Optically stimulated luminescence dating of glaciofluvial sediments on the Canterbury Plains, South Island, New Zealand

New Zealand is a key location for investigating the geomorphic response of fluvial systems over glacial–interglacial timescales, and as such provides a potentially rich archive of Quaternary climate change. Identification of the climatic response of fluvial systems requires the application of a reliable geochronological method to place the sedimentary record within the context of the regional climate history. Optically stimulated luminescence (OSL) dating offers the opportunity to generate ages from quartz in glaciofluvial sediments, and so has many possible applications in South Island. However, in applying this method, previous studies have encountered problems of low OSL signal intensities in quartz. This has limited the application of quartz OSL in South Island; most geochronological studies have instead used feldspar for luminescence dating, but have been affected by problems such as weathering. In this study, we found that although the OSL signal levels from quartz are low, a useable OSL signal can be observed from medium-sized aliquots containing ∼500 grains of quartz separated from samples from eastern South Island. Mathematical component separation of the quartz OSL signal indicated that the signal is dominated by a fast component. Ages produced using the central age model range from 18.2 ± 1.3 to 36.7 ± 2.9 ka, are in stratigraphic order, and agree with independent age control from two 14C ages. This study demonstrates the successful application of quartz OSL to glaciofluvial sediments from Canterbury, and its potential to provide a chronology for sedimentary records of climate change in this region.

► Application of luminescence dating to glaciofluvial sediments from New Zealand.
► Coarse-grained quartz from the Canterbury Plains is suitable for OSL dating.
► Low signal intensity of the quartz requires aliquots of ∼500 grains to be measured.
► The quartz signal is dominated by a fast component and suitable for a SAR protocol.
► The Canterbury Plains braided river gravels are likely to have accumulated during glacials.