INTERPRETATION OF HOLOCENE SEA-LEVEL TENDENCY AND INTERTIDAL SEDIMENTATION IN THE TEES ESTUARY USING SEDIMENT LUMINESCENCE TECHNIQUES - A VIABILITY STUDY

It is demonstrated that detailed examination of the photo- and thermoluminescence (PL, TL) of Holocene intertidal sediments can reveal important information regarding their depositional history in the context of sea level tendency and storm surge activity. The technique is particularly applicable to thick deposits of relatively uniform composition, and is demonstrated with a 1.7-m core of marine to brackish water silty clay taken from Cowpen Marsh in the Tees estuary, north-east England. This sedimentary unit is intercalated with an upper and a lower terrestrial peat bed, which have been radiocarbon dated to 5250 +/- 45 and 7065 +/- 45 C-14 years BP respectively. An investigation of the mineral composition and diatom assemblage of the silty clay facies reveals a marked hiatus in deposition towards the top of the minerogenic unit. Analysis of the luminescence profiles of the sediment illustrates that, below this hiatus, sedimentation was slow and continuous, with approximately 1.0 m of sediment being deposited in 1800 +/- 400 years, whilst above, sedimentation was rapid, with 0.7 m of sediment being deposited in 0 +/- 200 years. It is shown that variations in the luminescence of the sediments can be interpreted in terms of the onset of a positive sea level tendency period coupled with the occurrence of a low-frequency extreme water level event.