LIDAR-BASED DELINEATION OF KARST FEATURES IN THE GYPSUM PLAIN, EDDY COUNTY, NEW MEXICO AND CULBERSON COUNTY, TEXAS

Abstract

The Gypsum Plain of the Delaware Basin encompasses approximately 1,800 km2 of massive to laminated gypsum (anhydrite in the subsurface) outcrop of early Ochoan Castile and Salado strata. These extensive Permian-age evaporites host significant karst phenomena as a result of the region\u27s complex hydrogeologic system which has continuously evolved since the early Paleogene. Karst features that manifest surficially as sinkholes when breached range from extensive hypogene cave systems to epigene features and suffosion caves. In contrast, paleo-collapse structures forming breccia pipes attesting to more ancient karst within these strata often manifest as topographic highs across the Gypsum Plain. Until recently, the lack of accessible, high-resolution LiDAR (Light Detection and Ranging) data has restricted karst studies on the distribution and speleogenetic evolution of the entire Gypsum Plain to imagery analyses. In this study, high-resolution (70-centimeter accuracy) LiDAR data analyses were used to assess the spatial extent of major surficial karst manifestations through constructed Digital Elevation Models (DEMs). DEM analyses were used to delineate sinkhole features, while sinkhole morphometrics analyses was used to infer origins; high sphericity suggests collapse origins and low sphericity suggests solutional incision origins. After GIS-based verification, spatial sinkhole analyses were refined to produce a spatial density map of surficial karst manifestations across the Gypsum Plain. This includes the delineation of regions dominated by hypogene or epigene karst origins, as inferred from sinkhole morphometric analyses