Overview
At the completion of the survey new data were acquired over the planned area covering ~18,000 km2. When combined with archive data the MBES coverage encompasses ~ 40,000 km2. The TAN1608 MBES data collected offshore of Otago includes upper-slope portions of the Otago Fan Complex, and Centre and South Channels –tributaries that merge to form the Bounty Channel and Fan system to the east. This network of canyon-fed channels has been previously documented in general terms, but the bathymetric detail now afforded by MBES coverage was hitherto unknown.
Some of the key geomorphic features documented during the survey include:
- the narrow v-shaped canyon heads of the Otago Fan complex progressing into broad U-shaped canyons,
- the entrenched (250 m deep) sinuous Centre and South Channels with asymmetrical convex levees and associated sediment wave fields, low relief mounds or terraces, outer bank and point bars, and gully erosion features,
- the occurrence of cut-off or abandoned meanders suggesting an active and evolving channel-levee system,
- pockmarks predominately on the northern levees up to 200 m across and exhibiting up to 20 m relief.
- presence of previously up mapped “mud” volcanoes Combining these data with those collected during previous NIWA voyages has resulted in a dataset mapping the structure of the Otago Fan Complex seaward of the shelf break, and North, Centre and South Channels which merge to form the Bounty Channel.
Click link below to read the full voyage report: