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B 2143 Figure 31A

B 2143 Figure 31B

Figure 31. Radiometric ages of minerals in sample 796-48,277: A, Internal isochron showing mineral age of the monazite (4328.5 Ma), which replaced the host limestone marble and occurs as abundant inclusions in alkali amphibole; B, 40Ar/39Ar plateau showing age (343.13.0 Ma) of the coexisting alkali amphibole that replaced the monazite.

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Last updated 01.26.98