HR: 0800h
AN: V21B-0599    [Abstracts]
TI: Undulating Sediment Morphology in the Bismarck Sea, Papua New Guinea
AU: * Hoffmann, G D
EM: garyh@pmc.ucsc.edu
AF: University of California at Santa Cruz, 1156 High St, Santa Cruz, CA 95064
AU: Silver, E
EM: esilver@pmc.ucsc.edu
AF: University of California at Santa Cruz, 1156 High St, Santa Cruz, CA 95064
AU: Day, S
EM: sday@pmc.ucsc.edu
AF: University of California at Santa Cruz, 1156 High St, Santa Cruz, CA 95064
AU: Ward, S
EM: sward@pmc.ucsc.edu
AF: University of California at Santa Cruz, 1156 High St, Santa Cruz, CA 95064
AU: Driscoll, N
EM: ndriscoll@ucsd.edu
AF: Scripps Institute of Oceanography, UCSD, 9500 Gilman Drive, La Jolla, CA 92093
AU: Applegate, B
EM: bruce@soest.hawaii.edu
AF: University of Hawaii at Manoa, 1680 East-West Rd, POST 815, Honolulu, HI 96822
AB: In the Bismarck Sea along the north coast of Papua New Guinea, we detected seven large fields of wavelike structures in Nov-Dec, 2004 aboard the R/V Kilo Moana. These fields are up to 40 km long and 20 km wide, with wave heights reaching ~50 m. The average slope of the entire field is typically about 1 degree, with slopes locally reaching 10 degrees. Four of the fields are associated with upslope channels suggesting a depositional origin of the waves. The others are not, and may be related to contour currents, downslope creep, and/or debris flows. We compared measurements of wavelength, height, and asymmetry from the multibeam bathymetry, sidescan backscatter imagery, and high-resolution chirp seismic profiles obtained during the survey with the 9 distinguishing criteria of Lee et al. [2002, Mar. Geol., 192, 79-104]. Northeast of Uluwan volcano in New Britain, we have located five morphologically and spatially distinct wave fields. Four of these are close to one another and interact heavily in their distal portions, with one field crosscutting another, partially erasing and overprinting depositional features. Two of these are associated with channels cut by the Pandi River and its sister rivers that feed into Hixon Bay. These display several of the Lee et al. criteria, and thus they are consistent with a turbidity current origin for these fields. The other two display some deformational features, and were likely formed by several interacting processes. The fifth originates atop levee deposits associated with the Toru River and Sai River channels, which join just south of the small wave field. We suggest this wave field was formed by deposition related to flood events of these two rivers. We detected a sixth field in Kimbe Bay, associated with a large, previously unmapped fault. These waveforms display an arcuate structure in map view dissimilar to the typically parallel undulations identified as sediment waves elsewhere. The waves extend from Cape Reilnitz, and are bounded by a channel and fault to the east, and a basin extending from Commodore Bay to the west. We propose these waveforms were generated by deformation combined with differential deposition. The observations highlight the necessity for case-specific solutions for the formation and evolution of seafloor wavelike structures due to multiple interacting processes.
DE: 3002 Continental shelf and slope processes (4219)
DE: 3022 Marine sediments: processes and transport
DE: 3025 Marine seismics (0935, 7294)
DE: 3045 Seafloor morphology, geology, and geophysics
DE: 3070 Submarine landslides
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005