Correlation between shelf sediments near cape farewell and a numerical simulation of the Westland current

Abstract

Abstract The sediments on the north‐west shelf of the South Island, New Zealand, were mapped by van der Linden (1979: New Zealand Journal of Geology and Geophysics 12). He found that the underlying rocks of the Kahurangi Shoals date back at least 65 million years, but the sediments are generally in equilibrium with the present hydrological regime. The sediments are generally sand, although a belt of coarse elastics extends north‐east of the shoals which van der Linden suggested is associated with high currents. We have applied a numerical model to the north‐west shelf to simulate a mean Westland Current driven by shelf scale pressure gradients. No current‐meter data were available for this model and it was calibrated with limited drifter measurements. The isotachs derived from the model are very similar in shape to the contours of sediment mean grain size given by van der Linden (1979). Over the Kahurangi Shoals, the currents are high and grain size is also high. Conversely, a lobe of low grain size over ...