Rubio Peak Formation
{{Use American English|date=November 2020}}
{{Short description|A geologic formation in New Mexico}}
{{Infobox rockunit
| name = Rubio Peak Formation
| image =Monument Peak Lake Valley NM USA.jpg
| caption = Monument Peak, located near Lake Valley, New Mexico, USA, is underlain by Rubio Peak Formation.
| type = Formation
| age = {{Geological range|Eocene}}
| period = Eocene
| prilithology =
| otherlithology =
| namedfor =
| namedby = W.E. Elston
| year_ts = 1953
| region = New Mexico
| country = United States
| coordinates = {{coord|32.6899504|N|107.8944869|W|display=inline}}
| unitof = Spears Group
| subunits =
| underlies = Sugarlump Tuff
| overlies = early Tertiary plutons
| thickness = {{convert|5000|feet|meters}}
| extent =
| area =
| map = {{Location map+ | United States#New Mexico
| relief = 1
| width = 250
| float = center
| places =
{{Location map~ | United States#New Mexico
| lat_deg = 32.690
| lon_deg = -107.894
| mark = Orange pog.svg
| marksize = 12
}}
}}
| map_caption =
}}
The Rubio Peak Formation is a geologic formation located in southwestern New Mexico.{{sfn|Hernon|Jones|Moore|1953}} It is thought to have been deposited in the Eocene Epoch.{{sfn|Clemons|1982}}
Description
The formation is volcanic, consisting mostly of flows of amphibole latites to pyroxene andesites{{sfn|Clemons|1982}} and associated volcaniclastics and tuffs.{{sfn|Hernon|Jones|Moore|1964}} The flows have a silica content of 59-63%. The appearance is highly variable, from pinkish gray to red to brown to black, with large to small phenocrysts and with glassy to fully crystalline texture. However, the chemical composition is reasonably uniform across the formation.{{sfn|Clemons|1982}} The maximum thickness is as much as {{convert|5000|feet|meters}}. It lies on older Tertiary intrusive rocks and is overlain{{sfn|Hernon|Jones|Moore|1964}} and interfingers with{{sfn|Strangway|Simpson|York|1976}} the Sugarlump Tuff.
Oxygen isotope ratios suggest that the magma from which the formation solidified had its origin in the Earth's mantle and underwent a degree of fractional crystallization.{{sfn|Hoffman|Michelfelder|2018}}
The formation has not been directly dated. However, the overlying Sugarlump Tuff has been radiometrically dated as 35.17±0.12 million years old, so the Rubio Peak Formation cannot be younger than this nor older than the Tertiary rocks on which it was deposited. This suggests an Eocene age for the formation.{{sfn|Kelley|2021}}
Fossils
The formation contains Duchesnean and early Chadronian mammal fossils. These included a jaw of the brontothere Duchesneodus.{{sfn|Lucas|2015|p=154}}
History of investigation
The formation first appears informally in a chart prepared by R.M. Hernon and coinvestigators in 1953,{{sfn|Hernon|Jones|Moore|1953}} but was apparently first used in an unpublished paper by W.E. Elston that same year.{{sfn|Jicha|1954}} C.H. Dane and G.O. Bachman (1961) mapped the formation throughout southwestern New Mexico and extended the definition to include some flows that appeared to be of Cretaceous age,{{sfn|Dane|Bachman|1961}} but subsequent work has restricted the definition to flows near the type area and of Eocene to Olicocene age.{{sfn|Strangway|Simpson|York|1976}} The formation was assigned to the Spears Group by Steven M. Cather and coinvestigators in 1994, who excluded the volcanic units and restricted the formation to the associated volcaniclastics.{{sfn|Cather|Chamberlin|Ratte|1994}}
Footnotes
{{Reflist}}
References
