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Geochemical implications from Sr isotopes and K-Ar age determinations for the cook-austral islands chain

1984; Elsevier BV; Volume: 104; Issue: 1-2 Linguagem: Inglês

10.1016/0040-1951(84)90107-0

1879-3266

Jun‐ichi Matsuda, Kenji Notsu, Jun Okano, Katsumi Yaskawa, Leonard Chungue,

Geological and Geophysical Studies

Sr isotopes and K-Ar ages were determined for volcanic rocks from three islands, Samoa, Rarotonga and Rurutu in the Austral-Gilbert-Marshall chain. We have established that Rurutu originated from the same “hot spot” as Tubuai and Raivavae in the Cook-Austral chain as indicated by its 11 m.y. K-Ar age and (87Sr86Sr) ratios. The (87Sr86Sr) ratios for Rurutu, Tubuai and Raivavae lie in the restricted range 0.7026–0.7035. K-Ar ages of all volcanic rocks from Samoa and Rarotonga are all less than 4 m.y. and their (87Sr86Sr) ratios are much higher than those in Rurutu, Tubuai and Raivavae. These findings suggest that Samoa and Rarotonga did not originate in a single hot spot for the Cook-Austral islands.