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

Abstract

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 2 gas and contain signifi cant quantities of CO 2 (~34.6 mmol/kg), predominantly as H 2 CO 3 and HCO 3 -. 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 faultdamage zone act as pathways from the likely regional aquifer, the eolian Queantoweap Sandstone, through the overlying confi ning unit, the gypsiferous silty Seligman Member of the Kaibab Formation.Mass-balance modeling suggests that the majority of CO 2 discharge is the product of the quantitative dissolution of CO 2 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 2 is relatively low because Pah Tempe waters are grossly undersaturated in CO 2 at inferred minimum circulation depths and temperatures. Geological and geochemical data also suggest that the CO 2 is dominated by a crustal component complemented by minor mantle contributions.

Fault-Related Controls on Upward Hydrothermal Flow: An Integrated Geological Study of the Têt Fault System, Eastern Pyrénées (France)

“…Fault damage zones in gneiss appear important for localizing hydrothermal fluid upflow. Highly concentrated fractures in the Têt fault damage zone (Figure 8) are an efficient vertical pathway [27,36,90], previously identified in a similar hydrothermal system [16]. Fractures with Têt fault strikes (NE-SW) concentrate in its damage zone and are also represented at a regional scale [53].…”

“…Nonmagmatic hydrothermal systems in continental contexts involving high relief and hot springs [7] are rarely studied [8]. Further, processes acting in this kind of hydrothermal systems are essentially explored by numerical models [9,10] (e.g., the Dixie Valley geothermal field in Nevada [11][12][13]), and integrative geological studies as proposed in this paper are few in number [7,[14][15][16].…”

Tectonic control on travertine and calcareous tufa deposition in a low-temperature geothermal system (Sarteano, Central Italy)

“…Recently, studies of continental carbonates, utilizing travertines and/or calcareous tufa (Ford & Pedley 1996;Capezzuoli et al 2010) have increased; such studies include not only sedimentological and stratigraphical investigations but also work on neotectonics (Hancock et al 1999;Altunel 2005;Uysal et al 2009;Brogi et al 2010a), palaeoseismology (Sibson 1987;Altunel & Hancock 1993;Faccenna et al 1993;Martinez-Diaz & Hernandez-Enrile 2001;Altunel 2005;Hançer et al 2005;Piper et al 2007;Uysal et al 2007;Nishikawa et al 2012), isotopic geochemistry (Kele et al 2008(Kele et al , 2011, climatic changes (Sturchio et al 1994;Faccenna et al 2008) and fluid circulation in geothermal systems (Minissale et al 2000(Minissale et al , 2002Minissale 2004;Crossey et al 2006;Nelson et al 2009;Banerjee et al 2011).…”

Selection of Prebiotic Molecules in Amphiphilic Environments

“…Regarding the reaction conditions, tectonic fault zones offer a large range of temperatures and pressures depending on the depth of the reaction environment. Below a depth of approximately −1 km (with T > 304 K and p > 74 bar), the carbon dioxide will necessarily exist in the supercritical state [15]. At levels above −8 km, water is expected to occur in the liquid state.…”