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Structural transect of the southern Chihuahua Fold Belt between Ojinaga and Aldama, Chihuahua, Mexico

1994; Wiley; Volume: 13; Issue: 6 Linguagem: Inglês

10.1029/94tc00800

1944-9194

Peter Hennings,

Geological and Tectonic Studies in Latin America

A restorable structural transect has been constructed across the southern end of the Chihuahua Fold Belt segment of the Cordilleran foreland fold and thrust belt of northeastern Chihuahua, Mexico, and west Texas. The 160‐km transect begins near Ojinaga and ends near Aldama, Chihuahua. It has been found that the Mesozoic Chihuahua Trough was inverted by Laramide tectonism and regionally shortened approximately 20 km (about 9%) along the transect to form the Chihuahua Fold Belt. Along the transect the belt consists of two allochthons of opposing vergence directions. The décollement of the eastern, northeast vergent allochthon shallows from within the Jurassic evaporites, along the center of the belt, and surfaces in Upper Cretaceous clastic rocks at the eastern thrust front south of Ojinaga, Chihuahua. The eastern allochthon was shortened approximately 6 km and may be divided, from west to east, into main ranges and an eastern frontal zone. Structures of the main ranges are detached in Jurassic evaporites and were greatly influenced by syntectonic flowage, resulting in salt‐cored anticlines and salt withdrawal synclines. To the east the décollement shallows over the Tascotal basement block which formed a buttress to northeastward transport forming a frontal zone containing ramp‐related anticlines and emergent thrusts. The western allochthon is southwest vergent. The décollement cuts up section from the center of the belt, where Precambrian basement is detached in the Plomosas Uplift, to Lower Cretaceous carbonates of the western frontal zone. The western allochthon was shortened approximately 20 km at the Paleozoic level and approximately 11 km at the Mesozoic level. Local basement involvement in the Plomosas Uplift may result from strike‐slip deformation along a northwest trending basement fault.