Neodymium isotopic compositions and rare earth element data evidence boundary exchange in the southwestern tropical and equatorial Pacific

New rare earth element (REE) concentrations and neodymium (Nd) isotopic compositions measured between the southwestern Tropical and the central equatorial Pacific (112 samples) support the hypothesis that the main process driving the geochemical supply in this area is boundary exchange. Nd signatures confirm the major role of the Papua New Guinea coast but also reveal new candidates such as French Polynesia, Vanuatu, Fiji or Galapagos to explain the progressive geochemical enrichment of the waters along their pathways. The positive europium anomaly characterizing the REE patterns of the water masses also trace these continental inputs.

Grenier 2013

Click on the image to view it larger.

Figure: εNd of the dissolved fraction of the upper (top) and lower (bottom) thermocline water masses flowing in the Southwestern and Equatorial Pacific, identified by red dots on the adjacent θ-S plots. Each dot corresponds to a Nd sample and its colour refers to its εNd value. Currents are represented by grey arrows. Large red arrows illustrate areas along the water mass pathways where radiogenic supplies likely occur to explain observed εNd changes. The bathymetry shallower than 250m is coloured in brown.


Reference :

Grenier, M., C. Jeandel, F. Lacan, D. Vance, C. Venchiarutti, A. Cros, and S. Cravatte (2013), From the subtropics to the central equatorial Pacific Ocean: Neodymium isotopic composition and rare earth element concentration variations, /J. Geophys. Res. Oceans/, 118, doi:10.1029/2012JC008239.

Latest highlights

North-South section of bioactive cadmium, nickel, zinc, copper and iron along GEOTRACES transect GP19 in the Pacific Ocean

Zheng and his colleagues propose the first full sections of the simultaneous dissolved distributions of five nutrient-type trace metals in the western South Pacific Ocean.

MOTES: a new facility designed for trace element sampling in seawater

Zhang and a group of engineers and researchers from Shanghai and Qingdao are presenting a modular trace element sampling facility.

A thorough estimate of the hydrothermal plumes on neodymium concentration and isotope oceanic cycles

Basak and co-workers investigated the influence of particulate matter on neodymium distributions in the Southern East Pacific Rise Hydrothermal Plume.

What are the drivers of the distributions of cadmium, nickel, zinc, copper and cobalt, manganese and aluminium in the Atlantic Ocean? Two papers are tackling this issue

Chen and co-authors reveal that the distributions of dissolved tracers at depth in the South Atlantic are predominantly controlled by the mixing of North Atlantic Deep Water and waters of Antarctic origin…