Case Studies:Case study 40

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[edit] Analysis of Metavolcanic Rocks from the Vicinity of Fort Bragg, North Carolina

Brent V. Miller

[edit] Abstract

Samples of metamorphosed volcanic flows (dacite, andesite, and rhyolite) or metamorphosed volcanic-sedimentary detritus of similar composition (e.g.,mudstones of water-lain ash) were selected from archaeological quarry sites in southcentral North Carolina. Each site is identified as a potential raw-material source quarry for prehistoric Native American artifacts found on Fort Bragg. One cluster of quarries was sampled extensively to test for smaller-scale variability within a quarry group. This case study documents the results conducted to test methods of geochemical and isotopic discrimination of the prehistoric quarry sites. This is used for tracing Native Peoples' trading and travel routes in the southeastern United States. The Nd isotopic composition of rock samples from quarry sites clearly discrminate the Uwharrie 1, Cape Fear, Chatham 1 group of quarries. The Nd isotopic composition of samples from sites within the more extensively sampled Uwharries 1 group of quarries show good distinction that corresponds to a geological map unit.

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Samarium-Neodymium Isotope and Trace-Element Analysis of Metavolcanic Rocks from the Vicinity of Fort Bragg, North Carolina: A Pilot Study of Artifact Source Quarry Discriminatione.