Sr-Nd-Pb isotope ratios, geochemical compositions, and 40Ar/39Ar data of lavas from San Felix Island (Southeast Pacific): Implications for magma genesis and sources |
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| Authors: | KM Haase DF Mertz WS Sharp & C-D Garbe-Schönberg |
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| Affiliation: | Institut für Geowissenschaften der Universität Kiel, Olshausenstr. 40, 24118 Kiel, and, Max-Planck-Institut für Chemie, Postfach 3060, 55020 Mainz, Germany, and, Lamont-Doherty Earth Observatory of Columbia University, Palisades, New York 10964, U.S.A.,;Johannes Gutenberg-Universität, Institut für Geowissenschaften, 55099 Mainz, Germany, and, Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, U.S.A.,;Berkeley Geochronology Center, 2455 Ridge Road, Berkeley, California 94709, U.S.A.,;Institut für Geowissenschaften der Universität Kiel, Olshausenstr. 40, 24118 Kiel, Germany |
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| Abstract: | We present the first trace element and age data combined with new Sr, Nd, and Pb isotope ratios on lavas from San Felix Island in the Southeast Pacific. A 40Ar/39Ar plateau age of 421 ± 18 ka implies young intraplate volcanic activity in this region relative to the ～22 Ma old volcanism on the neighbouring Easter seamount chain (ESC). The incompatible element compositions of the San Felix magmas are similar to those of EM1-type basalts from Gough, although the isotopic compositions differ. San Felix formed some 20 Ma after the ESC plume affected the plate in this region but no chemical signature of the ESC material is observed in the young volcanic rocks. The composition of the San Felix basalts indicates a mantle source containing old continental lithospheric material from either metasomatized mantle or recycled sediments, which ascends in a weak mantle plume. |
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