STUDY OF THE CHAVES GEOTHERMAL-FIELD USING 3D RESISTIVITY MODELING

The present paper deals with the 3D modeling of a resistivity data set , carried out over the Chaves graben where the hot springs, with a tem perature reaching 78 degrees C, have a great economic importance. The main objective of the modeling was to incorporate the partial knowledg e obtained from previous 1D and 2D interpretations into a three dimens ional model. The 3D models of three rectangles and two dipole-dipole s urveys, which were performed to detect conductive zones associated wit h the hydrothermal circulation, depict the general form of the graben and the spatial configuration of the low resistivity zones (10-15 Ohm m). The achieved models exhibit several characteristics similar to tho se of previous 1D and 2D interpretations and are consistent with geolo gical information and new findings related to the bed-rock depth (1200 to 1500 m), the northern and southern borders of the conductive zones and its connection with the fault systems.