CO₂ hypogene speleogenesis in an endogenic travertine system, Mesa del Oro, New Mexico, USA

Authors

Victor J. Polyak, University of New Mexico, Albuquerque, USAFollow
Jeffrey R. Forbes, Idaho Falls, USAFollow
Michael N. Spilde, University of New Mexico, Albuquerque, USAFollow
Paula P. Provencio, University of New MexicoFollow
John R. Cochran, Albuquerque, USAFollow
Yemane Asmerom, University of New Mexico, Albuquerque, USAFollow

Highlights

• Whut Cave formed by CO₂ hypogene speleogenesis in an endogenic travertine deposit
• Much of the CO₂ in the system was sourced by local volcanic activity
• A Mn-oxide ore deposit associated with the cave is a product of speleogenesis
• Speleogenesis took place synchronously with deposition of the travertine and local volcanic activity between 900 and 300 kyr BP

Abstract

The Mesa del Oro travertine, deposited by upwelling CO₂-rich spring waters, is a large and thick mantle of calcite overlying soft Triassic Chinle Formation mudstones in western central New Mexico, USA. The travertine contains a system of small caves known as the Pronoun Cave Complex. Whut Cave is the largest known cave in the complex. While the travertine hydrologic system is no longer active, there is ample evidence that Whut Cave was formed by hypogene speleogenesis. The Whut Cave entrance is a small roughly circular shaft that descends ~four meters and intersects a linear fissure-controlled passage. Mn-oxide was once mined below the entrance, leaving a five-meter-deep pit that represents the path of upwelling waters that were likely charged with CO₂ and supersaturated with CaCO₃ once reaching the surface. The roomiest part of the cave is immediately adjacent to the entrance, defining where most of the upwelling of groundwater and gases took place. Gypsum and other sulfates were only noted microscopically. A sample of travertine at the surface near the entrance yielded a uranium-series age beyond the limit of the method and a δ²³⁴U age of 735 ± 109 ka BP (before present). A piece of breccia vein in the mine dump associated with the Mn-oxide ore, and a rill of a drape-like crust on the cave wall, both interpreted to be products of hypogene speleogenesis and representing the oldest speleogenetic material, yielded δ²³⁴U ages of 848 ± 110 and 723 ± 109 ka BP. Altogether, materials interpreted to be speleogenetic yielded ages of ~900 – 300 ka BP. Although the cave is dry and hydrologically inactive today, cave development by CO₂ hypogene speleogenesis was coeval with endogenic travertine deposition and nearby volcanism. Our interpretation suggests that all these events are linked.

DOI

https://doi.org/10.5038/1827-806X.53.2.2502

Creative Commons License

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

Recommended Citation

Polyak, V.J., Forbes, J.R., Spilde, M.N., Provencio, P., Cochran, J.R., Asmerom, Y., 2024. CO2 hypogene speleogenesis in an endogenic travertine system, Mesa del Oro, New Mexico, USA. International Journal of Speleology, 53(2), 159-167. https://doi.org/10.5038/1827-806X.53.2.2502