Northern Sourced Water dominated the Atlantic Ocean during the Last Glacial Maximum.

Pöppelmeier, F., Blaser, P., Gutjahr, Marcus , Jaccard, S. L., Frank, Martin , Max, L. and Lippold, J. (2020) Northern Sourced Water dominated the Atlantic Ocean during the Last Glacial Maximum. Open Access Geology, 48 (8). pp. 826-829. DOI 10.1130/G47628.1.

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Abstract

Increased carbon sequestration in the ocean subsurface is commonly assumed to have been one of the main causes responsible for lower glacial atmospheric CO2 concentrations. Remineralized carbon must have been stored away from the atmosphere for thousands of years, yet the water mass structure accommodating such increased carbon storage continues to be debated. Here, we present new sediment-derived bottom-water neodymium isotope records that allow fingerprinting of water masses and provide a more complete picture of the Atlantic Meridional Overturning Circulation geometry during the Last Glacial Maximum. These results suggest that the vertical and meridional structure of the Atlantic water mass distribution only experienced minor changes since the last ice age. In particular, we find no compelling evidence supporting glacial southern-sourced water substantially expanding to shallower depths and farther into the Northern Hemisphere than today, which had been previously inferred from stable carbon isotope (δ13C) reconstructions. We argue that depleted δ13C values observed in the deep Northwest Atlantic do not necessarily indicate the presence of southern-sourced water. Instead, these values may represent a northern-sourced water mass with lower than modern preformed δ13C values that were further modified downstream by increased sequestration of remineralized carbon, facilitated by a more sluggish glacial deep circulation, corroborating previous evidence.

Document Type: Article
Keywords: Arctic Ocean, Atlantic Meridional Overturning Circulation, C-13/C-12, carbon, Cenozoic cores, Holocene, isotope ratios, isotopes, last glacial maximum, marine sediments, metals, models, Nd-144/Nd-143
Research affiliation: MARUM
OceanRep > GEOMAR > FB2 Marine Biogeochemistry > FB2-MG Marine Geosystems
OceanRep > GEOMAR > FB1 Ocean Circulation and Climate Dynamics > FB1-P-OZ Paleo-Oceanography
Refereed: Yes
Open Access Journal?: No
Publisher: GSA (Geological Society of America)
Date Deposited: 23 Mar 2020 14:06
Last Modified: 08 Feb 2023 09:26
URI: https://oceanrep.geomar.de/id/eprint/49275

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