If you need an accessible version of this item please contact JSTOR User Support

Miocene Glacial Stratigraphy and Landscape Evolution of the Western Asgard Range, Antarctica

David R. Marchant, George H. Denton, David E. Sugden and Carl C. Swisher, III
Geografiska Annaler. Series A, Physical Geography
Vol. 75, No. 4, A Special Volume Arising from the Vega Symposium: The Case for a Stable East Antarctic Ice Sheet (1993), pp. 303-330
Published by: Wiley on behalf of the Swedish Society for Anthropology and Geography
DOI: 10.2307/521205
Stable URL: http://www.jstor.org/stable/521205
Page Count: 30
  • Download PDF
  • Cite this Item

You are not currently logged in.

Access your personal account or get JSTOR access through your library or other institution:

login

Log in to your personal account or through your institution.

If you need an accessible version of this item please contact JSTOR User Support
Miocene Glacial Stratigraphy and Landscape Evolution of the Western Asgard Range, Antarctica
Preview not available

Abstract

40Ar/39Ar dated in-situ volcanic ashfall deposits indicate that the surficial stratigraphy of the western Asgard Range in the Dry Valleys region extends back at least to 15.0 Ma. The preservation of Miocene and Pliocene colluvium and drift on valley slopes shows that major bedrock landforms are relict and that little slope evolution has occurred during the last 15.0 Ma. Major bedrock landforms can be compared directly with buttes, mesas, box canyons, and escarpments of platform deserts. Although glaciers played a role in shaping the present topography of the western Asgard Range, the main landforms were probably cut by progressive scarp retreat, propagation of embayments with theater-shaped heads, and isolation of buttes and mesas prior to 15.0 Ma. We also recognize a phase of wet-based alpine glacier expansion in theater-headed embayments prior to 15.0 Ma ago, along with a late-Miocene phase of northeast-flowing ice-sheet overriding between 14.8/ 15.2 Ma and 13.6 Ma. However, there is no evidence for notable glacier expansion during the last 13.6 Ma. Instead, in-situ ashfall deposits indicate persistent hyper-arid, cold-desert conditions with only minor advance (less than 2.5 km) of rock glaciers and glacierets at valley heads. Our results are consistent with Pliocene stability rather than meltdown of the adjacent East Antarctic Ice Sheet.

Page Thumbnails

  • Thumbnail: Page 
303
    303
  • Thumbnail: Page 
304
    304
  • Thumbnail: Page 
305
    305
  • Thumbnail: Page 
306
    306
  • Thumbnail: Page 
307
    307
  • Thumbnail: Page 
308
    308
  • Thumbnail: Page 
309
    309
  • Thumbnail: Page 
310
    310
  • Thumbnail: Page 
311
    311
  • Thumbnail: Page 
312
    312
  • Thumbnail: Page 
313
    313
  • Thumbnail: Page 
314
    314
  • Thumbnail: Page 
315
    315
  • Thumbnail: Page 
316
    316
  • Thumbnail: Page 
317
    317
  • Thumbnail: Page 
318
    318
  • Thumbnail: Page 
319
    319
  • Thumbnail: Page 
320
    320
  • Thumbnail: Page 
321
    321
  • Thumbnail: Page 
322
    322
  • Thumbnail: Page 
323
    323
  • Thumbnail: Page 
324
    324
  • Thumbnail: Page 
325
    325
  • Thumbnail: Page 
326
    326
  • Thumbnail: Page 
327
    327
  • Thumbnail: Page 
328
    328
  • Thumbnail: Page 
329
    329
  • Thumbnail: Page 
330
    330
  • Thumbnail: Page 
[unnumbered]
    [unnumbered]
  • Thumbnail: Page 
[unnumbered]
    [unnumbered]