24 Geophysics: Advances in Characterizing the Earth using Geophysical Techniques—From the Near-Surface to the Deep Earth (Posters)

Sunday, 4 November 2012
9:00 AM - 6:30 PM
Hall B

USING GROUND PENETRATING RADAR TO CHARACTERISE KARST FEATURES IN EDDY COUNTY, NEW MEXICO AND CULBERSON COUNTY TEXAS

Paper number: 24-5
Program: Technical Sessions
Time: 9:00 AM – 6:30 PM

Authors

Abstract

The main goals of this study are to test the usefulness of GPR for identifying buried sinkholes in the Castille Formation and characterizing the sinkhole origins as either solutional or collapse features. The Castille Formation, a highly soluble, gypsum-dominated unit, is ideal for the evaluation of subsurface karst features using the GPR technique, because GPR is a non-destructive geophysical method that uses radar pulses to image the subsurface, thus able to image the caves and sinkholes which are common throughout the gypsum strata. GPR data using a 100 MHz antennae were taken in Culberson County, Texas and Eddy County, New Mexico. Resulting profiles showed a pattern of radar reflections which reveals a possible series of filled sinkholes.

The sinkholes in the study area were both solutional and collapse forms. Analyses of the collapse sinkholes shows that they are the result of upward stoping subsurface voids, which is characterized by large electrical contrast between the unbroken host rock and the infilled collapse. The sinkholes thought to have originated due to solution, show surface disturbance on radargrams. The solutional sinkholes are epigene sinkholes and the collapse structures represent collapse into an underlying void, which may be either hypogene or epigene. A collapse sinkhole represents the surficial expression of a hypogene cave that has collapsed to the surface. The dominant process of sinkhole formation in the area is collapse of voids that are likely hypogene in origin. The results indicate that GPR can be successfully used to identify and characterise subsurface deposits.