Ventilation of the deep–ocean carbon reservoir during the last deglaciation: results from the Southeast Pacific

Type Article
Date 2019-12
Language English
Author(s) Martínez Fontaine Consuelo1, 3, 4, de Pol‐holz Ricardo2, Michel Elisabeth3, Siani Giuseppe4, Reyes‐macaya Dharma5, Martínez‐méndez Gema5, Devries Tim6, Stott Lowell7, Southon John8, Mohtadi Mahyar5, Hebbeln Dierk5
Affiliation(s) 1 : Departamento de Geología, Universidad de Chile
2 : Centro de Investigación GAIA-Antárctica (CIGA) and Network for Extreme Environments Research (NEXER), Universidad de Magallanes, Punta Arenas, Chile
3 : Laboratoire des Sciences du Climat et de l’Environnement (LSCE), Laboratoire mixte CNRS-CEA, Avenue de la Terrasse, 91198 Gif-sur-Yvette Cedex, Franc
4 : Geoscience Paris Sud (GEOPS) Universities of Paris Sud and Paris-Saclay, CNRS, 91405 Orsay, France
5 : MARUM, Center for Marine Environmental Sciences, University of Bremen, Leobener Straße, 28359 Bremen, Germany
6 : Earth Research Institute, UC Santa Barbara, Santa Barbara CA 93106-3060, USA
7 : Department of Earth Sciences, University of Southern California, Los Angeles, California 90089, USA
8 : Earth System Science Department, B321 Croul Hall, University of California, Irvine, California 92697, USA
Source Paleoceanography And Paleoclimatology (2572-4517) (American Geophysical Union (AGU)), 2019-12 , Vol. 34 , N. 12 , P. 2080-2097
DOI 10.1029/2019PA003613
WOS© Times Cited 1
Abstract

Coeval changes in atmospheric CO2 and 14C contents during the last deglaciation are often attributed to ocean circulation changes that released carbon stored in the deep ocean during the Last Glacial Maximum (LGM). Work is being done to generate records that allow for the identification of the exact mechanisms leading to the accumulation and release of carbon from the oceanic reservoir, but these mechanisms are still the subject of debate. Here we present foraminifera 14C data from five cores in a transect across the Chilean continental margin between ~540 m and ~3100 m depth spanning the last 20,000 years. Our data reveal that during the LGM waters at ~2000 m were 50 to 80 % more depleted in Δ14C than waters at ~1500 m when compared to modern values, consistent with the hypothesis of a glacial deep–ocean carbon reservoir that was isolated from the atmosphere. During the deglaciation, our intermediate water records reveal homogenization in the Δ14C values between ~800 and ~1500 m from ~16.5–14.5 ka cal BP to ~14‐12 ka cal BP, which we interpret as deeper penetration of Antarctic Intermediate Water. While many questions still remain, this process could aid the ventilation of the deep ocean at the beginning of the deglaciation, contributing to the observed ~40 ppm rise in atmospheric pCO2.

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Martínez Fontaine Consuelo, de Pol‐holz Ricardo, Michel Elisabeth, Siani Giuseppe, Reyes‐macaya Dharma, Martínez‐méndez Gema, Devries Tim, Stott Lowell, Southon John, Mohtadi Mahyar, Hebbeln Dierk (2019). Ventilation of the deep–ocean carbon reservoir during the last deglaciation: results from the Southeast Pacific. Paleoceanography And Paleoclimatology, 34(12), 2080-2097. Publisher's official version : https://doi.org/10.1029/2019PA003613 , Open Access version : https://archimer.ifremer.fr/doc/00591/70323/