A Conceptual Model for Hypogene Speleogenesis in Grand Canyon, Arizona
- 1k Downloads
Although Grand Canyon hosts exceptionally well‐formed vadose caves and exemplary paleokarst, it also contains hypogene caves that provide important information on the canyon’s age and evolution. These caves exhibit speleogenetic materials, passage morphologies, and locations near the top of the Mississippian Redwall Limestone that represent major hypogene dissolution phases. Cave origin resulted from CO2 and H2S in solutions that upwelled from depth and mixed with Redwall–Muav aquifer water. Lack of abundant speleogenetic gypsum suggests that CO2 was the primary solutional agent, while upwelling H2S likely played only a minor role. Each phase of hypogene speleogenesis in our model encompasses the following sub‐events, from deep to shallow: (1) dissolution of cave passages 500 ± 250 m below the water table or potentiometric surface, sometimes with Fe‐ and Mn‐oxide by-products; (2) deposition of calcite spar linings (~50–100 m below the water table); (3) deposition of calcite mammillary coatings (1–20 m below the water table); (4) deposition of calcite folia at the water table; and (5) deposition of gypsum rinds a few meters above the water table. Controls on the amount of cave dissolution and speleogenetic by-products probably include regional water table fluctuations during the Miocene and Pliocene, in combination with magmatic/tectonic pulses that pumped CO2 and H2S from below. The complete cycle of Grand Canyon hypogene speleogenesis includes a largely dissolutional phase under confined conditions and a later (mostly by-product) phase taking place under unconfined conditions. The process terminates when the water table descends below the cave.
KeywordsGrand Canyon Hypogene caves Calcite spar Confinement Supercritical CO2
We thank Paula Provencio for materials research and analyses that helped advance our understanding of speleogenetic by-product materials. We are grateful to Art and Peggy Palmer for discussions of hypogene speleogenesis in the Black Hills of South Dakota, Guadalupe Mountains, New Mexico, and Grand Canyon, which helped shape our ideas; and to Bogdan Onac for discussions of sulfur isotope geochemistry of Grand Canyon caves.
- Beus SS, Morales M (1990) Grand Canyon geology. Museum of Northern Arizona Press, Flagstaff, AZGoogle Scholar
- Blakey R, Ranney W (2008) Ancient landscapes. Grand Canyon Association, Grand Canyon, AZGoogle Scholar
- Decker DD, Polyak VJ, Asmerom Y (2015) Depth and timing of calcite spar and ‘spar cave’ genesis: implications for landscape evolution studies. In: Feinberg J, Gao Y, Alexander EC Jr (eds) Caves and Karst across time, vol 516. Geological Society of America, Special Paper, pp 103–111. doi: 10.1130/2015.2516(08)
- Egmeier SJ (1973) Cavern development by thermal waters with a possible bearing on ore deposition. Unpublished Ph.D. dissertation, Standford UniversityGoogle Scholar
- Hill CA (1996) Geology of the Delaware basin, Guadalupe, Apache, and Glass Mountains, New Mexico and West Texas. Permian Basin Section‐SEPM Publication, pp 96–39Google Scholar
- Hill CA, Polyak VJ, McIntosh WC, Provencio PP (2001) Preliminary evidence from Grand Canyon caves and mines for the evolution of Grand Canyon and the Colorado River system. In: Young RA, Spamer EE (eds) Proceedings of symposium at Grand Canyon National Park, June 2000, vol 12. Grand Canyon Association Monograph, pp 141–147Google Scholar
- Huntoon PW (2000) Variability of karstic permeability between unconfined and confined aquifers, Grand Canyon region, Arizona. Environ Eng Geosci VI(2):155–170Google Scholar
- Klimchouk AB (2007) Hypogene speleogenesis: hydrogeological and morphogenetic perspective. National Cave and Karst Research Institute, Carlsbad, NMGoogle Scholar
- Polyak VJ et al (2014) Isotopic studies of byproducts of hypogene speleogenesis and their contribution to the geologic evolution of the western United States. In: Kimchouk A, Sasowsky ID, Mylroie J, Engel SA, Engel AS (eds) Hypogene cave morphologies, vol 18. Karst Waters Institute Special Publication, pp 88–94Google Scholar
- Rice SE (2012) Surveying Leandras Cave, longest in Arizona. Cave and Karst Programs, National Park Service, Inside Earth 15(1):4–5Google Scholar