Holocene tidal levels and sedimentation rates using a diatom-based palaeoenvironmental reconstruction: The Tees estuary, northeastern England

An established diatom-based tidal level transfer function is used in combination with the present-day relationship between sedimentation rate and altitude to reconstruct Holocene tidal sediment accretion for the Tees estuary, northeastern England. The results from five cores reveal two periods of enhanced-sedimentation, the earlier of which (8000-6000 cal. BP) is related to relatively rapid sea-level rise and increasing tidal range. The later phase of increased tidal sedimentation also reflects an enhanced marine influence after c. 3000 cal. BP, but may also be attributed to climate- and human-induced changes in terrestrial sediment flux to the coastal zone. Comparison of the reconstructed sediment accretion rates with actual rates calculated from radiocarbon and luminescence dated sedimentary horizons reveals that this diatom-based approach overestimates sediment accretion by a factor of three. This overestimation is considered to be due to the contemporary sediment flux being an inappropriate analogue for the mid- to late Holocene rather than to any significant methodological flaws in the approach.