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Kieffer, B; Arndt, Nt; Weis, D. |
A bimodal volcanic sequence of 230 m thickness on Skiff Bank, a western salient of the northern Kerguelen Plateau, was drilled during ODP Leg 183. The sequence comprises three main units: a mafic unit of trachybasalt flows sandwiched between two units of trachytic or rhyolitic flows and volcaniclastic rocks. Although interpretation is complicated by moderate to strong alteration of the rocks, their original chemical character can be established using the least mobile major and trace elements (Al, Th, high field strength elements and rare earth elements). High concentrations of alkalis and incompatible trace elements indicate that both mafic and felsic rocks are alkalic. The felsic rocks may have been derived by partial melting of mafic rocks, followed by... |
Tipo: Text |
Palavras-chave: Ocean Drilling Program; Kerguelen Plateau; Skiff Bank. |
Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33406/31863.pdf |
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Weis, D; Frey, Fa; Schlich, R; Schaming, M; Montigny, R; Damasceno, D; Mattielli, N; Nicolaysen, Ke; Scoates, Js. |
The gravity and bathymetric highs on the Kerguelen Plateau in the southern Indian Ocean between the Kerguelen Archipelago and Heard Island are seamounts formed of Miocene alkalic basalts similar to those found on the islands. Dredging during the Kerimis survey cruise recovered >1 ton of mostly basaltic rocks. One of the dredges (D6) yielded a large volume of in situ alkalic picritic pillow basalts, the first picritic lavas recovered that are related to the Kerguelen plume. K-Ar and Ar-40-Ar-39 ages are between 18 and 21 Ma for all but one sample, and these ages are only slightly younger than the main phase of volcanism on the archipelago. The dredged lavas form three distinct groups based on chemical and isotopic compositions. Incompatible element... |
Tipo: Text |
Palavras-chave: Kerguelen; Trace elements; Isotopes; Mantle plume; Hot spot track; Picrites; Geochemistry; 1025 Geochemistry : Composition of the mantle; 1040 Geochemistry : Isotopic composition/chemistry; 1065 Geochemistry : Trace elements (3670). |
Ano: 2002 |
URL: https://archimer.ifremer.fr/doc/00223/33407/31856.pdf |
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