Puye Formation

The Puye Formation is a geologic formation exposed east of the Jemez Mountains of northern New Mexico. Radiometric dating constrains its age to between 5 and 2 million years, corresponding to the Pliocene epoch.

Puye Formation Stratigraphic range: Miocene to Pliocene
Puye Formation exposures in Rendija Canyon, New Mexico, USA
Type	Formation
Unit of	Santa Fe Group
Sub-units	Totavi Lentil
Underlies	Tewa Group
Overlies	Chamita Formation
Area	518 km^2
Thickness	221 metres (725 feet)
Lithology
Primary	Volcaniclastic
Other	Ignimbrite
Location
Coordinates	35.972°N 106.229°W / 35.972; -106.229
Region	New Mexico
Country	United States
Type section
Named for	Puye Escarpment
Named by	H.T.U. Smith
Year defined	1938

Description

The Puye Formation is a fanglomerate containing 25 pyroclasic flows, including pumicious ignimbrites and block-and-ash flows, erupted by vents of the Tschicoma Formation.[1] It is exposed from the mouth of Ancho Canyon in White Rock Canyon north to Santa Clara Peak, and generally underlies the Bandelier Tuff north and east of the city of Los Alamos, covering an area of 518 square kilometers.[2] It is best exposed in Guaje Canyon and on the southern end of the Puye Escarpment where it is a cliff-forming formation. It is 71 meters thick at the type section but thickens westward towards the Sierra de los Valles. Drilling has found that the formation is up to 221 meters thick.[3][4]The formation was deposited between 7 and 4 million years ago, based on radiometric dating of an ash bed in the upper part of the formation and the absence of Bearhead Rhyolite ash in the formation.[5][6]

The Totavi Lentil is the lowest part of the formation, some 24 meters thick, which consists of pebbles, cobbles, and small boulders of quartzite and granite with only limited volcanic debris, contrasting with the remainder of the formation.[4] This is separated by a significant unconformity from the underlying Chamita Formation.[6]

The main body of the Puye Formation consists of fanglomerates in which most of the detritus is volcanic rock of dacitic composition. There are also dacitic tephra beds and some basalt.[3] The formation shows cyclicity on the scale of 5 to 30 meters representing individual eruptive pulses in the northeastern Jemez highlands. Each sequence shows marked facies changes with increased distance from the eruptive center. Deposition ceased with reduction in Tschicoma volcanism and basinwide pedimentation due to downcutting of the Rio Grande. It is remarkably well preserved for an alluvial fan, due to its deposition in an active graben associated with Rio Grande Rift.[7]

A notable feature of exposures of the formation is the presence of pedestal rocks.[8]

• 
  Pedestal rocks in the Puye Formation
• 
  Cliffs of the Puye Formation along the Puye Escarpment

Economic geology

The formation is a high-yield aquifer exploited in the Los Alamos area.[9]

History of investigation

The formation was first named the Puye Gravel by H.T.U. Smith in his mapping of the Abiquiu quadrangle in 1938.[10] The name was changed to Puye Conglomerate by Roy Griggs in 1964, since the exposures he studied were consolidated enough to stand as cliffs. Griggs also designated a type section and divided the unit into an upper unnamed fanglomerate and a lower Totavi Lentil, named for a nearby settlement. Griggs assigned the formation to the Santa Fe Group.[3]

Because of its diverse lithology, the formation was renamed the Puye Formation by Bailey, Smith, and Ross in 1969 as part of their work establishing the stratigraphy of the Jemez Mountains.[4]

Footnotes

1. Turbeville et al. 1989
2. Turbeville et al. 1989
3. Griggs 1964, pp.28-37
4. Smith et al. 1969, p.12
5. Heiken et al. 1990, p.32
6. Kelley et al. 2013
7. Waresback and Turbeville 1990
8. Nocita 1986
9. Purtymun and Johansen, 1974, p.349
10. Smith 1938

References

• Griggs, R. L., 1964, Geology and ground-water resources of the Los Alamos area,New Mexico: U.S. Geol. Survey Water-Supply Paper 1753,107 p.
• Heiken, G; Goff, F; Gardner, J N; Baldridge, W S; Hulen, J B; Nielson, D L; Vaniman, D (May 1990). "The Valles/Toledo Caldera Complex, Jemez Volcanic Field, New Mexico". Annual Review of Earth and Planetary Sciences. 18 (1): 27–53. doi:10.1146/annurev.ea.18.050190.000331.
• Kelley, Shari A.; McIntosh, William C.; Goff, Fraser; Kempter, Kirt A.; Wolff, John A.; Esser, Richard; Braschayko, Suzanne; Love, David; Gardner, Jamie N. (June 2013). "Spatial and temporal trends in pre-caldera Jemez Mountains volcanic and fault activity". Geosphere. 9 (3): 614–646. doi:10.1130/GES00897.1.
• Nocita, Bruce W. (October 1986). "Pedestal rocks in the Pliocene Puye Formation, New Mexico". Sedimentary Geology. 49 (3–4): 193–200. doi:10.1016/0037-0738(86)90038-2.
• Purtymun, William D.; Johansen, Steven (1974). "General geohydrology of the Pajarito Plateau" (PDF). New Mexico Geological Society Field Conference Series. 25: 347–349. Retrieved 17 May 2020.
• Smith, H.T.U., 1938, Tertiary geology of the Abiquiu quadrangle, New Mexico: Journal of Geology, v. 46, no. 7, p. 933-965.
• Smith, R.L.; Bailey, R.A.; Ross, C.S. (1969). "Stratigraphic Nomenclature of ' Volcanic Rocks in the Jemez Mountains, New Mexico" (PDF). GEOLOGICAL SURVEY BULLETIN (1274-P). Retrieved 4 May 2020.
• Turbeville, B.N; Waresback, Damon B; Self, Stephen (February 1989). "Lava-dome growth and explosive volcanism in the Jemez Mountains, New Mexico: Evidence from the plio-pleistocene puye alluvial fan". Journal of Volcanology and Geothermal Research. 36 (4): 267–291. doi:10.1016/0377-0273(89)90074-7.
• Waresback, Damon B.; Turbeville, B. N. (March 1990). "Evolution of a Plio-Pleistocene volcanogenic-alluvial fan: The Puye Formation, Jemez Mountains, New Mexico". Geological Society of America Bulletin. 102 (3): 298–314. doi:10.1130/0016-7606(1990)102<0298:EOAPPV>2.3.CO;2.