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2008 annual meeting – Spruce Pine Mining District: Little Switzerland, North Carolina
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The weak zoning, presence of a quartz core, and the gradual coarsening of the graphic
feldspar-quartz intergrowths toward the core of the LUF1 pegmatite are features of many
Spruce Pine pegmatites (Olson, 1944; Lesure, 1968). Post-magmatic deformation;
deformed quartz and feldspar, and the mortar structure found in the LUF1 pegmatite are
common in other Spruce Pine granitic rocks. Overall, the LUF1 system appears to be a
good model for the Spruce Pine granitic rocks and pegmatites.
Muscovite class pegmatites, such as LUF1 and other Spruce Pine pegmatites, crystallize
at moderate to high pressure from magmas generated by anatectic melting (Ĉerný, 1991;
London, 2008). Cooling of these deep-seated mica pegmatites is slow, resulting in a
range of cooling ages and post-magmatic deformation and recrystallization.
ACKNOWLEDGMENTS
The late Dick Jahns was a friend of Spruce Pine pegmatites and his guidance in the early
stages of this study is acknowledged. Alex Glover was a valuable guide to many of the
Spruce Pine pegmatites during later stages of this study. Chris Fleisher aided with the
electron microprobe analyses at the University of Georgia and W. C. Luth did the
feldspar analyses at Sandia National Laboratory. The Geology Department of the
University of Georgia and the Geology Department at Appalachian State University
supported this study. Brian Veal worked with the author on studies of Spruce Pine
pegmatites and was a valuable colleague.
REFERENCES CITED
Abbott, R.N., Jr., and Raymond, L.A., 1984, The Ashe metamorphic suite northwest North Carolina:
Metamorphism and observations on geologic history: American Journal of Science, v. 284, p. 350-375.
Adams, M.G., Stewart, K.G., Trupe, C.H., and Willard, R.A., 1995, Tectonic significance of high-pressure
metamorphic rocks and dextral strike-slip faulting along the Taconic suture, in: J. P. Hibbard, C. R. van
Stall, and P.A. Cawood, eds., Current Perspectives in the Appalachian-Caledonian Orogen: Geological
Association of Canada Special Paper 41, p. 21-42.
Adams, M.G., and Trupe, C.H.,1997. Conditions and timing of metamorphism in the Blue Ridge thrust
complex, northwestern North Carolina and eastern Tennessee, in K. G. Stewart, M. G. Adams, and C. H.
Trupe, eds., Paleozoic Structure, Metamorphism, and the Tectonics of the Blue Ridge of Western North
Carolina: Carolina Geological Society 1997 Field Trip Guidebook, p. 33-47.
Aldrich, L.T., Wetherill, G.W., Davis, G.L., and Tilton, G.R., 1958, Radioactive ages of micas from
granitic rocks by Rb-Sr and K-Ar methods: Transactions of the American Geophysical Union, v. 39, p.
1124-1134.
Brobst, D.A., 1962, Geology of the Spruce Pine District, Avery, Mitchell and Yancey Counties, North
Carolina: U.S. Geological Survey Bulletin, 1122-A, 62p.
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