Tuesday, 28 August 2007 - 3:40 PM
2.P2.A-1
Evidence for synchronous glaciation of Antarctica and the Northern Hemisphere during the Eocene and Oligocene: Insights from Pacific records of the oxygen isotopic composition of seawater
Aradhna K. Tripati1, C.F. Dawber1, P. Ferretti1, J. Backman2, H. Elderfield1, and H. Macintyre3. (1) Earth Sciences, University of Cambridge, Cambridge, CB2 3EQ, United Kingdom, (2) Geology and Geophysics, Stockholm University, Stockholm, Sweden, (3) University of Leeds, Leeds, United Kingdom
Constraints on Earth's glacial history come from the deep-sea oxygen isotope (d18O) record. The growth of Antarctic ice during the early Cenozoic is modelled to have driven changes in seawater d18O of up to 0.5‰ (DeConto & Pollard, 2003). Larger shifts in the mean d18O of seawater therefore require some storage of ice in both hemispheres. In order to study the evolution of the cryosphere, we developed high-resolution records of seawater d18O for three Pacific sites. The seawater d18O reconstructions show that several large (>0.65‰) shifts in seawater d18O occurred throughout the middle Eocene to early Oligocene. Our records of seawater d18O indicate there was ice stored on Antarctica and in the Northern Hemisphere at about 44.5 Ma, 42 Ma, 38 Ma, and after 34 Ma.