| We are presenting a new set of K/Ar ages and geochemical analyses obtained on deep-sea samples dredged in 1999 on several seamounts of the Cook-Austral volcanic chains in the Pacific Ocean. The new geochemical results, together with published data on island samples, allow us to reveal a time evolution of the mantle source composition as well as an increase in geochemical variability of the superplume responsible for the regional South Pacific Superswell. Three identified volcanic stages of 58-40, 33-20 and 20-0 Ma are identified with signatures of mantle reservoir composition varying from close to C to N-MORB-types and C/HFMU-type, respectively. Using a geodynamic reconstruction for the most recent volcanic period, from 20 Ma to present, three hotspot... |
