Abstract of Climate Change on Mars: The Nature and History of Non-Polar Ice-Rich Deposits, by Seth Kadish, Ph.D., Brown University, May 2011.

Kadish, Seth J.

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Year:: 2011
Contributor:: Kadish, Seth J (creator); Head, James (Director); Mustard, John (Reader); Huang, Yongsong (Reader); Herbert, Timothy (Reader); Fastook, James (Reader); Brown University. Geological Sciences (sponsor)
Genre:: theses
Subject:: Mars; Climate; Craters; Climatology; Ice; Mars (Planet)
Extent:: xviii, 288 p.
DOI: https://doi.org/10.7301/Z09S1P9G

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Abstract:: This dissertation explores the recent history of non-polar ice-rich paleodeposits on Mars, primarily through the analysis of pedestal craters. Pedestal craters are defined by having a crater bowl perched near the center of a plateau that is surrounded by a marginal outward-facing scarp. This work documents significant evidence that they result from impacts into ice-rich material deposited at mid latitudes during periods of climate change resulting from excursions to higher obliquity. The impact armors the proximal surface. When the obliquity lowers, the icy substrate sublimates and deflates from the intercrater terrain, but it is preserved beneath the indurated pedestal surfaces. Chapter one details the evidence for a climate-related formation mechanism, including the latitude-dependent distribution of pedestal craters, which form poleward of ~35�, their circular planform, and the presence of sublimation pits located on the marginal scarps of some pedestals. Chapter two investigates a high-latitude subsample of the pedestal crater population that exhibits layers along the craters� scarps, including one on the south polar layered deposit. These provide evidence that pedestal craters are capable of preserving layered ice-rich material. Chapter three extrapolates implications about the thicknesses of ice-rich deposits on the basis of the heights of pedestal craters, outlining the geographic regions in which pedestals are particularly tall. The presence of pedestals that are superposed or draped on other pedestals provides evidence that the formation process is recurring. Chapter four considers two other crater morphologies: excess ejecta craters and perched craters. Through a geographic, age, and physical comparison, the morphologies are shown to be genetically related to pedestal craters, resulting from impacts into similar ice-rich substrates. Chapter five discusses the periodicity and pathways that ice-rich material may take from the poles to the mid and low latitudes. Data for the emplacement duration and recurrence of ice-rich material are placed in the context of climate model predictions. This yields a possible obliquity history for the past 200 Myr on Mars, and leads to the identification of significant climatic shifts.
Notes:: Thesis (Ph.D. -- Brown University (2011)

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Kadish, Seth J., "Abstract of Climate Change on Mars: The Nature and History of Non-Polar Ice-Rich Deposits, by Seth Kadish, Ph.D., Brown University, May 2011." (2011). Earth, Environmental and Planetary Sciences Theses and Dissertations. Brown Digital Repository. Brown University Library. https://doi.org/10.7301/Z09S1P9G

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Earth, Environmental and Planetary Sciences Theses and Dissertations

Theses and Dissertations for the Earth, Environmental and Planetary Sciences department.
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