Geochemical and Geochronological Data for Tama Seamount and Rarotonga Island, Cook Islands

This dataset presents new geochemical and geochronological data for volcanic rocks from the Cook Islands region, southwest Pacific Ocean, generated to evaluate the origin and activity of the proposed Rarotonga hotspot. Samples include submarine lavas dredged from the previously unsampled Tama Seamount (~80 km east–southeast of Rarotonga Island), lavas from the submarine flanks of Rarotonga Island, and a suite of xenoliths recovered from Tama Seamount. The xenolith assemblage includes OIB-type igneous rocks (nepheline syenite and hornblendite), MORB-type gabbro and basalt, and a peridotite, sampling multiple levels of the oceanic lithosphere.
The dataset comprises whole-rock major element concentrations (ICP-OES), trace element concentrations (ICP-MS), and high-precision radiogenic isotope ratios (Sr–Nd–Pb) measured by TIMS and MC-ICP-MS. New geochronological constraints are provided by 40Ar/39Ar incremental-heating ages of lava groundmass and biotite, and by zircon U–Pb ages obtained by LA–ICP–MS from a nepheline syenite xenolith. The age data document volcanism at Tama Seamount between ~0.82 and 0.66 Ma, younger than volcanism on Rarotonga Island.
These data enable direct comparison between Tama Seamount, Rarotonga Island, and other Cook–Austral volcanic centers, and provide new constraints on mantle source characteristics, lithospheric structure, and age–distance relationships along Pacific plate flowlines.