Abstract:
To test the potential of dinoflagellate cysts and acritarchs for long distance correlation, DSDP Hole 603C situated on the lower continental rise off New Jersey, DSDP Hole 610A in the Rockall Trough, eastern Atlantic, and ODP Hole 646B in the Labrador Sea (de Vernal and Mudie, 1989) have been compared. Some biostratigraphic events are clearly diachronous when compared with other regions, such as the first appearance of Ataxiodinium confusum (5.1 Ma in the Mediterranean, 4.2 Ma in DSDP Hole 603C), but others have emerged which might be applicable for interregional correlation.Shallow marine, imprecisely-dated Pliocene deposits in eastern England have already been analyzed for dinoflagellates, most of which have relatively long ranges within the Pliocene. However, the oldest deposit, assigned to the Coralline Crag Formation, contains abundant Operculodinium tegillatum which has a highest common occurrence in the latest early Pliocene (ca. 3.7 Ma) in both DSDP Hole 603C and ODP Hole 646B (as O. crassum in de Vernal and Mudie, 1989). Furthermore, Algal cyst type 2 of Head (1997) which is restricted in DSDP Hole 603C to a narrow interval (4.4-3.8 Ma) within the upper lower Pliocene where it occurs abundantly, is present in the lower part of the Coralline Crag Formation. These and other datums suggest that the Coralline Crag Formation can be placed within the late early Pliocene or earliest late Pliocene. The Walton Crag of eastern England, which succeeds the Coralline Crag, has been dated by pollen analysis at between 3.0 and 2.6 Ma. Dinoflagellates of the Walton Crag are fairly diverse (more than 21 taxa) but are mostly long ranging. Impagidinium multiplexum has not been reported from the Walton Crag, yet is present/common in later Plio-Pleistocene deposits of eastern England and the southern North Sea and has a well-defined first appearance at 2.8 Ma in the western North Atlantic. Since the Walton Crag represents paleoenvironments probably favorable to this species, its absence invites speculation that these deposits predate 2.8 Ma.