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

Surprisingly heavy silicon isotopes in the surface and deep Arctic Ocean

Brzezinski and his colleagues report on a comprehensive study of the Arctic Ocean silicic acid concentrations and silicon isotopic composition…

14.09.2021

Science Highlights

Unique winter dataset of particulate and dissolved cadmium in the Indian sector of the Southern Ocean

Cloete and collaborators analysed particulate and dissolved cadmium at 7 stations in austral winter along a North South section off South Africa.

06.09.2021

Science Highlights

A new proxy for ocean iron bioavailability

The approach established and verified in this study, opens a new way for determining dissolved iron bioavailability in samples across the ocean.

23.07.2021

Science Highlights

Scavenging differentiates the distribution of cadmium, nickel, zinc and copper in the North Pacific Ocean

Zheng and co-authors observed sectional distributions of cadmium, nickel, zinc, and copper in the North Pacific Ocean during three GEOTRACES related cruises…

19.07.2021

Rechercher