Magnetotelluric soundings along the COCORP seismic profile in the central Rio Grande rift
— Peter S. Mitchell and George R. Jiracek

Geophysical probing of the earth's crust and upper mantle has been accomplished primarily by seismic methods although important com- plementary information has been supplied by gravity, magnetic, and heat flow studies. Magnetotelluric (MT) soundings have more recently contributed to our understanding of the lithosphere by defining its elec- trical resistivity. The resistivity of earth materials in the subterranean environment is extremely sensitive to the prevailing temperature and moisture conditions. Indeed, the distribution with depth of electrically conducting zones may provide an effective measure of the temperature distribution in the earth (Adam, 1978; Shankland and Ander, 1981).

In 1977 and 1979, a total of 27 magnetotelluric stations were occupied in the region of the Rio Grande rift of central New Mexico (fig. 1). This paper presents the results of two-dimensional (2-D) modeling of 10 of those stations. Most of the 10 stations were located along the 1975-1976 Consortium for Continental Reflection Profiling (COCORP) seismic lines 1 and la (S-S in figs. 1 and 2). Therefore, the MT stations form a profile across the southern Albuquerque-Belen Basin of the Rio Grande rift. The profile is more than 100 km long, stretching from the Sierra Lucero in the west to the Estancia Basin in the east. Major objectives of the study were: (1) to compare the MT interpretations with the COCORP findings, and (2) to investigate the rift's crust and upper mantle transitional boundaries with the Basin and Range and the Great Plains tectonic provinces, to the west and east, respectively.