The flux and provenance of dust delivered to the SW Pacific during the last glacial maximum

The funding for the TAN1106 voyage was from the Coasts and Oceans Physical Resources program awarded to the National Institute of Water and Atmospheric Research, New Zealand. This work was funded by NERC studentship NE/L002531/1 to R.S. and NERC grant NE/J021075/1 to G.L.F. R.G. and A.B. were suppor...

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Bibliographic Details
Published in:Paleoceanography and Paleoclimatology
Main Authors: Trudgill, M. D., Shuttleworth, R., Bostock, H. C., Burke, A., Cooper, M. J., Greenop, R., Foster, G. L.
Other Authors: NERC, University of St Andrews.School of Earth & Environmental Sciences, University of St Andrews.St Andrews Isotope Geochemistry
Format: Article in Journal/Newspaper
Language:English
Published: 2021
Subjects:
Dust provenance
Nd
Sr
Pb isotopes
SW Pacific
232Th-fluxes
Subantarctic Zone
Last Glacial Maximum
GE Environmental Sciences
DAS
GE
Southern Ocean
Online Access:https://hdl.handle.net/10023/23291
https://doi.org/10.1029/2020PA003869
Description
Summary:The funding for the TAN1106 voyage was from the Coasts and Oceans Physical Resources program awarded to the National Institute of Water and Atmospheric Research, New Zealand. This work was funded by NERC studentship NE/L002531/1 to R.S. and NERC grant NE/J021075/1 to G.L.F. R.G. and A.B. were supported by NERC grant NE/M004619/1 awarded to A.B. Atmospheric dust is a primary source of iron (Fe) to the open ocean, and its flux is particularly important in the high nutrient, low chlorophyll (HNLC) Southern Ocean where Fe currently limits productivity. Alleviation of this Fe limitation in the Subantarctic Zone of the Atlantic by increased dust-borne Fe supply during glacial periods has been shown to increase primary productivity. However, previous work has found no such increase in productivity in the Pacific sector. In order to constrain the relative importance of Southern Ocean Fe fertilization on glacial-interglacial carbon cycles, records of dust fluxes outside of the Atlantic sector of the Southern Ocean at the Last Glacial Maximum (LGM) are required. Here we use grain size and U-series analyses to reconstruct lithogenic and CaCO3 fluxes, and Nd, Sr and Pb isotopes to ascertain the provenance of terrigenous material delivered to four deep-water cores in the SW Pacific Ocean over the last ~30kyr. We find evidence for an increase in the relative proportion of fine-grained (0.5-12 ?m) terrigenous sediment and higher detrital fluxes during the LGM compared to the Holocene. The provenance of the LGM dust varied spatially, with an older, more "continental" signature (low εNd, high 87Sr/86Sr) sourced from Australia in the northern cores, and a younger, more volcanogenic source in the southern cores (high εNd, low 87Sr/86Sr), likely sourced locally from New Zealand. Given this increase in lithogenic flux to the HNLC subantarctic Pacific Southern Ocean during the LGM, factors besides Fe-supply must have regulated the biological productivity here. Peer reviewed

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