HR: 1340h
AN: T13D-0500 [Abstracts]
TI: New Views of the Gulf of Alaska Margin Mapped for UNCLOS Applications
AU: * Mayer, L A
EM: larry.mayer@unh.edu
AF: University of New Hampshire, 24 Colovos Road, Durham, NH 03824
United States
AU: Gardner, J V
EM: jim.gardner@unh.edu
AF: University of New Hampshire, 24 Colovos Road, Durham, NH 03824
United States
AU: Armstrong, A
EM: andy.armstrong@noaa.gov
AF: National Oceanic and Atmospheric Administration, 1325 East West Highway, Silver Spring, MD 20910
United States
AU: Calder, B R
EM: brc@ccom.unh.edu
AF: University of New Hampshire, 24 Colovos Road, Durham, NH 03824
United States
AU: Malik, M
EM: mamalik@cisunix.unh.edu
AF: University of New Hampshire, 24 Colovos Road, Durham, NH 03824
United States
AU: Angwenyi, C
EM: clive@ccom.unh.edu
AF: University of New Hampshire, 24 Colovos Road, Durham, NH 03824
United States
AU: karlpata, S
EM: srinivas@ccom.unh.edu
AF: University of New Hampshire, 24 Colovos Road, Durham, NH 03824
United States
AU: Montoro-Dantes, H
EM: hugo@ccom.unh.edu
AF: University of New Hampshire, 24 Colovos Road, Durham, NH 03824
United States
AU: Morishita, T
EM: taisei@ccom.unh.edu
AF: University of New Hampshire, 24 Colovos Road, Durham, NH 03824
United States
AU: Mustapha, A
EM: abu@ccom.unh.edu
AF: University of New Hampshire, 24 Colovos Road, Durham, NH 03824
United States
AU: van Waes, M
EM: mark.vanwaes@noaa.gov
AF: National Oceanic and Atmospheric Administration, 1325 East West Highway, Silver Spring, MD 20910
United States
AU: Wood, D
EM: doug.wood@noaa.gov
AF: National Oceanic and Atmospheric Administration, 1325 East West Highway, Silver Spring, MD 20910
United States
AU: Withers, A
EM: tony@ccom.unh.edu
AF: Royal Australian Navy, 1 HIgh Street, Woollongong, NSW 2005
Australia
AB:
Article 76 of the UN Convention on the Law of the Sea (UNCLOS) outlines a series of criteria that may allow a coastal state
to extend its legal jurisdiction beyond the EEZ. The mapping required to support an UNCLOS submission generates datasets
useful to a wide spectrum of disciplines; the new maps will provide a new framework for the next generation of
continental-margin studies.
As part of an ongoing U.S. UNCLOS effort, >162,000 km2 of the Gulf of Alaska (GOA) margin between the 1 and 4.5 km isobaths
was mapped in 2005 with a 12-kHz multibeam echosounder (MBES) that provides bathymetry and co-registered backscatter. The
data have a spatial resolution of 100 m.
The north and east GOA shelf is truncated by the strike-slip Queen Charlotte-Fairweather and Transition Faults. The margin is
draped by overlapping submarine-fans e modified by incised channel-levee systems. The Baranof Fan is composed of several
fans. The southern-most mapped fan is a small feature from which springs the upper reaches of Mukluk Channel. Horizon
channel-levee complex traverses SW across the margin. The two channels meet ~80 km down slope at a 90? junction where Mukluk
Channel is captured by Horizon Channel. Chatham Fan covers more than 3000 km2 and is incised by an unnamed meandering
channel and built by an associated levee complex. The levee is incised by a meandering channel-levee complex. The sediments
of this fan have high backscatter. Vast zones of rotational sliding occupy the northern flanks of the levees. The slides
typically are retrogressive and shear-dominated with limited down slope movement.
The next fan complex to the north, Kruzofi fan, buries more than 7500 km2 of the margin. This fan developed between the levee
of Chatham fan and a curving depositional ridge. Gravity data implies that this ridge may be structurally controlled. The
growth of Kruzofi fan to the east appears to have been so rapid that the channels have been deflected to the NW so that they
trend sub-parallel to the margin for 60 km or more.
The margin west of 137?30'W, where the shelf is broader, lacks distinct large fan complexes and is offset by the Transition
Fault. Sediment is delivered to the abyssal plain through the main branch of the Surveyor Submarine Channel, an incised
branch whose origin is near the Alsek Valley, off the Alsek River. A branch of Surveyor Channel has its origin off Yakutat
but does not connect to the Yakutat Valley, suggesting that this branch may be inactive or that the style of sediment
bypassing in this region is different than for the main branch. Both branches run relatively straight; the main western
branch captures the eastern branch approximately 200 km from the shelf break and runs towards the Aleutian Trench.
In addition to the remarkable depiction of sediment delivery processes in the Gulf of Alaska, the survey also mapped several
exposed and buried seamounts, north of, but not parallel to, the Pratt-Welker seamount chain.
All data MBES data collected by the University of New Hampshire as well as derivative maps and images are publicly available
at http://www.ccom.unh.edu/unclos/html/index.htm within about a month of the completion of each cruise. The MBES data are in
three formats (ASCII xyz, SD and ESRI grid) so that they can easily be used in a wide variety of GIS packages.
DE: 8104 Continental margins: convergent
DE: 8106 Continental margins: transform
DE: 8175 Tectonics and landscape evolution
DE: 9355 Pacific Ocean
SC: Tectonophysics [T]
MN: Fall Meeting 2005