Antarctica A Keystone in a Changing World (2008) / Chapter Skim
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Landscape Evolution of Antarctica--S. S. R. Jamieson and D. E. Sugden
Landscape Evolution of Antarctica--S. S. R. Jamieson and D. E. Sugden
Pages 39-54
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From page 39... ...
Here we build a synthesis of ~13.5 Ma, offering potential for a long quantitative record Antarctic landscape evolution based on the geomorphology of of ice-sheet evolution with techniques such as cosmogenic passive continental margins and former northern mid-latitude isotope analysis. Pleistocene ice sheets.
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From page 40... ...
. The initial ~20 million years was marked by ice volume fluctuations breakup of Gondwana around most of East Antarctica took similar in scale to those of the Pleistocene ice sheets of the place between 160 Ma and 118 Ma.
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From page 41... ...
C G England Cape A Coastal piedmont 1396 Sperm Bluff N Roberts O M Main escarpment TT supercontinent far from the sea. The rifted margins would I I I II Miller Glacier trough Detour Nunatak 1120 C O Main valleys Gonville e have been subjected to fluvial processes related to the evolu- g and I I I Fault n Caius Range a 1670 I 1490 I I Main divide R I I M IL WILSO N I I tion of passive continental margins.
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From page 42... ...
Antarctic Evidence Such a conclusion is reinforced by investigation of the Figure 3 shows a reconstruction of the continental river pat- valley patterns on mountain areas rising above the present terns inferred to exist if the Antarctic ice sheet is removed and ice-sheet surface. Good examples of former fluvial valley the land compensated for isostatic depression by full flexural systems now occupied by local glaciers exist in the Transrebound.
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From page 43... ...
. to other sectors of East Antarctica without more detailed The floor of the southernmost Dry Valley, Taylor Valley, is evidence, but similar landscapes occur in the Shackleton below sea level toward the coast, where it is filled with over Range (Kerr and Hermichen, 1999)
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From page 44... ...
; rather than a few million, but there are important similari- Radial pattern of ice streams with beds tens of km ties in that the North American ice sheet was of similar size wide, streamlined bedforms in bedrock and drift, and sharply and volume as the Antarctic ice sheet, and in that both have defined boundaries (Stokes and Clark, 1999) ; and fluctuated in size in response to orbital forcing during their Radial pattern of meltwater flow crossing regional evolution, albeit to varying extents.
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From page 45... ...
. A B FIGURE 6 Model of the Antarctic ice sheet, generated using the GLIMMER 3-D thermomechanical model and the stepped transition from a Patagonian-style climate C D to the present polar climate.
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From page 46... ...
mountains, such as in Dronning Maud Land, along the Transantarctic Mountains, in the West Antarctic archipelago, and Antarctic Evidence in the high Gamburtsev Mountains in the interior. The ice spreads out from these mountain centers, first linking the The evidence of continental radial patterns of erosion is main East Antarctic centers and then the West Antarctic cen- spectacular.
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From page 47... ...
In the McMurdo Dry Valleys area parallel to Adelaide Island on the Antarctic Peninsula, have of the Transantarctic Mountains a phase of local glaciation is exploited the junction between basement and sedimentary represented by troughs identified on the inland flank of the rocks (Anderson, 1999)
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From page 48... ...
Flow in the the regional ice sheets are warm-based near their margins same direction under both local and continental modes will and inland to the vicinity of the equilibrium line where the favor elongated streamlined bedforms, perhaps with plucked B D Modeled Erosion Pattern Zero Max FIGURE 9 Modeled distribution of basal ice at the pressure melting point during intermediate and full stages of Antarctic glaciation (letters correspond to snapshots in Figure 6)
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From page 49... ...
Antarctica, such as the Amery Oasis bordering the Lambert Glacier (Hambrey et al., 2007) ; the Ross Sea area where CHRONOLOGY OF LANDSCAPE EVOLUTION the scouring is most prominent near sea level and can be traced to elevations of 1000-2100 m along the Transantarctic A number of dates help firm up the relative chronology of Mountains front (Denton and Sugden, 2005)
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From page 50... ...
. TABLE 1 The Chronology of Landscape Evolution in 3 He ages of individual dolerite clasts in meltwater Antarctica Based Mainly on Terrestrial Evidence deposits from the overriding ice sheet reveal exposure ages >55-34 Ma Passive continental margin erosion of coastal between 8.63 ± 0.09 and 10.40 ± 0.04 Ma.
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From page 51... ...
Outlet glaciers thicken and advance in a Patagonian-type climate, at least in the Transantarctic seaward in response to a lowering of sea level in the NorthMountains, and was centered on maritime mountains of East ern Hemisphere, as demonstrated in the case of the outlets and West Antarctica and high continental mountains in East flowing through the Transantarctic Mountains (Denton et Antarctica. The record from the Cape Roberts cores of fluctu- al., 1989)
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From page 52... ...
Synthesis. In Antarctic Cenozoic History from CIROS-1 Drillhole, the East Antarctic Ice Sheet.
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From page 53... ...
2005. Flow of the West Antarctic Ice tica: The relative role of rivers and ice sheets.
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From page 54... ...
R Raymond et al., USGS Open-File Report 2007-1047, Extended to glacial erosion within the Transantarctic Mountains.
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