HR: 1340h
AN: PP43B-1262    [Abstracts]
TI: Late Glaciation to early Holocene records of climatic and vegetation changes from Onepoto Crater, Auckland New Zealand: a biomarker and isotopic approach
AU: * Sikes, E L
EM: sikes@marine.rutgers.edu
AF: Marine Sciences Rutgers University, 71 Dudley Rd, New Brunswick, NJ 08901, United States
AU: Medeiros, P M
EM: medeiros@marine.rutgers.edu
AF: Marine Sciences Rutgers University, 71 Dudley Rd, New Brunswick, NJ 08901, United States
AU: Makou, M C
EM: makou.1@osu.edu
AF: Marine Sciences Rutgers University, 71 Dudley Rd, New Brunswick, NJ 08901, United States
AU: Augustinas, P
EM: p.augustinus@auckland.ac.nz
AF: Department of Geology University of Auckland, Private Bag 92019, Auckland, 1003, New Zealand
AB: A core taken from Onepoto Crater, a maar lake from the Auckland region of New Zealand, has excellent stratigraphy and robust age control based on well-dated and chemically distinguishable fallout tephra from the Taupo Volcanic Zone (TVZ). We present here a multi-proxy record including biomarkers and compound-specific isotopes on fatty acids that document ecological and climatological changes from the last glaciation to the early Holocene in northern New Zealand. All proxies indicate a drier and cooler climate in the glaciation followed by a rapid shift to warmer and wetter conditions at 17.6 ka that persisted until the early Holocene. The inferred arid conditions in the early part of the record are supported by markers such as charcoal abundances, but charcoal is absent after the climatic shift at 17.6 ka. New records of biomarkers and compound-specific isotopes on fatty acids from Onepoto Crater clarify changes in aridity associated with the glacial to interglacial climate shift documented by other proxies such as charcoal and pollen. Elevated abundances of marker lipids derived from biomass burning, such as dehydroabietic acid (a proxy for forest fires and by implication, aridity) and decreased ¹³C in terrestrially derived fatty acids indicate a return to somewhat dryer conditions during the Antarctic Cold Reversal (ACR) not present in other proxy records. The biomarker and isotopic data suggest drier conditions in the ACR that were not as intense as in the glaciation and remain unresolved by other proxies.
DE: 1041 Stable isotope geochemistry (0454, 4870)
DE: 1055 Organic and biogenic geochemistry
DE: 4914 Continental climate records
DE: 4942 Limnology (0458, 1845, 4239)
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2007 Fall Meeting