The Tucumcari Formation is a

geologic formation A geological formation, or simply formation, is a body of rock having a consistent set of physical characteristics ( lithology) that distinguishes it from adjacent bodies of rock, and which occupies a particular position in the layers of rock exp ...

New Mexico ) , population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano) , seat = Santa Fe , LargestCity = Albuquerque , LargestMetro = Tiguex , OfficialLang = None , Languages = English, Spanish ( New Mexican), Navajo, Ker ...

. It preserves

fossils A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved in ...

dating back to the Albian

Age Age or AGE may refer to: Time and its effects * Age, the amount of time someone or something has been alive or has existed ** East Asian age reckoning, an Asian system of marking age starting at 1 * Ageing or aging, the process of becoming older ...

of the

early Cretaceous The Early Cretaceous ( geochronological name) or the Lower Cretaceous (chronostratigraphic name), is the earlier or lower of the two major divisions of the Cretaceous. It is usually considered to stretch from 145 Ma to 100.5 Ma. Geology Pro ...

period.

Description

The formation consists of highly fossiliferous gray

shale Shale is a fine-grained, clastic sedimentary rock formed from mud that is a mix of flakes of clay minerals (hydrous aluminium phyllosilicates, e.g. kaolin, Al2 Si2 O5( OH)4) and tiny fragments (silt-sized particles) of other minerals, especial ...

and buff calcareous

sandstone Sandstone is a clastic sedimentary rock composed mainly of sand-sized (0.0625 to 2 mm) silicate grains. Sandstones comprise about 20–25% of all sedimentary rocks. Most sandstone is composed of quartz or feldspar (both silicates) ...

with some

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

nodules. It overlies the

Morrison Formation The Morrison Formation is a distinctive sequence of Late Jurassic, Upper Jurassic sedimentary rock found in the western United States which has been the most fertile source of dinosaur fossils in North America. It is composed of mudstone, sandsto ...

and is overlain by the Mesa Rica Sandstone. The formation is interpreted as marine shales deposited during the Kiowa-Skull Creek

transgression Transgression may refer to: Legal, religious and social *Sin, a violation of God's Ten Commandments or other elements of God's moral law *Crime, legal transgression, usually created by a violation of social or economic boundary **In civil law ju ...

. It is likely the lateral equivalent of the Glencairn Formation.

Fossils

More than 65 marine invertebrate species have been found in the Tucumcari Shale. The macrofossils are mostly bivalves, with some

gastropod The gastropods (), commonly known as snails and slugs, belong to a large taxonomic class of invertebrates within the phylum Mollusca called Gastropoda (). This class comprises snails and slugs from saltwater, from freshwater, and from land. T ...

s and

ammonoid Ammonoids are a group of extinct marine mollusc animals in the subclass Ammonoidea of the class Cephalopoda. These molluscs, commonly referred to as ammonites, are more closely related to living coleoids (i.e., octopuses, squid and cuttlefish) ...

s. Microfossils include

ostracod Ostracods, or ostracodes, are a class of the Crustacea (class Ostracoda), sometimes known as seed shrimp. Some 70,000 species (only 13,000 of which are extant) have been identified, grouped into several orders. They are small crustaceans, typic ...

s, foraminiferans, and palynomorphs. Species found in the formation include the solitary corals ''

Desmophyllum ''Desmophyllum'' is a genus of cnidarians belonging to the family Caryophylliidae The Caryophylliidae are a family of stony corals found from the tropics to temperate seas, and from shallow to very deep water. Genera *'' Africana'' Ocana & ...

'' and '' Platycyathus'', the bivalves '' Scabrotrigonia'', '' Pteria'', ''

Texigryphaea ''Texigryphaea'' is an extinct genus of oyster belonging to the order Ostreida and family Gryphaeidae. It dates to the Albian to Cenomanian Ages of the Cretaceous period and is primarily found in Texas and the southern Western Interior of North A ...

'', ''

Botula ''Botula'' is a genus of mussels in the family Mytilidae Mytilidae are a family of small to large marine and brackish-water bivalve molluscs in the order Mytilida. One of the genera, ''Limnoperna'', even inhabits freshwater environments. T ...

'', and ''

Lopha ''Lopha'' is a genus of marine bivalve molluscs in the family Ostreidae. The genus ''Lopha'' is present from the Triassic period in the Lower Norian age (216.5 ± 2.0 – 203.6 ± 1.5 Mya) to the recent age. Description ''Lopha'' species ha ...

'', and gastropod '' Turritella''. The shells show borings from clionid sponges and acrothoracic barnacles.

History of investigation

The unit was first described by

Jules Marcou Jules Marcou (April 20, 1824 – April 17, 1898) was a French-Swiss-American geologist. Biography He was born at Salins-les-Bains, Salins, in the ''département in France, département'' of Jura (département), Jura, in France. He was educated a ...

in 1858 as Bed E of the Pyramid Mountain section. In 1892, W.F. Cummins described the

Jurassic The Jurassic ( ) is a Geological period, geologic period and System (stratigraphy), stratigraphic system that spanned from the end of the Triassic Period million years ago (Mya) to the beginning of the Cretaceous Period, approximately Mya. The J ...

and Cretaceous section at Tucumcari Mountain as the "Tucumcari beds". Dobrovsky and Summerson assigned the unit to the

Purgatoire Formation The Purgatoire Formation is an abandoned (1987) Cretaceous period geologic formation classification. The classification was used in Colorado, New Mexico, and Oklahoma, with mentions in older geologic literature in neighboring states.Griggs and Re ...

as the Tucumcari Shale Member in 1947. Griggs and Read abandoned the Purgatoire Formation in southeastern New Mexico and raised the Tucumcari Shale to formation rank in 1959.

Footnotes

References

* * * * * * * {{cite journal , last1=Scott , first1=R.W. , last2=Holbrook , first2=J.M. , last3=Oboh-Ikuenobe , first3=F.E. , last4=Evetts , first4=M.J. , last5=Benson , first5=D.G. , last6=Kues , first6=B.S. , title=Middle Cretaceous stratigraphy, southern Western Interior Seaway, New Mexico and Oklahoma , journal=The Mountain Geologist , date=April 2004 , volume=41 , issue=2 , pages=33–61 , url=http://archives.datapages.com/data/rmag/mg/2004/scott.htm , accessdate=8 September 2020 Cretaceous formations of New Mexico

Description

Fossils

History of investigation

See also

Footnotes

References