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Measuring Carbon-based Contaminant Mineralization Using Combined CO2 Flux and Radiocarbon Analyses
Published on: October 21, 2016
14C activity and global carbon cycle changes over the past 50,000 years
K Hughen1, S Lehman, J Southon
1Department of Marine Chemistry and Geochemistry, Woods Hole Oceanographic Institution (WHOI), Woods Hole, MA 02543, USA. khughen@whoi.edu
Science (New York, N.Y.)
|January 13, 2004
Summary
This study calibrates the radiocarbon (14C) timescale up to 50,000 years using Ocean Drilling Program cores. Findings reveal significant 14C variations during the last glacial period, linked to geomagnetic events and ocean carbon cycle changes.
Area of Science:
- Paleoclimatology
- Geochronology
- Radiocarbon Dating
Background:
- The radiocarbon (14C) timescale is crucial for reconstructing past climate and events.
- High-resolution calibration of the 14C timescale beyond 30,000 years is limited.
- Geomagnetic field intensity variations and ocean carbon cycle dynamics can influence 14C reservoir ages.
Purpose of the Study:
- To establish a high-resolution calibration of the radiocarbon (14C) timescale back to 50,000 years before present.
- To investigate the causes of substantial 14C activity variations during the last glacial period.
Main Methods:
- Radiocarbon (14C) measurements of Ocean Drilling Program cores from the Cariaco Basin.
- Correlation of Cariaco Basin core chronology to the Greenland Ice Sheet Project 2 (GISP2) annual-layer counted chronology.
- Independent radiometric dating for calibration validation.
- Geochemical box model simulations.
Main Results:
- A robust, high-resolution radiocarbon (14C) timescale calibration was achieved up to 50,000 years before present.
- Significant 14C activity variations were reconstructed during the last glacial period.
- These variations correlate with geomagnetic field intensity minima (Laschamp, Mono Lake) and cosmogenic nuclide peaks.
Conclusions:
- Geomagnetically modulated changes in 14C production rate are a primary driver of observed 14C variability.
- Changes in deep-ocean ventilation and the global carbon cycle during glaciation likely contributed to the reconstructed 14C fluctuations.
- The study provides an accurate and extended radiocarbon (14C) timescale for paleoclimate research.
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