Abstract

Devonian strata in the northern half of Arizona are mostly early Late Devonian (Frasnian) carbonate rocks as much as 160 m (525 ft) thick but include some terrigenous clastic rocks of latest Middle Devonian (Givetian) and Frasnian age. Devonian sediments were deposited on a shallow marine cratonic platform bordered by the Defiance lowland to the east and by the continental shelf adjacent to the Cordilleran geosynclinal belt to the west.

The oldest dated Devonian rocks are quartz sandstones of the Beckers Butte Member (latest Givetian or earliest Frasnian) of the Martin Formation deposited in fluvial or shallow subtidal conditions in central Arizona. The Jerome Member of the Martin Formation in north central Arizona and its correlatives–the Aneth and Elbert Formations to the northeast and the Temple Butte Formation to the north and west–record mainly carbonate deposition across most of northern Arizona during Frasnian time. Environmental conditions were generally supratidal to restricted circulation subtidal in the northeast and more open marine subtidal in central and northwestern Arizona. In the Marble Canyon and eastern Grand Canyon area of north central Arizona was a positive feature (here called the Grand Canyon shelf) that remained at or near sea level and received minor carbonate and quartzose-carbonate sediments mainly in intertidal channels.