geothermal resource potential of the safford-san simon basin, arizona

Cactus Flat-Artesia Area
Geology
Figure 15 is a geologic map of the Cactus Flat-Artesia area.
The
Pinaleno Mountains, composed mainly of gneiss, form the western boundary of
the Safford Basin.
Physiographically, these mountains form a steep escarpment
cut deeply by several northeast-striking canyons which follow easily
eroded shear zones. These shear zones may allow significant ground water
recharge and enhance potential for forced convection in the adjacent basin.
During mapping of basin-fill sediments and surficial deposits, several
small pediment scarps transverse to drainage and parallel to the mountain front
were observed. Subsequent studies by Chris Menges (person. corom., 1980) have
documented shearing in the Cenozoic basin fill exposed in an arroyo north of
Marijilda Canyon adjacent to and on strike with one of the mapped scarps.
It
is believed these scarps represent at least one Pleistocene faulting episode.
In this area, gravel caps of various ages cover Cenozoic basin fill and form
the pediment surfaces.
The surfaces displaced by faulting may be mid-to-late
Pleistocene age, judging from their soil and caliche development (Morrison
and Menges, 1981). Recent and probable late Pleistocene gravel caps do not
have scarps.
Because the scarps are related to Pleistocene tectonism, they
may have an important bearing on the location of the areas with greatest geothermal
energy potential.
Pleistocene faults are frequently associated with
geothermal systems.
Apparently young faults provide good vertical permeability
for flows of thermal water.
Surface mapping of the basin-filling sediments shows that the top of
the green clay facies of Harbour (1966)
is about 3,340 feet of elevation.
Roadcuts along U.S.
666 near Artesia show outcrops of stratified clay and
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