The Gray Mesa 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 ...
in
New Mexico
)
, population_demonym = New Mexican ( es, Neomexicano, Neomejicano, Nuevo Mexicano)
, seat = Santa Fe, New Mexico, Santa Fe
, LargestCity = Albuquerque, New Mexico, Albuquerque
, LargestMetro = Albuquerque metropolitan area, Tiguex
, Offi ...
. Its fossil assemblage dates the formation to the
Moscovian
Moscovian may refer to:
*An inhabitant of Moscow, the capital of Russia
*Something of, from, or related to Moscow
*Moscovian (Carboniferous)
The Moscovian is in the International Commission on Stratigraphy, ICS geologic timescale a stage (strati ...
age of the
Pennsylvanian Pennsylvanian may refer to:
* A person or thing from Pennsylvania
* Pennsylvanian (geology)
The Pennsylvanian ( , also known as Upper Carboniferous or Late Carboniferous) is, in the International Commission on Stratigraphy, ICS geologic timesca ...
.
The formation as presently defined includes outcrops previously assigned to many local units, including the Los Moyos Formation, the Armendaris Group, and the Nakaye Formation.
Description
The formation consists mostly of
chert
Chert () is a hard, fine-grained sedimentary rock composed of microcrystalline or cryptocrystalline quartz, the mineral form of silicon dioxide (SiO2). Chert is characteristically of biological origin, but may also occur inorganically as a ...
y
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 wh ...
, with a few
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, especia ...
,
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 ...
, and
conglomerate
Conglomerate or conglomeration may refer to:
* Conglomerate (company)
* Conglomerate (geology)
* Conglomerate (mathematics)
In popular culture:
* The Conglomerate (American group), a production crew and musical group founded by Busta Rhymes
** Co ...
beds. It is exposed in the
Sandia Mountains
The Sandia Mountains ( Southern Tiwa: ''Posu gai hoo-oo'', Keres: ''Tsepe,'' Navajo: ''Dził Nááyisí''; Tewa: ''O:ku:p’į'', Northern Tiwa: ''Kep’íanenemą''; Towa: ''Kiutawe'', Zuni: ''Chibiya Yalanne'') are a mountain range located ...
, the Lucero Uplift (), the western
Jemez Mountains, and the
Manzano Mountains.
The formation has been mapped as the Los Moyos Formation in the Manzano Mountains, but
Spencer G. Lucas and coinvestigators have recommended abandoning the name Los Moyos Formation and using Grey Mesa Formation throughout the
Madera Group. The Gray Mesa Formation likely correlates with the
Porvenir Formation in the southeastern
Sangre de Cristo Mountains
The Sangre de Cristo Mountains ( Spanish for "Blood of Christ") are the southernmost subrange of the Rocky Mountains. They are located in southern Colorado and northern New Mexico in the United States. The mountains run from Poncha Pass in South ...
.
The formation is underlain at most locations by the
Sandia Formation
The Sandia Formation is a geologic formation in New Mexico, United States. Its fossil assemblage is characteristic of the early Pennsylvanian.
Description
The Sandia Formation is mostly shale with some sandstone and conglomerate but only minor ...
, with its base typically placed at the first massive marine limestone bed above the shales of the Sandia Formation. It is overlain by the
Atrasado Formation, with the contact placed at the base of a sandstone interval above the uppermost massive limestone of the Gray Mesa Formation.
Members
The lowermost Elephant Butte Member is about thick and is 78% limestone, half of which contains minor amounts of chert, with indistinct medium to thick bedding. Limestone intervals are thick and separated byh thin shale beds.
The middle Whiskey Canyon Member is about thick and is 46% very cherty limestone and 15% slightly cherty limestone, with perhaps 35% shale. Limestone intervals are up to thick and separated by shale beds that are , with one larger () shale interval in the middle of the member.
The uppermost Garcia Member is and is 39% non-cherty limestone, 18% cherty limestone, and 7% shale, sandstone, and conglomerate, with the rest covered. Its base is a thin sandstone on top of an eroded limestone bed. Algal limestone is abundant. Limestone intervals are thick and separated by shale beds that are .
