TAXONOMIC STUDIES OF LOWER JURASSIC RADIOLARIA FROM THE NICELY FORMATION, THE HYDE FORMATION, AND THE SNOWSHOE FORMATION, EAST-CENTRAL OREGON

This report presents a detailed taxonomic study of Lower Jurassic (upper Pliensbachian and lower Toarcian) Radiolaria from the Nicely Formation, the Hyde Formation, and the basal portion of the snowshoe Formation, east-central Oregon. In this study, all the radiolaria were extracted from micritic limestone nodules which often contain rich faunas. One hundred and six species are figured, one new family, two new subfamilies, fourteen new genera, and seventy eight new species are described. The stratigraphic distribution of these taxa is defined herein.; This study attempts to integrate the radiolarian assemblages with associated ammonite data and with new radiolarian biostratigraphic data from the Queen Charlotte Islands. The results of this research indicate that: (1) The basal portion (10 ft. above base) of the Warm Springs Member, Snowshoe Formation contains radiolarian fauna which is correlative with lower Toarcian radiolaria from the Queen Charlotte Islands. (2) The limestone nodules from lower part (210 ft. and 350 ft. above base) of the Hyde Formation contain a radiolarian fauna which is also correlative with that from the lower Toarcian strata in the Queen Charlotte Islands. (3) At the Morgan Mountain, two radiolarian faunas can be recognized from the Nicely Formation. All the limestone nodules from 40 ft. to 125 ft. above base of the Nicely Formation contain a similar upper Pliensbachian radiolarian fauna. Ammonites from associated beds are correlative with European margaritatus and spinatum Standard Zones. Radiolaria derived from a limestone nodule occurring on the top (300 ft. above base) of the Nicely Formation at the Morgan Mountain are tentatively assigned to upper Pliensbachian. (4) In the Suplee area, the upper part (20 ft. below top) of the type Nicely section contains a radiolarian fauna possibly of late Pliensbachian/early Toarcian age. This is indicated by the presence of Paltarpites in the upper part of type Nicely Formation. In Europe, Paltarpites ranges from the upper Pliensbachian to the basal Toarcian.