Hawaiian Ridge Age, Source, Composition and Melt Flux Variations: Implications for Plume Dynamics and Plate Kinematics

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Intellectual Merit. Linear ocean island chains are one of the most distinctive features on our planet. The Hawaiian-Emperor Chain is the classic example. It is one of the longest chains on Earth, both in time and space, active for 80+ Myr and extending ~6000 km in length. The Chain is tectonically simple, being distant from any plate margin or continent for the last 70+ Myr. Despite its importance to our understanding of mantle plumes and Cenozoic plate motion, there are large gaps in our knowledge of the age and geochemical variations along the Hawaiian portion of the Chain. Also, it records an unexplained, dramatic increase in magma flux over the last 30 Myr. To address these gaps in our understanding, it is proposed to: [1] Provide new 40Ar/39Ar ages, and whole-rock major, trace and isotopic (Pb, Sr, Nd and Hf) geochemistry for lavas from 20 volcanoes that span ~2150 km of the Hawaiian Ridge (NW of the Hawaiian Islands) using existing rock samples from the University of Hawaii collection. The geochemical data will be used to determine the long-term evolution of the Hawaiian mantle plume source components and to evaluate whether there have been systematic variations in mantle potential temperature, melting pressure, and/or source lithology during the creation of the Hawaiian Ridge. To the extent regional variations occur, they will be exploited to constrain variation in melt production along the Ridge. [2] Compute and compare the magma flux for the Hawaiian and Louisville Ridges using new age and IODP results for Louisville Ridge, and updated bathymetric data. [3] Utilize the new ages to revise Cenozoic Pacific plate motions and to compute differential motions as proxies for stress changes along the Ridge over time so as to evaluate the influences of plate motion on magma production. This cross-disciplinary project is potentially transformative regarding our understanding of how oceanic island and seamount chains are formed and evolve, and also how life has propagated along the Hawaiian Ridge. For example, results from this project will allow biologists to make better predictions about biogeography of native Hawaiian species and their evolution. Also, this study has the potential to shift our current perception of how mantle plumes and plate tectonics influence one another. Broader Impacts. An education module will be developed that integrates research with education. It will focus on developing cooperative, inquiry-based teaching materials that effectively simulate research experiences and build partnerships between educators and scientists. An interactive laboratory module on the Hawaiian Ridge will also be published with a user-friendly guide that will be accessible to teachers on the well-known Carleton University education website (http://serc.carleton.edu/NAGTWorkshops/petrology/index.html) and advertised on education listserver sites. This guide will provide a foundation for instructors at the university level (both introductory and for more advanced undergraduate courses) to use pertinent new research on the world?s classic example of a linear island chain, the Hawaiian Ridge, to engage students in research-based learning. A post-doc, and graduate and undergraduate students will be mentored in this project. Project results will be published in the international literature and data archived in international databases (e.g., PetDB; GEOROC; GEOCHRON). All samples will be given unique identification numbers and splits made available to the geosciences community for other studies.