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K-Ar dating of the cook-austral island chain: A test of the hot-spot hypothesis

1982; Elsevier BV; Volume: 12; Issue: 3-4 Linguagem: Inglês

10.1016/0377-0273(82)90027-0

1872-6097

Donald L. Turner, Richard D. Jarrard,

Geology and Paleoclimatology Research

40K-40Ar dating indicates that the Cook-Austral chain contains the island with the oldest exposed volcanic rocks on the Pacific plate (Mangaia, 19.3 ± 0.6 Ma B.P.). We have also determined ages from the previously undated islands of Atiu, Mitiaro, Mauke, and Rimatara and from Mangaia, Aitutaki and Rarotonga, for which only unlocated samples had been previously dated. Dated volcanism on Aitutaki spans an interval of at least 7 Ma. The ages from Aitutaki, Atiu, Mauke, Mitiaro, Rarotonga, and Rarutu are much younger than ages predicted by the "hot-spot" hypothesis, and ages from Rimatara may be older than predicted by the hot-spot hypothesis. However, both new and previously reported age data from Mangaia are consistent with the predicted age for this island. Virtually all age data from island and seamount chains on the Pacific plate are consistent with a "hot-line" hypothesis, which makes less specific age predictions than does the hotspot hypothesis.