INVESTIGATION OF TUFA DEPOSITS IN THE SPRING RIVER IN NORTHERN ARKANSAS

Events in summer 2018 led to a geologic review of naturally occurring deposits in the Spring River in northern Arkansas. The Spring River is fed by Mammoth Spring, a large spring on the Missouri-Arkansas border which produces roughly 230 million gallons of water per day (MGD). Most of these deposits appear as tufa dams that cause water to pool up. The review of the dams showed that there are roughly 96 of these features present in the first 45 miles downstream of Mammoth Spring. Although the appearance of tufa deposits on a spring-fed river in a karst region is not unusual, further review suggests these tufa deposits become more common farther away from Mammoth Spring (rather than close to the spring mouth). No major structural features have been mapped in this region of Arkansas, which poses additional questions regarding the deposition of these tufa dams.

Geophysical investigation using Resistivity and VLF have been undertaken in a meander bend to determine if these deposits underlie the former river channels, because this may give an idea of the age of the deposits. The geophysical data may also add to our understanding of structural controls in the area. Preliminary investigation of the dams using Google earth and ArcGIS have shown the dams to have distinct similar orientations which could suggest that there is structural control. Results of these geophysical and imagery analyses will be presented along with their interpretation relative to potential structural influences.