"INDUCED POLARIZATION DATA AT ... - University of Utah

Data Acquisition
FIELD SURVEY
CHU
During the summer of 1978, 15 line-km of multi-frequency IP data
were obtained across the Roosevelt Hot Springs geothermal system, along
the two profiles shown in Figure 1. Line 1 crosses the southern half of
the geothermal system while Line 2 crosses the northern portion. The
zone of maximum hydrothermal alteration (Parry et al, 1980) is situated
between Lines 1 and 2. However, permit restrictions limited the
traverses to roadways only, and hence the location and configuration of
the profile lines. The western ends of Lines 1 and 2 correspond to 2200
Nand 5950 N, respectively, of the dipole-dipole resistivity survey grid
established by Ward and Sill (1976); the base line of this grid is also
shown in Figure 1.
Drill hole data revealed that polarizable clays were primarily
confined to the upper portion of the holes (Ballantyne and Parry, 1978:
Rohrs and Parry, 1978; Ballantyne, 1978). The depth of K-feldspar
stability was estimated at 400m (Ward and Sill, 1976). To resolve zones
of possible alteration, we used the collinear dipole-dipole array, with
dipole lengths of 100m and 300m and maximum n spacings of 4 and 6,
respect ivel y.
The equipment used in the survey included the ZERO phase-sensitive
receiver (GDP-12/2G), a Geotronics FT20A transmitter and a motor