Petrology and geochronology of volcanic rocks from seamounts along and near the Hawaiian Ridge: Implications for propagation rate of the ridge

Abstract

Lavas from three seamounts along and three seamounts near the Hawaiian Ridge are petrographically and geochernically similar to lavas from the Hawaiian Islands. Rock types recovered include tholeftic and alkalic lavas. The composition of these lavas is virtually identical to that of lavas from the Hawaiian Islands. This indicates that the source composition and petrogenesis of lavas along the Hawaiian chain are very consistent. The three along-ridge seamounts are in areas where there were gaps in the radiometric age data base. New ages further document the linear age progression along the chain and define a new propagation rate of 9.6±0.4 cm/yr (which is identical to the present-day plate motion of the island of Hawaii). The near-ridge seamounts are Cretaceous in age (74–77 Ma) and are part of NNW-trending linear chains that predate and are unrelated to the NW- and N-trending Hawaiian and Emperor chains.