Volatile cycling of H2O, CO2, F, and Cl in the HIMU mantle : a new window provided by melt inclusions from oceanic hot spot lavas at Mangaia, Cook Islands
Cabral, Rita A.
Jackson, Matthew G.
Koga, Kenneth T.
Rose-Koga, Estelle F.
Hauri, Erik H.
Whitehouse, Martin J.
Price, Allison A.
Day, James M. D.
Kelley, Katherine A.
MetadataShow full item record
Mangaia hosts the most radiogenic Pb-isotopic compositions observed in ocean island basalts and represents the HIMU (high µ = 238U/204Pb) mantle end-member, thought to result from recycled oceanic crust. Complete geochemical characterization of the HIMU mantle end-member has been inhibited due to a lack of deep submarine glass samples from HIMU localities. We homogenized olivine-hosted melt inclusions separated from Mangaia lavas and the resulting glassy inclusions made possible the first volatile abundances to be obtained from the HIMU mantle end-member. We also report major and trace element abundances and Pb-isotopic ratios on the inclusions, which have HIMU isotopic fingerprints. We evaluate the samples for processes that could modify the volatile and trace element abundances postmantle melting, including diffusive Fe and H2O loss, degassing, and assimilation. H2O/Ce ratios vary from 119 to 245 in the most pristine Mangaia inclusions; excluding an inclusion that shows evidence for assimilation, the primary magmatic H2O/Ce ratios vary up to ∼200, and are consistent with significant dehydration of oceanic crust during subduction and long-term storage in the mantle. CO2 concentrations range up to 2346 ppm CO2 in the inclusions. Relatively high CO2 in the inclusions, combined with previous observations of carbonate blebs in other Mangaia melt inclusions, highlight the importance of CO2 for the generation of the HIMU mantle. F/Nd ratios in the inclusions (30 ± 9; 2σ standard deviation) are higher than the canonical ratio observed in oceanic lavas, and Cl/K ratios (0.079 ± 0.028) fall in the range of pristine mantle (0.02–0.08).
Author Posting. © American Geophysical Union, 2014. This article is posted here by permission of American Geophysical Union for personal use, not for redistribution. The definitive version was published in Geochemistry, Geophysics, Geosystems 15 (2014): 4445–4467, doi:10.1002/2014GC005473.
Showing items related by title, author, creator and subject.
Shimizu, Kenji; Shimizu, Nobumichi; Komiya, Tsuyoshi; Suzuki, Katsuhiko; Maruyama, Shigenori; Tatsumi, Yoshiyuki (2009-07)The volatile content of komatiite is a key to constrain the thermal and chemical evolution of the deep Earth. We report the volatile contents with major and trace element compositions of ~ 80 melt inclusions in chromian ...
Wanless, V. Dorsey; Shaw, Alison M.; Behn, Mark D.; Soule, Samuel A.; Escartin, Javier E.; Hamelin, Cedric (John Wiley & Sons, 2015-01-20)Here we present volatile, major, and trace element concentrations of 64 olivine-hosted melt inclusions from the Lucky Strike segment on the mid-Atlantic ridge. Lucky Strike is one of two locations where a crustal melt lens ...
Boron isotopic composition of olivine-hosted melt inclusions from Gorgona komatiites, Colombia : new evidence supporting wet komatiite origin Gurenko, Andrey A.; Kamenetsky, Vadim S. (2011-09-11)A fundamental question in the genesis of komatiites is whether 30 these rocks originate from partial melting of dry and hot mantle, 400−500°C hotter than typical sources of MORB and OIB magmas, or if they were produced ...