Cutler-Formation

The Cutler Formation, also Cutler Group, is a rock formation of sedimentary origin, which is located in the United States in the states of Arizona, located in northwestern New Mexico, in the southeastern Utah and southwestern Colorado in. She came in from the late Paleozoic Carboniferous ( Gzhelium ) until the end of the lower Permian ( Kungurian ) for deposit.

Stratigraphy

In Arizona and Utah, the rock unit is usually referred to as Cutler - group, but the USGS pulls Cutler Formation ago.

The formation can be divided into the following members ( from young to old):

  • De Chelly - Sandstone Member ( in Arizona, Colorado, New Mexico and Utah)
  • White Rim Sandstone Member ( only in Utah)
  • Organ Rock Shale Member ( in Arizona, Colorado, New Mexico, and Utah)
  • Cedar Mesa Sandstone Member ( in Arizona and Utah)
  • Halgaito Shale Member ( in Arizona, Colorado, New Mexico and Utah)
  • Elephant Canyon members (only in Utah)

The Cutler Formation transgrediert with her Halgaito Members marine Honaker Trail Formation from the Upper Pennsylvanian. They will in turn overlaid by Black Box Dolomite, the lateral equivalent of the Kaibab Limestone in the Grand Canyon (uppermost Permian), and the subsequent Triassic Moenkopi Formation.

Lateral equivalents are the Supai Group in Grand Canyon area of Arizona and the South East Sub - formation in New Mexico in the Southwest.

The total thickness of the Cutler Formation in the Paradox Basin reaches 3700 meters.

The Cutler Formation has no type locality. It was in 1905 appointed by their Erstbeschreibern Cross and Howe after the Cutler Creek, which flows about 6 kilometers north of Ouray in the Uncompahgre River. In a review of the findings of Cross and Howe Baker and Reeside divided in 1929 the formation as follows:

  • White Rim Sandstone Member
  • Organ rock Tongue
  • Cedar Mesa Sandstone
  • Halgaito Tongue at the base

In 1946 mapped Wood and Northrop, the formation and determined their geographical area. Wengerd and Matheny collected in 1958 the formation of a group, but this is not recognized by the USGS ( 2005).

Dissemination

The Cutler formation occurs in the following Sedimentationsräumen:

  • Black Mesa Basin
  • Paradox Basin
  • Piceance Basin
  • San Juan Mountains
  • San Juan Basin
  • Uinta Basin

Geological framework

The Permian red beds of the Cutler formation are a direct consequence of continued tectonic unrest that had led the Upper Carboniferous collision of Gondwana with Laurasias. Result was ultimately the formation of the supercontinent Gondwana. The Ouachita - Marathon orogenic belt formed on the south and east side of North America during the Ouachita orogeny out the continent forward -looking thrust movements lasted until the Permian to. The subduction at the western edge of North America continued during its continued so that the depositional environment of the Cutler Formation was exposed on both sides heavy tectonic stresses. The continental crust responded brittle and broke into several large clods. It created the Ancestral Rocky Mountains, a number of prominent basement blocks with intervening basins and troughs (see the above-mentioned depositional areas ). The tectonic movements were simultaneously accompanied by a general rise in sea level that led to the Absaroka - transgression.

At the time of deposition of the Cutler formation of the peak of the transgression was already exceeded again, marine sediments were now replaced by continental Schwemmfächersedimenten. Main source area of the sediments Cutler was the so-called Uncompahgre Uplift, who had gradually lifted the block of the Uncompahgre Mountains. At the southwestern edge of the Uncompahgre Mountains, the Paradox basin, which took up the detritus of the uplifting basement block was - it made the Cutler formation.

Sedimentary development

The Cutler Formation attains its maximum thickness in the Paradox Basin - 3700 meters in Moab. In the immediate vicinity of the Uncompahgre Mountains, the sediments are red-colored, ferruginous (hematite - leading ), coarse-grained arkoses and polymictic conglomerates that were formed under semiarid to arid paleoclimatic conditions. With increasing distance from the source area they lose grain size to be finally southwest deposited as fine-grained sandstones, siltstones and mudstones in the then near the coast of their original territory. It is these finer, more distal sediments, which allow a subdivision of the Cutler Formation in its individual members, in the immediate vicinity of the Uncompahgre Mountains, this is not the case here, the formation remains unarticulated.

Nevertheless, up to secrete three major cycles, which reflect the pulse-like fashion taking place lifting the Uncompahgre Mountains in the unorganized Schwemmfächersedimenten. So are excreted in New Mexico the El Cobre Canyon Formation and the younger Arroyo del Agua Formation - both world-renowned for its rich Tetrapodenfauna ( see below).

The Cutler Formation is considered as a whole a very complex built-up sediment body whose members are mostly interlink multiple times with each other. Further complications are caused by an extensive salt tectonics, which can be attributed to the subjacent evaporites of the Paradox Formation.

