The palynological expressions of post-Palaeogene upwelling: A review

This paper reviews the known palynological expressions of post-Palaeogene upwelling, and changes in upwelling. In Plio-Pleistocene upwelling regimes, levels of amorphogen tend to swamp other palynoclasts present; the application of transmission electron microscopy has great potential for elucidating the origins of amorphogen. The recovery of foraminiferal test linings may be controlled by their progressive microbial destruction; the more juvenile stages in the ontogenetic record stand the greatest chance of preservation. The study of dinoflagellate cyst biofacies offers the greatest potential for palynological characterization and interpretation of post-Palaeogene upwelling systems. Cysts of heterotrophic peridiniacean dinoflagellates (P-cysts) tend to dominate cysts of autotrophic gonyaulacacean forms (G-cysts). The ratio of P-cysts to G-cysts (P/G ratio) is therefore considered to be a useful indicator of variable upwelling strength in these settings, reflecting the degree of water column turbulence. It is uncertain to what degree alynological patterns recognizable in one system are representative of other contemporaneous upwelling regimes. Nevertheless, palynological studies of upwelling systems should be used to interpret geochemical data and thereby provide a tangible link between cause (palaeobiological) and effect (geochemical).