Thursday, 30 August 2007 - 12:10 PM
4.A.A-7
Late Miocene volcanism and glaciation at Minna Bluff, Antarctica
Thomas I. Wilch1, William C. McIntosh2, John L. Smellie3, Nelia W. Dunbar2, Andrew Fargo2, Mary K. Scanlan4, Paul D. Roberts1, and Kurt S. Panter5. (1) Department of Geological Sciences, Albion College, Albion, MI 49224, (2) Department of Earth and Environmental Sciences, New Mexico Tech, 801 Leroy Pl, Socorro, NM 87801, (3) Geological Sciences Division, British Antarctic Survey, High Cross, Madingley Road, Cambridge, CB3 0ET, United Kingdom, (4) Department of Geology, Bowling Green State University, 190 Overman Hall, Bowling Green, OH 43403, (5) Geology, Bowling Green State University, 190 Overman Hall, Bowling Green, OH 43403-0218
Well-exposed stratigraphic sections at Minna Bluff in the Ross Embayment provide records of ~11-7 Ma volcanism, glacial erosion, and glacial deposition. Stratigraphic alternations between rocks erupted in subaerial and subaqueous conditions are interpreted as syneruptive interactions between lava flows and a local ice cap. Widespread, undulating unconformities mantled by glacial and fluvial sediments exposed near the base of the sequences may indicate broader scale Ross Ice Sheet events. Ongoing geochronology, geochemistry, and lithofacies analysis will provide a more detailed glacial and volcanic record.
Minna Bluff is a significant topographic barrier that has effectively blocked the Ross Ice Shelf and the former Ross Sea Ice Sheet from flowing southward into McMurdo Sound. Documenting the timing of blockage of ice flow is critical for reconstructing past behavior of the Ross Ice Shelf/Ice Sheet and for interpreting the ANDRILL cores.