Description and development of the Cordilleran orogenic belt in the Southwestern United States and northern Mexico

Abstract

The Cordilleran erogenic belt forms a continuous zone of compressive deformation of Late Jurassic to Eocene age resulting from collision of the converging North American plate with northeast Pacific plates. The segment of the belt between El Paso, Texas, and Las Vegas, Nevada, differs from adjacent segments in that subordinate tectonic zones are truncated along an unusual kind of frontal zone. This difference is believed to result from a combination of oblique collision of the deformation zones with the semicratonic Colorado Plateau block, the effects of pre-orogenic basement faults along the southwest margin of that block, southward tilting and deep erosion along this frontal segment, and overprinting of extensional tectonism. The style of deformation across this segment of the erogenic belt varies systematically. In the fold-and-thrust zone (northern Chihuahua, Mexico), folds are large, open to moderately tight, and only slightly inclined, but disharmonic, over (that is, truncated against) genetically related thrust faults and small backthrusts in Permian and Mesozoic rocks. In an eastern intermediate zone (southwestern New Mexico and southeasternmost Arizona), folds are smaller, tighter, and more markedly inclined northeastward toward related shingled thrust faults and larger backthrusts. Likely, detachment occurred along the top of the crystalline basement of Precambrian age. In a western intermediate zone (much of southeastern and central southern Arizona), many folds are also small and are strongly inclined northeastward toward related thrust faults, but some erosional remnants of larger folds involve major thrust plates. Locally, crystalline basement rocks occur in these major plates. In the hinterland zone, many folds are recumbent, and thrust faults are numerous and commonly are parallel to bedding in ductily deformed thin plates of Phanerozoic rock and to foliation in massive plates of basement rock. Areas of mild deformation of a foreland zone lie northeast of, and beneath the fold-and-thrust zone. They are viewed as being external to the main part of the erogenic belt because their faults probably are not continuous with those of the erogenic belt proper in the level of relatively brittle deformation. This zone extends across the Colorado Plateau and east to the Rocky Mountain front. The style and age of deformation in this zone and that of the fold-and-thrust zone are most typically the Laramide phase of the orogeny.

Secuencias estratigráficas del Berriasiano-Aptiano en la Cuenca de Sabinas: su significado en el entendimiento de la evolución geológica del noreste mexicano

“…En adición a estos datos, en el Sistema Cordillerano (Orogenia Nevadiana) existen efectos tectónicos asociados al movimiento de placas del oeste de Norteamérica y también se reconoce una discordancia regional en el Berriasiano (Drewes, 1991). En este entorno geodinámico existe la disyuntiva para resolver cuál evento tuvo mayor influencia en el noreste de México; tal parece que el cambio relativo del nivel del mar predomina sobre la tectónica.…”

Tectonic history of the Chihuahua trough, Mexico and adjacent USA, Part II: Mesozoic and Cenozoic

“…Uphoff's interpretation is that the Cuchillo Formation (Aptian-Albian) is the oldest Mesozoic unit that is continuous across the "Clint fault" and he suggested that pre-Cuchillo Mesozoic activity along the fault removed any Jurassic rocks that were present to the north of the fault. Figure 15 shows an alternative interpretation to that shown by Uphoff (1978) and Drewes (1991a). Here the "Clint fault" is interpreted as a part of the Texas Lineament and is interpreted as a Jurassic basin-bounding fault that was reactivated during the Laramide orogeny as a reverse fault and again during Tertiary time as a normal fault; Paleozoic faulting along the Clint fault zone is possible but not necessary.…”

“…Depth of the section, in 2-way travel time is 4 seconds (fair to good reflectors to about 3 seconds), which corresponds to depths of 10 to 12 km (estimated from velocity data from a refraction survey reported by Tovar-R. et. al., 1978, p. 111) and should show thrust faulting at or above the maximum depth of sole thrusts (about 5 km) postulated by Corbitt (1988) and Drewes (1991a). Figure 30) also showed a reflection seismic line through PEMEX (MOY-1), and several lines (Figures 14 and 29) in the vicinity of PEMEX Banco Lucero-1 (BL-1) that do not show thrust faults.…”

“…Drewes (1991a) described the Cordilleran orogeny becoming progressively younger from west to east (late Jurassic to Eocene; includes Sevier and Laramide time slices of the Tectonic Map of North America) and placed deformation in northern Chihuahua in the Eocene. In a similar fashion, Keith and Wilt (1986) described four phases of Laramide orogeny (becoming younger toward the east) and placed events in New Mexico, directly north of the Chihuahua trough, in their culminant phase (45-55 Ma).…”

“…Two contrasting interpretations of Laramide deformation in adjacent Arizona and New Mexico have been advocated: 1) major décollement, within or at the base of the Paleozoic section, with northeast-directed thrusting (e.g., Corbitt, 1988;Drewes, 1991a); and 2) basement-cored uplifts separated by largely undeformed intermontane basins (e.g., Davis, 1979, Seager et al, 1986Mack and Clemons, 1988). Proponents of the décollement theory believe that the northern margin of the Chihuahua tectonic belt is part of the Cordilleran "overthrust" belt (e.g., Drewes, 1991a). Brown and Dyer (1987) suggested a faulted basement model for structures they described in northwestern Chihuahua.…”