Abstract

The portion of the Chihuahua Tectonic Belt that lies within the United States is 480 km (300 mi) long, extending from El Paso to Presidio, Texas. The frontal thrusts of the Chihuahua Tectonic Belt lie against the Diablo Platform and are coincident with part of the Texas lineament.

The stratigraphic sequence involved in thrusting ranges in age from Permian to upper Cretaceous. Low angle thrusts mapped from seismic data form a decollement in Permian and Jurassic evaporites.

Stratigraphic analysis of the Jurassic Malone Formation demonstrates that it is a fan-delta system resulting from early Jurassic normal faulting. This event may be correlated with the opening of the Gulf of Mexico and formation of the Chihuahua Trough, beginning in late Triassic. The Chihuahua Tectonic Belt includes the rocks deposited in the Chihuahua Trough and later deformed during Laramide events. The inferred sequence of tectonic events is: 1) Late Triassic-Early Jurassic normal faulting and formation of the Chihuahua Trough, 2) Laramide folding and thrusting, and 3) Basin-and-Range faulting.