TEMPORAL GEOCHEMICAL EVOLUTION IN OCEANIC INTRAPLATE VOLCANICS - A CASE-STUDY FROM THE MARQUESAS (FRENCH-POLYNESIA) AND COMPARISON WITH OTHER HOTSPOTS

Abstract

Sr-, Nd-isotopic and trace element data are reported for a suite of Marquesan volcanic rocks. These data complement earlier work on the island of Ua Pou and reveal that the marked shifts in source composition between shield-building and post-shield eruptives noted there are common to most islands in the archipelago. In addition, there appears to be a relationship between the magnitude of these shifts and the repose period between shield-building and post-shield activity such that, the longer the period of volcanic inactivity, the larger the isotopic and trace element differences between the two phases of volcanism. This, coupled with the compositional uniformity of the shield-building phase,..