Tectonic controls on the hydrogeology of the Rio Grande Rift, New Mexico

Abstract

In some situations, tilting of fault blocks can create "hydrologic windows" through low-permeability confining units (e.g., lacustrine/playa facies) when permeable strata are connected across fault blocks (Figure 1). Along the Rio Grande Rift in New Mexico it has been recognized for some time that fault block motion has served to localize hydrothermal spring activity [Barroll and Reiter, 1990; Witchef, 1988].In this paper we argue that progressive fault block motion controls the present-day and paleohydrology of the Rio Grande Rift by modifying the connections between aquifers and confining units. This hypothesis is illustrated and tested using a basin-scale mathematical model which represents both the past and present-day groundwater flow systems across the Rio Grande Rift near Socorro, New Mexico. A suite of numerical experiments is presented which investigates the hydraulic behavior of fault zones, fault block geometry, and 2641

“Sour gas” hydrothermal jarosite: ancient to modern acid-sulfate mineralization in the southern Rio Grande Rift

“…This renewed tectonism is characterized by alkaline magmatism, mainly alkali-olivine basalt, which has intensified over the last 5 my (Keller et al, 1990). Recent research points to a more continuous extension in the rift over the last 30 my (Keller and Cather, 1994;Mailloux et al, 1999), although the patterns of magmatism are the same for either model. The distribution of ages of hydrothermal jarosite from the RGR-type deposits corresponds to tectonic episodes within specific portions of the rift during this period of alkali magmatism, and by inference, reflects periods during which fluorine was introduced into the rift.…”

“…The RGR brines, however, contain a significant component derived from the dissolution of Permian evaporites (Bfhlke and Irwin, 1992). The salinity of this brine may vary for individual systems, depending on the history of the meteoric water system and the prior removal of salt from the system (Mailloux et al, 1999). Therefore, the trends off the meteoric water line may be due largely to the mixing of meteoric waters with brines.…”

“…Our model for RGR-type mineralization and the formation of sour gas hydrothermal jarosite (Fig. 7) combines geological information from Clemons (1996) and the hydrologic modeling of Mailloux et al (1999).…”

Dissolved noble gases and stable isotopes as tracers of preferential fluid flow along faults in the Lower Rhine Embayment, Germany

“…These barriers are created by the juxtaposition of aquifer-confining units such as clay beds with aquifer media at the location of the fault (Mailloux et al 1999) and/or fault zone deformation processes such as cataclasis (Fulljames et al 1997), diagenesis (Chan et al 2000;Dewhurst and Jones 2003) and clay smearing (Lehner and Pilaar 1997;Bense et al 2003;Egholm et al 2008), which reduce the permeability of the fault zone itself. The role of faults as barriers to groundwater movement has been widely described in the literature but much less documented is the ability of faults to simultaneously act as conduits for sub-vertical flow along the fault (Roberts et al 1996;Wiprut and Zoback 2000;Bense and Person 2006).…”

Fault architecture and deformation processes within poorly lithified rift sediments, Central Greece

“…Haneberg, 1995;Mailloux et al, 1999) and by introducing permeability heterogeneities and anisotropies within rocks (Bredehoeft et al, 1992;Caine et al, 1996) and sediments (Bense and Van Balen, 2004). As a result, faults can influence the accessibility of groundwater supplies Minor and Hudson, 2006;Caine and Minor, 2009) and/or provide pathways between aquifers for contaminants such as brines (Stamatis and Voudouris, 2003;Bense and Person, 2006), and complicate environmental challenges such as the safe burial of radioactive waste (Bredehoeft, 1997).…”