VOLCANIC GEOMORPHOLOGY AND ORIGIN OF THE NAIFEH AND UNKNOWN SEAMOUNT CLUSTER, NORTH WEST HAWAIIAN RIDGE

Intraplate volcanism is a magmatic process that occurs distal from plate boundaries. The most commonly suggested causes for intraplate volcanism are mantle plumes, lithospheric deformation, edge-driven convection, and arch volcanism. In order to investigate the various causes of intraplate volcanism a wider range of seafloor features need to be explored and sampled. During expedition NA101 the E/V Nautilus explored two chains of seamounts and guyots that sit 250-300 km northeast of Gardner Pinnacle and Necker Seamount, Northwest Hawaiian Ridge (NWHR). The two chains, named the Naifeh Cluster and Unnamed Cluster incorporate nine seamounts and two guyots and reside within the Papahānaumokuākea Marine National Monument. Here we present preliminary ⁴⁰Ar/³⁹Ar age determinations that indicate the seamounts predate any volcanism along the Hawaiian or Emperor Ridges. The geodynamic process that created the Naifeh and Unnamed Clusters are not well-constrained, although our model suggests a possible relationship to the seafloor fabric. The volcanism here is neither age-progressive nor contemporaneous with adjacent seamounts along the NWHR, which indicates these seamounts are not derived from mantle plume processes but more likely associated with tectonic processes in the region.