Geology and petrology of Raiatea Island (Society islands, French Polynesia)

Raiatea Island is made up of an alkali basaltic shield volcano, the upper 1000 m of which were emplaced between 2.75 and 2.52 Ma with an average construction rate of ca. 4 mm/year. Trachytic lavas were then emplaced between 2.54 and 2.44 Ma, both as flows and plugs along N-S trending fractures. Their geochemical characteristics point to a fractionation-controlled derivation from the basaltic magmas. Our new age set is consistent with a Pacific plate motion of 11 cm/year with respect to a fixed Society plume. (authors)