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Figure 7. Plot of (A) Zr and (B) Nb versus 104 × Ga/Al for basement rocks from the field trip area, compared to Neoproterozoic A-type granitoids from the central Appalachians (shaded field, 150 analyses from Tollo and Aleinikoff, 1996; Tollo and others, in press a). Diagrams modified after Whalen and others (1987). Symbols are the same as in figure 4. |