Land-ocean interaction in southern New Zealand during the past 200 ka

During the Late Quaternary global climate variations and interactions with the southern westerly wind belt and the adjacent surface ocean circulation caused glacier advances and retreats in New Zealand’s Southern Alps. Most studies in this region, however, focus on the last glacial period and evidence of older glacier activity is more fragmentary. The use of marine sediment cores as continuous archives for glacier fluctuations over glacial-interglacial cycles is a common method to circumvent such terrestrial archive limitations. Our study investigates the glaciation history of New Zealand’s South Island over the past 200,000 years and its interaction with paleoceanographic changes of the adjacent Southeast Tasman Sea. Solander Trough south of New Zealand represents a major conduit of terrestrial sediments from the Southern Alps. Core SO290-17-1 from Solander Trough is therefore ideally suited for a multi-proxy approach. The stratigraphy of the core is based on oxygen isotopes from benthic foraminifera and X-ray fluorescence core scanning, paleo- and rockmagnetic measurements. In addition, stable oxygen and carbon isotopes from planktic and benthic foraminifera are combined with the former methods for the paleoenvironmental reconstructions. The XRF Fe/Ca ratio indicates enhanced terrestrial inputs during MIS 2, MIS 4 and MIS 6. To investigate changes in sediment source and hence glacier dynamics on land, we use radiogenic neodymium isotopes (expressed in ɛNd) as a proxy for source-specific terrestrial input. Significant ɛNd changes in SO290-17-1 are expected in response to glacier fluctuations because of the complex geology (in nature and age) of the Fiordland and East Southland regions, on which glaciers fluctuated during the last glacial periods. Our data for MIS 4-6 will be compared to results obtained on core TAN1106-28 from the Solander Trough for MIS 1-4 (Toucanne et al., submitted).