Permian and Early(?) Triassic radiolarian faunas from the Grindstone terrane, central Oregon

Abstract

Moderately well preserved Permian (late Wolfcampian, Leonardian, Guadalupian, and Djulfian) and Early(?) Triassic radiolarian faunas from sedimentary mélange cherts of the Grindstone terrane in central Oregon are nearly identical to coeval chert faunas in Japan. These Permian faunas are similar to those used in constructing the radiolarian zonations for Japan and the Tethyan regions. Although several Oregon taxa have been reported from limestone sequences in the central United States, most of the Oregon forms have only been found in cherty rocks and nearly half have not previously been reported from North America. Forty-two taxa belonging to 19 genera (Albaillella Deflandre, Deflandrella De Wever and Caridroit, Entactinia Foreman, Entactinosphaera Foreman, Follicucullus Ormiston and Babcock, Haplentactinia Foreman, Hegleria Nazarov and Ormiston, Ishigaum De Wever and Caridroit, Kashiwara Sashida and Tonishi, Latentibifistula Nazarov and Ormiston, Latentifistula Nazarov and Ormiston, Nazarovella De Wever and Caridroit, Neoalbaillella Takemura and Nakaseko, Parentactinia Dumitrica, Praedeflandrella Kozur and Mostler, Pseudoalbaillella Holdsworth and Jones, Pseudotormentus De Wever and Caridroit, Quinqueremis Nazarov and Ormiston, and Triplanospongos Sashida and Tonishi) are systematically treated. Co-occurrences of some species in Oregon indicate that their ranges in North America may differ from those in Japan. This paper also contains the first illustrated record of Early(?) Triassic radiolarians from North America.