Chemical Recycling in Subduction Zones: Implications from B-Be-Li and Be Isotope Studies of Forearc Rocks

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In order to understand the recycling behavior of subduction-related fluids through forearc regions at convergent margins, and to better understand the origins of volcanic rock types unique to forearc regions, a study of B, Li, and 10/9Be systematics will be undertaken on suites of forearc lavas from Mexico, the Woodlark Basin and from Panama, and on serpentinites emplaced diapirically in the Marianas and Izu forearcs. Analyses for B, Be, and Li will be conducted by IC plasma spectrometry at Florida International University, while 10Be measurements will be made at the Department of Terrestrial Magnetism. Measurements of B and 10Be, unquivocal indicators of a subducted origin, will aid in identifying the sources of serpentinizing fluids in the Izu and Marianas and the magnitude of these fluid fluxes through the forearc. As in island arc volcanic rocks, measurements of light elements in forearc volcanics will allow us to identify and quantify the effects of subducted components, as well as to define the method by which trace elements are transported from the slab into lavas. Light element data from forearcs will be compared and combined with the existent database on arc volcanic rock in order to create a detailed model for the chemical cycle of fluids in subduction zones.