Direct-Current Resistivity Survey At Mokapu Penninsula Area (Thomas, 1986)
Exploration Activity: Direct-Current Resistivity Survey At Mokapu Penninsula Area (Thomas, 1986)
|Exploration Activity Details|
|Location||Mokapu Penninsula Area|
|Exploration Technique||Direct-Current Resistivity Survey|
Geophysical surveys on Mokapu were restricted to three Schlumberger soundings (Fig. 17). The results of these soundings appeared to indicate a highly resistive surface section underlain by one or more layers of intermediate to low resistivity (Fig. 18). Basement resistivities in all cases were less than 3 ohm.m and were interpreted to correspond to alluvial layers saturated with cold seawater (Lienert, 1982). --- A separate geophysical analysis performed on the Koolau caldera area (Kauahikaua, 1981 a) synthesized existing self-potential, gravity, seismic and aeromagnetic data with recently acquired resistivity soundings. An analysis of the observed remnant magnetization within the caldera complex suggested that subsurface temperatures ranged from less than 300degrees C to no more than 540degrees C. The resistivity data indicated that the electrical basement, to a depth of 900 m, had resistivities ranging from 42 ohm.m to more than 1000 ohm.m, which is considered to be within the expected range for basalts (or alteration suites) saturated by cold, fresh to saline water. No substantial effects on the resistivities were observed that were interpreted to be due to thermal influences. In the light of the geophysical data just reviewed, it may be assumed that if a thermal resource is associated with the Koolau caldera, its temperature is probably very low.
- Donald M. Thomas (1 January 1986) Geothermal Resources Assessment In Hawaii