Infrared and Red Stimulated Luminescence Dating of Late Quaternary Nearshore Sediments from Spitsbergen, Svalbard

Abstract

This study examined the potential of infrared (IRSL) and red (RSL) stimulated luminescence to provide ages for fine-grained polymineral extracts from sublittoral strata from deglacial-emergence sequences on Brøggerhalvøya, Linnedalen, and Kapp Ekholm, west Spitsbergen. IRSL analyses of modern and ca. 12-ka-old sediment indicate that residual levels defined after 10 and 60 min of filtered sunlight provide close minimum and maximum age estimates, respectively, whereas full solar resetting gave age overestimates by 2 to 18 ka. Although red stimulation yields concordant ages for modern and Holocene sediments, RSL is not currently as robust a geochronometer as IRSL, but is a complementary measure to evaluate IRSL age estimates. Sublittoral strata from the penultimate deglacial sequence (Episode B) on Brøggerhalvøya gave IRSL and RSL ages of ca. 80 ± 10 ka and presumably correlative strata from Kapp Ekholm and Linnedalen yielded IRSL ages of ca. 70 ± 10 ka. Pre-penultimate deglacial event sediments (Episode C) from Brøggerhalvøya gave bracketing average IRSL ages of 118 ± 17 and 153 ± 21 ka. IRSL analyses for Formation B at Kapp Ekholm is less definitive with average minimum and maximum ages of 117 ± 19 ka and 195 ± 13 ka; the latter age is favored, although it is substantially older than a previously reported age of ca. 120 ka. IRSL is a more consistent geochronometer for dating waterlain sediments from Spitsbergen than TL, but there still remains considerable variability in the extent of solar resetting of IRSL of sublittoral sediments, that erodes precision particularly for ages <50 ka. These new luminescence age estimates indicate deglacial events at ca. 70, 140, and potentially at 190 ka that generally correspond to the early and later parts of Oxygen Isotope Stage 5 and late Stage 7. The inferred timing of deglacial events indicate that demise of a marine-based Barents Sea ice sheet may be associated with rising global sea level into an interglacial or an interstadial, rather than purely radiative forcing.