LACUSTRINE SEDIMENT TRAPS AND THEIR EFFECT ON CONTINENTAL-SHELF SEDIMENTATION - SOUTH ISLAND, NEW-ZEALAND

Seismic data and cores from the Waitaki continental shelf, New Zealand, indicate a major reduction in terrigenous deposition about 10,000 years ago when the accumulation of extensive marine sand wedges ceased. This change reflects the impact of lacustrine traps on the main sediment supplier to the shelf, the Waitaki River. Prior to 10,000 years BP, lakes Ohau, Pukaki and Tekapo were glaciated and glacio-fluvial detritus was fed directly to the river and shelf where marine deposition was ca. 6.8×106 t/yr. Following deglaciation, the newly created lakes acted as efficient sediment traps that denied the river 22.2×106 t/yr. Accordingly, modern shelf deposition is around 0.04×106 t/year. © 1990 Springer-Verlag New York Inc.