Paper No. 257-14
Presentation Time: 5:00 PM
CLIMATIC AND OCEANOGRAPHIC CONDITIONS IN THE GULF OF PAPUA, PAPUA NEW GUINEA, DURING THE BøLLING-ALLERøD, YOUNGER DRYAS, AND MELTWATER PULSE-1B: A PALYNOLOGICAL ANALYSIS
THOMAS, Marie Louise, Hess Corporation, 1501 McKinney Street, Houston, TX 77010; Department of Geology & Geophysics, Louisiana State University, E235 Howe-Russell Geoscience Complex, Baton Rouge, LA 70803, WARNY, Sophie, Department of Geology and Geophysics, and Museum of Natural Science Baton Rouge, USA, Louisiana State University, E235 Howe-Russell Geoscience Complex, Baton Rouge, LA 70803, BENTLEY, Samuel J., Department of Geology & Geophysics, Louisiana State University, Baton Rouge, LA 70803; Coastal Studies Institute, Louisiana State University, Baton Rouge, LA 70803, JARZEN, David M., Paleobotany and Paleoecology, Cleveland Museum of Natural History, 1 Wade Oval Drive, University Circle, Cleveland, OH 44106, DROXLER, André W., Earth Science, Rice University, 6100 Main Street, Houston, TX 77005, HOWELL, Ashley L., Department of Geology & Geophysics, Louisiana State University, E235 Howe-Russell Geoscience Complex, Baton Rouge, LA 70803, HARPER, Brandon B., Earth Science, Rice University, 6100 Main Street, MS-126, Houston, TX 77005, NITTROUER, Charles, School of Oceanography, University of Washington, Box 357940, Seattle, WA 98195 and XU, Kehui, Department of Oceanography and Coastal Science, Louisiana State University, 2165 Energy, Coast and Environment Building, Baton Rouge, LA 70803, marthomas@hess.com
In an effort to better understand climatic, oceanographic, and sedimentological changes in the Gulf of Papua (GoP) over the last 14.5 kyr, palynological analysis was performed on three sediment cores (MV-41, MV-46, and MD-50). These cores were collected on cruises conducted by the MARGINS S2S (Source-to-Sink) and the PECTEN (Past Equatorial Climate: Tracking El Niño) initiatives. Samples were collected from each core at approximately 50 cm intervals and were processed using a hydrochloric acid, hydrofluoric acid, and controlled oxidation (MD-50)/non-oxidant (MV-41, MV-46) procedure. The cores underwent several analyses:
14C geochronology, magnetic susceptibility, stable isotope analysis (
18O and
13C; MD-50 only), and clay mineral maturity analysis.
Changes in palynomorph assemblages provided data on the climatic regimes that characterized Papua New Guinea (PNG) during the Bølling-Allerød Interstadial (14.5 to 12.5 kyr BP), the Younger Dryas (12.5 to 11.5 kyr BP), Meltwater Pulse-1B (11.5 to 10.5 kyr BP), and the Holocene (10.5 kyr BP to present). The palynological data showed that the climate remained tropical for the past 14.5 kyr and that summer sea-surface temperature remained above 11.5º C, even during the Younger Dryas, although a reduced PNG vegetative cover marked this climatic interval. Decreases in mangrove pollen abundance and increases in marine palynomorphs mark the end of transgression and modern sea level highstand conditions at approximately 5 to 6 kyr BP. Intensification of the El Niño Southern Oscillation (ENSO) and an increase in climate seasonality was observed in the oxygen isotopic results from MD-50 at ~5,000 yr BP. Although pollen evidence for an ENSO-dominated climate was expected, the vegetation remained stable throughout the study. Sediment transport pathways in the GoP remained fairly constant throughout the time interval. When combined with palynological analysis, sediment maturity, which was determined from illite to smectite ratios, helped to determine sourcing for the cores. In particular, MV-41 was comprised of Vailala and Lakekamu river catchment sediments; MV-46 of Fly, Bamu, Turama, Kikori, and Purari sediments; and MD-50 of carbonate sediments sloughed from surrounding reefs.
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