Quaternary and Pliocene faults in the La Jencia and southern part of the Albuquerque-Belen Basins, New Mexico--Evidence of fault history from fault-scarp morphology and Quaternary geology
Michael N. Machette
The La Jencia and Albuquerque-Belen basins are two of the main structural depressions in the central part of the Rio Grande rift of New Mexico. Within these two basins are many faults that displace basin- fill deposits of Pliocene and Quaternary age and surficial deposits of middle and late Quaternary age. None of the faults I have studied in these basins show evidence of historical ground breakage; however, several show evidence of Holocene movement, and many show evidence of late Pleistocene movement. Recently published neotectonic maps of the Rio Grande rift (Woodward and others, 1975; Hawley, 1978) included many of the faults described in this report; however, no systematic study of ages or amounts of fault movement has been made previously.
This report considers only faults with Quaternary or Pliocene movement and includes information on the amount of fault displacement, the age of displaced deposits, the recency of fault movement, and the morphology of some fault scarps. These data were derived from published and unpublished geologic maps and reports, from low-altitude aerial photography, from studies of Quaternary deposits along the faults, and from an analysis of fault-scarp morphology. Where several sources of map data were available, I used those compiled at larger scales and those that focus on late Cenozoic structure and stratigraphy.
The faults shown on the map (fig. 1) provide direct evidence of Quaternary or Pliocene movement; those faults that lie entirely within Miocene or older rocks are not shown. The reader should be aware of this selection, especially if data from this report are used in hazards assessment, in regional structural analysis, or in other studies.
- Machette, Michael N., 1982, Quaternary and Pliocene faults in the La Jencia and southern part of the Albuquerque-Belen Basins, New Mexico--Evidence of fault history from fault-scarp morphology and Quaternary geology, in: Albuquerque Country II, Grambling, J. A.; Wells, S. G., New Mexico Geological Society, Guidebook, 33rd Field Conference, pp. 161-169.