Export production in the New-Zealand region since the Last Glacial Maximum ...

• Main Authors: Chase, Zanna, Johnson, Sean, Kinsely, Les, Jacobsen, Geraldine, Jaccard, Samuel, Noble, Taryn L., Bostock, Helen, Kitchener, Priya, Townsend, Ashley T., Neil, Helen, Durand, Axel
• Format: Text
• Language: English
• Published: Elsevier 2017
• Subjects: 550 Earth sciences & geology; New Zealand; Southern Ocean
• Online Access: https://dx.doi.org/10.7892/boris.101072; https://boris.unibe.ch/101072/

Increased export production (EP) in the Subantarctic Zone (SAZ) of the Southern Ocean due to iron fertilisation has been proposed as a key mechanism for explaining carbon drawdown during the last glacial maximum (LGM). This work reconstructs marine EP since the LGM at four sites around New Zealand. For the first time in this region, 230-Thorium-normalised fluxes of biogenic opal, carbonate, excess barium, and organic carbon are presented. In Subtropical Waters and the SAZ, these flux variations show that EP has not changed markedly since the LGM. The only exception is a site currently north of the subtropical front. Here we suggest the subtropical front shifted over the core site between 18 and 12ka, driving increased EP. To understand why EP remained mostly low and constant elsewhere, lithogenic fluxes at the four sites were measured to investigate changes in dust deposition. At all sites, lithogenic fluxes were greater during the LGM compared to the Holocene. The positive temporal correlation between the ...