Fossils
The Elephant Butte Member contains silicified fossils of the
demosponge
Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include 76.2% of all species of sponges with nearly 8,800 species worldwide (World Porifera Database). They are sponges with a soft body that covers a hard ...
''
Chaetetes
Demosponges (Demospongiae) are the most diverse class in the phylum Porifera. They include 76.2% of all species of sponges with nearly 8,800 species worldwide (World Porifera Database). They are sponges with a soft body that covers a hard, ...
'',
brachiopod
Brachiopods (), phylum Brachiopoda, are a phylum of trochozoan animals that have hard "valves" (shells) on the upper and lower surfaces, unlike the left and right arrangement in bivalve molluscs. Brachiopod valves are hinged at the rear end, ...
s, solitary
coral
Corals are marine invertebrates within the class Anthozoa of the phylum Cnidaria. They typically form compact colonies of many identical individual polyps. Coral species include the important reef builders that inhabit tropical oceans and secre ...
s and
fusulinid
The Fusulinida is an extinct order within the Foraminifera in which the tests are traditionally considered to have been composed of microgranular calcite. Like all forams, they were single-celled organisms. In advanced forms the test wall was dif ...
s. The Whiskey Canyon Member contains
crinoid
Crinoids are marine animals that make up the Class (biology), class Crinoidea. Crinoids that are attached to the sea bottom by a stalk in their adult form are commonly called sea lilies, while the unstalked forms are called feather stars or coma ...
s, brachiopods, solitary corals, rare calcareous algae, and fusulinids. The Garcia Member contains crinoids, brachiopods, rare
bryozoans, fusulinids, calcareous algae, and oncoids.
History of investigation
The unit was first designated as the Gray Mesa Member of the Madera Group by Kelley and Wood in 1946.
The Pennsylvanian stratigraphy of New Mexico has historically been unusually complex and inconsistent, with dozens of names for groups, formations, and members. Kues and Giles recommended that the name Madera Group be applied to similar exposures of shelf and marginal basin beds of Desmoinean (upper
Moscovian
Moscovian may refer to:
*An inhabitant of Moscow, the capital of Russia
*Something of, from, or related to Moscow
*Moscovian (Carboniferous)
The Moscovian is in the International Commission on Stratigraphy, ICS geologic timescale a stage (strati ...
) to early Virgilian age found from north-central and central New Mexico south along the west side of the Orogrande Basin as far as the
Caballo
Caballo may refer to:
Places
* Caballo, New Mexico
* Caballo Island (in the Philippines)
* Caballo Lake
* Caballo Mountain, Spain
* Caballo Mountains
The Caballo Mountains, (Spanish: "horse") are a mountain range located in Sierra and Doña A ...
and
Robledo Mountains. Lucas and coinvestigators recommend discarding the name Los Moyos Formation and using Grey Mesa Formation throughout the
Madera Group. With the Elephant Butte, Whiskey Canyon, and Garcia Formations redesignated as members of the Gray Mesa Formation, the Armendaris Group is abandoned as a synonym for the Gray Mesa Formation. The Nakaye Formation of the
Fra Cristobal and
Caballo Mountains
The Caballo Mountains, ( Spanish: "horse") are a mountain range located in Sierra
Sierra (Spanish for "mountain range" and "saw", from Latin '' serra'') may refer to the following:
Places Mountains and mountain ranges
* Sierra de Juárez, a m ...
is also abandoned as a synonym for the Gray Mesa Formation.
See also
*
List of fossiliferous stratigraphic units in New Mexico
This article contains a list of fossil-bearing stratigraphic units in the state of New Mexico, U.S.
Sites
See also
* Paleontology in New Mexico
References
*
{{DEFAULTSORT:Fossiliferous stratigraphic units in New Mexico
New Mexico
...
*
Paleontology in New Mexico
Paleontology in New Mexico refers to paleontological research occurring within or conducted by people from the U.S. state of New Mexico. The fossil record of New Mexico is exceptionally complete and spans almost the entire stratigraphic colu ...
Footnotes
References
*
*
*
*
*
*
{{Chronostratigraphy of Colorado, Paleozoic state=expanded
Carboniferous formations of New Mexico
Permian System of North America
Carboniferous southern paleotropical deposits
Limestone formations of the United States