Bulletin 132 — Geology and paleontology of the Santa Fe Group, southwestern Albuquerque Basin, Valencia County, New Mexico

By R. P. Lozinsky and R. H. Tedford, 1991, 36 pp., 3 tables, 20 figs., 3 sheets, 2 appendices.

This report on the geology and paleontology of the southwestern Albuquerque Basin is the first study of the Santa Fe Group that combines surface and subsurface information to interpret the depositional history of the area. Although the main focus is on the Santa Fe Group, pre-Santa Fe Tertiary deposits and the erosion history of the surrounding uplifts are discussed. Incorporated into the study are detailed field mapping, oil-test-well analysis, sandstone petrology, and paleontology.

The uppermost Oligocene to middle Pleistocene Santa Fe Group is the major synorogenic deposit of the Rio Grande rift. Sedimentary fill of the Santa Fe Group includes piedmont-alluvial, playa, fluvial, and eolian deposits that locally reach thicknesses of over 4,000 m. The thickest exposed section of the Santa Fe Group lies in the southwestern part of the basin. Most studies of the Santa Fe Group have been conducted in the northern part of the Albuquerque Basin, whereas in the southwestern part have been few. Thus, the southwestern part of the basin is a critical area for studying the Santa Fe Group and the depositional history of the Albuquerque Basin.

Santa Fe Group crops out in the southwestern Albuquerque Basin occur in the Gabaldon badlands and Bobo Butte areas. Two oil test wells located near the Gabaldon badlands, the Humble Santa Fe Pacific #1 and Shell Santa Fe Pacific #2, penetrate the Santa Fe Group and pre-Santa Fe Tertiary deposits and bottom in Mesozoic bedrock.

In the Gabaldon badlands, the thickness of the exposed Santa Fe Group is at least 1,138 m and may be as much as 1,800 m. In the Humble Santa Fe Pacific #1 and Shell Santa Fe Pacific #2 wells, the Santa Fe thickness is 1,494 and 1,460 m respectively. The thickness of the exposed Santa Fe section at Bobo Butte is 246 m. In the oil test wells, up to 1,079 m of pre-Santa Fe Group Tertiary deposits, which are correlative with possible Baca Formation and an unnamed post-Baca/pre-Santa Fe unit, underlie the Santa Fe Group. These pre-Santa Fe deposits indicate the presence of a depositional basin that predates the Albuquerque Basin.