- {{cite journal |last1=Cather |first1=Steven M. |last2=Chamberlin |first2=R.M. |last3=Ratte |first3=J.C. |year=1994 |title=Tertiary stratigraphy and nomenclature for western New Mexico and eastern Arizona |journal=New Mexico Geological Society Field Conference Series |volume=45 |pages=259–266 |url=https://nmgs.nmt.edu/publications/guidebooks/downloads/45/45_p0259_p0266.pdf |access-date=25 August 2020}}
- {{cite journal |last1=Clemons |first1=R.E. |year=1982 |title=Geology of Massacre Peak quadrangle, Luna County, New Mexico |journal=New Mexico Bureau of Mines and Mineral Resources Geologic Map |volume=51 |url=https://ngmdb.usgs.gov/Prodesc/proddesc_73054.htm |access-date=6 August 2020}}
- {{cite journal |last1=Dane |first1=C.H. |last2=Bachman |first2=G.O. |year=1961 |title=Preliminary geologic map of the southwestern part of New Mexico |journal=U.S. Geological Survey Miscellaneous Investigations Series Map |volume=I-344 |url=https://ngmdb.usgs.gov/Prodesc/proddesc_1673.htm |access-date=6 August 2020}}
- {{cite journal |last1=Hernon |first1=R.M. |last2=Jones |first2=W.R. |last3=Moore |first3=S.L. |year=1953 |title=Some geological features of the Santa Rita quadrangle |journal=New Mexico Geological Society Field Conference Guidebook |volume=4 |pages=117–129 |url=https://nmgs.nmt.edu/publications/guidebooks/downloads/4/4_p0117_p0130.pdf |access-date=6 August 2020}}
- {{cite journal |last1=Hernon |first1=R.M. |last2=Jones |first2=W.R. |last3=Moore |first3=S.L. |year=1964 |title=Geology of the Santa Rita quadrangle, New Mexico |journal=U.S. Geological Survey Geologic Quadrangle Map |volume=GQ-306 |url=http://ngmdb.usgs.gov/Prodesc/proddesc_766.htm |access-date=6 August 2020}}
- {{cite journal |first1=M. |last1=Hoffman |first2=G.S. |last2=Michelfelder |year=2018 |title=Oxygen isotope variations in Paleogene volcanic rocks from southern New Mexico: Insight on crustal contamination and magmatic sources |pages=189–196 |journal=New Mexico Geological Society Field Conference Series |volume=69 |url=https://nmgs.nmt.edu/publications/guidebooks/downloads/69/69_p0189_p0196.pdf |access-date=11 March 2021}}
- {{cite journal |last1=Jicha |first1=H.L. Jr. |year=1954 |title=Geology and mineral deposits of Lake Valley quadrangle, Grant, Luna, and Sierra Counties, New Mexico |journal=New Mexico Bureau of Mines and Mineral Resources Bulletin |volume=37 |url=https://geoinfo.nmt.edu/publications/monographs/bulletins/downloads/37/Bulletin_37.pdf |access-date=6 August 2020}}
- {{cite web |last1=Kelley |first1=Shari A. |title=Cookes Peak |url=https://geoinfo.nmt.edu/tour/landmarks/cookes_peak/home.html |website=New Mexico Bureau of Geology & Mineral Resources |publisher=New Mexico Tech |access-date=15 July 2021 |ref={{Harvid|Kelley|2021}}}}
- {{cite journal |last1=Lucas |first1=Spencer G. |editor1-last=Lucas |editor1-first=S.G. |editor2-last=Sullivan |editor2-first=R.M. |title=Fossil Vertebrates in New Mexico |journal=New Mexico Museum of Natural History and Science Bulletin |date=2015 |volume=68 |pages=149–157 |url=https://books.google.com/books?id=S--oDQAAQBAJ&dq=%22Rubio+Peak+Formation%22&pg=PA149 |access-date=15 July 2021 |location=Eocene fossil vertebrates of New Mexico}}
- {{cite journal |last1=Strangway |first1=D.W. |last2=Simpson |first2=J. |last3=York |first3=D. |year=1976 |title=Paleomagnetic studies of volcanic rocks from the Mogollon Plateau area of Arizona and New Mexico |journal=New Mexico Geological Society Special Publication |volume=5 |pages=119–125}}