HR: 1340h
AN: PP33B-1276    [Abstracts]
TI: 10Be Surface-Exposure Chronology of Moraines Deposited During the Last Glacial Maximum in the New Zealand Southern Alps
AU: * Putnam, A
EM: aaron.putnam@umit.maine.edu
AF: Department of Earth Sciences - University of Maine, 228 Bryand Global Sciences Ctr, Orono, ME 04473, United States
AU: Schaefer, J
EM: schaefer@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964, United States
AU: Doughty, A
EM: alice.doughty@umit.maine.edu
AF: Department of Earth Sciences - University of Maine, 228 Bryand Global Sciences Ctr, Orono, ME 04473, United States
AU: Denton, G
EM: gdenton@maine.edu
AF: Department of Earth Sciences - University of Maine, 228 Bryand Global Sciences Ctr, Orono, ME 04473, United States
AU: Kaplan, M
EM: kaplan@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964, United States
AU: Andersen, B
EM: aaron.putnam@umit.maine.edu
AF: University of Oslo, Guiv. 74, Heggedal, 1384, Norway
AU: Barrell, D
EM: d.barrell@gns.cri.nz
AF: GNS Science, 764 Cumberland Street, Dunedin, 1000, New Zealand
AU: Finkel, R
EM: rfinkel@llnl.gov
AF: Lawrence Livermore National Laboratory, P.O. Box 808, L-206, Livermore, CA 94550, United States
AU: Schwartz, R
EM: roseanne@ldeo.columbia.edu
AF: Lamont-Doherty Earth Observatory, 61 Route 9W, Palisades, NY 10964, United States
AB: Timing, amplitude and driving mechanisms of the Last Glacial Maximum (LGM) remain still controversial due to scarcity of well-dated and reliable records from extra-polar areas in general, and from the Southern Hemisphere in particular. We present a new LGM glacier reconstruction based on more than 100 ¹⁰Be surface-exposure ages of moraine boulders from the New Zealand Southern Alps. High precision and internal consistency characterize data sets from two key basins, which indicate that maximum ice extent was achieved more than 10 ky prior the termination of the LGM. Glacial conditions persisted throughout the LGM in New Zealand's Southern Alps, despite rapidly rising local insolation at that time. The palaeosnowline estimates of Porter (1975), taken together with data from this study, suggest that snowlines were between ~875 and ~750 m lower during the LGM. This glacial record exhibits a tight correspondence in timing and duration to LGM cooling as shown by South Island pollen stratigraphy, temperature and carbon dioxide signatures from Antarctic ice cores, global sea-level reconstructions, and chronologies of mountain glacier activity from both polar hemispheres. The striking agreement among these records suggests that a global mechanism drove glacial activity in the Southern Alps during the LGM, and that insolation cannot be the main driving force.
DE: 1105 Quaternary geochronology
DE: 1130 Geomorphological geochronology
DE: 1150 Cosmogenic-nuclide exposure dating (4918)
DE: 1620 Climate dynamics (0429, 3309)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting