|Mantle heterogeneity beneath the Nazca Plate: San Felix and Juan Fernandez islands|
Gerlach, D.C.; Hart, S.R.; Morales, V.W.J.; Palacios, C. (1986). Mantle heterogeneity beneath the Nazca Plate: San Felix and Juan Fernandez islands. Nature (Lond.) 322(6075): 165-169
In: Nature: International Weekly Journal of Science. Nature Publishing Group: London. ISSN 0028-0836, more
Basalts; Earth mantle; Geochemistry; Lava; Volcanism; ISE, Chile, Desventurados I., San Felix I. [Marine Regions]; Nazca Plate; PSW, Chile, Juan Fernandez I. [Marine Regions]; Marine
|Authors|| || Top |
- Gerlach, D.C.
- Hart, S.R.
- Morales, V.W.J.
- Palacios, C.
The islands of San Felix, San Ambrosio and the Juan Fernandez group comprise one of the few subaerial occurrences of intraplate oceanic volcanism between the Mid-Atlantic Ridge and the East Pacific Rise south of 20 degree S, and are therefore valuable in the assessment of large-scale geochemical heterogeneities in the Earth's mantle. The authors present here the results of a preliminary Sr, Nd and Pb iosotopic study of basic lavas from these islands. All samples show a moderate Dupal signature (anomalous Sr, Nd and Pb isotopic compositions). Basalts from the Juan Fernandez group lie close to the mantle plane, whereas basalts from San Felix display unusual isotopic characteristics which plot well below the Nd-Sr oceanic array. Based on this data, they propose the delineation of a new mantle array, linear in Nd-Sr-Pb isotopic space, with Tubuaii and Walvis Ridge as end members. The mixing relationships exhibited by this array suggest that both end members are geographically contiguous, and probably reside in delaminated sub-continental lithosphere.