Aeromagnetic study of the Colorado River delta area, Mexico.

Abstract

An aeromagnetic study of the Colorado River delta area, Baja California, Mexico, was undertaken to determine the basement structure under relatively nonmagnetic sediments and to compare magnetic values with the rock type in outcrop areas. From an economic point of view, there is a close relationship between basement structure and lithology and geothermal heat sources. From an academic point of view this study can also relate the basement structure with spreading centers. The Colorado River delta area was flown in July 1971, using a flight-line spacing of 5 km and a constant barometric elevation of 2,000 feet (0.610 km) above mean sea level over most of the area. The barometric elevation over the mountains was 2,500 feet (0.762 km). The residual aeromagnetic map of the area was obtained by subtracting the International Geomagnetic Reference Field from the total intensity magnetic values. The major result of this work is the discovery of an apparent spreading center, herein named Panga de Abajo, at lat 32 º2' N., long 115 º12' W. The association of this probable spreading center with a geothermal field could not be established with this survey. However, the aeromagnetic survey places bounds on a new area that should be studied in the future, using more detailed geophysical methods.