Angwenyi, Clive

Armstrong, Andy

Calder, Brian R.

Gardner, James V.

Karlapati, Srinivas

Malik, Mashkoor A.

Mayer, Larry A.

Montoro, Hugo

Morishita, Taisei

Mustapha, Abubakar

English

UNH Scholars' Repository

University of New HampshireUniversity of New Hampshire Scholars' RepositoryCenter for Coastal and Ocean Mapping Center for Coastal and Ocean Mapping2005New Views of the Gulf of Alaska Margin Mappedfor UNCLOS ApplicationsLarry A. MayerUniversity of New Hampshire, larry.mayer@unh.eduJames V. GardnerUniversity of New Hampshire, Durham, jim.gardner@unh.eduAndy ArmstrongUniversity of New Hampshire, DurhamBrian R. CalderUniversity of New Hampshire, Durham, brian.calder@unh.eduMashkoor A. MalikUniversity of New HampshireSee next page for additional authorsFollow this and additional works at: https://scholars.unh.edu/ccomPart of the Oceanography and Atmospheric Sciences and Meteorology CommonsThis Report is brought to you for free and open access by the Center for Coastal and Ocean Mapping at University of New Hampshire Scholars'Repository. It has been accepted for inclusion in Center for Coastal and Ocean Mapping by an authorized administrator of University of NewHampshire Scholars' Repository. For more information, please contact nicole.hentz@unh.edu.Recommended CitationMayer, Larry A.; Gardner, James V.; Armstrong, Andy; Calder, Brian R.; Malik, Mashkoor A.; Angwenyi, Clive; Karlapati, Srinivas;Montoro, Hugo; Morishita, Taisei; and Mustapha, Abubakar, "New Views of the Gulf of Alaska Margin Mapped for UNCLOSApplications" (2005). Center for Coastal and Ocean Mapping. 1269.https://scholars.unh.edu/ccom/1269AuthorsLarry A. Mayer, James V. Gardner, Andy Armstrong, Brian R. Calder, Mashkoor A. Malik, Clive Angwenyi,Srinivas Karlapati, Hugo Montoro, Taisei Morishita, and Abubakar MustaphaThis report is available at University of New Hampshire Scholars' Repository: https://scholars.unh.edu/ccom/1269New Views of the Gulf of Alaska Margin Mapped for UNCLOS Applications. Larry A. Mayer, James V. Gardner, Andy Armstrong, Brian R. Calder, Mashkoor Malik, Clive Angwenyi , Srinivas Karlipata, Hugo Montoro-Dantes, Taisei Morishita, and Abubakar Mustapha , University of New Hampshire, Durham, NH Mark Van Waes and Doug Wood, NOAA, Silver Spring, MD Anthony Withers, Royal Australian Navy, Woollongong, NSW, Australia   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. 

New Views of the Gulf of Alaska Margin Mapped for UNCLOS Applications

https://scholars.unh.edu/cgi/viewcontent.cgi?article=2269&amp;context=ccom

New Views of the Gulf of Alaska Margin Mapped for UNCLOS Applications

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