Day 0 East Road Log : Sevilleta National Wildlife Refuge Visitor Center to Bernardo, across the Rio Grande, to the east side of the refuge between Black Butte and Cibola Drainage, southwest of the Los Pinos Mountains
— D.W. Love, B.D. Allen, A.J. Rinehart, B.A. Frey, S.G. Lucas, P.A. Scholle, D.S. Ulmer-Scholle, and S.C. Hook
This pre-meeting road log begins at the gate leading to the Sevilleta National Wildlife Refuge (NWR) Visitor Center just west of interchange 169 on I-25. The first 15 miles of the route north and east through Bernardo crosses basin-fill deposits, terraces, and modern floodplain and channel of the Rio Grande, Rio Puerco, and tributaries from the southeastern Albuquerque Basin. Stops 1 and 2 orient participants to the subtle geomorphology and diverse sediment sources forming features surrounding Turututu (Black Butte) on the northern edge of Sevilleta NWR. The route south to Stop 3 climbs a large fan complex deposited by the Palo Duro drainage before it incised northwest-directed Palo Duro Canyon into Paleozoic, Mesozoic and Paleogene bedrock. Stop 3 presents a panorama of structural and erosional features and complex stratigraphy of Sevilleta NWR at the southeastern boundary of the Albuquerque Basin.
After Stop 3, depending on the interests of participants, four options are possible. The first option is to continue south to see Mesozoic stratigraphy (Triassic, Jurassic and Cretaceous units are all exposed) and structural complexity west of an extensive north-south monoclinal structure. This option also visits the Sevilleta reference section of Cretaceous strata. The second option is to examine complicated structure and stratigraphy west of a second north-south monoclinal structure exposed in Palo Duro Canyon. The Permian San Andres Formation is locally overturned, to the west, whereas the vertical Triassic Ojo Huelos limestone strata at the base of the slope indicate that up is to the east. Normal faults to the west repeat Cretaceous units and involve strata as young as Eocene Spears Formation. The third option is to hike (~ 1 mile round trip) to see brick-red metasomatic episyenites invading Proterozoic granite and simple pegmatites in a subdued mile-long outcrop separated from the Proterozoic of the Los Pinos Mountains to the east by 7 miles. The fourth option is to visit a well-exposed Pennsylvanian bioherm in a spectacular slot canyon near Cibola Spring in the southern foothills of the Los Pinos Mountains. Participants may choose more than one option as long as they remain in groups with leaders and are back in Belen in time for the icebreaker.
Note: Full-text Fall Field Conference road logs for recent guidebooks are only available in print.
- Love, D.W.; Allen, B.D.; Rinehart, A.J.; Frey, B.A.;Lucas, S.G.; Scholle, P.A.; Ulmer-Scholle, D.S.; Hook, S.C., 2016, Day 0 East Road Log : Sevilleta National Wildlife Refuge Visitor Center to Bernardo, across the Rio Grande, to the east side of the refuge between Black Butte and Cibola Drainage, southwest of the Los Pinos Mountains, in: The Geology of the Belen Area, Frey, Bonnie A.; Karlstrom, Karl E.; Lucas, Spencer G.; Williams, Shannon; Zeigler, Kate; McLemore, Virginia; Ulmer-Scholle, Dana S., New Mexico Geological Society, Guidebook, 67th Field Conference, pp. 1-22. https://doi.org/10.56577/FFC-67.1