An improved radiocarbon chronology and calibration over the Laschamp event: 14C – 10Be cross synchronisation
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Date
2010-07-04
Journal Title
Journal ISSN
Volume Title
Publisher
Geological Society of Australia
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. Lashamp/Mono Lake excursion, circa 41 ka BP). Understanding these changes and synchronising variations in palaeomagnetic intensity derived from various marine sediment cores can often help constrain the quality of 14C dating, particularly in the interval between 20 and 50 ka ago, and establish reliable chronologies for ocean sedimentation rate changes. A common often used proxy for these palaeomagnetic changes is atmospheric fallout of 10Be in marine sediments. We are investigating the Core MD – 982167, which was recovered from the Scott Plateau in the Eastern Indian Ocean at latitude of 13°S. The MD‐982167 already has an established stable isotope stratigraphy and a high sedimentation rate of 10 to 20 cm per ka. A series of 14C and 10Be determinations in foramifera and fine fraction of the core sediments as a function of core depth have been obtained. Palaeomagnetic measurements with the aim to determine the position of geomagnetic disturbances like Laschamp and Mono Lake as recorded in the ocean sediments were also done on the samples from the same core. Synchronisation of palaeomagnetic, 10Be and radiocarbon records together with the application of 10Be pulse as a global chronostratigrafic marker is discussed. An improved chronology for this high resolution core that has recorded brief, less than one thousand year duration, climatic events during the studied time interval will allow much better correlation between marine sedimentary records and the detailed chronologies established from the ice cores.
Description
Keywords
Beryllium 10, Carbon 14, Magnetic fields, Quaternary period, Lakes, Sediments, Seas, Indian Ocean, Drill cores
Citation
Levchenko, V., Opdyke, B., Fink, D., Mifsud, C., Williams, A., & Klootwijk. (2010). An improved radiocarbon chronology and calibration over the Laschamp event: 14C – 10Be cross synchronisation. Paper presented at Australian Earth Sciences Convention 2010 (AESC 2010), 4th – 8th July 2010. Canberra, Australia: National Convention Centre, (pp. 74).