Spore-Pollen Correlation of Cretaceous Rocks of Northern and Southern Hemispheres: ABSTRACT

Abstract

This paper summarizes published and unpublished palynological data from Upper Jurassic and Cretaceous sediments of northwest Europe, Russia, North and Central America, the Middle East, North and West Africa, South America, Australia, and New Zealand. Many publications could be considered only in a very general way or had to be disregarded because of the inadequate illustrations and descriptions of species and nomenclatural confusion or because of the complete lack of stratigraphic data. Numerous very distinctive forms of spores and pollen grains, some of which can be assigned with confidence to living families of plants, make their first appearance in the fossil record during Upper Jurassic and Cretaceous time. They are accompanied in the marine sediments by the incoming of equally distinctive forms of microplankton. Based mainly on the incoming of such forms of spores, pollen, and microplankton, many authors have erected varying numbers of palynological subdivisions for use purely in local correlation in their respective areas. Some, but unfortunately few, by comparison with spores, pollen, and microplankton from sections independently dated by other fossils such as ammonites or foraminifera, have attempted to correlate local palynological subdivisions with the stan ard biostratigraphic units of the Cretaceous. A compilation of results from published works, together with unpublished results from Royal Dutch/Shell Group palynologists, suggests the following generalized sequence of spore and pollen floras and their approximate correlation with the standard biostratigraphic units. Upper Cretaceous: Floras with increasing numbers of species of dicotyledonous pollen grains. Tendency toward typical Northern and Southern Hemisphere floras is apparent in the Lower Senonian and is clearly marked by the Upper Senonian. In most areas considered, a broad 3-fold palynological subdivision is apparent, which is correlated generally with the Cenomanian-Turonian, Lower Senonian, and Upper Senonian. Aptian-Albian: First appearance of generally small and more or less sculptureless tricolpate dicotyledonous pollen grains in both Hemispheres. Last appearance in most areas of the Northern Hemisphere of such typical Jurassic-Lower Cretaceous forms as Classopollis torosus, Caytonipollenites pallidus, Pilosisporites trichopapillosus. Hauterivian - Barremian: Northern Hemisphere floras generally characterized by co-occurrence of Jurassic and older Cretaceous forms of spores and pollen together with Ephedra-like pollen and rare monosulcate pollen grains with clearly differentiated exine (Clavatipollenites). Not sufficient data from Southern Hemisphere for comparison. Valanginian: In both Northern and Southern Hemispheres generally characterized by abundant specimens of Cicatricosisporites dorogensis and related forms together with abundant typical Jurassic gymnosperm and pteridosperm pollen. Clearly separated from Jurassic in Northern Hemisphere by first appearance of a number of forms including Appendicisporites. The paleontological and stratigraphic evidence used in the correlation of local palynological subdivisions with the biostratigraphic units within the areas considered, is summarized in the form of range charts, and some of the more distinctive species of spores and pollen are illustrated by photomicrographs. End_of_Article - Last_Page 262------------