Fayetteville Shale facts for kids

Quick facts for kids Fayetteville Shale Stratigraphic range: Carboniferous: Mississippian (Serpukhovian)
Outcrop of the lower Fayetteville Shale in northern Arkansas
Type	Geological formation
Sub-units	Wedington Sandstone Member
Underlies	Pitkin Limestone, Hale Formation
Overlies	Ruddell Shale, Batesville Sandstone Moorefield Shale
Area	Arkansas and Oklahoma
Thickness	50 to 500 feet (15 to 152 m)
Lithology
Primary	Shale
Other	Sandstone, limestone
Location
Region	Arkansas
Country	United States
Extent	50 miles (80 km)
Type section
Named for	Fayetteville, Washington County, Arkansas
Named by	Frederick Willard Simonds
The Fayetteville formation runs widespread across Arkansas

The Fayetteville Shale is a geologic formation of Mississippian age (354–323 million years ago) composed of tight shale within the Arkoma Basin of Arkansas and Oklahoma. It is named for the city of Fayetteville, Arkansas, and requires hydraulic fracturing to release the natural gas contained within.

Nomenclature

Photograph of the Wedington Sandstone Member (mistaken as Batesville Sandstone) circa 1891

Named by Frederick Willard Simonds in 1891, Simonds recognized what is now the Fayetteville Shale as three separate formations overlying the now abandoned Wyman Sandstone: the Fayetteville Shale, the Batesville Sandstone, and the Marshall Shale. In 1904, the name "Fayetteville Shale" replaced all three of these names. The Fayetteville Shale that Simonds recognized is now considered as the lower Fayetteville Shale. Simonds' Batesville Sandstone was found to be the same as the Wyman Sandstone, and replaced the name "Wyman Sandstone", while Simonds' Batesville Sandstone became known as the "Wedington Sandstone Member" presumably after Wedington Mountain. The name Marshall Shale was abandoned and is now known as the upper Fayetteville Shale.

Natural gas

Gas production from Fayetteville Shale

The formation holds natural gas in a fine-grained rock matrix which requires hydraulic fracturing to release the gas. This process became cost-effective in some shales such as the Fayetteville after years of experimentation in the Barnett Shale in North Texas, especially when combined with horizontal drilling.

The Fayetteville Shale play began in July 2004 by Southwestern Energy Company in north-central Arkansas with the Thomas #1-9 vertical well in Conway County, Arkansas. In February 2005, Southwestern Energy drilled the first horizontal well, the Seeco-Vaughan #4-22H, also in Conway County.

The US Energy Information Administration estimated that the 5,853 square miles (15,160 km²) shale play held 13,240 billion cubic ft (375 billion cubic meters) of unproved, technically recoverable gas. The average well was estimated to produce 1.3 billion cubic feet of gas. As of 2018, new drilling in the Fayetteville Shale had ceased and almost 1/5 of wells were abandoned.

Paleontology

Flora

Because the Fayetteville Formation is a marine unit, most of the plants found in the black shales must have been washed into the Carboniferous sea from a landmass. However one unit within the formation, the Weddington Sandstone Member, is a series of river deposited sand beds. Fossil plants from this unit were probably deposited closer to their source.

Artist's impression of a Lepidodendron

Fauna

Vertebrates

• Carcharopsis wortheni
• Ozarcus mapesae

Echinoderms

Fossil of the upper portion of Taxocrinus (on the right)

• Acrocrinus constrictus
• Agassizocrinus conicus
• Alcimocrinus ornatus
• Allocatillocrinus carpenteri
• Ampelocrinus erectus
• Aphelecrinus exoticus

• A. planus

• Childonocrinus trinodus
• Cymbiocrinus gravis
• Dasciocrinus aulicus
• Heliosocrinus aftonensis
• Intermediacrinus modernus
• Linocrinus
• Mantikosocrinus castus
• Onchyocrinus
• Onychocrinus pulaskiensis
• Ophiurocrinus hebdenensis
• Pentremites platybasis

• P. pulchellus

• Phacelocrinus
• Phanocrinus

• P. alexanderi
• P. cylindricus
• P. formosus

• Scytalocrinus aftonensis
• Taxocrinus cestriensis

• T. whitefieldi.

• Ulrichicrinus chesterensis

Cephalopods

Fossil of Goniatites

Corals

• Amplexus expansus
• Michelinia meekana
• Palaecris carinata

Bivalves

Aviculopecten subcardiformis from the Logan Formation (Lower Carboniferous) of Wooster, Ohio (external mold).

• Aviculopecten squamula

• Aviculopecten jennyi
• Aviculopecten multilineatus
• Aviculopecten morrowensis
• Aviculopecten inspeciosus

• Canyella peculiaris
• Cardiomorpha inflata
• Conocardium peculiare
• Cypricardia fayettevillensis
• Cyprecardella sublata
• Edmondia equilateralis
• Palaeoneilo sera
• Phestia stevensiana
• Sphenotus branneri

• Sphenotus washingtonensis
• Sphenotus dubius
• Sphenotus meslerianus

Brachiopods

• Adairia adairensis
• Inflatia gracilis

• Inflatia cherokeensis
• Inflatia pusilla
• Inflatia inflata

• Orthotetes protensus

• Orthotetes subglobosus

Gastropods

Platyceras sp. from Museo di Storia Naturale di Milano.

• Euconospira disjuncta
• Mourlonia lativittata
• Patellilabia laevigata
• Platyceras subelegans

• Platyceras compressum

• Sinuitina venata
• Trepospira discus

Arthropods

A life-reconstruction of the trilobite Paladin.

• Amphissites
• Bairdia
• Cyrtoproetus kerhini
• Kirkbya
• Geisina
• Glyptopleura
• Graphiadactyllis
• Orthobairdia
• Paladin murconatus
• Paraparchites
• Roundyella
• Sansabella
• Serenida

Ostracods

• Cavellina
• Kegelites
• Sargentina

Bryozoans

Foraminifera

• Earlandia
• Eosigmoilina rugosa