Open AccessHydrous upwelling across the mantle transition zone beneath the Afar Triple Junction
Author(s) -
Thompson D. A.,
Hammond J. O. S.,
Kendall J.M.,
Stuart G. W.,
Helffrich G. R.,
Keir D.,
Ayele A.,
Goitom B.
Publication year - 2015
Publication title -
geochemistry, geophysics, geosystems
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.928
H-Index - 136
ISSN - 1525-2027
DOI - 10.1002/2014gc005648
Subject(s) - upwelling , transition zone , geology , mantle (geology) , hotspot (geology) , geophysics , mantle wedge , mantle convection , core–mantle boundary , petrology , subduction , seismology , oceanography , tectonics
The mechanisms that drive the upwelling of chemical heterogeneity from the lower to upper mantle (e.g., thermal versus compositional buoyancy) are key to our understanding of whole mantle convective processes. We address these issues through a receiver function study on new seismic data from recent deployments located on the Afar Triple Junction, a location associated with deep mantle upwelling. The detailed images of upper mantle and mantle transition zone structure illuminate features that give insights into the nature of upwelling from the deep Earth. A seismic low‐velocity layer directly above the mantle transition zone, interpreted as a stable melt layer, along with a prominent 520 km discontinuity suggest the presence of a hydrous upwelling. A relatively uniform transition zone thickness across the region suggests a weak thermal anomaly (<100 K) may be present and that upwelling must be at least partly driven by compositional buoyancy. The results suggest that the lower mantle is a source of volatile rich, chemically distinct upwellings that influence the structure of the upper mantle, and potentially the chemistry of surface lavas.