AN ELECTRICAL MODEL FOR THE SUB‐ICELANDIC CRUST

Abstract

Active resistivity and magnetotelluric experiments in southwest Iceland suggest typical resistivities for the crust of 10 to 100 ohm‐m. These low crustal resistivities are compared with calculations on the expected resistivity of fluid‐saturated crustal rocks for plausible ranges of temperature, pore‐pressure, and water chemistry. The comparison of the synthetic models with actual field data suggests: (1) The suppression of resistivity at shallow depth is caused by regional hydrothermal activity. (2) Appreciable effects from water are obtained from depths to 8 or 10 km. (3) Below 10 km the effects from conduction along electrolytic paths are probably dominated by conduction in the solid rock itself.