Distribution of Calcareous Dinoflagellates in Cenozoic Sediments of Site 366, Eastern North Atlantic

Abstract

Paleocene to Pleistocene calcareous dinoflagellates in samples from DSDP Leg 41, Site 366 on the Sierra Leone Rise in the eastern North Atlantic are described using scanning electron microscopy (SEM). Two new species of Thoracosphaera were encountered. One species is rejected representing a diagenetically altered modification. Several species are described and illustrated for the first time by SEM examinations.The stratigraphic distribution of individual species described here shows restricted ranges, although a few long-ranging species are present. More complete investigation of regionally widespread material may result in using calcareous dinoflagellates as valuable index fossils.

Dinoflagellate contributions to the deep sea

“…Loeblich III (Plate 1.4, figures 1-11): Spinose calcareous cysts generaly resembling those described from Peridinium trochoideum by Wall and Dale (1968b) and Wall et al (1970). Details of the forms encountered here seen in SEM were very similar to those described by Fütterer (1977) as Peridinium cf. Peridinium trochoideum (Stein) Lemmermann.…”

“…Calciodinellum operosum Deflandre, 1947 (Plate 1.1, figure 13; Plate 1. of Deflandre (1947Deflandre ( ,1948 and Wall and Dale (1968b), while skeletal details (including the range of variabilty) seen in SEM agreed with the description of Fütterer (1977).…”

“…Its abundance here suggests that these cysts are rou tinely produced by oceanic dinoflagellates, probably smal orthoperidiniums belonging to the genera Scrippsiella or Ensiculifera (Type 9, Table 1.2). The second most abundant calcareous cyst, Calciodinellum (Type 2, Table 1.3) is previously recorded from deep sea sediments (e.g., Fütterer, 1977) and slope water plankton and a cyst with cell contents was seen by the author in a slope water plankton sample taken September 21, 1971, off the East Coast, U.S.A. (39°56'N, 70059'W).…”

“…were probably included under this "taxon" in quantitative counts using the light microscope. These almost certainly included T. albatrosiana sensu Fütterer (1977) (Plate 1.3, figure 12) and the "granular form" of T. albatrosiana of Fütterer (1977) (Plate 1.1, figures 9-11). They may also have included T. albatrosiana Kamptner, 1963, sensu Fütterer (1977 (Plate 1.3, figures 1-8).…”

“…Fütterer (1977) described some from pelagic sediments of Oligocene to Pleistocene age at DSDP Leg 41, Site 66, on the Sierra Leone Rise in the eastern North Atlantic, and Gilbert and Clark (1983) from Late Cenozoic sediments from the Central Arctic Ocean.…”