Allochthonous and indigenous palynomorphs from the Devensian of the Warham Borehole, Stiffkey, north Norfolk, England; evidence for sediment provenance

Abstract

SUMMARY Late Devensian glaciolacustrine sediments proved by the Warham Borehole, near Stiffkey, north Norfolk, have yielded abundant and diverse recycled palynomorphs of Carboniferous, Permian, Triassic, Jurassic, Early Cretaceous and Palaeogene age. Indigenous Quaternary palynomorphs are a relatively minor component of the palynofloras; Carboniferous and Jurassic palynomorphs are the most commonly occurring forms. Middle Jurassic spores and pollen and Toarcian (Lower Jurassic) and Kimmeridgian (Upper Jurassic) dinoflagellate cysts are prominent, and the latter may indicate derivation from particularly resistant Toarcian and Kimmeridgian lithologies. Surprisingly, few grains were derived from the Chalk Group, which crops out locally. The recycled palynomorphs are interpreted as having been derived from local glacial deposits and then incorporated into the glaciolacustrine sediments of proglacial Lake Stiffkey, at the margin of the Late Devensian ice sheet. The lowest sample studied was the most productive palynologically. It was probably derived from nearby Lowestoft Till, an interpretation that agrees with the sedimentological evidence. The allochthonous palynomorphs from samples collected higher in the glaciolacustrine succession were probably derived from glaciogenic sediments deposited at the margin of the Late Devensian ice sheet. Based on the palynofloras, the Late Devensian ice flowed south from Scotland across the northern Pennines and NE England, down the western flank of the North Sea Basin to north Norfolk. The terrestrial nature of the indigenous Quaternary palynomorphs recovered is consistent with an ice-marginal and glaciolacustrine depositional setting.