An improved radiocarbon chronology for MD-982167, eastern Indian Ocean: synchronizing paleomagnetic intensity and 10Be across the Laschamp event

Levchenko, VA; Fink, D; Opdyke, BN; Mifsud, C; Williams, AG; Klootwijk, C

An improved radiocarbon chronology for MD-982167, eastern Indian Ocean: synchronizing paleomagnetic intensity and 10Be across the Laschamp event

Date

2009-06-02

Authors

Publisher

20th International Radiocarbon Conference

Abstract

The production rate of cosmogenic isotopes 10Be and 14C is influenced by variations in the primary cosmic-ray flux and by changes of the Earth’s magnetic field, which has experienced a number of significant perturbations during the late Quaternary (e.g. Laschamp excursion, ca. 41 kyr BP). Understanding these changes and synchronizing variations in paleomagnetic intensity derived from various marine sediment cores can often help constrain the quality of 14C dating, particularly for times beyond IntCal04 between 30 and 50 kyr ago, leading to improved overall core chronologies and determination of ocean sedimentation rates. An often used proxy for these paleomagnetic changes is the concentration of atmospheric fallout of 10Be in marine sediments. The ocean core MD-982167 recovered from the Scott Plateau in the eastern Indian Ocean (13°09′S, 121°35′E; depth of 1981m) has an established δ18O stable isotope stratigraphy and a high sedimentation rate of 10 to 20 cm/kyr based on a preliminary chronology tied to ice-core records. This in turn makes MD-982167 amenable to high-resolution 10Be assay across the Laschamp period. We have completed measurements of 10Be and 14C (in both foraminifera and fine sediments) and paleomagnetic intensity in core MD-982167. We are able to correlate variations in 10Be with paleomagnetic intensity recorded in these ocean sediments based on our detailed radiocarbon age-depth profile and confirm a strong presence of the Laschamp excursion at 39.9 ± 1.3 kyr BP. Comparing the variations of atmospheric-derived 10Be in MD-982167 tied to our improved radiocarbon chronology with 10Be established from the ice cores and will allow much better correlation between marine sedimentary and ice-core records across recent stadial and interstadial climatic events.

Keywords

Carbon 14, Indian Ocean, Paleomagnetism, Beryllium 10, Quaternary period, Isotope dating

Citation

Levchenko, V., Fink, D., Opdyke, B., Mifsud, C., Williams, A., & Klootwijk, C. (2009). An improved radiocarbon chronology for MD-982167, eastern Indian Ocean: synchronizing paleomagnetic intensity and 10Be across the Laschamp event. Presentation to the 20th International Radiocarbon Conference, 31st May - 5th June 2009, Big Island, Hawaii: Kailua-Kona.