Age, geochemistry and melt flux variations for the Hawaiian Ridge

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http://abstractsearch.agu.org/meetings/2012/FM/DI41B-02.html
Author(s): Garcia, M. O.; Weis, D. A.; Greene, A. R.; Wessel, P.; Harrison, L.; Tree, J. P.
Author Affiliation(s): Primary:
University of Hawaii, Honolulu, HI, United States
Other:
University of British Columbia, Vancouver, BC, Canada
Hawaii Pacific University, Honolulu, HI, United States
Volume Title: AGU 2012 fall meeting
Source: American Geophysical Union Fall Meeting, Vol.2012; American Geophysical Union 2012 fall meeting, San Francisco, CA, Dec. 3-7, 2012. Publisher: American Geophysical Union, Washington, DC, United States
Note: In English. 2 refs.
Summary: The Hawaiian Ridge portion of the Hawaiian-Emperor Chain, the classic example of a mantle plume produced linear island chain, is 6000 km in length, active for 80+ Myr, and tectonically simple. Despite its importance to our understanding of mantle plumes and Cenozoic plate motion, there are large data gaps for the age and geochemistry of lavas from volcanoes along the Hawaiian Ridge (HR) portion of the Chain. Ages: Only volcanoes near the Hawaiian-Emperor bend and in the Hawaiian Islands have modern Ar-Ar ages, leaving a gap of 2000 km where existing K-Ar ages suggest synchronous volcanism over a 1000 km section. Geochemistry: There is a 2900 km gap in high precision geochemical data for the HR. The Emperor Seamounts (>45 Ma) have better regional coverage of recent isotopic data and show a correlation of Sr isotope composition with age of the underlying oceanic lithosphere (Regelous et al. 2003). The HR has an unexplained, exponential increase in magma flux over the last 30 Myr (Vidal & Bonneville 2004). Potential explanations for the increase in magma flux include: changes in melting conditions (temperature and/or pressure), change in source fertility related to rock type (pyroxenite vs. peridotite) or previous melting history, and/or changes in plate stresses resulting from reconfigurations of plate motion. Our new multi-disciplinary project will: 1) Determine 40Ar/39Ar ages, and whole-rock major, trace element, and Pb, Sr, Nd and Hf isotopic geochemistry for lavas from 20 volcanoes spanning ≈2150 km of the HR (NW of the Hawaiian Islands). 2) Use the geochemical data 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 HR. If so, are they responsible for the 300% variation in melt production along the Ridge? Also, we will assess when the more fertile Loa source component appeared. 3) Reassess models for the origin of the HR using the new 40Ar/39Ar ages. 4) Recompute and compare the magma flux rate for the Hawaiian and Louisville Ridges using our new HR ages and IODP results for Louisville Ridge, and updated bathymetric data for both chains. 5) Utilize the new ages to revise Cenozoic Pacific plate motions and to compute differential motions as proxies for stress changes along the HR with time to evaluate the effects of plate motion on magma flux rate. These studies will have fundamental implications for mantle plume sources, plume dynamics, and plate kinematics. Vidal V, Bonneville A, 2004. J. Geophys. Res., 109, B03104, doi:10.1029/2003JB002559 Regelous M, Hofmann AW, Abouchami W, Galer SJG, 2003. Jour. Petrol. 44, 113-140
Year of Publication: 2012
Research Program: IODP Integrated Ocean Drilling Program
Key Words: 02 Geochemistry; Chemical composition; East Pacific; Geochemistry; Hawaiian Ridge; Integrated Ocean Drilling Program; North Pacific; Northeast Pacific; Pacific Ocean
Record ID: 2014090462
Copyright Information: GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data supplied by, and/or abstract, Copyright, American Geophysical Union, Washington, DC, United States

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