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Description
Understanding the structural evolution of planetary surfaces provides key insights to their physical properties and processes. On the Moon, large-scale tectonism was thought to have ended over a billion years ago. However, new Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) high resolution images show the Moon’s surface in

Understanding the structural evolution of planetary surfaces provides key insights to their physical properties and processes. On the Moon, large-scale tectonism was thought to have ended over a billion years ago. However, new Lunar Reconnaissance Orbiter Camera (LROC) Narrow Angle Camera (NAC) high resolution images show the Moon’s surface in unprecedented detail and show many previously unidentified tectonic landforms, forcing a re-assessment of our views of lunar tectonism. I mapped lobate scarps, wrinkle ridges, and graben across Mare Frigoris – selected as a type area due to its excellent imaging conditions, abundance of tectonic landforms, and range of inferred structural controls. The distribution, morphology, and crosscutting relationships of these newly identified populations of tectonic landforms imply a more complex and longer-lasting history of deformation that continues to today. I also performed additional numerical modeling of lobate scarp structures that indicates the upper kilometer of the lunar surface has experienced 3.5-18.6 MPa of differential stress in the recent past, likely due to global compression from radial thermal contraction.

Central pit craters on Mars are another instance of intriguing structures that probe subsurface physical properties. These kilometer-scale pits are nested in the centers of many impact craters on Mars as well as on icy satellites. They are inferred to form in the presence of a water-ice rich substrate; however, the process(es) responsible for their formation is still debated. Previous models invoke origins by either explosive excavation of potentially water-bearing crustal material, or by subsurface drainage of meltwater and/or collapse. I assessed radial trends in grain size around central pits using thermal inertias calculated from Thermal Emission Imaging System (THEMIS) thermal infrared images. Average grain size decreases with radial distance from pit rims – consistent with pit-derived ejecta but not expected for collapse models. I present a melt-contact model that might enable a delayed explosion, in which a central uplift brings ice-bearing substrate into contact with impact melt to generate steam explosions and excavate central pits during the impact modification stage.
ContributorsWilliams, Nathan Robert (Author) / Bell, James (Thesis advisor) / Robinson, Mark (Committee member) / Christenen, Philip (Committee member) / Farmer, Jack (Committee member) / Shirzaei, Manoochehr (Committee member) / Arizona State University (Publisher)
Created2016
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Description
On Mars, sedimentary deposits reveal a complex history of water- and wind-related geologic processes. Central mounds – kilometer-scale stacks of sediment located within craters – occur across Mars, but the specific processes responsible for mound formation and subsequent modification are still uncertain. A survey of central mounds within large craters

On Mars, sedimentary deposits reveal a complex history of water- and wind-related geologic processes. Central mounds – kilometer-scale stacks of sediment located within craters – occur across Mars, but the specific processes responsible for mound formation and subsequent modification are still uncertain. A survey of central mounds within large craters was conducted. Mound locations, mound offsets within their host craters, and relative mound heights were used to address various mound formation hypotheses. The results suggest that mound sediments once filled their host craters and were later eroded into the features observed today. Mounds offsets from the center of their host crater imply that wind caused the erosion of central mounds. An in depth study of a single central mound (Mt. Sharp within Gale crater) was also conducted. Thermal Emission Imaging System Visible Imaging Subsystem (THEMIS-VIS) mosaics in grayscale and false color were used to characterize the morphology and color variations in and around Gale crater. One result of this study is that dunes within Gale crater vary in false color composites from blue to purple, and that these color differences may be due to changes in dust cover, grain size, and/or composition. To further investigate dune fields on Mars, albedo variations at eight dune fields were studied based on the hypothesis that a dune’s ripple migration rate is correlated to its albedo. This study concluded that a dune’s minimum albedo does not have a simple correlation with its ripple migration rate. Instead, dust devils remove dust on slow-moving and immobile dunes, whereas saltating sand caused by strong winds removes dust on faster-moving dunes.

