Abstract

OVIEDO-PADRON, Edgar Gerardo et al. Tectonics of the Sierra Cuesta El Infierno and its possible relation to faults reactivated near the Plomosas uplift, Chihuahua, México. Rev. mex. cienc. geol [online]. 2010, vol.27, n.3, pp.389-411. ISSN 2007-2902.

Geologic and structural mapping of volcanic rocks in sierra Cuesta El Infierno, located on the western flank of the Plomosas uplift, allowed us to divide the Paleogene volcanic section into two succesions. The volcanic rocks unconformably overlie sedimentary rocks of the Chihuahua fold belt. The lower volcanic succession felsic ash flow tuffs and epiclastic continental deposits) is separatedfrom the upper volcanic succession (andesitic lavaflows with interlayered rhyolitic ash flow tuff) by a small angular unconformity. The volcanic successions are exposed in northern and southern structural domains of the SCI, which are separated by an inferred basement fault (N70°W) with a complex history. The basement fault acted since middle to late Paleogene as a transfer zone that accommodated the deformation of fault systems with different trends in the areas located north and south of its trace. The basement fault also controlled the distribution ofsome of the ash flow tuffs, the eruption of the lava flows, and the local Basin and Range strain pattern during the Cenozoic. A SSE-plunging syncline with a N20°W trend associated with a system of listric normal faults parallel to the fold axis and a small roll-over anticline occur in rocks of the lower volcanic succession in the northern structural domain. The syncline is interpreted as a fault bendfold. In the southern domain of the study area, we recognize an accommodation zone between two antithetic listric faults that consists of a N45°W-trending antiform.

Keywords : tectonics; Paleogene; Basin and Range; sierra Cuesta El Infierno; Chihuahua; México.

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