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dc.contributor.author le Roex, A. P.
dc.contributor.author Schilling, J. G.
dc.contributor.author le Roux, P. J.
dc.contributor.author Perkins, W. W.
dc.contributor.author Schimizu, N.
dc.contributor.author Pearce, Nicholas J. G.
dc.date.accessioned 2011-10-06T10:19:16Z
dc.date.available 2011-10-06T10:19:16Z
dc.date.issued 2011-10-06
dc.identifier.citation le Roex , A P , Schilling , J G , le Roux , P J , Perkins , W W , Schimizu , N & Pearce , N J G 2011 , ' Mantle heterogeneity beneath the southern Mid-Atlantic Ridge: trace element evidence for contamination of ambient asthenospheric mantle ' Earth and Planetary Science Letters , pp. 479-498 . en
dc.identifier.other PURE: 171489
dc.identifier.other dspace: 2160/7606
dc.identifier.uri http://hdl.handle.net/2160/7606
dc.description le Roux, P. J., le Roex, A. P., Schilling, J. G., Schimizu, N., Perkins, W. W., Pearce, N. J. G. (2002). Mantle heterogeneity beneath the southern Mid-Atlantic Ridge: trace element evidence for contamination of ambient asthenospheric mantle. Earth and Planetary Science Letters, 203 (1), 479-498. Article Number: PII S0012-821X(02)00832-4. en
dc.description.abstract We report new trace element data for an extensive suite of quench basalt glasses dredged from the southern Mid-Atlantic Ridge (MAR) between 40degreesS and 52.5degreesS. Ratios between highly incompatible trace elements are strongly correlated and indicate a systematic distribution of incompatible element enriched mid-ocean ridge basalt (MORB) (E-type: Zr/Nb = 5.9-19, Y/Nb = 0.9-8.4, (La/Sm)(n) = 1.0-2.9) and incompatible element depleted MORB (N-type: Zr/Nb = 30-69, Y/Nb = 11-29, (La/Sm)(n) = 0.48-0.79) along this section of the southern MAR. A notable feature of N-type MORB from the region is the higher than usual Ba/Nb (4-9), La/Nb (1.2-2.4) and primitive mantle normalised K/Nb ratios (>1). Ba/Nb ratios in E-type MORB samples from 47.5 to 49degreesS are especially elevated (>10). The occurrence and geographic distribution of E-type MORB along this section of the southern MAR can be correlated with the ridge-centred Shona and off-axis Discovery mantle plumes. In conjunction with published isotope data for a subset of the same sample suite [Douglass et al., J. Geophys. Res. 104 (1999) 2941], a model is developed whereby prior to the breakup of Gondwana and the opening of the South Atlantic Ocean, the underlying asthenospheric mantle was locally contaminated by fluids/melts rising from the major Mesozoic subduction zone along the south-southwest boundary of Gondwana, leaving a subduction zone geochemical imprint (elevated (K/Nb)n and Sr-87/Sr-86 ratios, decreased Nd-143/Nd-144 ratios). Subsequent impingement of three major mantle plume heads (Tristan/Gough, Discovery, Shona) resulted in heating and thermal erosion of the lowermost subcontinental lithosphere and dispersal into the convecting asthenospheric mantle. With the opening of the ocean basin, continued plume upwelling led to plume-ridge interactions and mixing between geochemically enriched mantle derived from the zShona and Discovery mantle plumes, material derived from delamination of the subcontinental lithosphere, and mildly subduction zone contaminated depleted asthenospheric mantle. (C) 2002 Elsevier Science B.V. All rights reserved. en
dc.format.extent 20 en
dc.language.iso eng
dc.relation.ispartof Earth and Planetary Science Letters en
dc.title Mantle heterogeneity beneath the southern Mid-Atlantic Ridge: trace element evidence for contamination of ambient asthenospheric mantle en
dc.type Text en
dc.type.publicationtype Article (Journal) en
dc.contributor.institution Institute of Geography & Earth Sciences en
dc.contributor.institution Quaternary Environmental Change Group en
dc.description.status Peer reviewed en


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