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Chapter 9,896

Large-scale chemical and thermal division of the Pacific mantle

Vlastelic, I.; Aslanian, D.; Dosso, L.

Nature 399(6734): 5-50

1999


ISSN/ISBN: 0028-0836
Accession: 009895435

Sr, Nd, and Pb isotope data from the Pacific Antarctic ridge are reported. These data reveal the existence of different isotopic signatures north and south of the Easter microplate at 25[degree] S. The argument in favor of 2 large-scale geochemical domains was further strengthened by the discovery of different average depths of the ridge axes north and south of the 25[degree] S boundary, which was situated at the southeastern end of the Darwin rise/Pacific Superswell area. This area is thought to be a zone of upwelling from the lower mantle that has persisted since Cretaceous times. This upwelling may have brought about a separation into 2 mantle domains with their own convective histories, thus giving rise to slight differences in their average isotopic signatures and thermal regimes.

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