Figure F1. Diagram of total alkalis vs. silica, recalculated on a volatile-free basis, for volcaniclastic sediments drilled in the Tiarei area in Tahiti. Solid circles = fine-grained volcaniclastic sediments, open triangles = more altered coarse-grained volcaniclast samples, solid triangles = less altered coarse-grained volcaniclast samples (high degree of alteration based on unusually very low incompatible trace element content). A, B, and C fields = magmatic lineages identified in Tahiti (e.g., Duncan et al., 1987; Cheng et al., 1993).
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