The Impact of the Final Lake Agassiz Flood Recorded in Northeast Newfoundland and Northern Scotian Shelves Based on Century-Scale Palynological Data - Abrupt Climate Change: Mechanisms, Patterns, and Impacts - page 151

indication of lower SSS. Increased nutrient inputs can also
trigger dinoflagellate blooms, which suggest increased melt-
water

tepikiense, N. labyrinthus, Spiniferites spp, Ataxiodinium
choanum, and A. tamarense type cyst. Similar assemblages
occur in Canadian Arctic channel core tops [Mudie and
Rochon, 2001].
Dinoflagellate cyst assemblage zone SA1 (650 - 750 cm) is
dominated by O. centrocarpum (50

flow to the area during that interval. Similar increases
in A. tamarense were observed in early Holocene assem-
blages from the Scotian Shelf [Levac, 2001].
The lower part of dinocyst zone 4 (200

350 cm) is dom-
inated by I. minutum and Brigantdinium spp, with small
proportions of P. dalei, O. centrocarpum and N. labyrinthus.
The proportions of A. tamarense, and I. pallidum are notably
lower, and S. elongatus is absent. High percentages of
I. minutum indicate that sea surface conditions are still cold,
but the near disappearance of I. pallidum and A. tamarense
suggests that the meltwater in

- 60%), P. dalei and Bri-

gantedinium spp, with small percentages of Spiniferites spp
(mainly S. ramosus and S. elongatus).
Assemblages in dinocyst zone SA2 (500

-

650 cm) are
markedly different from the rest of the core. This zone is
defined by the maximum relative abundance of N. laby-
rinthus and of other minor species, including B. tepikiense
and S. quanta. It is also characterized by a peak in the
abundance of I. minutum. S. quanta is more abundant in the
middle of zone SA2. This depth interval contains the Lake
Agassiz

-

uence was reduced.
In the upper part of dinocyst zone 4 (0 - 200 cm), the
proportion of most minor taxa increases. O. centrocarpum
reaches 10%

15%, S. elongatus reappears, and N. laby-
rinthus is present in every sample. This assemblage is similar
to those of the neritic portion of the Northeast Newfoundland
Shelf today [Levac, 2002].

- flood deposits, and assemblages (especially the peak

values of I. minutum) indicate lower SST. In the upper part of
the zone, the presence of two warm indicators, A. choanum
and S. mirabilis, as well as decreased proportions of I.
minutum, indicate the cold episode had ended.
O. centrocarpum and Brigantedinium spp dominate the
assemblages of dinocyst zone SA3 (180

agellate cyst
assemblages throughout core 12 (Figure 11) are dominated by
Brigantedinium spp, O. centrocarpum,andP. d a l e i .Minor
species are I. minutum, Selenopemphix quanta, Bitectatodinium

5.3.2. Dinoflagellate Cysts in Core 12. Dino

500 cm). Among
the accompanying taxa, Spiniferites spp (mainly S. ramosus
and S. elongatus) and P. dalei are the most abundant. There is

-

Figure 11. Dinoflagellate cysts diagram for core HU84011-12, St. Anne ' s Basin. Ages are the same as in Figures 7 and 9.
Lines on the right are the results of the cluster analysis.