Luminescence chronology of loess-paleosol sequences from southern South Island, New Zealand

The loess-paleosol sequences in New Zealand are among the thickest in the southern hemisphere, and preserve an important terrestrial record of paleoclimatic changes. Unlike loess-paleosol sequences in North Island, most of those in South Island lack discrete chronostratigraphic marker ash beds, excepting perhaps the widespread similar to 24 ka Kawakawa Tephra. Therefore, any specific correlation to marine isotope stage (MIS) proxy records or to loess-paleosol sequences in the northern hemisphere has been unknown. Hence, we applied luminescence sediment dating to four key loess-paleosol sequences from southern South Island. Although these pioneering results suggest that further sampling and luminescence dating are needed, they do provide: (1) the first numeric age constraint (44 +/- 3 ka on overlying loess) for the end of deposition of the geomorphically and paleoclimatically important Edendale Terrace gravels;, (2) the first numeric evidence that the youngest loess-paleosol unit (L1) at the near-coastal Romahapa and inland Stewarts Claim sites began to be preserved much earlier (at similar to 60 ka) than at the inland Kingston Crossing site (similar to 35 ka); (3) the first direct evidence that the 6 in Romahapa sequence extends at least to similar to 350 ka, the oldest yet TL-dated such sequence in South Island. Furthermore, the stratigraphically self-consistent (with one exception) luminescence ages between similar to 60 and similar to 350 ka conflict with a previous indirect chronostratigraphy inferred from trace concentrations of glass shards. This trace-shard chronology implies a major hiatus in loess-paleosol preservation (missing at least MIS 6-7) not recognized by luminescence dating. (C) 2002 Elsevier Science Ltd. All rights reserved.