Upper Cretaceous Planktonic Foraminifera from West Side of Sacramento Valley: ABSTRACT

Abstract

Outcrop samples from widely spaced localities in the Venado, Yolo, Sites, Funks, Guinda, and Forbes Formations, Yolo and Colusa Counties, California, contain a sparse but diagnostic fauna of planktonic Foraminifera. About 30 species are presently recognized, the greatest number of species and individuals belonging to the genus Globotruncana. These planktonics are described and preliminary correlations made with Cretaceous strata elsewhere. The siltstone and sandstone of the Venado Formation contain bi-keeled globotruncanids, Globotruncana helvetica, and species of Hedbergella suggestive of a Turonian age. These strata and the shales of the middle and upper Yolo Formation are tentatively correlated with Members II and III of the Redding area, California. Planktonic assemblages from the Sites, Funks, and End_Page 1083------------------------------ Guinda Formations include species of Globotruncana, Hastigerinoides, Schackoina, Hedbergella, and Heterohelix, and are assigned an early Senonian age. The Forbes Formation is characterized by Globotruncana arca, and species of Pseudotextularia and Globigerinelloides. These fossils occur in other described Campanian microfaunas from the Stanford University campus, the Marlife Formation of Fresno County, and the Kelly Ranch of Carlsbad. The pelagic Foraminifera from this area are correlative with microfaunas from the Austin and Taylor Groups of the Gulf Coast, and from the Turonian to Campanian stages of Europe. End_of_Article - Last_Page 1084------------