Geology of the Sierra of Oposura, Moctezuma, State of Sonora, Mexico

Abstract

The Sierra of Oposura (or La Madera) is located at about 200 km to the NE of the city of Hermosillo. The study area lies within the subprovince of Parallel Valleys and Ranges of the physiographic province of the Sierra Madre Occidental. The Sierra of Oposura and the adjacent Valley of Moctezuma are limited by NW-SE trending normal faults and locally are the most important morphologic features.

The pre-batholithic rocks consist of a sequence of limestone and shale of Early Cretaceous age. These rocks are overlain in angular unconformity by an Upper Cretaceous sequence of mainly andesític flows and tuffs, which also includes ignimbrite and conglomerate in the upper part. These two sequences are intruded by the Oposura Batholith. lntrusive contacts may be observed to the south and east of the study area. To the west, the batholithic rocks are in fault contact with Tertiary clastic rocks... In order to continue, download full text in PDF.