Reports

Lead Isotope Identification of Sources of Galena from Some Prehistoric Indian Sites in Ontario, Canada

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Science  08 Feb 1980:
Vol. 207, Issue 4431, pp. 640-643
DOI: 10.1126/science.207.4431.640

Abstract

Lead isotopic compositions of 12 galenas from five late Archaic-initial Woodland grave and habitation sites in southern Ontario have made it possible to determine the "most likely" source areas for the galenas. For one of the oldest sites (Finlan), the most likely source is in the southwestern Upper Mississippi Valley (Wisconsin-Illinois-Iowa) mineral district. The seven Finlan galenas exhibit a range of isotopic ratios; three of the largest specimens have substantial isotopic variations (up to 1.8 percent in the ratio of lead-207 to lead-206) on a scale of a few centimeters. This suggests that the lead isotopic zoning ascribed to the Upper Mississippi Valley area is not sufficiently well defined to enable us to determine if all the Finlan samples were derived from a single mineral deposit. Galenas from the other sites (Constance Bay, Hind, Bruce Boyd, and Picton) most probably originated in the southeastern Ontario-northwestern New York area. Isotopic differences among the Constance Bay, Hind, and Bruce Boyd galenas, on the one hand, and the Picton galena, on the other, suggest that at least two distinct sources in that region were exploited.