Date of Graduation

Fall 2009

Degree

Master of Science in Geospatial Sciences

Department

Geography, Geology and Planning

Committee Chair

Robert Pavlowsky

Keywords

floodplains, geomorphology, Pearson Creek, mining pollution, land use

Subject Categories

Mining Engineering | Sedimentology | Stratigraphy

Abstract

Contaminated historical mining sediment has been used in the past as a stratigraphic tracer to study the effects of settlement on floodplain deposition. Lead and zinc mining near Pearson Creek watershed (58 km2), Springfield, Missouri began around 1885, peaked around 1912, and ended by 1920. The purpose of this study is to use the historical stratigraphic record in floodplain deposits to determine channel response to land use changes. The objectives are to (1) determine the magnitude and distribution of mining-contaminated sediment within active and historical alluvial deposits; (2) identify geo-stratigraphic assemblages using floodplain sedimentology and trace-metal dating; and (3) use geo-stratigraphic assemblages to develop a geomorphic model of historical floodplain evolution. Geochemical and textural data from soil samples collected along cross-sections were used to identify geo-stratigraphic assemblages and calculate sedimentation rates. Three assemblages were identified based on down-core stratigraphic patterns of Zn and soil color: Terrace Veneer, Floodplain Drape, and Channel Fill. Mean Zn concentration increased from Terrace Veneer (85 ppm) to Floodplain Drape (396 ppm) to Channel Fill (1,441 ppm). Sedimentation rates were highest during the mining period (mean=2.20 cm/yr) and decreased during the post-mining period (mean=0.64 cm/yr). Terrace abandonment and vertical accretion of uncontaminated sediment were dominant during the pre-mining period. Lateral migration upstream and vertical accretion downstream dominated during the mining-period. Vertical accretion has dominated the post-mining period. Alluvial deposits along lower Pearson Creek are contaminated with mining-related Zn and post-settlement land use changes have influenced floodplain sedimentation patterns.

Copyright

© Patrick James Womble

Campus Only

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