HR: 1330h
AN: PP32A-0278    [PDF]
TI: Marine Isotopic Stage 5e in the Southwest Pacific: Similarities with Antarctica and ENSO Inferences
AU: * Pelejero, C
EM: Carles.Pelejero@anu.edu.au
AF: Earth Environment, Research School of Earth Sciences, The Australian National University, Mills Rd., Canberra, ACT 0200 Australia
AU: * Pelejero, C
EM: Carles.Pelejero@anu.edu.au
AF: Petroleum and Marine Division, Geoscience Australia, GPO Box 378, Canberra, ACT 2601 Australia
AU: Calvo, E
EM: Eva.Calvo@anu.edu.au
AF: Earth Environment, Research School of Earth Sciences, The Australian National University, Mills Rd., Canberra, ACT 0200 Australia
AU: Calvo, E
EM: Eva.Calvo@anu.edu.au
AF: Petroleum and Marine Division, Geoscience Australia, GPO Box 378, Canberra, ACT 2601 Australia
AU: Logan, G A
EM: graham.logan@ga.gov.au
AF: Petroleum and Marine Division, Geoscience Australia, GPO Box 378, Canberra, ACT 2601 Australia
AU: De Deckker, P
EM: patrick.dedeckker@anu.edu.au
AF: Department of Geology, The Australian National University, The Australian National University, Canberra, ACT 0200 Australia
AB: Here we present a detailed record of alkenone-derived sea surface temperature (SST) offshore western New Zealand (Core SO136-GC3; $42\deg$18'S, $169\deg$53'E, 958m water depth), covering the penultimate deglaciation and last interglacial. We focus on Marine Isotopic Stage 5e, which is characterized by three main singular features: first, maxima SSTs (18.5 to $19.5\deg$C) are 3.5 to $4.5\deg$C higher than today for the studied site. Second, surface warming peaked about 4.5 kyr ahead of the ice volume interglacial minimum recorded by planktonic foraminifera oxygen isotopes. And third, the decline of temperatures towards Stage 5d started earlier than ice volume minimum, leaving a mean duration for the whole warm stage of only about 5 kyr. These features of Stage 5e off New Zealand exhibit striking similarities to the record of air temperatures at Vostok, Antarctica. In addition, changes in latitudinal SST gradients for the Southwest Pacific have also been assessed by SST comparison between our core and published SST data from a key equatorial core (ODP 806B; $0\deg$19.1'N, $159\deg$21.7'E, 2520m water depth). This comparison shows that a significantly lower thermal gradient characterized the austral western Pacific Ocean during the whole deglaciation and Stage 5e. In this region, low modern SST gradients usually parallel positive values of the Southern Oscillation Index and thus La Ni\~{n}a conditions. By inference, we suggest that our assessed low gradients might be indicative of a prevalence of La Ni\~{n}a conditions, particularly during early Stage 5e.
DE: 1620 Climate dynamics (3309)
DE: 3344 Paleoclimatology
DE: 4267 Paleoceanography
DE: 9355 Pacific Ocean
DE: 9604 Cenozoic
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting