HR: 1400h
AN: OS23B-07    [Abstracts]
TI: Sedimentary Environments and Processes in the Vicinity of Quicks Hole, Elizabeth Islands, Massachusetts
AU: * Poppe, L J
EM: lpoppe@usgs.gov
AF: USGS, 384 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Ackerman, S D
EM: sackerman@usgs.gov
AF: MA CZM, 384 Woods Hole Road, Woods Hole, MA 23510, United States
AU: Moser, M S
EM: marc.s.moser@noaa.gov
AF: NOAA, 439 West York Street, Norfolk, VA 23510, United States
AU: Stewart, H F
EM: helen.stewart@noaa.gov
AF: NOAA, 439 West York Street, Norfolk, VA 23510, United States
AU: Foster, D S
EM: dfoster@usgs.gov
AF: USGS, 384 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Blackwood, D S
EM: dblackwood@usgs.gov
AF: USGS, 384 Woods Hole Road, Woods Hole, MA 02543, United States
AU: Butman, B
EM: bbutman@usgs.gov
AF: USGS, 384 Woods Hole Road, Woods Hole, MA 02543, United States
AB: Continuous-coverage multibeam bathymetric models and sidescan sonar imagery, verified with bottom sampling and photography, provide 1) detailed basemaps that yield topographic and geological perspectives of the sea floor, 2) a fundamental framework for research and management activities, and 3) information on sedimentary environments and processes. Interpretations presented here are based on NOAA hydrographic survey H11076 that covers approximately 23 sq. km around Quicks Hole, a major passage through the Elizabeth Islands chain, offshore southeastern Massachusetts. Bouldery gravels overgrown with seaweed and sessile fauna dominate the sea floor in Quicks Hole, along shorelines, and on isolated bathymetric highs. These deposits, which reflect environments of erosion and nondeposition, are winnowed lags of till from the exposed Buzzards Bay moraine. The sea floor south of the Hole in Vineyard Sound is characterized by environments associated with coarse bedload transport and covered with transverse and barchanoid sand waves. Transverse waves exceed 7 m in amplitude, have slip faces predominantly oriented to the west and southwest, and have straight, slightly sinuous, or curved crests. Megaripples, which mimic asymmetry of the transverse waves but not necessarily their orientation, are commonly present on stoss slopes; current ripples are ubiquitous. These smaller bedforms suggest that transport is active and that sand waves are propagating under the present hydraulic regime. Net sediment transport is primarily to the west and southwest as evidenced by comparisons with data from an earlier hydrographic survey, orientation of barchanoid waves, and asymmetry of transverse waves and of scour marks around boulders and shipwrecks. The sea floor across the northern part of the study area in Buzzards Bay and away from the opening to Quicks Hole is more protected from wind- and tidally-driven currents. Environments here are primarily characterized by processes associated with sorting or reworking. Faint current ripples and biologically induced resuspension reflect these processes. Crabs, whelk, and shell debris are locally common. The sea floor north of Nashawena Island and in small patches in the lee of nearby isolated bathymetric highs is characterized by low backscatter, a flat undulating appearance, and predominant long-term deposition. In these areas clayey silt accumulates in low-energy environments, and amphipod and polychaete tubes, shrimp burrows, and snail and crab tracks are common.
UR: http:pubs.usgs.gov/of/2006/1357/
DE: 3002 Continental shelf and slope processes (4219)
DE: 3022 Marine sediments: processes and transport
DE: 3045 Seafloor morphology, geology, and geophysics
SC: Ocean Sciences [OS]
MN: 2007 Joint Assembly