Normapolles and triporate pollen assemblages from the Raritan and Magothy Formations (Upper Cretaceous) of New Jersey

Abstract

Of the palynological zones proposed for the Cretaceous System of the Middle Atlantic Coastal Plain, the species composition of zones IV, V, and VII are the least known. Previous studies have shown that zones IV, V, and VII occur within the Raritan and Magothy Formations of northern New Jersey. Therefore, in order to characterize the assemblages that constitute these zones, a principal coordinates analysis was run on the Normapolles and triporate pollen from selected lithologic units of the Raritan and Magothy Formations.

Results of the analysis suggest the presence of four assemblage zones within this stratigraphic interval. The zones are formally named and described in this report. In ascending stratigraphic order, the zones are referred to as the Complexiopollis‐Atlantopollis Zone, the Complexiopollis exigua‐Santalacites minor Zone, the Pseudoplicapollis longiannulata‐Plicapollis incisa Zone, and the ?Pseudoplicapollis cuneata‐Semioculopollis verrucosa Zone. The nominate species of these zones are also formally described herein.

The Complexiopollis‐Atlantopollis Zone occurs in the Woodbridge Clay and Sayreville Sand Members of the Raritan Formation. The only Normapolles or triporate species observed in this zone belong to the nominate genera. The zone is dated as middle to possibly late Cenomanian in age.

The Complexiopollis exigua‐Santalacites minor Zone occurs in the South Amboy Fire Clay Member of the Raritan Formation and the basal part of the Old Bridge Sand Member of the Magothy Formation. The zone is dominated by species of Complexiopollis, Santalacites minor n. sp., and Momipites fragilis Frederiksen & Christopher 1978, with Labrapollis spp. becoming a dominant element in the uppermost part of the zone. A major biostratigraphic break apparently occurs between this and the underlying zone. The Complexiopollis exigua‐Santalacites minor Zone is considered middle to late Turonian in age.

The Pseudoplicapollis longiannulata‐Plicapollis incisa Zone occurs in the uppermost part of the Old Bridge Sand and the Amboy Stoneware Clay Members of the Magothy Formation. Although the genera Plicapollis, Pseudoplicapollis, Trudopollis, and Osculapollis first occur in the underlying Complexiopollis exigua‐Santalacites minor Zone, they all show an increase in species diversity and abundance in the Pseudoplicapollis longiannulata‐Plicapollis incisa Zone. This zone is considered Coniacian(?) to early Santonian in age.

The ?Pseudoplicapollis cuneata‐Semioculopollis verrucosa Zone occurs in the “Morgan”; and “Cliffwood beds”; of the Magothy Formation. This zone contains the largest number of biostratigraphically useful species of any of the zones discussed. In contrast to the underlying zones, many of these species occur commonly in the ?Pseudoplicapollis cuneata‐Semioculopollis verrucosa Zone. The age of the zone is considered early to late Santonian.

The biostratigraphic fidelity of each species was calculated in order to quantitatively determine its usefulness as a guide to a particular zone. Assemblage plates of the biostratigraphically significant species that characterize each zone are presented.