Dead horse graben: A west Texas accommodation zone

The Cretaceous rocks of the Dead Horse graben area underwent two superposed deformations. Laramide (latest Cretaceous to early Tertiary) left‐transpression structures are overprinted by a Basin and Range (Miocene to Recent) accommodation zone. During Laramide shortening, two northwest trending sets of monoclines developed: an en echelon set over a left‐slip basement fault and a single monocline draped over the uplifted edge of a rotated basement block. Basin and Range extension caused northerly trending half‐grabens that have opposing asymmetry: downthrown‐to‐the‐east north of the study area and downthrown‐to‐the‐west south of the area. These half‐grabens are separated by an accommodation zone, expressed as a northwest trending, right‐lateral pull‐apart graben. The normal faults of the pull‐apart graben flatten at a shallower depth than those of the half‐grabens. This suggests not only that accommodation zones can be mechanically layered but that this layering can occur on a scale different from the adjacent half‐grabens. The northwest trend and superposition of both sets of structures implies a tectonic control by the preexisting structural fabric of the Texas Lineament.