Stratigraphy and Tectonic Implications of Paleogene Strata in the Laramide Galisteo Basin, North-Central New Mexico
Stratigraphy and tectonic implications of Paleogene strata in the Laramide Galisteo Basin, north-central New Mexico by Spencer G. Lucas, New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, New Mexico 87104; Steven M. Cath er, New Mexico Bureau of Mines and Mineral Resources, Socorro, New Mexico 87801; John C. Abbott, Department of Geosciences, New Mexico Institute of Mining and Technology, Socorro, New Mexico 87801; and Thomas E. Williamson, New Mexico Museum of Natural History and Science, 1801 Mountain Road NW, Albuquerque, New Mexico 87104 Abstract Mexico has long been identified as the Formation, however, are green andred. base of the Galisteo Formation. This Although the Mesaverde-Galisteo con- We exclude the lower 0-442 m from boundary is a profound regional uncon- tact locally appears to be the Galisteo Formation and identify it as a formity between rocks of Late Cretaceous conformable, regionally the contact is new, unconformity-bounded and putative early Eocene age that has a major unconformity representing stratigraphic unit, the Diamond Tail been interpreted to reflect a major pulse in much of the Late Cretaceous and Formation. The Diamond Tail Formation Laramide tectonism. This pulse estab- probably some of the early Tertiary (Stearns, 1943; Gorham, 1979; is dominantly coarse-grained subarkosic lished the Laramide Galisteo Basin as a Beaumont, 1979). to arkosic sandstone and con- depocenter during Paleogene time. Here, we glomeratic sandstone with lesser reinterpret the stratigraphic relationships These criteria of Stearns (1943) for se- amounts of drab, green, gray, and lecting the Mesaverde-Galisteo contact maroon mudstone. It crops out in of the lower part of the Galisteo Formation are well accepted and have provided the north-central New Mexico in the Hagan and modify previous concepts of the late basis for most subsequent mapping (e.g., Basin and the Madrid-Cerrillos- Laramide evolution of the Galisteo Basin.
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