Marquenas Formation

The Marquenas Formation is a geological formation that crops out in the Picuris Mountains of northern New Mexico. Detrital zircon geochronology gives it a maximum age of 1435 million years, corresponding to the Calymmian period.

Marquenas Formation Stratigraphic range: Calymmian
Marquenas Formation with crosscutting dike, Picuris Mountains
Type	Formation
Overlies	Piedra Lumbre Formation
Thickness	500 m (1,600 ft)
Lithology
Primary	Quartzite
Other	Metaconglomerate
Location
Coordinates	36.207°N 105.820°W / 36.207; -105.820
Region	Picuris Mountains, New Mexico
Country	United States
Type section
Named for	Cerro de las Marquenas (36.207°N 105.820°W / 36.207; -105.820)
Named by	Long
Year defined	1976
Marquenas Formation (the United States) Show map of the United States Marquenas Formation (New Mexico) Show map of New Mexico

Description

The Marquenas Formation was first believed to be over 80% quartzite, with the rest mostly metaconglomerate. The metaconglomerate lenses are found throughout the formation but particularly towards its top, and it was designated the Marquenas Quartzite.[1] However, Bauer and Williams noted that the unit is about equally divided between quartzite and metaconglomerate, which led them to redesignated it as the Marquenas Formation.[2] It can be divided into a lower, highly strained, poorly sorted boulder conglomerate; a middle quartzite member; and an upper, highly strained, pebble-to-cobble conglomerate.[3] Cross stratification shows that the layering is overturned, and this supported the interpretation of the formation as part of the Vadito Group, likely correlating with the Big Rock Formation of the Tusas Mountains.[2] but detrital zircon geochronology establishes a maximum age of 1435 Mya, much younger than the Vadito Group.[4] The provenance of the quartzite clasts in the Marquenas Formation remain uncertain, since they contain no aluminum silicate minerals and little crossbedding, but both are present in the Ortega Formation, the most likely local source rock.[2]

A metamorphosed tuff bed in the Pilar Formation yields an age of 1488 ± 6 Mya, and the Piedra Lumbre Formation likewise contains zircons dated to 1425 Mya. This suggests that the Pilar Formation and Piedra Lumbre Formation should be removed from the Hondo Group, and grouped with the Marquenas Formation as sediments deposited by the Picuris orogeny.[5]

• 
  Coarse conglomerate at the base of the Marquenas Formation
• 
  Middle quartzite section of Marquenas Formation
• 
  Sample of quartzite from the middle section of the Marquenas Formation
• 
  Upper beds of Marquenas Formation

History of investigation

The beds were originally assigned to the lower conglomerate member of the Vadito Formation by Arthur Montgomery in 1958, who estimiated the thickness as up to 600 meters.[3] Long broke the beds out as the Marquenas Quartzite in 1976 and named them after Cerro de las Marquenas.[1] Bauer and Williams redesignated unit as the Marquenas Formation in their sweeping revision of the stratigraphy of Precambrian rocks in northern New Mexico in 1989.[2]

Footnotes

1. Long 1976, pp.47-53
2. Bauer and Williams 1989, p.49
3. Montgomery 1976, pp.22-24
4. Jones et al. 2011
5. Daniel et al. 2013

References

• Bauer, Paul W.; Williams, Michael L. (August 1989). "Stratigraphic nomenclature ol proterozoic rocks, northern New Mexico-revisions, redefinitions, and formaliza" (PDF). New Mexico Geology. 11 (3). Retrieved 15 April 2020.
• Daniel, Christopher G.; Pfeifer, Lily S.; Jones, James V, III; McFarlane, Christopher M. (2013). "Detrital zircon evidence for non-Laurentian provenance, Mesoproterozoic (ca. 1490–1450 Ma) deposition and orogenesis in a reconstructed orogenic belt, northern New Mexico, USA: Defining the Picuris orogeny". GSA Bulletin. 125 (9–10): 1423–1441. doi:10.1130/B30804.1. Retrieved 17 April 2020.
• Jones, James V., III; Daniel, Christopher G.; Frei, Dirk; Thrane, Kristine (2011). "Revised regional correlations and tectonic implications of Paleoproterozoic and Mesoproterozoic metasedimentary rocks in northern New Mexico, USA: New findings from detrital zircon studies of the Hondo Group, Vadito Group, and Marqueñas Formation". Geosphere. 7 (4): 974–991. doi:10.1130/GES00614.1. Retrieved 15 April 2020.
• Long, P.E. (1976). "Precambrian granitic rocks of the Dixon-Penasco area, northern New Mexico" (PDF). New Mexico Bureau of Mines and Mineral Resources Open-file Report Series. 71. Retrieved 17 April 2020.
• Montgomery, Arthur (1953). "PreCambrian Geology of the Picuris Range, northcentral New Mexico" (PDF). State Bureau of Mines and Mineral Resources Bulletins. 30.