Development of a correlated Fe‐Mn Crust stratigraphy using Pb and Nd isotopes and its application to paleoceanographic reconstruction in the Atlantic

Josso, P.; Horstwood, M.S.A.; Millar, I.L.; Pashley, V.; Lusty, P.A.J.; Murton, B. ORCID: https://orcid.org/0000-0003-1522-1191. 2020 Development of a correlated Fe‐Mn Crust stratigraphy using Pb and Nd isotopes and its application to paleoceanographic reconstruction in the Atlantic. Paleoceanography and Paleoclimatology, 35 (10), e2020PA003928. https://doi.org/10.1029/2020PA003928

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Official URL: http://dx.doi.org/10.1029/2020PA003928

Abstract/Summary

Eight ferromanganese crust samples spanning the complete depth range of Tropic Seamount in the north‐east Atlantic were analysed for Pb and Nd isotopes to reconstruct water mass origin and mixing over the last 75 Ma. Pb isotopes were determined by LA‐MC‐ICP‐MS, which enables the rapid production of large, high spatial‐resolution datasets. This makes it possible to precisely correlate stratigraphy between different samples, compare contemporaneous layers, and create a composite record given the abundance of hiatuses in crusts. Pb and Nd isotope data show the influence of various oceanic and continental end‐members in the north‐east Atlantic Ocean. This reflects its evolution from a restricted, isolated basins in the Late Cretaceous with influxes from the Tethys Ocean, to an increasingly well‐mixed, large‐scale basin, with a dominant Southern Ocean signature until the Miocene. Less‐radiogenic Nd isotope signatures suggest Labrador Sea Water influenced the north‐east Atlantic basin as early as 17‐15 Ma, flowing through a northern route such as the Charlie‐Gibbs Fracture Zone. Pb and Nd isotopes highlight the increasing influence of Saharan aeolian dust input about 7 Ma, imparting a less‐radiogenic excursion to the binary mixing between North Atlantic water masses and riverine discharge from West and Central Africa. This highlights the influence of aeolian dust input on the open ocean Pb and Nd budget, and supports an early stage of North African aridification in the Late Miocene. This signature is overprinted about 3 Ma to the present by a strong North Atlantic Deep Water signature following the onset of Northern Hemisphere glaciation.

Item Type:	Publication - Article
Digital Object Identifier (DOI):	https://doi.org/10.1029/2020PA003928
ISSN:	2572-4517
Date made live:	06 Oct 2020 10:05 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/528638

Item Type:

Publication - Article

Digital Object Identifier (DOI):

https://doi.org/10.1029/2020PA003928

ISSN:

2572-4517

Date made live:

06 Oct 2020 10:05 +0 (UTC)

URI:

https://nora.nerc.ac.uk/id/eprint/528638