Figure F5. A. Correlation between Ba flux in subducted sediment and Ba enrichment of arc basalts for various arcs (Ant = Northern Antilles, Mar = Mariana, T = Tonga, Mex = Mexico, J = Java, Al = Aleutians, and G = Guatemala) around the world (after Plank and Langmuir, 1993). Open circles = three different sediment flux estimates for the Mariana, based on the three ODP sites drilled during Leg 129 (800-802) (Plank and Langmuir, 1998). Note Izu volcanics are lower in Ba/Na than Mariana volcanics by a factor of two. Drilling at Site 1149 will help to test if the low Ba/Na of the Izu volcanics is related to a lower Ba sediment flux. Shown for reference are the average Mariana Ba sediment flux and the flux for a 400-m section of chert (with 125 ppm Ba, similar to the upper radiolarites in Hole 801C; Karl, et al., 1992). B. Contrasting Pb isotopic composition of Mariana (open circle) and Izu-Bonin (solid circle) arc volcanics. Mariana volcanics form a mixing trend (arrow), almost perfectly coincident with mixtures of ODP Site 801 sediment (open boxes) and basalt (solid boxes) averages. Drilling at Site 1149 will test whether the Izu-Bonin arc trend (arrow) is consistent with different subducted material than that from the Mariana. Modern Pacific MORB data are shown for reference. Data sources: Elliott et al., 1997; Gill et al., 1994; Plank and Langmuir, 1998; Castillo et al., 1992.