Epigene and hypogene gypsum karst manifestations of the Castile Formation: Eddy County, New Mexico and Culberson County, Texas, USA

Abstract

. Permian evaporites of the Castile Formation crop out over ~1,800 km2 in the western Delaware Basin (Eddy County, New Mexico and Culberson County, Texas, USA) with abundant and diverse karst manifestations. Epigene karst occurs as well-developed karren on exposed bedrock, while sinkholes dominate the erosional landscape, including both solutional and collapse forms. Sinkhole analyses suggest that more than half of all sinks are the result of upward stoping of subsurface voids, while many solutional sinks are commonly the result of overprinting of collapsed forms. Epigene caves are laterally limited with rapid aperture decreases away from insurgence, with passages developed along fractures and anticline fold axes. Hypogene karst occurs as diverse manifestations, forming the deepest and longest caves within the region as well as abundant zones of brecciation. Hypogene caves exhibit a wide range of morphologies from complex maze and anastomotic patterns to simple, steeply dipping patterns, but all hypogene caves exhibit morphologic features (i.e. risers, outlet cupolas and half-tubes) that provide a definitive suite of evidence of dissolution within a mixed convection (forced and free convection) hydrologic system. Extensive blanket breccias, abundant breccia pipes and numerous occurrences of calcitized evaporites indicate widespread hypogene speleogenesis throughout the entire Castile Formation. Although most cave and karst development within the Castile outcrop region appears to have hypogene origins, epigene processes are actively overprinting features, creating a complex speleogenetic evolution within the Castile Formation. Keywords: hypogenic caves, epigenic overprint, speleogenesis, evaporites, geomorphology Received 21 July 2007; Revised 16 October 2007; Accepted 8 November 2007Permian (Fig. 2) (Scholle et al, 2004). Limited studies on specific caves or local karst regions have been conducted within the evaporite facies of the Permian Basin, including karst studies in the San Andres Formation (Forbes & Nance, 1997) and Seven Rivers Formation (Stafford et al, 2007a;Land, 2006) of the Artesia Group, the Castile Formation (Sares, 1984;Nance, 1993), and the Salado and Rustler Formations (Hill, 1996). However, no studies have been conducted to evaluate the full range of cave and karst development within any of the evaporitic units of the region. Cave exploration has been conducted by the Gypsum Karst Project (GYPKAP) of the National Speleological Society throughout the evaporite karst regions of New Mexico (Eaton, 1987; Belski, 1992;Lee, 1996). Documentation of evaporite karst regions within Texas has been conducted by the Texas Speleological Survey (TSS) (e.g. Redell & Fiesler, 1977). Although all of the evaporite facies of the region deserve comprehensive study, it is beyond the scope of a single study; therefore, this research focuses specifically on karst development in one evaporitic unit, the Castile Formation because it is the largest continuous outcrop of a single evaporite formation in the Permian Basin...

Gypsum speleogenesis: a hydrogeological classification of gypsum caves

“…Some examples of such cave conduits are the Mosquera Cave in Beuda (Girona, Spain) (Calaforra & Pulido-Bosch, 1989;Miret & García, 1999), the Rio Stella-Rio Basino in Emilia Romagna (Forti, et al, 1989;De Waele, 2010, the Grave Grubbo-Vallone Cufalo in Calabria (Ferrini & Pasqua, 1998;Ferrini & Moretti, 2003), the actual Aquafredda level in the Spipola cave system (De Waele et al, 2017) and the Parks Ranch Cave in the gypsum plain of New Mexico related to the Black River (Calaforra & Forti, 1994;Calaforra, 1998). Interestingly, this last example of gypsum multi-base level cave also shows vestiges of an early hypogene genesis (Stafford et al, 2008b). ) d Gypsum halokinetic caves whose speleogenesis is linked to the presence of halokinetic (diapiric) phenomena that produce a continuous upward movement on a large geological scale.…”

Evaporite karst geohazards in the Delaware Basin, Texas: review of traditional karst studies coupled with geophysical and remote sensing characterization

“…Hypogene caves cut across lithologic boundaries with regularity, showing little to no preferential development with transitions between varved gypsum, recrystallized (selenite) gypsum or other secondary sulfate fabrics. Most hypogene caves occur proximal to the underlying contact with siliclastic strata, where ascending, solutionallyaggressive fluids are sourced (Stafford et al, 2008b); therefore, documented hypogene caves occur in greater frequency proximal to the western margin of the Gypsum Plain where surface denudation, and subsequent cave breaching, has been greatest and total thickness of the Castile Formation has been greatly reduced. It is probable, that significant hypogene karst development continues near the lower contact of the Castile Formation further to the east, but surface denudation has not proceeded far enough to induce system breaching to enable human exploration.…”

“…Karst development within the greater Delaware Basin is common and widespread, most notably, the world famous carbonate caves of the Guadalupe Mountains (e.g., Carlsbad Cavern, Lechuguilla Cave), but also cave development in mixed carbonate / evaporite strata of the Northwestern Shelf (e.g., Coffee Cave) (Stafford et al, 2008a) and evaporite karst development within the Delaware Basin (e.g., Gypsum Plain) (Stafford et al, 2008b). Although karst phenomena have been documented in the Salado and Rustler formations (Stafford et al, 2009), the most extensive evaporite karst development documented in the Gypsum Plain is within the Castile Formation outcrop region and thus is the emphasis of this study.…”

“…Hypogene caves occur as a continuum between more classically defined, multi-storey maze caves hundreds of meters in survey length in strata that are complexly folded and fractured to single, riser features that can extend to depths of 100 m in poorly fractured rock (Stafford et al, 2008b). All hypogene caves exhibit the morphometric suite of rising flow features that have been defined as characteristic of hypogene speleogenesis (Klimchouk, 2007) and show little lithologic control (Fig.…”

“…Surficially, intrastratal dissolution manifests as both negative and positive relief structures, forming either solution grabens and subsidence troughs or resistant brecciated hills (Stafford et al, 2008b,d). Widespread intrastratal dissolution has removed halite interbeds from the Castile outcrop and subcrop region as solutionallyaggressive, ascending fluids delivered from underlying siliciclastic strata (Guadalupian strata of the Bell and Cherry Canyon formations) migrated updip towards the west in the past (Stafford et al, 2008b, d resulted in differential collapse and settling across the region including development of laterally-extensive, blanket breccias that provide high permeability flow paths for migration of fluids (Stafford et al, 2008b). In more intensely affected regions, solution grabens up to 30 m deep have developed while subsidence valleys infilled with Cenozoic clastics are common proximal to persistent fluvial bodies (Maley & Huffington, 1953).…”