LIMITATIONS OF THERMOLUMINESCENCE TO DATE WATERLAIN SEDIMENTS FROM GLACIATED FJORD ENVIRONMENTS OF WESTERN SPITSBERGEN, SVALBARD

A fundamental problem in the TL dating of waterlain sediments, particularly in the Arctic, is the accurate determination of the level of solar resetting prior to deposition. This study determined the effect of wavelength on the solar resetting of the TL signal and concomitant effects on the accuracy of TL age estimates for late glacial and modern glacial and nearshore marine sediments from fiords on Spitsbergen. The reduction in TL level decreases with filtering of wavelengths above 400 nm. Modern and Late Weichselian tills have TL levels at saturation, probably received no light exposure prior to deposition and thus cannot be dated by TL. Glacial-marine sediments deposited within 0.5 km of a glacier terminus yielded TL age estimates 10 times the known age presumably because these sediments received limited light exposure prior to deposition. Modern sublittoral sediments and fiord muds yielded TL apparent ages between < 1-7 ka, in general agreement with a previous TL age estimate and the known age for these samples. However, sublittoral sediments deposited ca. 10 ka BP yielded overestimates in TL ages by 17 to 32 ka, considerably older than a previous TL age estimate of 9.9 +/- 1.1 ka. We believe the difference in accuracy of TL age determinations for the modern and late glacial sediments is primarily a function of depositional environment. The TL of modern fiord sediments are not an appropriate analog for sediments deposited during the late glacial when relative sea-level and glacial coverage were changing rapidly.