Keller, R. A. and Graham, D. W. and Farley, K. A. and Duncan, R. A. and Lupton, J. E. (2004) Cretaceous-to-recent record of elevated 3He/4He along the Hawaiian-Emperor volcanic chain. Geochemistry, Geophysics, Geosystems, 5 (12). 2004GC000739. ISSN 1525-2027 http://resolver.caltech.edu/CaltechAUTHORS:KELggg04
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Helium isotopes are a robust geochemical tracer of a primordial mantle component in hot spot volcanism. The high 3He/4He (up to 35 RA, where RA is the atmospheric 3He/4He ratio of 1.39 × 10−6) of some Hawaiian Island volcanism is perhaps the classic example. New results for picrites and basalts from the Hawaiian-Emperor seamount chain indicate that the hot spot has produced high 3He/4He lavas for at least the last 76 million years. Picrites erupted at 76 Ma have 3He/4He (10–14 RA), which is at the lower end of the range for the Hawaiian Islands but still above the range of modern mid-ocean ridge basalt (MORB; 6–10 RA). This was at a time when hot spot volcanism was occurring on thin lithosphere close to a spreading ridge and producing lava compositions otherwise nearly indistinguishable from MORB. After the hot spot and spreading center diverged during the Late Cretaceous, the hot spot produced lavas with significantly higher 3He/4He (up to 24 RA). Although 3He/4He ratios stabilized at relatively high values by 65 Ma, other chemical characteristics such as La/Yb and 87Sr/86Sr did not reach and stabilize at Hawaiian-Island-like values until ~45 Ma. Our limited 3He/4He record for the Hawaiian hot spot shows a poor correlation with plume flux estimates (calculated from bathymetry and residual gravity anomalies [Van Ark and Lin, 2004]). If 3He is a proxy for the quantity of primordial mantle material within the plume, then the lack of correlation between 3He/4He and calculated plume flux suggests that variation in primordial mantle flux is not the primary factor controlling total plume flux.
|Additional Information:||Copyright 2004 by the American Geophysical Union. Received: 6 April 2004; Revised: 8 September 2004; Accepted: 26 October 2004; Published: 31 December 2004. We are grateful to Asish Basu for use of unpublished helium data and to Marcel Regelous for assistance in selecting the Suiko Seamount samples. We are also grateful to Emily Van Ark and Jian Lin for sharing their plume flux calculations prior to publication. Analytical work on the ODP and DSDP samples was supported by NSF funds managed through the JOI/USSSP. The helium isotope laboratory at the Newport PMEL is supported by the NOAA Vents Program.|
|Subject Keywords:||Hawaiian-Emperor chain; helium; MORB; 1040 Geochemistry: Isotopic composition/chemistry; 8124 Tectonophysics: Earth's interior—composition and state (1212); 9355 Information Related to Geographic Region: Pacific Ocean|
|Official Citation:||Keller, R. A., D. W. Graham, K. A. Farley, R. A. Duncan, and J. E. Lupton (2004), Cretaceous-to-recent record of elevated 3He/4He along the Hawaiian-Emperor volcanic chain, Geochem. Geophys. Geosyst., 5, Q12L05, doi:10.1029/2004GC000739.|
|Usage Policy:||No commercial reproduction, distribution, display or performance rights in this work are provided.|
|Deposited By:||Archive Administrator|
|Deposited On:||19 Dec 2005|
|Last Modified:||26 Dec 2012 08:42|
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