HR: 1340h
AN: B43E-1657    [Abstracts]
TI: High-resolution seismic imaging of continental shelf and slope sediments and associated dynamic processes on the Otago Margin: East coast of the South Island, New Zealand
AU: * Gorman, A R
EM: andrew.gorman@otago.ac.nz
AF: University of Otago, Department of Geology, P O Box 56, Dunedin, 9054, New Zealand
AU: Hill, M G
EM: matth.galloway@gmail.com
AF: University of Otago, Department of Geology, P O Box 56, Dunedin, 9054, New Zealand
AU: Koons, P O
EM: peter.koons@maine.edu
AF: University of Maine, Department of Geological Sciences, Orono, ME 04469, United States
AU: Landis, C A
EM: landis@clear.net.nz
AF: University of Otago, Department of Geology, P O Box 56, Dunedin, 9054, New Zealand
AU: Allan, T M
EM: Tim.Allan@omv.com
AF: OMV New Zealand, Level 10 Deloitte House, 10 Brandon Street, Wellington, 6001, New Zealand
AU: Johnstone, T
EM: tanyaj@tgsnopec.com.au
AF: TGS, Level 5, 1100 Hay Street, West Perth, WA 6005, Australia
AU: Orpin, A R
EM: a.orpin@niwa.co.nz
AF: National Institute of Water and Atmospheric Research, Private Bag 14901, Wellington, 6021, New Zealand
AU: Gray, F L
EM: geology@otago.ac.nz
AF: University of Otago, Department of Geology, P O Box 56, Dunedin, 9054, New Zealand
AU: Wilson, D
EM: dwilson4@houston.westerngeco.slb.com
AF: WesternGeco, 10001 Richmond Avenue, Houston, TX 77042, United States
AU: Osterberg, E C
EM: erich.osterberg@maine.edu
AF: University of Maine, Department of Geological Sciences, Orono, ME 04469, United States
AB: The seafloor off the southeastern coast of the South Island of New Zealand is characterised by a narrow (15- to 30-km-wide) shelf cut by a set of submarine canyons that feed into the Bounty Trough. On the outermost Otago Shelf, between the Papanui and Saunders submarine canyons, the regional shelf break is interrupted by a <1 km² bench at a depth of ~220 m. Fishermen dredging for scallops on this bench discovered a collection of carbonate chimneys that are connected to one of several significant seafloor vents along the east coast of New Zealand. A strong correlation appears to exist between the location of the chimneys and the heads of submarine canyon systems. Our work investigates some of the geological processes in place on this continental margin that have led to the present vent system and its underlying fluid pathways. A series of high-resolution single-channel seismic reflection surveys has been undertaken over the last 18 years on the Otago Shelf to address a range of sedimentological, stratigraphic, structural and hydrogeological aims. These data were collected on board the University of Otago RV Munida using a Ferranti Ocean Research Equipment (ORE) Geopulse sub-bottom profiling system (boomer). Analogue recordings of these data have recently been digitised, merged with survey data, and archived in SEG-Y format. This has facilitated further processing and analysis of the dataset. Two of these seismic lines image the bench-like feature on which the chimneys are found. These data will be used to investigate the following questions. (1) What role do coast-perpendicular or coast- parallel structures and lowstand sedimentary features have on fluid migration on the shelf? (2) What is the nature of groundwater flow within the shelf and how is it affected by Pleistocene-to-recent sea level variation? (3) What is the linkage between vent/chimney and canyon development on this passive margin?
DE: 0930 Oceanic structures
DE: 0935 Seismic methods (3025, 7294)
DE: 3021 Marine hydrogeology
DE: 3025 Marine seismics (0935, 7294)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting