HR: 0800h
AN: C51A-0085    [Abstracts]
TI: Evidence for Northern Hemisphere Glaciation Back to 44 Ma From Ice-Rafted Debris in the Greenland Sea
AU: Shorttle, O
EM: os258@cam.ac.uk
AF: University of Cambridge, Downing Street, Cambridge, Cam CB2 3EQ, United Kingdom
AU: * Tripati, A
EM: atri02@esc.cam.ac.uk
AF: University of Cambridge, Downing Street, Cambridge, Cam CB2 3EQ, United Kingdom
AU: Eagle, R A
EM: rae28@cam.ac.uk
AF: University of Cambridge, Downing Street, Cambridge, Cam CB2 3EQ, United Kingdom
AU: Dawber, C
EM: cfd25@esc.cam.ac.uk
AF: University of Cambridge, Downing Street, Cambridge, Cam CB2 3EQ, United Kingdom
AU: Morton, A
EM: a.c.morton@heavyminerals.fsnet.co.uk
AF: CASP, 181A Huntingdon Road, Cambridge, Cam CB3 ODH, United Kingdom
AU: Dowdeswell, J
EM: jd16@cam.ac.uk
AF: University of Cambridge, Downing Street, Cambridge, Cam CB2 3EQ, United Kingdom
AU: Atkinson, K
EM: ka298@cam.ac.uk
AF: University of Cambridge, Downing Street, Cambridge, Cam CB2 3EQ, United Kingdom
AU: Bahe, Y
EM: yannick.bahe@gmx.de
AF: University of Cambridge, Downing Street, Cambridge, Cam CB2 3EQ, United Kingdom
AU: Shaw, R
EM: kincsem@ntlworld.com
AF: University of Cambridge, Downing Street, Cambridge, Cam CB2 3EQ, United Kingdom
AU: Thanabalasundaram, L
EM: Lavaniya_89@yahoo.de
AF: University of Cambridge, Downing Street, Cambridge, Cam CB2 3EQ, United Kingdom
AU: Khadun, E
EM: nutemma@hotmail.com
AF: University of Cambridge, Downing Street, Cambridge, Cam CB2 3EQ, United Kingdom
AB: The widely accepted age estimate for the onset of glaciation in the Northern Hemisphere ranges between 2 and 15 million years ago (Ma). However, recent studies indicate the date for N. Hemisphere glacial onset may be significantly older [1,2,3]. We report the presence of ice-rafted debris (IRD) in ~44 to 39 Ma sediments from the Greenland Sea, evidence for glaciation in the North Atlantic during the Middle Eocene to Late Eocene. We also have developed a high-resolution record of ice-rafting for the late Eocene through early Oligocene (39-30 Ma). Detailed sedimentological evidence indicates that glaciers extended to sea level in the region during part of the study interval, allowing icebergs to be produced. Peaks in IRD accumulation are observed at ~40-42 Ma, IRD may have been sourced from tidewater glaciers, small ice caps, and/or a continental ice sheet. Foraminiferal records from the deep Pacific show that several shifts in seawater δ¹⁸O of greater than 0.6‰ occurred during these intervals, consistent with the build-up of ice in both hemispheres [1,4]. [1] Tripati, A., Backman, J., Elderfield, H. and Ferretti, P. Eocene bipolar glaciation associated with global carbon cycle changes. Nature 436, 341–346 (2005). [2] Moran, K., Backman, J., Brinkhuis, H., Clemens, S.C., Cronin, T., Dickens, G.R., Eynaud, F., Gattacceca, J., Jakobsson, M., Jordan, R.W., Makinski, M., King, J., Koc, N., Krylov, A., Martinez, N., Matthiessen, J., McInroy, D., Moore, T.C., Onodera, J., O'Regan, M., Plike, H., Rea, B., Rio, D., Sakamoto, T., Smith, D.C., Stein, R., St. John, K., Suto, I., Suzuki, N., Takahashi, K., Watanabe, M., Yamamoto, M., Farrell, J., Frank, M., Kubik, P., Jokat, W., and Kristoffersen, Y., 2006, The Cenozoic palaeoenvironment of the Arctic Ocean, Nature, 441, 601–605. [3] Eldrett, J., Harding, I., Wilson, P., Butler, E. and Roberts, A., 2007, Continental ice in Greenland during the Eocene and Oligocene, Nature, 446, 176-179. [4] Dawber, C. and Tripati, A., 2007, Evidence for Early Cenozoic glaciation from a record of seawater δ¹⁸O at ODP Site 1209: Exploring the paradigm of an ‘ice-free' Middle Eocene, Fall AGU abstract.
DE: 1616 Climate variability (1635, 3305, 3309, 4215, 4513)
DE: 1621 Cryospheric change (0776)
DE: 1641 Sea level change (1222, 1225, 4556)
DE: 4926 Glacial
SC: Cryosphere [C]
MN: 2007 Fall Meeting