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2008 annual meeting – Spruce Pine Mining District: Little Switzerland, North Carolina
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FIGURE CAPTIONS
Figure 1. Geochronology of the Spruce Pine area. The histogram is based on work by Goldberg and
Dallmeyer (1997) on amphibolite, mica schist and gneiss; the country rocks for the Spruce Pine plutonic
suite. Garnet ages are by Nd-Sm, hornblende ages are by Rb-Sr and Ar-Ar, muscovite dates are by Ar-Ar.
Ages of the Spruce Pine granitic rocks are shown by arrows over the top of the histogram and include U-Pb
ages on uraninite (Aldrich et al., 1958) and zircon (Johnson et al., 2001), Rb-Sr whole rock isochrons on
pegmatites (Kish, 1983, 1989), and K-Ar dates on muscovite as compiled by Lesure (1968). Below the
histogram is the model for deformation (F1, F2, F3) and metamorphism (M1, M2, M3) in the Spruce Pine
area as proposed by Butler (1973).
Figure 2. General geology (modified from Brobst, 1962) of the Minpro pluton and the location of the
LUF1 pegmatite (Luf).
Figure 3. Geologic map of a portion of the LUF1 pegmatite.
Figure 4. Composition of muscovite from the LUF1 pegmatite compared to muscovite from other Spruce
Pine pegmatites.
Figure 5. Compositions of muscovite from the LUF1 pegmatite and other Spruce Pine granitic rocks
compared to the field for igneous white mica from granitic rocks (Miller et al., 1981).
Figure 6. Composition of garnet from the LUF1 pegmatite compared to garnet from other Spruce Pine
granitic rocks. The other Spruce Pine granitic rocks include samples from Deer Park pegmatite (DP),
Crabtree Creek Falls pegmatite (CTCF), McKinney Mine pegmatite (MP), Sink Hole pegmatite (SH), and
Day Book pegmatite (DB).
Figure 7. Melting relations of the Spruce Pine granite taken from Vaughn (1963) and Fenn (unpublished
data). Cooling paths for LUF feldspars (LUF Fs) are based on estimates of pre-exsolution feldspars
following the methods of Whitney and Stormer (1977). See text for details.
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