CSDMS 2016 annual meeting poster HarrisonGray
Ongoing investigations into the connections between mineral luminescence and geomorphic processes
Shannon Mahan, U.S. Geological Survey Denver Colorado, United States. smahan@usgs.gov
Greg Tucker, University of Colorado - Boulder Boulder Colorado, United States. gtucker@colorado.edu
Abstract:
A main component of modern geomorphic research is centered on testing of conceptual and numerical models with the hopes of better developing predictions of landscape and landform evolution. A key issue for testing these geomorphic models is a lack of simplified means to quantify common Earth surface processes such as sediment transport in rivers and on hillslopes. One possible avenue is to use a property of minerals known as luminescence. Luminescence is a phenomenon that arises when electrons are displaced and “trapped” within the crystal lattice due to exposure to background ionizing radiation. These electrons only gain the energy needed to escape these traps when exposed to sunlight, heat, or pressure, yielding measurable photons in the process, thus ‘luminescence.’ This property has been used as a geochronometer for the past ~35 years. In this presentation, we show results from numerical modeling of geomorphic transport of quartz and feldspar fine sand (90-250 µm grain size) in rivers and in hillslopes and the expected luminescence for each grain of sand. We explore the distributions and magnitudes of luminescence measurements and show how they can be quantitatively tied to geomorphic process. In particular, we show that researchers can extract virtual river velocities and rates of exchange with floodplain storage centers and estimate vertical diffusivities in hillslope soils. Current work to test these results with independently obtained values is ongoing and we show that our preliminary results match model predictions. There exists significant potential to use luminescence as a process-sensitive geomorphic tracer.
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