Hypogenic Speleogenesis of the Castile Formation: Culberson County, Texas and Eddy County, New Mexico
Kevin W. Stafford
New Mexico Institute of Mining and Technology, Earth & Environmental Science Dept. Socorro, New Mexico 8780, USA
Hypogenic speleogenesis is common within the Castile Formation of the Western Delaware Basin (Southeastern New Mexico and Far West Texas), as evidenced by the clustered distribution of karst features within the outcrop region and extensive free-convention features observed in individual caves. Dense clusters of hypogenic caves are commonly associated with calcitized evaporites and selenite masses, suggesting a genetic relationship. Abundant diagenetic patterns within the region indicate extensive, regional, confined speleogenesis that is not limited to cave development.
Brecciation is common throughout the Castile Formation, indicating extensive subsurface dissolution and collapse processes. Breccia pipes, resulting from upward stoping of subsurface voids, suggest confined transverse flow, while blanket breccias and subsidence troughs suggest confined lateral flow component. Calcitized evaporites are extensive throughout the Castile Formation, resulting from bacterial sulfate reduction in the presence of ascending hydrocarbons. Large, economic native sulfur deposits associated with some calcitization indicate limited cross-formational flow of oxic waters contemporaneous with calcitization, while selenite masses associated with other calcitized masses indicate significant intrastratal flow of oxic waters locally.
Hypogenic caves, breccias, calcitization, native sulfur and selenite masses suggest that hypogene processes have dominated sulfate diagenesis within the Delaware Basin. Surface denudation and epigenic processes significantly overprint hypogene products, resulting in greater complexity in the speleogenetic evolution of the Castile Formation.
AAPG Search and Discovery Article #90070 © 2007 AAPG Foundation Grants in Aid