{{Short description|Geologic formation in New Mexico, US}} {{Infobox rockunit | name = Flechado Formation | image = Flechado Formation bluffs.jpg | caption = Flechado Formation at its type section, Rio Pueblo Valley, New Mexico. | type = Formation | age = {{Geological range|Moscovian}} | prilithology = Sandstone, shale | otherlithology = Siltstone, limestone, conglomerate | namedfor = Flechado Creek | namedby = P.K. Sutherland | year_ts = 1963 | region = New Mexico | country = United States | coordinates = {{coord|36.1623943|N|105.5786314|W|display=inline}} | unitof = | subunits = | underlies = Alamitos Formation | overlies = Tererro Formation | thickness = {{convert|2500|feet|meter|abbr=on}} | extent = | area = | map = {{Location map+ | United States#New Mexico | relief = 1 | width = 250 | float = center | places = {{Location map~ | United States#New Mexico | lat_deg = 36.162 | lon_deg = -105.579 | mark = Cyan pog.svg | marksize = 12 }} }} | map_caption = }} {{commons}} The '''Flechado Formation''' is a geologic formation in the northern Sangre de Cristo Mountains of New Mexico. It preserves fossils dating back to the early to middle Pennsylvanian.{{sfn|Sutherland|1963}}
==Description== The Flechado Formation consists of low-feldspar sandstone and shale alternating with thin beds of limestone. The total thickness is {{convert|2500|feet|meter|abbr=off}}.{{sfn|Sutherland|1963}} It overlies the Tererro Formation{{sfn|Armstrong|Mamet|1974}} and is overlain by the Alamitos Formation. {{sfn|Sutherland|1963}} The formation is well to extremely well cemented in the type area, so that it can be difficult to distinguish from the Precambrian Ortega Formation.{{sfn|Aby|Hallet|2007}}
The formation grades laterally into the La Pasada Formation to the south of the Rio Pueblo, with the clastic beds of the Flechado abruptly thinning and transitioning to carbonate beds of the La Pasada over a distance of about {{convert|5|miles|km|abbr=off}}.{{sfn|Sutherland|1963}}
The terrigenous sediments of the Flechado Formation were likely derived from the southern part of Uncompahgre uplift during uplift on the west side of the Picuris-Pecos fault.{{sfn|Sutherland|1963}} <gallery> File:Flechado Formation type closeup.jpg|Close view of Flechado Formation at its type section. </gallery>
==Fossils== Fossils are scarce in the upper portion of the Flechado Formation, but middle Desmoinesian (upper Moscovian) brachiopods are found about {{convert|800|feet|meters|abbr=off}} below the top of the formation. Atokan (lower Moscovian) fusulinids and brachiopods are found in the lower part, which also contains broken crinoid, bryozoan, and algal remains. {{sfn|Sutherland|1963}}
==History of investigation== The formation was first described by P.K. Sutherland in 1963.{{sfn|Sutherland|1963}}
==See also== {{Portal|Earth sciences|Paleontology}} * List of fossiliferous stratigraphic units in New Mexico * Paleontology in New Mexico
==Footnotes== {{Reflist}}
==References== * {{cite journal |last1=Aby |first1=Scott |last2=Hallet |first2=Ben |title=Geologic Map of the Tres Ritos Quadrangle, Taos County, New Mexico |journal=New Mexico Bureau of Geology and Mineral Resources Open-file Digital Geologic Map |date=May 2007 |volume=OF-GM 145 |url=https://geoinfo.nmt.edu/publications/maps/geologic/ofgm/downloads/145/TresRitosReport.pdf |accessdate=22 August 2020}} * {{cite journal |last1=Armstrong |first1=A.K. |last2=Mamet |first2=B.L. |year=1974 |title=Biostratigraphy of the Arroyo Penasco Group, Lower Carboniferous (Mississippian), north-central New Mexico |journal=New Mexico Geological Society Field Conference Series |volume=25 |pages=145–158 |url=https://nmgs.nmt.edu/publications/guidebooks/downloads/25/25_p0145_p0158.pdf |accessdate=29 July 2020}} * {{cite encyclopedia |last1=Sutherland |first1=P.K. |year=1963 |title=Paleozoic rocks |editor1-last=Miller |editor1-first=J.P. |editor2-last=Montgomery |editor2-first=Arthur |editor3-last=Sutherland |editor3-first=P.K. |encyclopedia=Geology of part of the southern Sangre de Cristo Mountains, New Mexico: New Mexico Bureau of Mines and Mineral Resources Memoir 11 |pages=22–44 |url=https://geoinfo.nmt.edu/publications/monographs/memoirs/downloads/11/Memoir-11.pdf |accessdate=29 July 2020}}
Category:Carboniferous formations of New Mexico Category:Carboniferous southern paleotropical deposits Category:Siltstone formations of the United States Category:Sandstone formations of the United States Category:Shale formations of the United States Category:Limestone formations of the United States Category:Conglomerate formations of the United States