TORONTOTORONTO Vol. 8, No. 4 April 1998 Call for Papers GSA TODAY — page C1 A Publication of the Geological Society of America Electronic Abstracts Submission — page C3 Antarctic Neogene Landscapes—In the 1998 Registration Refrigerator or in the Deep Freeze? Annual Issue Meeting — June GSA Today Introduction The present Molly F. Miller, Department of Geology, Box 117-B, Vanderbilt Antarctic landscape undergoes very University, Nashville, TN 37235, [email protected] slow environmental change because it is almost entirely covered by a thick, slow-moving ice sheet and thus effectively locked in a Mark C. G. Mabin, Department of Tropical Environmental Studies deep freeze. The ice sheet–landscape system is essentially stable, and Geography, James Cook University, Townsville, Queensland 4811, Australia, [email protected] Antarctic—Introduction continued on p. 2 Atmospheric Transport of Diatoms in the Antarctic Sirius Group: Pliocene Deep Freeze Arjen P. Stroeven, Department of Quaternary Research, Stockholm University, S-106 91 Stockholm, Sweden Lloyd H. Burckle, Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY 10964 Johan Kleman, Department of Physical Geography, Stockholm University, S-106, 91 Stockholm, Sweden Michael L. Prentice, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH 03824 INTRODUCTION How did young diatoms (including some with ranges from the Pliocene to the Pleistocene) get into the Sirius Group on the slopes of the Transantarctic Mountains? Dynamicists argue for emplacement by a wet-based ice sheet that advanced across East Antarctica and the Transantarctic Mountains after flooding of interior basins by relatively warm marine waters [2 to 5 °C according to Webb and Harwood (1991)]. However, those calling for relative ice-sheet stability since the Miocene have interpreted these diatoms as wind transported (e.g., Denton et al., 1991). Pliocene Deep Freeze continued on p. 4 Glacial Transport of Diatoms in the Antarctic Sirius Group: Pliocene Refrigerator David M. Harwood, Department of Geosciences, University of Nebraska—Lincoln, Lincoln, NE 68588 Peter-N. Webb, Department of Geological Sciences and, Byrd Polar Research Center, Ohio State University, Columbus, OH 43210 INTRODUCTION Figure 1. Oliver Bluffs in the Dominion Range at lat 85°S and 1760 m above sea level. The outcrop of the Meyer Desert Formation is fresh, trimmed by The use of marine diatoms to date the Sirius Group (Fig. 1) is the most recent advance of the Beardmore Glacier (Denton et al., 1989), a focal point of the debate on Neogene Antarctic glacial history. and is eroding. The sequence of the Meyer Desert Formation at Oliver Bluffs The Pliocene age of the diatoms is not disputed, as diatom bios- comprises ~80 m of interbedded diamictite and laminated mudstone, with tratigraphy is well established for this region (Harwood and minor peat and marl, which represent glacial, fluvial, lacustrine, and marsh or swamp environments that accumulated near sea level and were subsequently uplifted at least 1300 m (Webb et al., 1996). Photo by P.-N. Webb. Pliocene Refrigerator continued on p. 4 GSA TODAY April IN THIS ISSUE Vol. 8, No. 4 1998 Antarctic Neogene Landscapes— Center Section — TORONTO In the Refrigerator or in Preliminary Announcement for the GSA TODAY (ISSN 1052-5173) is published monthly the Deep Freeze? .................... 1 1998 GSA Annual Meeting ........... C1 by The Geological Society of America, Inc., with offices at 3300 Penrose Place, Boulder, Colorado. Mailing address: P.O. 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Written permission is required from GSA for all other debate—how to interpret evidence for the forms of capture, reproduction, and/or distribution of any and the preserved terrestrial record of age of these dynamic glacial deposits item in this publication by any means, including posting on authors’ or organizational Web sites, except that permission Quaternary glaciations suggests a cold based on interpretation of the apparently is granted to authors to post the abstracts only of their sci- polar ice sheet that expanded and con- age-diagnostic diatoms that they contain. ence articles on their own or their organization’s Web site tracted only modestly compared to providing the posting includes this reference: “The full paper was published in the Geological Society of America’s news- the much more spectacular comings and STABILIST VIEW magazine, GSA Today, [include year, month, and page num- goings of the great Northern Hemisphere Strong evidence supporting the sta- ber if known, where article appears or will appear].” GSA ice sheets. Over the past 15 years, glacial provides this and other forums for the presentation of bilist interpretation of a Miocene switch geologists and others have focused atten- diverse opinions and positions by scientists worldwide, from warm, dynamic ice sheet to cold, regardless of their race, citizenship, gender, religion, or polit- tion on older pre-Quaternary glacial stable ice sheet comes from features at ical viewpoint. Opinions presented in this publication do not deposits (Sirius Group) in the Trans- reflect official positions of the Society. high elevations in the Dry Valleys. There, antarctic Mountains that give tantalizing unconsolidated, unweathered, and un- SUBSCRIPTIONS for 1998 calendar year: Society glimpses of a much more dynamic Antarc- eroded ash beds within a few centimeters Members: GSA Today is provided as part of membership tic ice sheet that existed before the present dues. 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