Using Ground Penetrating Radar to characterise karst features in Eddy County, New Mexico and Culberson County, Texas.

摘要

The main goals of this study are to test the usefulness of Ground Penetrating Radar (GPR) for identifying buried sinkholes in the Castile Formation, characterize the sinkhole origins as either solutional or collapse features and to test the usefulness of GPR to evaluate sedimentary fills in karst features. The Castile Formation, a highly soluble, gypsum-dominated unit, is ideal for the evaluation of subsurface karst features using the GPR technique. GPR is a non-destructive geophysical method that uses radar pulses to image the subsurface, thus it is able to image the caves and sinkholes which are common throughout the gypsum strata. GPR data was taken in Culberson County, Texas and Eddy County, New Mexico. Resulting profiles showed a pattern of radar reflections which reveal a series of possible filled sinkholes.;The sinkholes in the study area were found to be both solutional and collapse type features. 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, which are 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 is a hypogene cave. 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 characterize subsurface deposits.