IODP Proceedings    Volume contents     Search



Preservation of dinoflagellate cysts and pollen was generally good, although palynomorphs were frequently obscured by the abundant terrestrial organic matter (cuticle and wood fragments) observed in all slides. No oxidation was undertaken during processing in order to reduce loss of sensitive dinoflagellate cysts, but oxidation and other steps to concentrate the pollen fraction are advised for future pollen and spore studies from this interval.

Dinoflagellate cysts

On average, 203 specimens were counted per sample (range = 7–374 specimens). Twenty five taxa or groups of dinoflagellate cysts were identified. Count data are included in Table T1, and relative abundance of selected taxa shown in Figure F1.

Assemblages were dominated by Brigantedinium spp., which made up 78% of the assemblage on average (range = 36%–98%). Other common taxa occurring throughout the sequence were Selenopemphix quanta and Selenopemphix nephroides (Selenopemphix undulata Verleye and Louwye was not differentiated from S. nephroides). Bitectatodinium tepikiense, ?Islandium minutum, and Quinquecuspis concreta were common in a few samples.

Gonyaulacoid cysts were considerably rarer than peridinoid cysts. The most frequently occurring form was Operculodinium centrocarpum sensu Wall and Dale, which never exceeded 10% of the assemblage. These proportions are similar to those recorded in surface sediment from the area (Crouch et al., 2010; Prebble et al., 2013).

The dinoflagellate cyst assemblages are likely too uniform to allow detailed paleoenvironmental reconstruction, although this uniformity may itself demonstrate a degree of consistency of the surface-water masses in the area on glacial–interglacial timescales.

Pollen and spores

On average, 124 pollen and spore grains were counted per sample (range = 2–450 specimens). Sixty seven taxa or groups of pollen and spores were identified. Count data are included in Table T2, and relative abundance of selected taxa is shown in Figure F1.

Spores, dominated by Cyathea, composed on average 15% (range = 3%–35%) of the pollen and spore assemblages. Gymnosperm pollen was dominated by Prumnopitys/Podocarpus species and Halocarpus. The most common angiosperm pollen was from Poaceae, Asteraceae, and F. fusca.

An alternation of two broad pollen associations was observed. Pollen of Poaceae, Halocarpus, Phyllocladus, and Caryophyllaceae/Chenopodiaceae, interpreted to represent an alpine or cooler climate vegetation, alternates with a pollen assemblage dominated by F. fusca and Prumnopitys/Podocarpus, reflecting warmer/interglacial conditions.