Date of Graduation

5-2025

Document Type

Thesis

Degree Name

Bachelor of Science in Physics

Degree Level

Undergraduate

Department

Physics

Advisor/Mentor

Dumond, Gregory

Committee Member

Kennefick, Julia

Second Committee Member

Kennefick, Daniel

Abstract

The Benton Uplift west of Hot Springs, AR is underlain by a paired gravity anomaly on the order of 80 mGal. Nicholas & Rozendal (1975) have theorized that the gravitational low is caused by a “downwarp of the crust into the mantle”1 however the cause of the gravitational high is still debated. This paired gravity anomaly within the Benton Uplift follows the Ouachita orogenic belt southwest for 500 miles where it meets the Marathon uplift in southwest Texas. We conducted a gravity survey along a 108-km-long transect east of two previous gravity surveys.2,3 We corrected the data from this transect using Oasis Montaj and, alongside magnetic data from the United States Geological Survey, we built a model within Geosoft GM-SYS of the cross section of our study area.4 The topography of the upper crust within our cross section is consistent with the cross section from Mickus & Keller (1992), Figure 5, however the mafic intrusion under the Ouachita accretionary wedge was absent within our data, likely because our transect did not go south enough. Previous research has theorized the gravity maximum to be caused by a combination of basement uplifts and mafic intrusions produced during aborted Precambrian rifting along the Ouachita orogenic belt.5 Additional seismic and magnetic surveys south of the study area and across the Ouachita orogenic belt are needed to further test the hypothesis that a combination of basement uplifts and dense deep crustal mafic intrusions are the most likely cause of the paired gravity anomalies.

Keywords

Geophysics; Ouachita Mountains; Benton Uplift; Arkansas; Gravity; Gravimetry

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