Abstract

Devonian strata in the northern half of Arizona are mostly early Upper Devonian (Frasnian) carbonate rocks up to 160 m thick but include some terrigenous clastics of latest Middle Devonian (Givetian) and Frasnian age. Devonian sediments were deposited on a shallow-marine cratonic platform bordered by the Defiance lowland area to the east and by the continental shelf adjacent to the Cordilleran geosynclinal belt to the west.

The Beckers Butte Member of the Martin Formation accumulated as fluvial to subtidal sands in a small embayment southwest of the Defiance area during latest Givetian or earliest Frasnian time. In early Frasnian time, the Aneth Formation and unit 1 of the Jerome Member, Martin Formation, were deposited as fine-grained intertidal carbonates in northeastern and central Arizona, while the lower Temple Butte Formation carbonates formed in a more open circulation subtidal marine environment in northwestern Arizona. Between these two areas the Marble Canyon-eastern Grand Canyon area was a positive feature (here called the Grand Canyon shelf) that remained very near sea level and received little or no sediment.

By late Frasnian time depositional environments in northeastern Arizona had changed from intertidal-supratidal conditions to those of a shallow subtidal sea with restricted circulation in the east (the Elbert Formation pelleted carbonate rocks) and more open-marine circulation toward the south and west (the fossiliferous carbonate rocks of the upper Jerome Member and western Temple Butte Formation). The Grand Canyon shelf received carbonate sediments in intertidal channels and on a shallow subtidal platform to form the thin Temple Butte Formation.

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