Volcanic field at the foot of the east slopes of the Sangre de Cristo (Rocky) Mountains and Fort Union and Santa Fe trail
alkali basalt, andesite, and dacite
The Ocate volcanic field consists of at least 16 flows and about 50 associated vents ranging in age from 8.34±0.50 Ma to 0.81±0.14 Ma. Like the RCVF, three major topographic levels of lava flows relate to three age groups: (1) older than 5 Ma, which includes flows capping mesas with surfaces around 3000 m in elevation and an apparent E-W fissure line of vents near Wagon Mound; (2) 5-4 Ma, which includes most of the flows around Agua Fria; and (3) younger than 4 Ma, which includes the most abundant flows in the OVF and such vents as Cerrito Pelon, Cerro Negro, Cerro del Oro and Maxon Crater. Maxon crater consists of a large cluster of scoria cones defining the summit substantial shield volcano which Interstate 25 crosses between Watrous and Springer. Flows from Maxon crater flowed 90 km eastward along the canyon cut by the Mora River. Remnants of these flows occur 100 m below the rim of the canyon and 125 m above the present level of the river. The youngest flows in the field were erupted from Cerro del Oro, in the central part of Charette Mesa, northwest of Wagon Mound.
Cerro Pelon volcanic center as seen from Fort Union National Monument. Photo L. Crumpler
Wagon Mound viewed from the outskirts of the small town of the same name. The structure consists of an elongate thick basaltic lava and tuff breccia section striking along a local fissure line, now topographically inverted. Wagon Mound was a prominent sight along the Santa Fe Trail. Photo L. Crumpler
View Ocate Volcanic Field in a larger map
Petrology/ General Geology:
Aubele, J. C., and L. S. Crumpler, 2001, Raton-Clayton and Ocate volcanic fields. NM Geol. Soc. 52nd Field Conference Guidebook, p. 69-76.
Calvin, E.M., 1987, A review of the volcanic history and stratigraphy of northeastern New Mexico, the Ocate and Raton-Clayton volcanic fields: NM Geological Society, 38th Field Conference, Guidebook, p. 83-85.
Dungan, M.A., Thompson, R.A., and Stormer, J.S., 1989, Rio Grande rift volcanism: northeastern Jemez zone, New Mexico, in Field Excursions to Volcanic Terranes in the Western United
States, vol. 1, Southern Rocky Mountain Region: NM Bureau Mines Min. Res., Mem. 46, p. 474-475.
Nielsen, R.L. and Dungan, M.A., 1985, The petrology and geochemistry of the Ocate volcanic field, north-central NM: Geological Society of America Bulletin, v. 96, no. 3, p. 296-312.
O‘Neill, J.M., 1988, Late Cenozoic physiographic evolution of the Ocate volcanic field: U.S.Geological Survey, Prof. Paper 1478-B.
O’Neill, J.M, 1989, Late Cenozoic volcanism, uplift, and erosion, Ocate volcanic field, north-central NM: summary: in Chapin, C.E., and Zidek, J., eds., Field Excursions to Volcanic Terranes in
the West ern United States, vol. 1: Southern Rocky Mountain Region: NM Bur. Mines and Min. Res., Mem. 46, p. 466-486.
O‘Neill, J.M. and Mehnert, H.H., 1988, Petrology and physiographic evolution of the Ocate volcanic field, north-central New Mexico: U. S. Geological Survey Prof. Paper 1478-A.
Scott, G.R., Wilcox, R.E., and Mehnert, H.H., 1990, Geology of volcanic and subvolcanic rocks of the Raton-Springer area, Colfax and Union Counties, NM: U.S. Geological Survey Prof. Paper 1507, 58p.
All text and photo credit due to Dr. Larry Crumpler, New Mexico Museum of Natural History and Science
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