Enhanced fracture permeability and accompanying fluid flow in the footwall of a normal fault: The Hurricane fault at Pah Tempe hot springs, Washington County, Utah

S.T. Nelson, A.L. Mayo, S. Gilfillan, S.J. Dutson, R.A. Harris, Z.K. Shipton, D.G. Tingey

Research output: Contribution to journalArticlepeer-review

Abstract / Description of output

The Pah Tempe hot springs discharge ∼260 L/s of water at ∼40 °C into the Virgin River in the footwall damage zone of the Hurricane fault at Timpoweap Canyon, near Hurricane, Utah, USA. Although these are Na-Cl waters, they actively discharge CO gas and contain significant quantities of CO (∼34.6 mmol/kg), predominantly as HCO and HCO. Because of excellent exposures, Pah Tempe provides an exceptional opportunity to observe the effects of enhanced fracture permeability in an active extensional fault. Pah Tempe waters have been deeply circulated (>5 km; >150 °C) into basement rock as illustrated by the clear water-rock exchange of oxygen isotopes. Waters were probably recharged under colder climate conditions than present and therefore have a prolonged subsurface residence. Discharge of both water and gas in the springs correlates to the density of fractures in carbonate rocks above stream level. This observation suggests that clusters of high fracture density in the fault-damage zone act as pathways from the likely regional aquifer, the eolian Queantoweap Sandstone, through the overlying confining unit, the gypsiferous silty Seligman Member of the Kaibab Formation. Mass-balance modeling suggests that the majority of CO discharge is the product of the quantitative dissolution of CO gas at depth within the fault zone. Upon discharge, most of the carbon is released to the surface as dissolved species. It appears that the subsurface production rate of CO is relatively low because Pah Tempe waters are grossly undersaturated in CO at inferred minimum circulation depths and temperatures. Geological and geochemical data also suggest that the CO is dominated by a crustal component complemented by minor mantle contributions.
Original languageEnglish
Pages (from-to)236-246
Number of pages11
JournalGSA Bulletin
Volume121
Issue number1-2
DOIs
Publication statusPublished - 1 Jan 2009

Keywords / Materials (for Non-textual outputs)

  • hydrogeology
  • CO2 flux
  • damage zone
  • aqueous geochemistry
  • structural geology

Fingerprint

Dive into the research topics of 'Enhanced fracture permeability and accompanying fluid flow in the footwall of a normal fault: The Hurricane fault at Pah Tempe hot springs, Washington County, Utah'. Together they form a unique fingerprint.

Cite this