FN Archimer Export Format PT J TI Effect of melt/mantle interactions on MORB chemistry at the easternmost Southwest Indian Ridge (61 to 67°E) BT AF PAQUET, M. CANNAT, M. BRUNELLI, D. HAMELIN, C. HUMLER, E. AS 1:1;2:1;3:2,3;4:4;5:5; FF 1:;2:;3:;4:;5:; C1 Univ Paris Diderot, Sorbonne Paris Cite, Inst Phys Globe Paris, Equipe Geosci Marines,CNRS,UMR7154, Paris, France. Univ Modena & Reggio Emilia, Dipartimento Sci Chim & Geol, Modena, Italy. CNR ISMAR, Inst Marine Sci, Bologna, Italy. Univ Bergen, Ctr Geobiol, Bergen, Norway. Univ Nantes, CNRS, Lab Planetol & Geodynam, UMR 6112, Nantes, France. C2 UNIV PARIS 07, FRANCE UNIV MODENA & REGGIO EMILIA, ITALY IAMC CNR, ITALY UNIV BERGEN, NORWAY UNIV NANTES, FRANCE IF 3.201 TC 34 UR https://archimer.ifremer.fr/doc/00353/46457/46212.pdf https://archimer.ifremer.fr/doc/00353/46457/46213.csv https://archimer.ifremer.fr/doc/00353/46457/46214.csv https://archimer.ifremer.fr/doc/00353/46457/46215.csv https://archimer.ifremer.fr/doc/00353/46457/46216.csv https://archimer.ifremer.fr/doc/00353/46457/46217.csv https://archimer.ifremer.fr/doc/00353/46457/46218.csv https://archimer.ifremer.fr/doc/00353/46457/46219.csv https://archimer.ifremer.fr/doc/00353/46457/46220.txt https://archimer.ifremer.fr/doc/00353/46457/46221.eps https://archimer.ifremer.fr/doc/00353/46457/46222.eps https://archimer.ifremer.fr/doc/00353/46457/46223.eps https://archimer.ifremer.fr/doc/00353/46457/46224.eps https://archimer.ifremer.fr/doc/00353/46457/46225.eps https://archimer.ifremer.fr/doc/00353/46457/46226.eps https://archimer.ifremer.fr/doc/00353/46457/46227.eps https://archimer.ifremer.fr/doc/00353/46457/46228.eps https://archimer.ifremer.fr/doc/00353/46457/46229.eps https://archimer.ifremer.fr/doc/00353/46457/46230.eps https://archimer.ifremer.fr/doc/00353/46457/46231.pdf https://archimer.ifremer.fr/doc/00353/46457/46232.pdf LA English DT Article CR EDUL-MD107 MD 183 / SMOOTHSEAFLOOR BO Marion Dufresne AB The easternmost part of the Southwest Indian Ridge (61°-67°E) is an end-member of the global ridge system in terms of very low magma supply. As such, it is a good laboratory to investigate the effect of melt/mantle interactions on the composition of erupted basalts: for a given volume of erupted basaltic melt, the volume of reacted mantle is potentially greater than at more magmatically robust ridges. We analyzed major, trace element and isotopic compositions in three groups of rocks: plagioclase-bearing ultramafic and gabbroic rocks dredged in nearly amagmatic spreading corridors; basalts from the sparse volcanic cover of these corridors (“ultramafic seafloor basalts”); and basalts dredged from the intervening, more volcanically active domains (“volcanic seafloor basalts”). Ultramafic seafloor basalts have significantly lower CaO and Al2O3 contents at a given MgO than most volcanic seafloor basalts. We propose that both types of basalts are derived from similar parental melts, but that the ultramafic seafloor basalts are more affected by reactions between these parent melts and the mantle rocks in the lithosphere below the ridge. We infer that these reactions occur in the walls of conduits that allow the aggregated melts extracted from the melting mantle to rise through the axial lithosphere and to the eruption sites. The principal effect of these reactions is to enrich the asthenospheric melts in MgO through olivine dissolution. This effect is not expected to be as noticeable, but could still play a role in basalt petrogenesis at more magmatic regions of the global slow-spreading MOR system. PY 2016 PD NOV SO Geochemistry Geophysics Geosystems SN 1525-2027 PU Amer Geophysical Union VL 17 IS 11 UT 000392717400019 BP 4605 EP 4640 DI 10.1002/2016GC006385 ID 46457 ER EF