Luminescence dating of young coastal deposits from New Zealand using feldspar

摘要

A new measurement protocol has been tested on K-feldspars from Whanganui Inlet and Parengarenga Harbour, New Zealand. A Single Aliquot Regenerative (SAR) dose protocol, using two successive infrared (IR) stimulations (post-IR IR SAR protocol) is setup for these young (1000 years) coastal sediments. Significant anomalous fading (g 2days =7 %/decade) is observed using the conventional IR signal measured at 50?°C. In contrast, the fading rate of the IR signal measured at elevated temperature (150?°C) after the IR stimulation at 50?°C (a post-IR IR signal) is not significant (g 2days a?¤ 1 %/decade). Surprisingly low residual infrared stimulated luminescence (IRSL) signals were observed for a surface sample, suggesting that accurate ages as young as a??50 years can be obtained for these recent deposits. IRSL ages ranging between 48?±6 years and 1050?±50 years are obtained from six samples, indicating that sediment accumulation has occurred at the two sites during the last millennia, despite a falling trend in relative sea-level in Whanganui Inlet and a stable relative sea-level at Parengarenga Harbour.