HR: 0800h
AN: PP51F-1368    [Abstracts]
TI: Continental and Marine Climate Records from Chile and the Southeast Pacific: Joint Pollen, Oxygen Isotope, and Radiolaria Records from ODP Sites 1233 and 1234
AU: * Heusser, L
EM: heusser@ldeo.columbia.edu
AF: Lamont Doherty Earth Observatory, Rt. 9W, Palisades, NY 10965 United States
AU: Heusser, C
AF: New York University, 100 Clinton Road, Tuxedo, NY 10987 United States
AU: McManus, J
EM: jmcmanus.whoi.edu
AF: Woods Hole Oceanographic Institution, Woods Hole, Woods Hole, MA 02543 United States
AU: Mix, A
EM: mix@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331 United States
AU: Pisias, N
EM: pisias@coas.oregonstate.edu
AF: College of Oceanic and Atmospheric Sciences, Oregon State University, Corvallis, OR 97331 United States
AB: Rapidly-deposited sediments (1-3m/kyr) from ODP Site 1233 (41ø0.005'S, 74ø26.992'W, 838m water depth) document millennial-scale changes in the response of Chilean plant communities to atmospheric circulation in the southeast Pacific over the past 60ka. Pollen data from the upper 95m of Site 1234 (36ø13.153'S, 73ø40.902'W) replicate and extend the terrestrial record through the last glacial cycle (MIS 1-MIS5e), thus providing the first record of vegetation and climate from the last interglacial in temperate South America. Both Sites monitor a major discontinuity in Chilean climate - the transition between northern semi-arid, summer dry-winter wet climate and southern year-round, rainy, cool temperate climate. Downcore changes in diagnostic pollen from xeric and mesic vegetation (Lowland Deciduous Beech forest, Valdivian Evergreen Forest, and Subantarctic Evergreen Forest and Parkland) reflect frequent latitudinal shifts of the southern westerlies during MIS 2 and MIS 3. During most of the last glacial, cool, mesic rainforests composed of evergreen beech (Nothofagus dombeyi) and conifers, such as the endangered Prumnopitys andina, characterized coastal Chile. Late Pleistocene, intervals of heavy rainfall and lower temperatures inferred from expansion of Subantarctic Parkland correspond with regional glacial events, and the structure and variability of southern Chilean vegetation and climate correspond with changes in marine surface waters offshore and in Antarctic ice core data. In the last 140,000 years, only during MIS 5e was vegetation of southern Chile similar to that of the Holocene. At the MIS 6/5e transition, coeval with the rapid shift to light isotopic values, glacial vegetation was rapidly replaced by plant communities associated with Mediterranean climate. An increased prominence of halophytic vegetation suggests that MIS 5e was more arid and possibly warmer than MIS 1. Lowland Deciduous Beech Forest (N. obliqua) extended well into the interval of ice growth of MIS 5d, thus interglacial conditions in southern Chile were not synchronous with global ice volume.
DE: 9355 Pacific Ocean
DE: 9360 South America
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 1520 Magnetostratigraphy
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting