Basalts from Mururoa, Fangataufa and Gambier islands (French Polynesia): Geochemical dependence on the age of the lithosphere

• Published in: Earth and planetary science letters Vol. 117; no. 1; pp. 89 - 100
• Main Authors: Dupuy, Claude, Vidal, Philippe, Maury, RenéC., Guille, Gérard
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier B.V 01.05.1993; Elsevier
• Subjects: Crystalline rocks; Earth sciences; Earth, ocean, space; Exact sciences and technology; Igneous and metamorphic rocks petrology, volcanic processes, magmas; Isotope geochemistry; Isotope geochemistry. Geochronology; Pacific Ocean; Oceania; French Polynesia; models; Nd-144/Nd-143; volcanic rocks; lithosphere; alkali basalts; drilling; isotope geochemistry; Mururoa Atoll; igneous rocks; atolls; partial melting; rare earths; major elements; trace elements; hot spots; Pb/Pb; tholeiitic basalt; Sr-87/Sr-86; metasomatism
• ISSN: 0012-821X; 1385-013X
• DOI: 10.1016/0012-821X(93)90119-T

Basaltic volcanics from Mururoa, Fangataufa and Gambier islands, which belong to the Pitcairn island chain, have been studied for trace elements and Sr, Nd and Pb isotopic composition. While the trace element ratios remain constant, the 87Sr/ 86Sr ratios range from 0.70292 to 0.70367, 143Nd/ 144Nd ranges from 0.51303 to 0.51288 and the 206Pb/ 204Pb isotopic composition ranges from 18.99 to 19.62. These values, which are clearly distinct from those of Pitcairn basalts, vary according to distance from the present hot spot and are correlated with the age of the underlying lithosphere. It is suggested that the basalts studied were produced by variable degrees of partial melting from an oceanic lithospheric plate metasomatized by prior passage over the Easter hot spot.