Martian Dune Fields: Aeolian Activity, Morphology, Sediment Pathways, and Provenance

Wind has likely been the dominant geologic agent for most of Mars’ history. The wide-spread nature of sand dunes there shows that near-surface winds have commonly interacted with plentiful mobile sediments. Early studies of these dunes suggested minimal activity, dominantly unidirectional simple dune morphologies, and little variations in basaltic sand compositions. This dissertation examines martian sand dunes and aeolian systems, in terms of their activity, morphologies, thermophysical properties, sand compositions, geologic contexts, and source-lithologies using new higher-resolution orbital data. Although previous evidence for contemporary dune activity has been limited, results presented in Chapter II show substantial activity in Endeavour Crater, Meridiani Planum. The translation and erosion of dunes there constitutes the largest contemporary movement of sand-sized sediment reported on Mars to date and demonstrates that Endeavour crater has been subject to wind profiles exceeding the threshold velocity at the surface (daily/seasonally and/or episodically) in the recent past. Global mapping has shown dune fields to dominantly occur in topographically benign locations (e.g., craters, polar basins), where the largest exception is the Valles Marineris (VM) rift system. Chapter III documents multiple occurrences of “wall dunes” found several kilometers above the canyon floor. These relatively unique dune morphologies show that wind blown sediment has interacted with local and regional topography and are relevant for understanding aeolian sediment flux, sediment sources, and wind directions. Chapter IV provides results of a low- to mid-latitude survey of all martian dune fields in comparison to the extensive dune population in VM to test the effect of local and regional environments on duneform properties. That study found VM dune fields to be qualitatively and quantitatively distinct from other dune populations, most readily attributed to the rift’s unusual setting. Sources and pathways of the martian sand have largely been uncertain. Chapter V documents likely sediment sources and pathways for the VM dune populations, where local and regional derivation of dune sand has occurred. We find in some chasmata dune sand is dominantly derived from Noachian-aged (altered and unaltered) igneous wall materials, whereas in other chasmata dunes are sourced from Early Hesperian-aged sulfate-bearing sedimentary layered deposits

Orbital evidence for more widespread carbonate-bearing rocks on Mars

Carbonates are key minerals for understanding ancient Martian environments because they are indicators of potentially habitable, neutral-to-alkaline water and may be an important reservoir for paleoatmospheric CO_2. Previous remote sensing studies have identified mostly Mg-rich carbonates, both in Martian dust and in a Late Noachian rock unit circumferential to the Isidis basin. Here we report evidence for older Fe- and/or Ca-rich carbonates exposed from the subsurface by impact craters and troughs. These carbonates are found in and around the Huygens basin northwest of Hellas, in western Noachis Terra between the Argyre basin and Valles Marineris, and in other isolated locations spread widely across the planet. In all cases they cooccur with or near phyllosilicates, and in Huygens basin specifically they occupy layered rocks exhumed from up to ~5 km depth. We discuss factors that might explain their observed regional distribution, arguments for why carbonates may be even more widespread in Noachian materials than presently appreciated and what could be gained by targeting these carbonates for further study with future orbital or landed missions to Mars

Orbital evidence for more widespread carbonate-bearing rocks on Mars

Carbonates are key minerals for understanding ancient Martian environments because they are indicators of potentially habitable, neutral-to-alkaline water and may be an important reservoir for paleoatmospheric CO_2. Previous remote sensing studies have identified mostly Mg-rich carbonates, both in Martian dust and in a Late Noachian rock unit circumferential to the Isidis basin. Here we report evidence for older Fe- and/or Ca-rich carbonates exposed from the subsurface by impact craters and troughs. These carbonates are found in and around the Huygens basin northwest of Hellas, in western Noachis Terra between the Argyre basin and Valles Marineris, and in other isolated locations spread widely across the planet. In all cases they cooccur with or near phyllosilicates, and in Huygens basin specifically they occupy layered rocks exhumed from up to ~5 km depth. We discuss factors that might explain their observed regional distribution, arguments for why carbonates may be even more widespread in Noachian materials than presently appreciated and what could be gained by targeting these carbonates for further study with future orbital or landed missions to Mars

Mars as a "natural laboratory" for studying surface activity on a range of planetary bodies

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Observing Mars from Areostationary Orbit: Benefits and Applications

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Forward-central two-particle correlations in p-Pb collisions at root s(NN)=5.02 TeV

Two-particle angular correlations between trigger particles in the forward pseudorapidity range (2.5 2GeV/c. (C) 2015 CERN for the benefit of the ALICE Collaboration. Published by Elsevier B. V.Peer reviewe

Event-shape engineering for inclusive spectra and elliptic flow in Pb-Pb collisions at root(NN)-N-S=2.76 TeV

Peer reviewe