Paper No. 6
Presentation Time: 9:50 AM
LEAD AND SULFUR ISOTOPIC STUDIES APPLIED TO THE PROVENANCE OF GALENA ARTIFACTS IN NATIVE AMERICAN BURIAL AND HABITATION SITES - SOUTHEASTERN AND CENTRAL UNITED STATES
The provenance of galena artifacts recovered from late Archaic – Mississippian archaeological burial and habitation sites in southeastern and central United States, ranging from Florida to Oklahoma, has been determined by combined lead and sulfur isotope measurements. A lead isotope database of Mid Continental ore deposits allows us to determine, with a fair degree of certainty, the source of the galena found at these sites. Most of the seventeen archaeological burial/habitation sites selected for this study contain galena artifacts that have a very restricted range in 206Pb/204 Pb ratios (21.8-22.1) and two groups of sulfur isotopic values δ 34S (+5.0 to 0 and -5 to -7). Lead ore deposits in the midcontinent are stratabound, “Mississippi Valley” type deposits that are characterized by very radiogenic lead isotopic ratios, matching the observed isotopic ratios of the galena artifacts. Mississippi Valley galena deposits can have significant variation in lead isotopic ratios ranging from variations within individual crystals to mine and region-wide variations. The combined lead and sulfur isotopic values of the artifacts suggest that the Central Missouri lead district was the most likely source of galena for fourteen of the sites. Three sites, located in Oklahoma, Missouri and Illinois have isotopic characteristics indicating a source associated with the Upper Mississippi Valley lead district. The available evidence indicates no significant change in the source of galena for a time span of over a thousand years.