LIMITATIONS OF INFRARED STIMULATED LUMINESCENCE IN DATING HIGH ARCTIC MARINE-SEDIMENTS

The accuracy of infra-red stimulated luminescence (IRSL) dating was evaluated for modern, late glacial (11 to 13 ka) and older (70 +/- 10 ka and 125 +/- 10 ka) nearshore marine sediments from west Spitsbergen. Despite the increased sensitivity of the IRSL signal to solar reduction compared with thermoluminescence, the IRSL signal of these sediments was not totally reset, resulting in overestimates of a few 1000 to 10,000 years. Subtraction of residuals determined after 10 or 60 minutes of filtered light exposure (wavelengths <540 nm blocked) yielded apparently concordant age estimates. However, some samples exhibited significant anomalous fading even after preheating and storage; at least one sample exhibited some increase in the IRSL signal. Although the consistency of the IRSL age estimates are encouraging, the need for caution in luminescence geochronology is emphasized because of outstanding questions on signal stability and the extent of solar resetting.