Date of Graduation

Spring 2020

Degree

Master of Science in Geospatial Sciences

Department

Geography, Geology, and Planning

Committee Chair

Doug Gouzie

Keywords

Spring River, Arkansas, tufa, core analysis, geophysics, and biogenic

Subject Categories

Geology | Geophysics and Seismology | Hydrology

Abstract

The Spring River is fed by Mammoth Spring, a large spring on the Missouri-Arkansas border which produces roughly 240 million gallons of water per day (MGD). In this area there are deposits that appear as dams which cause water to pool upstream. Aerial analysis of the dams shows that there are approximately 100 of these features present in the first 45 miles downstream of Mammoth Spring. These deposits, known as tufa, are not uncommon in a karstic area of a spring fed river, but these are more frequent farther downriver than near the mouth of the spring. Preliminary mapping data shows structural features in this region of Arkansas. Geophysical studies using resistivity and VLF were conducted in meander bends to determine if tufa deposits underlie the former river channels. The geophysical data suggests joints/fractures under the riverbanks that go toward the river and near the tufa. Imagery study of the deposits using Google Earth and ArcGIS show the dams to have similar orientations in both N to S and NE to SW trend, which suggests structural control. Eight core samples were taken from three different dam locations to understand the vertical extent of the deposits. The core holes range in depth from two feet to nine feet. Detailed core logs, calculated surface porosity, core hole depth, and GPS location were created for each core sample taken. Thin sections were made from several core samples and show a biogenic/stromatolitic growth pattern with secondary crystal growth. SEM analysis showed the growth of filaments in the pore spaces on each sample of the tufa.

Copyright

© Tyler W. Engelbart

Open Access

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