Plasma oxidation and accelerator mass spectrometry of charcoal and inorganic Australian rock paintings

CHED 257

Jeremy L Mackey, mackey.jeremy@gmail.com1, Josh D Loewen, jlgfpr85@sbcglobal.net1, Karen L. Steelman, ksteel@uca.edu1, Josephine McDonald, JMcDonald@jmcdchm.com.au2, Peter Veth, peter.veth@aiatsis.gov.au2, and Thomas P Guilderson, guilderson1@popeye.llnl.gov3. (1) Department of Chemistry, University of Central Arkansas, 205 Laney Hall, 201 Donaghey Ave., Conway, AR 72035, (2) Centre for Cross-Cultural Studies, Australian National University, Canberra, ACT, 0200, Australia, (3) Center for AMS, LLNL, 7000 East Avenue, Mail Code L-397, Livermore, CA 94551
Rock paintings from the Australian Western Desert were radiocarbon dated using plasma oxidation and accelerator mass spectrometry. Nine charcoal and twelve inorganic-pigmented samples were treated with sodium hydroxide to remove potential humic acids. Plasma oxidation converted organic material in the paint samples to carbon dioxide and water. Samples of unpainted rock contained insignificant amounts of organic contamination, allowing for successful analyses. Bayesian statistical calibration, SHCal04, of ages ranging from 10±35 years BP (modern) to 3190±60 years BP demonstrated a precise calendar age range for samples from the same location consistent with known pre-historic occupation patterns. To our knowledge, this is the first instance that both charcoal and inorganic-pigmented paint samples have been dated from the same image. Results support the accuracy of using plasma oxidation to accurately radiocarbon date inorganic-pigmented paintings.
 

Undergraduate Research Poster Session: Analytical Chemistry
11:00 AM-1:00 PM, Monday, April 7, 2008 Morial Convention Center -- Hall A, Poster

Division of Chemical Education

The 235th ACS National Meeting, New Orleans, LA, April 6-10, 2008