sharp; orbital mapping; remote sensing; spectroscopy; stratigraphy