Coyote Butte Limestone


The Coyote Butte Limestone is a geologic formation in Oregon. It preserves fossils dating back to the Sakmarian to Kungurian stages of the Permian period, spanning an estimated 23 million years. The formation occurs in isolated buttes to the north; Triangulation Hill, and south; type locality and name giver Coyote Butte and Tuckers Butte, on either side of the Grindstone and Twelvemile Creeks in Crook County, Oregon.

Description

The Coyote Butte Formation was first defined by Merriam and Berthiaume in 1943. The formation crops out in isolated buttes south and north of the Grindstone and Twelvemile Creeks in Crook County, central Oregon. The formation comprises an uncommonly unaltered and well-exposed set of Permian shallow marine and reefal limestones in the [|tectonically] complex Permian present-day Pacific margin of western North America.
The Coyote Butte Formation is represented by isolated limestone hills, of which most appear to have the same stratigraphic and biostratigraphic sequence and appear to be right-side-up. The resistant limestone blocks stand above the surrounding rocks of the "melange." The Coyote Butte Formation represents shallow-water carbonate-platform deposition and contains a varied faunal assemblage of corals, bryozoans, algae, fusulinids, brachiopods, crinoids, and conodonts.

Paleogeographic situation

The formation is dated to the Sakmarian to Kungurian stages of the Early to Middle Permian period, spanning an estimated 23 million years from 296 to 273 Ma. During these times, what is now central Oregon, was located at the edge of Pangea in the northern paleotemperate zone, at paleolatitudes of 16-18° North.

Tectonics

The hinterland of the carbonate platform where the Coyote Butte Limestone was deposited, was formed by the Arizonan and Utahan arid landscapes of a Pangea starting to break up. This occurred before the Sonoma orogeny was active in western North America and during the Alleghanian orogeny in eastern Laurentia and western Europe.
The 23 million year deposition coincided with impact of the Clearwater West crater, dated at 286.2 ± 2.6 million years ago.

Paleontological significance

The formation is the only discovered Paleozoic fossiliferous formation in the state of Oregon, and comprises an uncommonly unaltered and well-exposed set of Early to Mid Permian shallow marine and reefal limestones in the tectonically complex Permian present-day Pacific margin of western North America. The formation just predates Olson's Extinction; a mass extinction that occurred in the early Guadalupian of the Permian period and which predated the Permian–Triassic extinction event.

Fossil content

Among others, the following fossils have been reported from the formation:

Brachiopods

?Alexenia occidentalisAnidanthus minorAntiquatonia cooperiCalliprotonia inexpectatumKochiproductus transversusKrotovia oregonensis?Marginifera profundosulcataMartinia berthiaumeiProbolionia posteroreticulata?Proboscidella carinataRostranteris sulcatum 0Spiriferella pseudodrascheiStenoscisma cf. plicatumTiramnia semiglobosa
  • ''Yakovlevia transversa''

Trilobites

Rostroconchia

  • Conocardiida
  • * Conocardiidae
  • ** ''Arceodomus sphairikos''

Gastropods

Polyplacophora

  • Neoloricata
  • * Acutichitonidae
  • ** Arcochiton soccus
  • * Homeochiton triangularis
  • * Gryphochitonidae
  • ** Gryphochiton planoplata
  • * Lepidopleuridae
  • ** ?Chauliochiton sp.
  • ** Pterochiton sp.
  • * Strobilepidae
  • ** ''Diadeloplax apiculatus''

Corals

Cystolonsdaleia berthiaumiPetalaxis occidentalisWilsonastraea ochocoensis
  • ''Protowentzelella sp.''

Correlations

Geologic correlations