During the late Neogene, the Lambert Glacier-Amery Ice Shelf drainage system flowed across Prydz Bay in an ice stream that reached the shelf edge and built a trough mouth fan on the upper continental slope. The adjacent banks saw mostly subglacial till deposition beneath slower-moving ice. The fan consists mostly of debris flow deposits derived from the melting out of subglacial debris at the grounding line at the continental shelf edge. Thick debris flow intervals are separated by thin mudstone horizons deposited when the ice had retreated from the shelf edge. Age control at Ocean Drilling Program Site 1167 indicates that the bulk of the trough mouth fan was deposited prior to ~780 ka with as few as three debris flow intervals deposited since then. This stratigraphy indicates that extreme advances of the Lambert Glacier-Amery Ice Shelf system ceased during the mid-Pleistocene. Possible causes for this change are progressive over-deepening of the inner shelf, a reduction in maximum ice volumes in the interior of the East Antarctic Ice Sheet caused by temperature change, and a change in the interaction of Milankovich cycles and the response time of the ice sheet.
1O’Brien, P.E., Cooper, A.K., Florindo, F., Handwerger, D.A., Lavelle, M., Passchier, S., Pospichal, J.J., Quilty, P.G., Richter, C., Theissen, K.M., and Whitehead, J.M., 2004. Prydz Channel Fan and the history of extreme ice advances in Prydz Bay. In Cooper, A.K., O’Brien, P.E., and Richter, C. (Eds.), Proc. ODP, Sci. Results, 188 [Online]. Available from World Wide Web: <http://www-odp.tamu.edu/publications/188_SR/016/016.htm>. [Cited YYYY-MM-DD]
2Geoscience Australia, GPO Box 378, Canberra ACT 2904, Australia. phil.obrien@agso.gov.au
3Department of Geological and Environmental Sciences, Stanford University, Building 320, Room 118, Stanford CA 94305, USA.
4Istituto Nazionale di Geofisica e Vulcanologia, Via di Vigna Murata 605, 00143 Rome, Italy.
5Department of Geology and Geophysics, University of Utah, 1460 East 135 South, Room 719, Salt Lake City UT 84105, USA.
6Geological Sciences, British Antarctic Survey, High Cross, Madingley Road, Cambridge CB3 OET, United Kingdom.
7NITG-TNO–National Geological Survey, Geo-Marine and Coast, PO Box 80015, 3508 TA Utrecht, The Netherlands.
8Department of Geology, Florida State University, Tallahassee FL 32306, USA.
9School of Earth Sciences, University of Tasmania, Sandy Bay Campus, GPO Box 252-79, Hobart TAS 7050, Australia.
10Department of Geology, University of Louisiana, PO Box 44530, Lafayette LA 70504-0002, USA.
11Department of Geosciences, University of Nebraska, 214 Bessy Hall, Lincoln NE 68588-0340, USA.
Initial
receipt: 30 May 2003
Acceptance: 28 April 2004
Web publication: 30 July 2004
Ms 188SR-016