Tepee Structures--A Closer Examination Involving Carbonate Formations of Upper Permian, Southeastern New Mexico, and Upper Cretaceous, Southwestern Texas

Brian K. McDaniel

A comparison of tepee structures involving the Permian back-reef rocks of the Guadalupe Mountains in southeastern New Mexico with tepees of the Upper Cretaceous shelf rocks of the Val Verde basin in southwestern Texas shows that tepee structures can form in distinctly different depositional settings. Tepee structures of the Guadalupian Carlsbad group in southeastern New Mexico are representative of peritidal tepees. These tepees are developed in fenestral limestone sheets, which range from wackestone to dolomitic grainstone (whose constituent grains include pisoliths), and are characterized by sheet cracks and boxwork fabrics. Terrigenous siliciclastic sand commonly underlies and intrudes these structures. However, tepees of the Upper Cretaceous carbonates in the Val Verd basin are submarine tepees developed mainly in wackestone to packstone and lacking many of the fabrics observed in the peritidal tepees from the Guadalupe Mountains.

Petrographic observations suggest that tepees forming in different hydrological settings are characterized by distinct cement types and diagenetic fabrics allowing paleoenvironmental recognition and producing models for dolomitization. Tepees also provide an important, albeit minor, structural control in speleogenesis as related to their ability to enhance porosity and permeability. As paleokarst systems are becoming increasingly popular exploration targets, these structures can provide additional resources for exploration, thus adding new insight into mature karst areas.

AAPG Search and Discovery Article #91026©1989 AAPG Southwest Section, March 19-21, 1989, San Angelo, Texas.