Exploracion carbonífera en la Cuenca de Ojinaga, Chihuahua

http://dx.doi.org/10.18268/BSGM1984v45n3a3

Fernando Cabrera, Gerardo Narváez, José Ma. Chávez, Raúl Hernández, Jorge Alcantara y Filiberto Gómez

C.F.E.

Abstract

The geology and coal occurrences are described and an account of the relationship between them is given; a preliminary assesment of this coal seams within the Ojinaga basin is presented. The studied area covers 15000 km² in the northeastern part of Chihuahua; field surveys produced new, unpublished data, specially from the southern part of the basin.

Outcrops are compased mainly of Jurassic and Cretaceous sedimentary units, which belong to an evaporite sequence and are exposed in the north western most part of the area; also present is a thick section of Cretaceous sedimentary rocks, the main bulk of which is of Lower Cretaceous age. Upper Cretaceous units are predominantly clastic, with facies changes throughout the basin, therefore, changing the stratigraphic nomenclature of these units. Cretaceous and Tertiary intrusions as sills and dikes of basic composition, massive felsic bodies and Tertiary extrusive rocks, composed of thick volcaniclastic and pyroclastic units represent the top-rnost sequences.

Late Cretaceous sediments were deposited under an SE prograding delta regime. Within them, those with greatest interest are the El Picacho and Aguja Continental Formations, since they host the coal seams, both equivalent and belonging to a delta plain environment.

Within these fomations, sub-bituminous coal occurrences were frequently observed, with an adequated grade its utilization in electric power plants. Thicknesses vary from 0.4-1.2 m, allowing for an estimate of 300 millions tons of coal resources.