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Reconstruction of LGM and Post LGM Glacial Environment of McMurdo Sound: Implications for Ice Dynamics, Depositional Systems and Glacial Isostatic Adjustment

Stutz, James Edward, II
http://rave.ohiolink.edu/etdc/view?acc_num=osu1324595182

Abstract Details

2012, Master of Science, Ohio State University, Geological Sciences.
McMurdo Sound represents a landscape at the crossroads of the West and East Antarctic Ice Sheets and has seen repeated occupation by both cold and warm based ice. Current ice sheet reconstructions place grounded ice across McMurdo Sound at the Last Glacial Maximum (LGM), thus the seafloor is expected to display morphologic features recording the LGM glaciation. Analysis of high-resolution multibeam bathymetry data and seismic surveys documents landforms marking glacial-geological processes beneath and at the margins of the ice sheets and are used to help determine the extent and style of glacial behavior on glacially influenced continental margins. The dominant morphologic features on the seafloor of McMurdo Sound are channel systems emanating eastward from the fjords of the Transantarctic Mountains (TAM) coast and northward from beneath the McMurdo Ice Shelf. A wide range of channel systems is observed. MacKay Sea Valley, at the northern limit of McMurdo Sound, displays a 6-8km wide, u-shaped valley with lineations formed by streaming ice of the expanded MacKay Glacier. A large submarine outwash fan extends 10’s of km eastward from the mouth of the sea valley. The Wilson and Taylor Sea Valleys cross and incise the western shelf and slope of McMurdo Sound, and show characteristics of sediment gravity flow transport and deposition. Wilson and Taylor Sea Valleys are .5-2km wide, do not contain features indicative of streaming ice, and appear to splay into numerous generations of fan systems at channel mouths. These channel/fan systems display cross-cutting relationships that record the changing position, over time, of the ice margin along the TAM coast. In the Erebus Basin, the ~north-south trending moat in eastern McMurdo Sound with depths >900 m, a continuous, broad, anastomosing channel system transports material derived from beneath the McMurdo Ice Shelf and/or the steep eastern slope of Ross Island along the axis of the Erebus basin. The dominance of channel systems indicates abundant water from ice margins, leading to sediment gravity flow depositional systems and large-scale sediment transport across the Sound and ultimately northward out of the Sound. Flat-topped mounds at ~500 mbsl in southeastern McMurdo Sound may represent subglacial erosion of preexisting features, placing a constraint on grounded ice limits. A prominent, linear escarpment is observed on the western slope at ~500mbsl and may record the waning ice sheet to ice shelf transition along the TAM coast during the waning phase of the LGM. Together these observations suggest that the McMurdo Ice Sheet was grounded throughout McMurdo Sound at the LGM and may have experienced a rapid break out at 11 and 10 ka BP, that restricted grounded ice to depths of <~500 meters. A new, integrated digital elevation model from Ross Island across McMurdo Sound and into the TAM reveals how seafloor features are connected to glacial features observed on land and provides a means to reconstruct regional ice thickness. Improved understanding of the LGM glacial record in McMurdo Sound provides a template for regional reconstructions of glacial behavior important for interpreting records from seismic data and sedimentary rock cores, for modeling of glacial isostatic adjustment.
Terry Wilson (Advisor)
Peter Webb (Committee Member)
Larry Krissek (Committee Member)
138 p.
Geological
Bathymetry; Antarctica; Ice Sheet; McMurdo; Glacial Geology

Recommended Citations

Citations

  • Stutz, II, J. E. (2012). Reconstruction of LGM and Post LGM Glacial Environment of McMurdo Sound: Implications for Ice Dynamics, Depositional Systems and Glacial Isostatic Adjustment [Master's thesis, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1324595182

    APA Style (7th edition)

  • Stutz, II, James. Reconstruction of LGM and Post LGM Glacial Environment of McMurdo Sound: Implications for Ice Dynamics, Depositional Systems and Glacial Isostatic Adjustment. 2012. Ohio State University, Master's thesis. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1324595182.

    MLA Style (8th edition)

  • Stutz, II, James. "Reconstruction of LGM and Post LGM Glacial Environment of McMurdo Sound: Implications for Ice Dynamics, Depositional Systems and Glacial Isostatic Adjustment." Master's thesis, Ohio State University, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=osu1324595182

    Chicago Manual of Style (17th edition)

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© 2012, all rights reserved.
This open access ETD is published by The Ohio State University and OhioLINK.