Masters Theses

Date of Award

5-2005

Degree Type

Thesis

Degree Name

Master of Science

Major

Geology

Major Professor

Steven Driese, Larry McKay

Committee Members

Edmund Perfect

Abstract

This research concerns the weathering of carbonate bedrock and subsequent genesis and properties of carbonate-derived residuum in Knox County, Tennessee. The carbonate-derived residuum evaluated in this study is classified as an Ultisol, and comprises up to 11 m of regolith overlying Mascot Fm. dolostone bedrock within the Valley and Ridge Province of East Tennessee. Morphological, textural, geochemical, and mineralogical analyses were performed on entire soil profiles and subjacent bedrock from core samples retrieved from 7 boreholes. Findings of this research reveal that the regolith is derived primarily from extensive weathering of the parent bedrock, but with evidence of substantial reworking of materials by flowing water, slope movement and pedogenesis, and possible inputs of material from other sources that include the overlying bedrock (Chickamauga Group). The occurrence of at least one paleosol found near the base of borehole 1 further supports this assertion. Based upon data that include mass-balance calculations for strain (volume change), translocations of clay-constituent elements (relative to TiO2), as well as physical characteristics of underlying Mascot Fm. bedrock that includes percentages of insoluble residues and estimated thickness of the bedrock at the study site, it is apparent that the Mascot Dolomite is a primary parent material for these soils. However, much clay has been introduced and translocated during soil genesis, and can only be accounted for by the addition of materials from outside (and stratigraphically overlying) sources in conjunction with the weathering of extensive thickness of dolostone bedrock. A multi-stage, 2-D conceptual model has been proposed to account for long-term Ultisol maturation within a dynamic geomorphic surface. Boundaries between genetic units within the soil residuum and overlying colluvium have been homogenized by advanced Ultisol pedogenesis, however, they are still detectable upon close inspection. Furthermore, results suggest that pore structure and macroporosity occlusion is most dependent on illuviation of pedogenic clays and precipitation of mineral precipitates, which commonly extend from 2 m depth down to the bedrock contact.

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