A comparison of multiple luminescence chronometers at Voordrag, South Africa

A suite of 10 samples collected from an 11 m thick colluvial sequence at Voordrag, KwaZulu-Natal, South Africa, have been used to undertake a comparison of different luminescence methods. Good agreement is found between single grain quartz optically stimulated luminescence (OSL) and single grain K-feldspar post-infrared infrared-stimulated luminescence (post-IR IRSL) ages, with the exception of the basal samples where the quartz OSL signal is saturated. Multiple grain quartz OSL consistently yields ages older than single grain OSL methods. Multiple grain feldspar ages derived from the IRSL50 signal are underestimated due to anomalous fading. A previously published radiocarbon chronology yields ages that are younger than those from single grain quartz OSL and post-IR IRSL, and this is most likely due to contamination with younger carbon. Identifying the effect of saturation on the quartz OSL signal remains challenging when quartz is dated in isolation. However, using a paired quartz/feldspar dating approach is an effective way of identifying the impact of saturation on the OSL signal.