Devonian brachiopods from Northeastern Washington: Evidence for a non-allochthonous terrane and Late Devonian biogeographic update
Published:July 01, 2008
Peter E. Isaacson, 2008. "Devonian brachiopods from Northeastern Washington: Evidence for a non-allochthonous terrane and Late Devonian biogeographic update", The Terrane Puzzle: New Perspectives on Paleontology and Stratigraphy from the North American Cordillera, Robert B. Blodgett, George D. Stanley, Jr.
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There are several isolated outcrops (outliers?) of Devonian rocks in the Pacific Northwest (Washington and Oregon), USA. A locality in northeastern Washington, Limestone Hill, is considered in detail, and other small outcrops in northwest Washington and central Oregon are discussed. Limestone Hill is a Paleozoic outlier. The locality has Ordovician and Silurian (Llandovery and Wenlock) strata, Lower Devonian (Lochstone conglomerate, and Upper Devonian (Frasnian) carbonates with fossils. It has long been known that the area has many allochthons, and it has been assumed that Limestone Hill represents lithologies deposited much farther west. More recent data suggest that Limestone Hill is parautochthonous. Several brachiopod taxa, previously unknown from the Frasnian portion of Limestone Hill, have been found recently and are described herein. The brachiopod faunule consists of Emanuella sp., “Allanella” engelmanni, Cyrtina sp., Thomasaria sp., and an athyridid. These brachiopods appear to be like coeval faunas in Idaho, Montana, Utah, and Nevada, although more species assignments must be made. Frasnian brachiopods are in serious need of updates, as Famennian miospore and acritarch data suggest significant basin restriction and reduced seaway connectivity, with at least ephemerally extensive land areas with ubiquitous land plant taxa.