Distribution of palynomorphs in recent bottom sediments offshore Niger delta: A preliminary study

Abstract

A palynological and sedimentological study of recent bottom sediments from shallow proximal and distal locations offshore Niger Delta was carried out in order to assess the distribution of palynomorphs viz-a-viz the lithofacies in the study area. Fractions of the sediments were subjected to standard laboratory treatments to recover palynomorphs and to make deductions on their lithofacies types. The salinity and pH values of the sediments were also recorded. The most abundant palynomorphs recovered were those of Poaceae, Rhizophora, Elaeis guineensis, Alchornea cordifolia, and spores of fern species. Four lithofacies types were recognized across the locations. They are: Poorly sorted sands (I), Moderately sorted sands (II), Hard textured shale (III) and Sandy shale (IV). Shallow distal locations recorded higher proportions of palynomorphs than deeper proximal locations. Distal location A1 had the highest number of palynomorphs while proximal location B4 is devoid of palynomorphs. The result also revealed that sandy samples from proximal locations (B2,4,5,6) had paucity of palynomorphs; samples with mixture of sand and shale i.e., paralic (B1, 3 and A4) had moderately abundant palynomorphs while shaly samples in distal locations A1, 2, 3 had the highest number of palynomorphs. Seafloor morphology/topography made different areas to have different lithofacies at the same period, hence, low palynomorph recovery in sandy deposits may not always indicate dry paleoclimate condition of source area. Palynomorph abundance in the sediments studied seems to be guided primarily by lithofacies and salinity.