A preliminary assessment of the symmetry of source composition and melting dynamics across the Azores plume

Journal article


Publication Details

Author(s): Beier C, Turner S, Plank T, White W
Journal: Geochemistry Geophysics Geosystems
Publisher: American Geophysical Union (AGU)
Publication year: 2010
Volume: 11
ISSN: 1525-2027


Abstract


In order to undertake a preliminary assessment of the extent of symmetry in source composition and melting dynamics in the Azores plume we present new ICP-MS trace element data along with Sr, Nd, Pb, and U-Th-Ra isotope data for samples from the islands Flores and Corvo west of the Mid-Atlantic Ridge. We also present data from a picrite from Faial and new ICP-MS trace element data for 28 basaltic lavas from the eastern Azores Plateau to augment data published previously from these samples. Rare earth element data for primitive lavas (MgO ≥ 5% and Mg # ≥ 60) have La/YbN ∼ 10 and variable Ce and/or Eu anomalies. Multi-incompatible trace element patterns normalized to primitive mantle are convex upward with small negative Th and K ± Pb anomalies. While lavas to the east are characterized by low Nb/Zr and generally lower La/Yb ratios (with the notable exception of eastern So Miguel), lavas from the western islands have slightly higher Nb/Zr and La/Yb inferred to reflect smaller degrees of partial melting. The Sr-Nd-Pb isotope systematics imply that Corvo and Flores sample components which range from an isotopic source commonly found in the Azores (e.g., at the eastern island of Graciosa) to a more depleted, MORB-like mantle sampled at the Mid-Atlantic Ridge. However, in common with uncontaminated samples from São Miguel, the Corvo and Flores samples appear to have slightly lower 230Th excesses and higher La/Yb, Tb/Yb than the other Azores islands or the Mid-Atlantic Ridge samples. The trace element and isotope data indicate a relatively symmetric pattern with distance across the MAR, while U-Th disequilibria, and thus inferred melting dynamics, appear less symmetric. Nevertheless, the data suggest that heterogeneities in source composition do not have a large effect on melting dynamics, at least within the Azores islands. Copyright 2010 by the American Geophysical Union.



FAU Authors / FAU Editors

Beier, Christoph PD Dr.
Lehrstuhl für Endogene Geodynamik


External institutions
Columbia University
Cornell University
Macquarie University


How to cite

APA:
Beier, C., Turner, S., Plank, T., & White, W. (2010). A preliminary assessment of the symmetry of source composition and melting dynamics across the Azores plume. Geochemistry Geophysics Geosystems, 11. https://dx.doi.org/10.1029/2009GC002833

MLA:
Beier, Christoph, et al. "A preliminary assessment of the symmetry of source composition and melting dynamics across the Azores plume." Geochemistry Geophysics Geosystems 11 (2010).

BibTeX: 

Last updated on 2018-08-08 at 04:31