Biogeographic Significance of Early Cretaceous Foraminifera from Budden Canyon Formation, Northwestern Sacramento Valley, California: ABSTRACT

Abstract

A foraminiferal fauna of 189 species and varieties has been recovered from strata of Barremian-early Cenomanian age in the Chickabally Member of the Budden Canyon Formation. Calcareous perforate species, typified by the lagenids and rotaliids and, to a smaller degree, by the rotaliporids and buliminids, and among the arenaceous groups by the lituolids and valvulinids, constitute the major elements of the fauna. The Foraminifera show close affinities with contemporaneous, medium-depth faunas widely distributed in the lower and middle latitudes of the northern hemisphere. Many lagenid and rotaliid species in particular appear to be conspecific with forms described from Europe and Trinidad. Common genera recorded for the first time from the Pacific Coast include Falsoguttulina, Pseudosigmoilina, Reinholdella, and Spiroplectinata. However, a persistent endemic element also can be recognized in the Chickabally assemblages, especially in arenaceous forms, the buliminids and the rotaliids. Resemblance of this microfauna to the marginal and neritic assemblages of the Gulf Coast and Alaska is less marked, and very little relation to the specialized brackish-water and quiet shallow-marine assemblages f the western interior is apparent. Regional correlations demonstrate that, during the late Early Cretaceous, benthonic Foraminifera favoring an offshore, medium-depth, muddy-bottom milieu were extant from Europe through North Africa, the Caribbean, and western North America, their distribution being facilitated by widespread tropical conditions and interconnected seaways. End_of_Article - Last_Page 775------------