Direct-Current Resistivity At Haleakala Volcano Area (Thomas, 1986)
Exploration Activity: Direct-Current Resistivity At Haleakala Volcano Area (Thomas, 1986)
|Exploration Activity Details|
|Location||Haleakala Volcano Area|
|Exploration Technique||Direct-Current Resistivity Survey|
The field survey program on the northwest rift zone consisted of soil mercury and radon emanometry surveys, groundwater temperature and chemistry studies, Schlumberger resistivity soundings and self-potential profiles. Geophysical and geochemical surveys along this rift (southwest) were limited by difficult field conditions and access limitations. The geophysical program consisted of one Schlumberger sounding, one self-potential profile and one controlled-source electromagnetic sounding. The geochemical data collected included a reconnaissance soil mercury and radon emanometry survey and a limited groundwater sampling program. A single Schlumberger resistivity sounding was attempted north of the trace of the east rift zone at an elevation of approximately 110 m a.s.l. (Fig. 28). The resistivity structure defined by this sounding indicated moderate resistivities (2300- 7750 ohm-m) to near sea-level, corresponding to unsaturated ash and basalt layers, underlain by lower resistivity layers (150- 370 ohm.m) indicated to be cold freshwater- and cold seawater-saturated basalt, respectively (Mattice, 1981). Three groundwater sources on the east rift were sampled (Table 7). Measured temperatures ranged from 18.5 to 20.2degrees C. The chloride/magnesium ion ratio in one of the wells was within the normal range, whereas the other two showed marked deviations from expected ratios. One well was also found to have an abnormally high sulfate concentration. All three wells are located in the same general area and are sampling water from the basal lens; however, the anomalous wells are reportedly not pumped on a continuous basis. Thus, although the samples acquired show distinct anomalies, the association with a potential geothermal resource cannot be confirmed at present.
- Donald M. Thomas (1 January 1986) Geothermal Resources Assessment In Hawaii