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.
Suggested CitationGeochemistry, Geophysics, Geosystems 15 (2014): 4445–4467
Showing items related by title, author, creator and subject.
Insight into volatile behavior at Nyamuragira volcano (D.R. Congo, Africa) through olivine-hosted melt inclusions Head, Elisabet M.; Shaw, Alison M.; Wallace, Paul J.; Sims, Kenneth W. W.; Carn, Simon A. (American Geophysical Union, 2011-10-04)We present new olivine-hosted melt inclusion volatile (H2O, CO2, S, Cl, F) and major element data from five historic eruptions of Nyamuragira volcano (1912, 1938, 1948, 1986, 2006). Host-olivine Mg#'s range from 71 to 84, ...
Volatile (F and Cl) concentrations in Iwate olivine-hosted melt inclusions indicating low-temperature subduction Rose-Koga, Estelle F.; Koga, Kenneth T.; Hamada, Morihisa; Helouis, Thomas; Whitehouse, Martin J.; Shimizu, Nobumichi (Springer, 2014-08-01)Investigation of olivine-hosted melt inclusions provides information about the abundance of volatile elements that are often lost during subaerial eruptions of lavas. We have measured the abundances of H2O, CO2, F, Cl, and ...
Trace element geochemistry of oceanic peridotites and silicate melt inclusions : implications for mantle melting and ocean ridge magmagenesis Johnson, Kevin T. M. (Massachusetts Institute of Technology and Woods Hole Oceanographic Institution, 1990-06-15)The mantle melting process is fundamental to basalt genesis and crustal accretion at mid-ocean ridges. It is believed that melts ascend more rapidly than the surrounding mantle, implying a process similar to fractional ...