320 A revised radiolarian zonation for the Upper Jurassic of western North America

A revised radiolarian zonation for the Upper Jurassic of western North America - BAP #320 An accurate radiolarian zonation for the Upper Jurassic is critical to unraveling the stratigraphy and tectonic history of much western North America. To meet this end a revised zonation is presented for the Upper Jurassic of the California Coast Ranges. Zone 1, 2, 3 and 4 of Pessagno (1977a, 1977b) are redefined and related as accurately as possible to Upper Jurassic chronostratigraphic units. Discrepancies between European, Deep Sea Drilling Project, and North American biostratigraphic and chronostratigraphic data are analyzed. We conclude that many of the problems surrounding the correlation of North American Jurassic strata with those in the Mediterranean area are due to paleo-oceanographic factors closely related to plate tectonics. Even if preservational and taxonomic problems are excluded, correlation of Tethyan European Upper Jurassic radiolarian assemblages with those of either Boreal