Physical Sciences and Mathematics Commons^™

Investigating The Complexity Of Impact Crater Ejecta, Michael Raymond Zanetti

Arts & Sciences Electronic Theses and Dissertations

The formation of an impact crater ejecta blanket can be viewed as a form of organized chaos. Material that is ejected from a crater is heavily brecciated, but falls back to the surface along ballistic trajectories, generally preserving an inverted sense of the original stratigraphy. As the ejecta re-impacts the area surrounding the crater it forms a thick blanket of ejected material and reworked target surface that gradually thins away from the crater rim. Within the crater, crater modification processes, such as wall terrace formation and impact melt drainage, transform the crater in expectable ways.

The approach adopted in this …

Ion Interactions At The Mineral-Water Interface During Biogeochemical Iron And Manganese Cycling, Margaret A. G. Hinkle

Arts & Sciences Electronic Theses and Dissertations

The biogeochemical cycling of iron and manganese involves the reductive dissolution and oxidative precipitation of Fe(III) and Mn(IV/III) oxides. Biogenic Fe(III) and Mn(IV/III) oxides are often characterized by high surface areas and therefore high sorptive capacities. As a result, these minerals can substantially alter the chemistry of natural waters and the availability of micronutrients in soils and sediments by scavenging trace metals. Recent research indicates that the adsorption of aqueous Fe(II) onto Fe(III) oxides involves oxidative adsorption, electron transfer, and subsequent reductive dissolution at another surface site [a process collectively referred to as `electron transfer-atom exchange' (ET-AE)]. Aqueous Mn(II) adsorption …

Photometric Investigations Of Lunar Landing Sites And Silicic Regions Using Lro Narrow Angle Camera Images, Ryan Nicole Watkins

Arts & Sciences Electronic Theses and Dissertations

The reflectance properties of a planetary surface are related to the physical and compositional properties of that body. Photometry is a powerful method for determining differences in composition and regolith structure, and photometric data from orbital images coupled with soil sample data can greatly enhance our understanding of the regolith properties of our nearest neighbor, the Moon. At the time of writing, the United States has no operating missions on the Moon and no future plans to send robots or humans to study our nearest neighbor, so we must rely on remote sensing data to provide us with information about …