Extreme lowering of deglacial seawater radiocarbon recorded by both epifaunal and infaunal benthic foraminifera in a wood-dated sediment core

• Main Authors: P. A. Rafter, J.-C. Herguera, J. R. Southon
• Format: Article
• Language: English
• Published: Copernicus Publications 2018-12-01
• Series: Climate of the Past
• Online Access: https://www.clim-past.net/14/1977/2018/cp-14-1977-2018.pdf

<p>For over a decade, oceanographers have debated the interpretation and reliability of sediment microfossil records indicating extremely low seawater radiocarbon (<span class="inline-formula">¹⁴C</span>) during the last deglaciation – observations that suggest a major disruption in marine carbon cycling coincident with rising atmospheric <span class="inline-formula">CO₂</span> concentrations. Possible flaws in these records include poor age model controls, utilization of mixed infaunal foraminifera species, and bioturbation. We have addressed these concerns using a glacial–interglacial record of epifaunal benthic foraminifera <span class="inline-formula">¹⁴C</span> on an ideal sedimentary age model (wood calibrated to atmosphere <span class="inline-formula">¹⁴C</span>). Our results affirm – with important caveats – the fidelity of these microfossil archives and confirm previous observations of highly depleted seawater <span class="inline-formula">¹⁴C</span> at intermediate depths in the deglacial northeast Pacific.</p>