Abstract

An active plate boundary with a high sediment output, three major submarine channels, and the world's largest deep western boundary current (DWBC) make up an extensive recycling system along the 4500 km continental margin, east of New Zealand. Seismic reflection, sedimentary, and oceanographic data demonstrate that detritus from the rising mountains of the New Zealand plate boundary is transferred to the Southwest Pacific abyssal floor by turbidity currents flowing along Solander (>450 km long), Bounty (950 km), and Hikurangi (1400 km) channels. These conduits discharge directly into the DWBC, which transports material north to form a series of sediment drifts. The northernmost drift, containing sediment from Hikurangi Channel and eroded drifts to the south, is now subducting into Kermadec Trench. Geochemical data suggest that sediment is recycled through the mantle to re-emerge in the arc volcanic rocks. Thus one cycle is completed and a new one begins.

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