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B 2143 Figure 32A

B 2143 Figure 32B

Figure 32. Radiometric ages of minerals in sample 8B7: A, Internal isochron showing mineral age of the bastnaesite (555+-11 Ma), which replaced the host dolostone marble; B, 40Ar/39Ar plateau showing age (395.5+-4.4 Ma) of the coexisting alkali amphibole.

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Last updated 01.26.98