Palynology of the Lower Cretaceous Hundleby Clay Member of the Claxby Ironstone Formation in eastern England and its biostratigraphic and palaeoenvironmental significance

Abstract

Palynomorph assemblages recovered from five samples of the Hundleby Clay Member of the Claxby Ironstone Formation contain abundant dinoflagellate cysts and miospores (spores and pollen grains). The cyst assemblages are sufficiently diverse to enable an age determination of early Valanginian for all five samples, although it is possible that evidence from the highest two samples indicates a younger age, but no younger than earliest Hauterivian. The miospore assemblage is consistent with these suggestions. A close comparison can be made with palynomorph assemblages from the Speeton Clay Formation at outcrop in East Yorkshire, and indicates a possible correlation with Beds D4–D3 ( Paratollia – Polyptychites ammonite zones), supporting the age determination. The overall composition of the palynological matter recovered from each sample, i.e. their palynofacies, suggests that the whole of the sedimentary succession accumulated in a nearshore marine setting, with deposits at the base of the exposure (samples 1 and 2) reflecting a more distal shelf environment than those from higher up and at the top of the section examined (samples 4, 5 and 3).