Date of Award

Spring 8-31-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

First Advisor

Gregory E. Tucker

Second Advisor

Robert S. Anderson

Third Advisor

Shannon A. Mahan

Fourth Advisor

Harihar Rajaram

Fifth Advisor

D. Nathan Bradley

Abstract

Sediment tracing over long timescales (10,000 - 100,000's of years) is difficult because of a lack of applicable methods. This is a problem because quantifying the movement of sediment over long timescales is needed to answer questions about landscape evolution and sediment transport. Luminescence, a property of minerals such as quartz and feldspar, has potential as a sediment tracing tool. Luminescence is a dynamic property that decreases while in sunlight and increases while buried in sedimentary deposits. As grains of quartz and feldspar sand are transported across landscapes, they experience varying intervals of sunlight exposure and burial. This can be exploited to uncover new information on sediment transport.

This dissertation explores and develops the use of luminescence as a sediment tracer in geomorphic environments. First, I describe a new theoretical model for luminescence as a sediment tracer in fluvial environments. This model is derived from a combined conservation of sediment mass and absorbed radiative energy as luminescence. I show that predictions from the model match previously published data and I show that by fitting the model to field data, the model can be used to estimate parameters relevant to sediment transport. Next, I describe a field-based study applying the theoretical model to new field data obtained from the mid-Atlantic region of the United States. I show that in rivers where the model assumptions are applicable, the model can reproduce sediment transport information obtained from non-luminescence methods. Changes in lithology, hillslope sediment flux, or anthropogenic modification, requires a greater collection of field data and can preclude the use of the simplified form of the model. To expand luminescence up to the landscape scale, I introduce a theoretical model of luminescence in hillslope soils and compare the model with previously published data to quantify new soil mixing rates. Both the river and hillslope applications of luminescence show significant potential for uncovering new information on sediment transport.

Available for download on Sunday, October 10, 2021

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