Ba. Tocher et I. Jarvis, DINOCYST DISTRIBUTIONS AND STRATIGRAPHY OF 2 CENOMANIAN-TURONIAN BOUNDARY (UPPER CRETACEOUS) SECTIONS FROM THE WESTERN ANGLO-PARIS BASIN, Journal of micropalaeontology, 14, 1995, pp. 97-105
The dinoflagellate cyst distributions and stratigraphies of two repres
entative Cenomanian/Turonian (C/T) boundary sections from the Maine an
d Normandy regions of northern France are described. Siliciclastic-ric
h sediments which characterize the Upper Cenomanian in Maine, contrast
with the coeval nodular chalk and hardground lithofacies of Normandy.
Both areas display a transition to marry chalks in the Lower Turonian
. Dinocyst assemblages are characterized by low diversities (38 taxa)
and low overall abundances, and relatively few stratigraphically signi
ficant species. The continued occurrence of Epelidosphaeridia spinosa
(Cookson & Hughes) Davey in the Upper Cenomanian of Maine is noted. Re
sults are compared and contrasted with those from coeval sections else
where in the Anglo-Paris Basin. A major decline in cyst abundance and
diversity is typical of the C/T boundary interval, which is characteri
zed by a dominance of tolerant cosmopolitan forms such as Circulodiniu
m distinctum (Deflandre & Cookson) Jansonius, Hystrichosphaeridium bow
erbankii Davey & Williams, Oligosphaeridium complex (White) Davey & Wi
lliams, Odontochitina costata Alberti; emend. Clarke & Verdier and O.
operculata (O. Wetzel) Deflandre & Cookson.