Many oceanic volcano chains are formed by hotspots in the Earth's mantle. Most of the volcanism associated with hotspots is thought to occur directly over the mantle hotspot constructing features Hawaiian, Canary, Society island chains. However, this main phase is commonly followed by a period of quiescence and then a secondary volcanic phase. Diamond Head volcano on O`ahu, Hawaii, is a textbook example of secondary volcanism. The cause of such late-stage volcanism remains an enigma.
This three-year project, funded jointly by the Divisions of Earth and Ocean Sciences, will examine the what (compositions), where (distribution and volumes), when (ages), and why (mechanisms) of secondary volcanism on and around the northern Hawaiian Islands. It is a coordinated land- and sea-based project with four main phases: (1) onshore mapping, sampling, and compilation of water well information to determine the volumes, ages and compositions of rejuvenated volcanism on Kaua`i and O`ahu. (2) A 28-day marine expedition to map the Kaua`i and Ni`ihau submarine volcanic fields with multibeam bathymetry and acoustic imagery, and to sample many of its volcanoes using the JASON2 ROV to characterize the petrology, geochemistry (major & trace elements, and isotopes) and ages of these lavas. (3) Integration of these results with previous surveys and petrologic/geochemical studies to establish a quantitative database for Hawaiian volcanic evolution. (4) Geodynamic modeling of this database to evaluate mechanisms for secondary volcanism. A first-order objective will be to establish how the submarine form of volcanism relates in space, time, volume, and composition to the nearby main shield volcanoes and their associated onshore secondary volcanism. Results will feed numerical modeling efforts to test proposed origins of secondary volcanism such as small-scale mantle convection driven by thermal and/or compositional buoyancy.
The broader impacts of the proposed project include a K-12 interactive education program involving lesson-planning and interactive web activities with sciences classes throughout the state of Hawaii before, during and after our marine work. Also, we will mentor several graduate and undergraduate students on research projects. We will recruit underrepresented students in our research, give public lectures to school groups and the local community on Hawaiian volcanism, and gain a better understanding of the volcanic environment which impacts all life in Hawaii.
