Luminescence from glacimarine sediment-trap samples at the Antarctic Peninsula

Radiocarbon (14C) dating yields variable and high reservoir and core-top ages for glacimarine sediments around Antarctica. To test the suitability of luminescence as an alternate dating method we investigated the effectiveness of clock zeroing (by daylight) within fine-silt-size siliciclastic sediments from year-long vertical-array sediment traps in Andvord Bay and Brialmont Cove at the Antarctic Peninsula. Both long-bleach and short-bleach multi-aliquot IR-PSL (infrared photon stimulated luminescence) and single-aliquot, post-IR blue-PSL dating tests were conducted. As well, dual-bandwidth-bleaching thermoluminescence (TL) tests were performed on samples from Brialmont Cove. These TL bleaching tests indicate that silt from the middle and bottom traps at this site has had little or no exposure to daylight, but that silt from the top trap has had some exposure. All 24 samples (representing different seasons and different trap depths) exhibit anomalously old apparent ages (12 ka-60 ka) across annual seasons and depths of deposition when either long-bleach multi-aliquot or late-background-subtraction single-aliquot PSL procedures were employed. Thus regional bottom silts would be unsuited for dating by these two luminescence dating approaches. However, a short-bleach multi-aliquot IR-PSL procedure yields the expected zero ages for several samples, a promising result that requires further exploration.