Estudio gravimétrico en la zona geotérmica de La Presita, Culiacán, México

Abstract

A gravity survey was conducted in 1981 in La Presita geothermal area near the city of Culiacán, Sinaloa, México. A total of 306 stations were occupied in an area of approximately 290 km2. The data have been reduced and processed by means of a series of algorithms fully described in this work. A two-dimensional inversion scheme to interpret the data was u sed. From the results of the inversion we infer the presence of a N-NW trending "horst"-type structure, predominant in the surveyed area. To the west of the area of interest, the basement structure suggests the presence of a normal fault not shown at the surface but consistent with the fault system and fractures occurring regionally. To the East, the horst is limited by the large basin of the Humaya river whose sediment thickness is near 1 km. Poor evidence exist as to the southern extension of his "horst-like" structure. We believe that the geothermal zone of La Presita is characterized by a system of normal faults that allows thermal waters. to rise to the surface. However, little geophysical evidence exists to infer the prese~ce of a large anomalous zone in depth.