MULTI-STAGE LARAMIDE DEFORMATION OF THE GALISTEO BASIN AREA, NORTH-CENTRAL NEW MEXICO

A subcrop map of the Tertiary Diamond Tail Formation in the Galisteo basin, south of Santa Fe, New Mexico, shows a large, open to the north, U-shaped pattern for Phanerozoic (Mississippian to Late Cretaceous) strata. The pattern defines a broad, southwest-plunging anticlinal nose extending from the Precambrian core of the Sangre de Cristo range at Canoncito which is bound on the southeast by a southeast-facing monocline along the Tijeras-Canoncito fault zone. These relationships indicate two phases of Laramide deformation. In the first, the Maestrichtian or early Paleocene Brazos-Sangre de Cristo uplift extended at least 12 km southwest from the present bold mountain front of the Sangre de Cristo range. The second deformation phase followed beveling of the Phanerozoic section, when the shoulder of the Sangre de Cristo uplift collapsed forming part of the NNW-trending Echo Park-type Galisteo basin, filled with Late Paleocene or Early Eocene Diamond Tail and Eocene Galisteo Formations and the Oligocene Espinaso Volcanics. Fracture studies (Erslev, 2001) indicate two subsequent pulses of Laramide regional compression in the Galisteo area with Post-Diamond Tail (Early Eocene) maximum compression oriented ENE and post-Galisteo (Late Eocene/Oligocene?) compression oriented NNE.

The erosional edge of the Campanian Point Lookout Sandstone beneath the Diamond Tail Formation lies just south of Galisteo Creek and is not offset laterally across the long-lived, northeast-trending, Tijeras-Canoncito fault zone. This has regional implications for Laramide development of northern New Mexico as it does not support models that assign right slip of this age to this fault zone.