Denver, CO, United States
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Polyak V.J.,University of New Mexico | DuChene H.R.,2333 San Juan Dr. | Davis D.G.,441 S. Kearney St | Palmer A.N.,New York University | And 2 more authors.
International Journal of Speleology | Year: 2013

Uranium-series analyses of water-table-type speleothems from Glenwood Cavern and "cavelets" near the town of Glenwood Springs, Colorado, USA, yield incision rates of the Colorado River in Glenwood Canyon for the last ~1.4 My. The incision rates, calculated from dating cave mammillary and cave folia calcite situated 65 and 90 m above the Colorado River, are 174 ± 30 m/My for the last 0.46 My and 144 ± 30 m/My for the last 0.62 My, respectively. These are consistent with incision rates determined from nearby volcanic deposits. In contrast, δ234U model ages (1.39 ± 0.25 My; 1.36 ± 0.25 My; and 1.72 ± 0.25 My) from three different samples of mammillary-like subaqueous crust collected from Glenwood Cavern, 375 m above the Colorado River, yield incision rates of 271 +58/-41 m/My, 277 +61/-42 m/ My, and 218 +36/-27 m/My. These data suggest a relatively fast incision rate between roughly 3 and 1 Ma. The onset of Pleistocene glaciation may have influenced this rate by increasing precipitation on the Colorado Plateau starting at 2.5 Ma. Slowing of incision just before 0.6 Ma could be related to the change in frequency of glacial cycles from 40 to 100 kyr in the middle Pleistocene. This interpretation would suggest that the cutting power of the Colorado River prior to 3 Ma was smaller. An alternative interpretation involving tectonic activity would invoke an episode of fast uplift in the Glenwood Canyon region from 3 to 1 Ma.


Lechuguilla Cave, a complex three-dimensional cave with a single known entrance, is located in remote desert terrain in Carlsbad Caverns National Park, in southeastern New Mexico, USA. The Guadalupe Mountains there contain uplifted limestone and dolomite rock in the Permian-age Capitan Reef complex. Hundreds of caves have been found in this region, but Lechuguilla Cave greatly exceeds the size of all others known. It was only a small pit mined for bat guano in the early twentieth century. In the 1970s the Cave Research Foundation performed digs at the bottom, where profuse air movement had been noted in the debris. This work ceased but another team of cavers visited in 1984, hearing and feeling the significant air, and began a digging project approved by the Park. The cavers dug into continuing passage in 1986. It was explored in three major branches, generally trending west/southwest to east/northeast, parallel to the reef face, with north-south connections along deep rift features. Depositional and corrosional events during sulfuric-acid speleogenesis created remarkable speleothems and speleogenesis, and the cave has often been called “the Jewel of the Underground”. The rapidly growing cave passed 80 km of surveyed length by 1990. Within the first ten years of exploration, 28 large-scale expeditions led to the cave reaching 113 km in length. From 1997 to 2013, 109 additional kilometers were mapped with smaller teams of up to 12 cavers per expedition. Exploration and mapping is now done in three to five expeditions per year, and recent work has focused on climbs and smaller leads such as tight crawls and fissures that were previously passed. Significant discoveries continue to be found using these techniques. The cave reaches a depth of 475 m and has been mapped to over 222 km in length. Exploration to the extreme ends is efficiently done with multi-day expeditions, using established camps in each branch. Cavers from the United States and dozens of other countries have been involved in this mapping project. The cave now has more than 35,000 survey stations, and the complexity of the maze of passages creates significant challenges for cartographers. Based on ever-present airflow and porosity of the bedrock, it is expected that this cave will continue to surprise and delight explorers and speleo-scientists in the future. © 2016, Instituto Geologico y Minero de Espana. All rights reserved.


Davis D.G.,441 S. Kearney St.
International Journal of Speleology | Year: 2012

Two recent papers have proposed radically different modes of origin for cave folia. Audra et al. (2009) propose subaqueous origin of carbonate folia via hypogenic CO2 bubble trapping, with concurrent condensation-corrosion and evaporative precipitation within individual folia gas pockets. Queen (2009) proposes that at least some folia are analogous to suboceanic tufa-tower "flanges" and may result from subaqueous freshwater mixing into a briny environment. The purpose of this paper is to show that neither of these mechanisms can be the fundamental process responsible for folia morphology in cave deposits, and that accretion from adherent particles at fluctuating interfaces is the only mechanism that has been shown to apply to folia of all compositions and in all cave environments where they are known to occur.

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