The subdivided Cutler Formation begins with a performance from north west transgression, which was deposited the carbonate sediments of the Elephant Canyon members. Using Fusuliniden can the Elephant Canyon Members a oberkarbonisches age ( Gzhelium ) can be assigned. To the southeast it dovetails with the siliciclastic, fluvial red sediments and loess deposits of Halgaito Shale Members. These two basal member then of the Cedar Mesa Sandstone Member, a relatively fine-grained, white sandstone, the striking cliffs are superimposed forms. The Cedar Mesa Sandstone Member contains partially fossilized sand banks along with barrier island ( northwest section), but mainly consists of the aeolian deposits of a coastal ergs (main wind direction northwest) and subordinate Sabkhasedimenten (southeast section). It dovetails his hand towards the east and southeast with the fluvial red beds of the Organ Rock Shale Members, relatively fine-grained, erodible arkoses from the Uncompahgre Mountains. Since only fine-grained sediments from the Uncompahgre Mountains were delivered, this can be close to an already extensive leveling of Grundgebirgblocks. The Cedar Mesa Sandstone Member is then gradually into the White Rim Sandstone Members on, a white, obliquely layered, very compact sandstone aeolian origin ( coastal Sanddünenfazies, prevailing wind direction also Northwest). Even the White Rim Sandstone Member dovetails in an easterly direction with the red-colored body rock Shale Members, with very impressive color contrasts arise. The Cutler Formation concludes with the de Chelly - Sandstone Member, which is only slightly younger than the White Rim Sandstone Members. This is to orange-red, obliquely stratified sandstones, which also formed a very large Erg in the southwest part of the depositional environment. The orientation of the dune fields suggests northern to north-east winds, which blew out the sand fraction from the area of the now almost leveled Uncopahgre Mountains toward shallow sea.

Mineral resources

Besides hematite contains the Cutler formation of uranium, vanadium, copper, barium, and rare earths. The uranium is found as intra formation elle enrichment in fluvial sandstones, but also can to fissure fillings lara mix age be bound ( about 60 million years). Locality of the latter type is Kane Creek in Utah.

Fossil content

The Cutler Formation hosts a rich Tetrapodenfauna and their trace fossils and contains two fish, plant remains, brachiopods, bryozoans, crinoids, corals, and the already mentioned Fusuliniden.

Fish:

  • Etosteorhachis - Neopterygii?
  • Xenacanthus - Elasmobranch

Tetrapods:

  • Aerosaurus - Pelycosaurier
  • Anconastes vesperus - amphibian
  • Bolosaurus - Original Anapside - Bolosauridae
  • Broiliellus - Temnospondyle
  • Chenoprosopus - Temnospondyle
  • Desmatodon - Original Amniot
  • Diadectes - Original Amniot
  • Ecolsonia - Temnospondyle
  • Edaphosaurus novomexicanus - Pelycosaurier
  • Eryops - Temnospondyle
  • Limnoscelis - Anthracosaurier
  • Oedaleops - Pelycosaurier
  • Ophiacodon - Pelycosaurier
  • Platyhystrix - Temnospondyle
  • Rhiodenticulatus - Original Anapside - Captorhinidae
  • Seymouria - Anthracosaurier
  • Sphenacodon - Pelycosaurier
  • Stegotretus - Micro dinosaurs
  • Tseajaia - Original Amniot
  • Zarcasaurus - Diapside - Araeoscelidae
  • Zatrachys - Temnospondyle

Tetrapodenspuren:

  • Batrachichnium - amphibian
  • Dimetropus - Reptile
  • Dromopus - Reptile
  • Limnopus - amphibian

Plants:

  • Alethopteris serlii
  • Callipteris
  • Neuropteris scheuchzeri
  • Walchia

Diadectes

Edaphosaurus

Eryops

Limnoscelis

Ophiacodon

Platyhystrix

Seymouria

Sphenacodon

Tseajaia

Zatrachys

Walchia

The Tetrapodenfunde made ​​in New Mexico made ​​it possible for Lucas, three land vertebrate biozones (English LVF - "land - vertebrate faunachron ") to distinguish that can be used for global correlation of terrestrial deposits ( from young to old):

  • Seymourium - chakterisiert by the Anthracosaurier Seymouria - Artinskian to Kungurian
  • Coyoteum - characterized by the Pelycosaurier Sphenacodon - Gzhelium to Artinskian
  • Cobreum - characterized by the original Amniot Desmatodon and Anthracosaurier Limnoscelis - Gzhelium
Gzhelian Canyonlands-Nationalpark Moenkopi-Formation Ouray (Colorado) Group (stratigraphy) Monument Valley Desert climate Anthracosauria
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