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Removal of Coal Contaminants from Chaco Canyon Radiocarbon Samples

Author(s): Kenneth Tankersley

Year: 2017

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Summary

Micro-flotation, a specific gravity separation technique, was successfully used to remove coal contaminants from radiocarbon samples obtained from profiles, unit excavations, and solid sediment cores in Chaco Canyon, New Mexico. Coal from the Cretaceous Menefee Formation occurs throughout Chaco Canyon in aeolian, alluvial, colluvial, and anthropogenic sediments. The Menefee Formation contains carbonized broadleaf angiosperm and gymnosperm plants and, as such, paleobotanical analysis was not effective in the identification and removal of coal contaminants. The effectiveness of micro-flotation as a pretreatment procedure was evaluated by: i) comparing AMS radiocarbon ages on processed and unprocessed samples from the same archaeological contexts; ii) comparing a processed sample of carbonized hardwood charcoal with a sample of uncarbonized hardwood from the same archaeological context; and iii) comparing radiocarbon ages on a split sample of processed bulk carbon. The comparisons confirmed the effectiveness of micro-flotation in processing samples for radiocarbon dating in Chaco Canyon and would be applicable for similar locations elsewhere in the world.


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Removal of Coal Contaminants from Chaco Canyon Radiocarbon Samples. Kenneth Tankersley. Presented at The 81st Annual Meeting of the Society for American Archaeology, Vancouver, British Columbia. 2017 ( tDAR id: 429775)


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Spatial Coverage

min long: -115.532; min lat: 30.676 ; max long: -102.349; max lat: 42.033 ;

Record Identifiers

Abstract Id(s): 16297

Arizona State University The Andrew W. Mellon Foundation National Science Foundation National Endowment for the Humanities Society for American Archaeology Archaeological Institute of America