Geological Society of America

T257 Integration of Microfossils and Sedimentology in Stratigraphic Analysis

Tuesday, 3 November 2015
1:30 PM - 5:30 PM
Room 349/350

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

Paper number: T257-15
Program: Technical Sessions
Time: 5:00 PM – 5:15 PM

Authors

Marie Louise Thomas Presenting Author
Houston, TX
Marie Louise Thomas Presenting Author
Louisiana State University, Baton Rouge, LA
Sophie Warny
Louisiana State University, Baton Rouge, LA
Samuel J. Bentley
Louisiana State University, Baton Rouge, LA
David M. Jarzen
Cleveland Museum of Natural History, Cleveland, OH
André Droxler
Rice University, Houston, TX
Ashley L. Howell
Louisiana State University, Baton Rouge, LA
Brandon B. Harper
Rice University, Houston, TX
Charles Nittrouer
University of Washington, Seattle, WA
Kehui Xu
Louisiana State University, Baton Rouge, LA

Abstract

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.