Palynological Characterisation of Depositional Environment: Marine

Palynological assemblages from marine deposits frequently contain dinoflagellate cysts and acritarchs, and there is usually a major contribution from the brackish water coastal vegetation. It is rarely possible to distinguish a particular marine depositional environment based on palynology alone. Trends recognised in the composition of the assemblages provide useful indications. Nearshore fluviomarine deposits generally contain diverse, well mixed, poorly size-sorted pollen and spore assemblages which are carried in by rivers from a variety of parent plant associations upstream. These assemblages give the best general impression of overall floral development in the area and can be used for chronostratigraphic evaluations and palaeo-geographic and palaeo-climatic reconstructions on a regional scale. Further offshore there is usually a reduction in the overall quantity of organic matter. Palynomorph assemblages tend to be less diverse and better sorted, with smaller, lighter and more buoyant elements which have been transported out by currents. There may also be a relatively high proportion of wind transported pollen. Local current patterns can severely distort these overall trends. The distribution of species of smaller benthonic foraminifera therefore provide a better indication of marine depositional environments in the Brunei Darussalam area.

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