Observations on palynology of the Tukau Formation in northwest Sarawak, Malaysia

This palynological study analysed 15 samples of the Tukau Formation, comprising intensely bioturbated sandy mudstone and organic-rich mudstones. Diverse vegetation types, including hinterland, mangroves, back mangroves, and montane regions, characterise the landscape of the region during the Tukau sediment deposition. Certain palynomorph types, such as Rhizophora type, Laevigatosporites sp., Elaeocarpus type, Euphorbiaceae, and Verrucatosporites usmensis (Stenochlaena), dominated the pollen assemblage, which represents the ancient landscape at that time. The influx of non-mangrove palynomorphs from the hinterland, likely transported by water, underscores the role of fluvial processes in controlling pollen distribution. Notably, the presence of age-specific marker pollen, such as Florschuetzia levipoli, Florschuetzia meridionalis, and Florschuetzia trilobata, confirms the age of the formation as Middle Miocene or younger. The presence of Acrostichum aureum pollen suggests a warm and humid tropical climate. Recognition of mangrove pollen from both front and back mangrove vegetation suggests deposition in the seaward region of the coast with significant tidal influences.