Project Info

Characterizing geochemical signatures of the deep-mantle Dupal anomaly

Richard Palin | rmpalin@mines.edu

During a review of worldwide igneous rock chemistry, Hart (1984) noticed that oceanic basalts with high 207Pb/204Pb and 208Pb/204Pb ratios for a given value of 206Pb/204Pb almost always erupt from mid-ocean ridges and volcanoes situated at about 30° S, indicating the presence of a geochemically unique mantle reservoir at this equivalent deep-Earth latitude. This isotopic signature was termed the Dupal anomaly, although its origin remains incompletely understood. More recently, Goldstein et al. (2008) identified rare basalts from the Arctic ocean (Gakkel Ridge) that exhibit similar isotopic ratios, suggesting that the mechanism behind the Dupal anomaly may be more pervasive that first thought. Despite this work, no systematic investigation has been performed into a major or trace element compositions of Dupal-anomaly basalts, which may provide new insight into the origin of this geological feature. Such a study can be facilitated by the recent advent of Big Data and has the potential to provide new compositional tracers for elucidating the operation of unobservable, deep-Earth processes.

More Information

Goldstein, S.L., Soffer, G., Langmuir, C.H., Lehnert, K.A., Graham, D.W. and Michael, P.J., 2008. Origin of a ‘Southern Hemisphere’ geochemical signature in the Arctic upper mantle. Nature, 453(7191), p.89.
Castillo, P., 1988. The Dupal anomaly as a trace of the upwelling lower mantle. Nature, 336(6200), p.667.
Hart, S.R., 1984. A large-scale isotope anomaly in the Southern Hemisphere mantle. Nature, 309(5971), p.753.

Grand Engineering Challenge: Not applicable