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Labanieh, Shasa; Chauvel, Catherine; Germa, Aurelie; Quidelleur, Xavier. |
In subduction zones, melting and dehydration of the subducted slab introduce material into the mantle wedge and modify its chemical and isotopic composition. As a consequence, island arc lavas differ significantly from mid-ocean ridge basalts and ocean island basalts. In some arcs, the composition of lavas is strongly influenced by the sedimentary material introduced with the slab; in others, magma composition is mainly affected by aqueous fluids released by the slab. The Lesser Antilles arc is known for its extreme continental-crust-like signature but for some Lesser Antilles lavas subducted sediments are barely involved and enrichment in fluid-mobile elements (Ba, U, Sr, Pb, etc.) is the dominant feature. Here we evaluate whether La/Sm is a quantitative... |
Tipo: Text |
Palavras-chave: Lesser Antilles; Slab dehydration; Sediment melting; Island arcs; Subduction zones. |
Ano: 2012 |
URL: http://archimer.ifremer.fr/doc/00113/22392/20234.pdf |
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Revillon, Sidonie; Guillou, Herve; Maury, Rene C.; Chauvel, Catherine; Aslanian, Daniel; Pelleter, Ewan; Scao, Vincent; Loubrieu, Benoit; Patriat, Martin. |
The Marquesas Island chain in Polynesia is quite unusual because the alignment of the islands on the Pacific oceanic plate (N40°W) does not follow the plate motion in the region (N65°W). The exact location of the active hotspot is unknown but has been predicted to underlie the Marquesas Fracture Zone Ridge. Nevertheless, no concrete evidence exists. Here, we document the occurrence on this ridge of fresh tephrites dated at ~ 92 ka by the 40Ar-39Ar method. The lavas dredged on a small seamount have trace element contents and Sr, Nd, Pb isotopic compositions typical of the southwest Marquesas Islands, the Fatu Hiva group. This discovery demonstrates that the Marquesas plume is still active and it puts new constraints on its present location. It also supports... |
Tipo: Text |
Palavras-chave: Submarine volcanism; Ar-40-Ar-39 ages; Geochemistry; Plume; Marquesas; French Polynesia. |
Ano: 2017 |
URL: https://archimer.ifremer.fr/doc/00407/51832/52431.pdf |
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