Micro-flotation removal of coal contaminants from archaeological radiocarbon samples from Chaco Canyon, New Mexico, USA. (April 2017)

• Record Type: Journal Article
• Authors: Tankersley, Kenneth Barnett; Owen, Lewis A.; Dunning, Nicholas P.; Fladd, Samantha G.; Bishop, Katelyn J.; Lentz, David L.; Slotten, Venicia
• Is Part Of: Journal of archaeological science. Volume 12(2017)
• Page Start: 66
• Page End: 73
• Publication Date: 2017-04
• Subjects: Micro-flotation -- Specific gravity separation -- Coal -- Contaminant -- Chaco Canyon -- New Mexico -- Ancestral Puebloan -- Southwestern North America -- Sediment cores -- Bulk carbon samples -- Radiocarbon samples; Archaeology -- Periodicals; Archaeology -- Research -- Periodicals; 930.1
• DOI: 10.1016/j.jasrep.2017.01.029
• Languages: English
• ISSNs: 2352-409X

Abstract

Abstract: 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, USA. 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. Highlights: Coal occurs in archaeological and geological contexts at Chaco Canyon, New Mexico. Coal is a radiocarbon sample contaminant at Chaco Canyon and at other locations around the world. Micro-flotation removed coal contaminants from geological and archaeological radiocarbon samples from Chaco Canyon. Micro-flotation can remove coal and other forms of ancient carbon contaminants from radiocarbon samples.