Fossil pollen and spores of the Jurassic-Cretaceous Great Valley Sequence, northwestern California

This study of the stratigraphic distributions of pollen and spore species encountered in the Tithonian to Turonian (Uppermost Jurassic to Lower Upper Cretaceous) interval of the marine turbiditic Great Valley Sequence (GVS) contributes a terrigenous palynomorph biostratigraphy to the existing marine foraminiferal, radiolarian, dinoflagellate, and macrofossil zonations of the Sequence. Ninety-five surface samples collected at Watson, McCarty, and Dry Creeks and seven other California localities, reveal a paleotemperate palynoflora, with abundant bisaccates and trilete spores throughout. Classopollis is inconspicuous except in Aptian and Turonian samples. The Upper Jurassic to Lower Cretaceous palynoflora is characterized by Vitreisporites, Cerebropollenites, Osmundacidites, and Distaltriangulisporites. The spore species decrease in abundance and diversity in the Aptian to Albian transition zone. Upper Cretaceous (Cenomanian-Turonian) samples have frequent Polycingulatisporites reduncus and Quadripollis krempii, as well as monocolpate, tricolpate and tricolporate angiosperms, which are rare in Aptian and Albian samples and increase to dominance in the Turonian.;The major palynofloral change at the Albian-Cenomanian boundary coincides with previously reported foraminiferal and radiolarian zone boundaries, and with a reported paleocurrent direction shift from southward to southwestward flow. The Lower Cretaceous palynoflora in the GVS is most similar to those of northern and western Canada, while that of the Lower Upper Cretaceous in the GVS resembles those of the eastern and southeastern United States.;The geographic distribution of common widespread Jurassic-Cretaceous species is documented in a table of published occurrence records from twelve regions on five continents, the GVS data providing a western North American contribution to the worldwide picture.;Possible morphological trends observed in GVS strata are found to be without phylogenetic significance when evaluated in the light of palynological data from other localites. Paleoecological and migrational or transport phenomena are recognized as necessary to account for the observed differences among orders of appearance of taxa worldwide.