Tracing water mass mixing in the Cape Basin and the restricted Angola Basin with radiogenic neodymium isotopes

In the frame of GEOTRACES cruise GA08, Rahlf et al. (2020, see reference below) determined seawater profiles of dissolved radiogenic neodymium isotope signatures (εNd) and neodymium concentrations across the restricted western Angola Basin and along the northern Cape Basin to investigate mixing and provenance of water masses. Nd isotope compositions of deep water masses in both basins primarily reflect conservative water mass mixing, except the central Angola Basin, which is significantly overprinted by terrestrial inputs. Bottom waters of the Cape Basin show some excess Nd concentrations released from detrital sediments, however, without significantly changing their Nd isotopic compositions ranging between εNd -9.6 and 10.5. Highly unradiogenic εNd signatures of up to -17.6 in the upper water column originate from a west African coastal plume in the Angola Basin and from Mozambique Channel surface waters advected into the Cape Basin.

19 Rahlf

Figure: Nd isotope distributions in the western Angola Basin (left section) and the northern Cape Basin (right section) along the cruise track of GA08, combined with isotope data obtained further south from cruise ANT-XXIIV/3 (Stichel et al., 2012). Dashed lines indicate approximate boundaries of the prevailing water masses. The figure is adopted from Rahlf et al. (2020). Click here to view the figure in new window.

References:

Rahlf, P., Hathorne, Ed., Laukert, G., Gutjahr, M., Weldeab, S., Frank, M. (2020). Tracing water mass mixing and continental inputs in the southeastern Atlantic Ocean with dissolved neodymium isotopes. Earth Planet. Sci. Lett., in press, DOI: 10.1016/j.epsl.2019.115944.

Stichel, T., Frank, M., Rickli, J., Haley, B.A. (2012). The hafnium and neodymium isotope composition of seawater in the Atlantic sector of the Southern Ocean. Earth Planet. Sci. Lett. 317–318, 282–294.

Latest highlights

Science Highlights

The most important thorium-234 disequilibrium compilation you ever saw

Elena Ceballos-Romero and her colleagues propose a comprehensive global oceanic compilation of Thorium-234 measurements.

23.06.2022

Science Highlights

Machine learning approach led to the first iron climatology

Huang and co-workers propose the first data-driven surface-to-seafloor dissolved iron climatology.

21.06.2022

Science Highlights

Insight on the aluminium cycling during the inter-monsoon period in the Arabian Sea and Equatorial Indian Ocean

Full vertical water column profiles were established by Singh and Singh along the GI05 transect in the Indian Ocean during the fall inter-monsoon period in 2015.

Science Highlights

Distributions, boundary inputs, and scavenging processes of trace metals in the East Sea (Japan Sea)

Seo and his colleagues show pronounced atmospheric and shelf inputs of trace elements in the Japan Sea.

14.06.2022

Rechercher