--> Abstract: Determining the Volatile Budget of the Galapagos Plume: Contributions from Deep and Shallow Sources, by Mary E. Peterson, Alberto E. Saal, Erik H. Hauri, Mark D. Kurz, Reinhard Werner, Folkmar Hauff, Dennis J. Geist, and Karen S. Harpp; #90181(2013)

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Determining the Volatile Budget of the Galapagos Plume: Contributions from Deep and Shallow Sources

Mary E. Peterson1, Alberto E. Saal1, Erik H. Hauri2, Mark D. Kurz3, Reinhard Werner4, Folkmar Hauff4, Dennis J. Geist5, and Karen S. Harpp6
1Brown University, Providence, RI
2Carnegie Institution of Washington, Washington DC
3Woods Hole Oceanographic Institute, Woods Hole, MA
4GEOMAR, Kiel, Germany
5University of Idaho, Moscow, ID
6Colgate University, Hamilton, NY

The study of volatiles (H2O, CO2, F, S, and Cl) is important because volatiles strongly influence properties and processes in the mantle. We present new volatile data obtained from 89 submarine glass chips, which show variations between regional mantle sources forming the Galapagos plume. Our glasses show 4 end-member compositions: a group with a plume signature (3He/4He >20*atmospheric ratio), two trace element enriched groups, and a trace element depleted group. We use ratios in this discussion to account for melting and crystal fractionation. Degassing has affected the concentration of CO2. However, variable amounts of degassing in this suite are evidence for a characteristic slow eruption rate shared between plumes. Assimilation of hydrothermally altered material has increased the volatile concentrations of the trace element depleted group. This increase, however, is correlated with plagioclase contamination, showing the contamination occurs in the lower crust. The high 3He/4He group falls at a lower H2O/Ce than expected for a plume, indicating that the Galapagos plume may be more viscous than previously thought. This group also has a F/Nd ratio equivalent to the primitive mantle, while the two trace element enriched groups average higher values of F/Nd. This has the two-fold implication of tying F to an indicator of source and adding to the body of evidence that suggests the high 3He/4He component is sampling primitive mantle. Our results can be applied to volatile studies of other plumes, expanding our knowledge of the volatile budget of the mantle.

AAPG Search and Discovery Article #90181©2013 AAPG/SEG Rocky Mountain Rendezvous, University of Wyoming, Laramie, Wyoming, September 27-30, 2013