HAL will be down for maintenance from Friday, June 10 at 4pm through Monday, June 13 at 9am. More information
Skip to Main content Skip to Navigation
Journal articles

Multiscale chemical heterogeneities beneath the eastern Southwest Indian Ridge (52°E-68°E): Trace element compositions of along-axis dredged peridotites

Abstract : [1] The Southwest Indian Ridge is characterized by frequent outcrops of mantle rocks in a very slow spreading context. In situ measurements of trace element concentrations in pyroxenes of these rocks, and associated petrogenetic modeling, are reported. Overall, the measured compositions cover the whole range typically observed for abyssal peridotites. The greatest subkilometer-scale compositional variability is observed in the region east of the Melville fracture zone. The best explanation for the observed variability is given by concurrent melting and migration of melts strongly enriched in the most incompatible rare earth elements, such as those produced by a garnet-bearing source, or by refertilization with mixed garnet-and spinel-derived partially aggregated melts. Because the regionally associated basalts bear no "garnet signature" in their chemical compositions, we conclude that the residual mantle preserves the signature of a mantle source component that does not appear in the erupted magmas. Comparison between along-axis variations of basalt isotopic compositions and peridotite chemical compositions suggests that local isotopic enrichments displayed by some basalts can be associated with the "garnet signature" in the peridotite and that our sampling represents only a fraction of the global variability of the subaxial mantle. To the west of the Melville fracture zone, samples are more depleted and homogeneous at dredge scale. In addition to containing enriched components, petrologic modeling indicates that the peridotitic mantle beneath the entire section underwent (previous?) partial melting in the garnet stability field before melting at lower pressures.
Document type :
Journal articles
Complete list of metadata

Cited literature [114 references]  Display  Hide  Download

Contributor : Eva Fareau Connect in order to contact the contributor
Submitted on : Friday, October 12, 2018 - 2:45:10 PM
Last modification on : Monday, May 16, 2022 - 8:20:23 AM


Publisher files allowed on an open archive



Monique Seyler, Daniele Brunelli, Michael Toplis, Catherine Mevel. Multiscale chemical heterogeneities beneath the eastern Southwest Indian Ridge (52°E-68°E): Trace element compositions of along-axis dredged peridotites. Geochemistry, Geophysics, Geosystems, AGU and the Geochemical Society, 2011, 12 (9), pp.n/a - n/a. ⟨10.1029/2011gc003585⟩. ⟨insu-01894477⟩



Record views


Files downloads