Neogene stratigraphy and structure of the Dixon area, Espanola Basin, north-Central New Mexico

Purpose The purpose of this study was to map and analyze the Neogene stratigraphy and structure of the Dixon area, New Mexico. Special attention was focused on the petrography, facies relationships, and provenance of units within the Santa Fe Group that had not been studied previously. Also, detailed mapping was intended to permit a better understanding of the structural history of the Espanola basin. The Dixon area was chosen because preliminary reconnaissance suggested that detailed work would be of considerable help in determining the Tertiary basin evolution, and because it lies between areas mapped by Manley (1977) Muehlberger (1979). This paper originates from the author's University of New Mexico M.S. thesis (Steinpress, 1980). Location and Access The Dixon area is located approximately 55 km north of Santa Fe in north-central New Mexico (Fig. 1). The map area (Fig. 2) includes approximately 67 km2 (that portion of T. 23 N., R. 10 E. south of the Rio Grande and the six northernmost sections of T. 22 N., R. 10 E. The area includes exceptionally good exposures of Tertiary sedimentary rocks. The map boundary on the east (township line) was chosen to exclude areas to the east underlain mostly by Precambrian rocks. The southern boundary (southern section lines of sections 1 6, through T. 22 N., R. 10E) was chosen to give a slight overlap with Manley's (1977) map area. The western and northern boundaries (township lines and the Rio. Grande, respectively) were chosen to exclude areas where the Tertiary sedimentary rocks were largely covered by basalt and landslide debris. Excellent access is provided by U. S. Route 68 and State Route 75. Dirt roads and jeep trails provide additional access along several major arroyos. © 1981 The Geological Society of America, Inc.