Unconfined hypogene evaporite karst: West Texas and southeastern New Mexico, USA

Authors

Kevin W. Stafford, Stephen F. Austin State UniversityFollow
Jon T. Ehrhart, Stephen F. Austin State UniversityFollow
Adam F. Majzoub, Stephen F. Austin State UniversityFollow
Jessica M. Shields, Stephen F. Austin State UniversityFollow
Wesley A. Brown, Stephen F. Austin State UniversityFollow

Highlights

• Hypergene and hypogene processes have created a complex speleogenetic history for the Delaware Basin
• Unconfined hypogene evaporite karst occurs as artesian-like discharge features and venting structures within the Delaware Basin
• Electrical resistivity analyses coupled with field excavations confirm speleogenetic models based on surficial manifestations
• Diverse evaporite karst manifestations create complex geohazards within the Delaware Basin

Abstract

Diverse karst phenomena occur throughout the Gypsum Plain where the Castile Formation crops out over ~1800 km² in West Texas and southeastern New Mexico. Hypergene karst is extensive and widespread, while traditional hypogene karst manifestations (both caves and intrastratal dissolution) occur in high frequency in the western outcrop region where surface denudation has been the greatest so as to induce surficial breaching. Unconfined hypogene karst occurrences have been recently identified, including two general variations: 1) artesian-like discharge features; and 2) venting structures. Artesian-like discharge features arise at surficially-breached hypogene caves and through high permeability regions on the margins of breccia pipes; these occur when aquifer pressures within the underlying Bell Canyon siliciclastics are sufficiently elevated subsequent to anomalously high precipitation events. Venting structures associated with condensation corrosion-like processes coupled with ascending moisture-rich vapor occur as fracture vents and hydration buckles; fracture vents develop along near-vertical joint sets and hydration buckles form at intermittent zones of high permeability within the core regions of breccia pipes. All venting structures form highly porous, low density, secondary sulfate mineralization at the land surface, creating local topographic highs decimeters to a meter in scale that preclude interception of meteoric waters into these unconfined hypogene karst features. The Gypsum Plain hosts complex karst phenomena that present unique engineering challenges as variable geohazard occurrences ranging from shallow, hypergene caves to deep, complex, hypogene features both formed in semi-confined and unconfined speleogenetic conditions.

DOI

https://doi.org/10.5038/1827-806X.47.3.2166

Creative Commons License

This work is licensed under a Creative Commons Attribution-Noncommercial 4.0 License

Recommended Citation

Stafford, Kevin W.; Jon T. Ehrhart; Adam F. Majzoub; Jessica M. Shields; and Wesley A. Brown. 2018. Unconfined hypogene evaporite karst: West Texas and southeastern New Mexico, USA. International Journal of Speleology, 47: 293-305.
Available at: https://digitalcommons.usf.edu/ijs/vol47/iss3/3