On the Moon, explosive volcanic deposits within Oppenheimer crater that were emplaced ballistically were investigated. Lunar Reconnaissance Orbiter (LRO) Diviner Radiometer mid-infrared data, LRO Camera images, and Chandrayaan-1 orbiter Moon Mineralogy Mapper near-infrared spectra were used to test the hypothesis that the pyroclastic deposits in Oppenheimer crater were emplaced via Vulcanian activity by constraining their composition and mineralogy. The mineralogy and iron-content of the pyroclastic deposits vary significantly (including examples of potentially very high iron compositions), which indicates variability in eruption style. These results suggest that localized lunar pyroclastic deposits may have a more complex origin and mode of emplacement than previously thought.
ContributorsBennett, Kristen Alicia (Author) / Bell, James F. (Thesis advisor) / Christensen, Phillip (Committee member) / Clarke, Amanda (Committee member) / Robinson, Mark (Committee member) / Whipple, Kelin (Committee member) / Arizona State University (Publisher)
Created2016
ContributorsButler, Robb (Conductor) / McCreary, Kimilee (Conductor) / Bakko, Nicki L. (Conductor) / Schreuder, Joel (Conductor) / Larson, Matthew (Performer) / Ortman, Mory (Performer) / Graduate Chorale I (Performer) / Graduate Chorale II (Performer) / ASU Library. Music Library (Publisher)
Created1999-12-02
ContributorsMack, Christopher G. (Conductor) / Medlock, Jeffrey A. (Conductor) / Carr, Phillip (Conductor) / Neufeld, Charles (Conductor) / Gust, Leighton (Conductor) / Staininger, Lynn (Performer) / Woodrow, Marie (Performer) / Capps, Ferald (Performer) / Graduate Chorale I (Performer) / Graduate Chorale II (Performer) / ASU Library. Music Library (Publisher)
Created1991-02-21
ContributorsKlevberg, Janet (Performer) / McCreary, Kimilee (Performer) / Samuelsen, Thea (Performer) / Weber, Steven T (Performer) / Vollema, Donald (Performer) / Woodrow, Marie (Performer) / Graduate Chorale (Performer) / Recital Chorale (Performer) / ASU Library. Music Library (Publisher)
Created1990-02-22
ContributorsKoloch, Bradley (Performer) / Robinson, Mark (Performer) / Shaffer, Richard (Performer) / Woodrow, Marie (Performer) / Samuel, Christopher (Performer) / Listerud, L. Brian (Performer) / Graduate Chorale (Performer) / Recital Chorale (Performer) / ASU Library. Music Library (Publisher)
Created1989-11-16
ContributorsWeber, Steven T (Performer) / Robinson, Mark (Performer) / Copeland, Jill (Performer) / Darrough, Galen P. (Performer) / Nemko, Deborah (Performer) / Arizona Statesmen (Performer) / Women's Choir (Performer) / ASU Library. Music Library (Publisher)
Created1990-04-26
ContributorsRobinson, Mark (Conductor) / Shryock, Darin W. (Conductor) / Shaffer, Richard (Conductor) / Topping, David (Conductor) / Engelson, Robert (Performer) / Kelly, Kathleen (Performer) / Graduate Chorale (Performer) / Recital Chorale (Performer) / ASU Library. Music Library (Publisher)
Created1989-02-23
ContributorsZeeman Rugen, Kira (Conductor) / Banta, Joanna (Performer) / Huff, Michael (Conductor) / Li, Lin (Performer) / Graduate Chorale I (Performer) / Graduate Chorale II (Performer) / ASU Library. Music Library (Publisher)
Created2001-11-29
ContributorsCarter, Julie (Performer) / Gust, Leighton (Performer) / Staininger, Lynn (Performer) / Topping, David (Performer) / Woodrow, Marie (Performer) / Graduate Chorale (Performer) / Recital Chorale (Performer) / ASU Library. Music Library (Publisher)
Created1990-11-29