EVIDENCE FOR GREATER ANCESTRAL ROCKY MOUNTAIN FAULT ZONES FROM THE CUERVO BASIN, EASTERN NEW MEXICO

The Cuervo Basin is a subbasin of the larger Tucumcari Basin in east-central New Mexico. The basin is asymmetric and elongated in a NE-SW direction, approximately 22km long and 10km wide. The basin is one of the of the 'elevator basins' of Broadhead, so called because it deepened rapidly in Pennsylvanian time as part of the development of the Greater Ancestral Rocky Mountains. The basin is an extensional half-graben bounded to the NW by a SE-dipping listric normal growth fault, approximately 5 km deep and predominantly filled with rocks of Atokan-Desmoinian age. The geometry, depth, and rapid development of the Cuervo Basin indicate that it is a pull-apart graben formed by strike-slip motion and possible reactivation of an older fault zone. Evidence suggests the Cuervo Basin formed along an E-W trending zone of left-slip which forms the northern boundary for the larger transrotational setting of the Tucumcari Basin. This bounding lineament extends eastward into the panhandle of Texas as suggested by Brister, and is likely continuous with the zone separating he Amarillo-Wichita Uplift from the Palo Duro Basin. The westward continuation of the zone is unclear at present and is being investigated.