Direct Radiocarbon Dating of Rock Art

Abstract

ABSTRACT. In 14C dating of pictographs, we use a low-temperature oxygen plasma coupled with high-vacuum techniques to selectively remove carbon-containing material in the paint without contamination from the rock substrate, even if limestone (CaCO3). In addition to one previously published measurement, we analyzed two more pictograph samples, which are in accord with archaeological inference. A sample of known age charcoal, also processed by our method, matched the control. This technique produces little mass fractionation, the maximum 813C being 0.16%o from the untreated sample. Limestone decomposition does not occur during our procedure. Although the technique development is in its infancy, these new results demonstrate that our non-destructive technique has great potential for producing accurate 14C ages.

Analysis of the rock accretions in the lower pecos region of southwest texas

“…Radiocarbon assays have been reported on three Pecos River pictographs, with ages ranging from 3000 to 4200 years B.P. (Russ et al, 1992). These dates agree with the 3000-4000 year interval Turpin (1990) suggested based on evidence of peak population intervals.…”

“…Thus there is potential for obtaining chronological information based on dating the oxalate in the accretion. The 14C dates of the oxalate crusts are similar to the reported ages of the pictographs (Russ et al, 1992;Turpin, 19901, but further research is needed to determine whether the crusts have distinct temporal sequences.…”

Nondestructive Radiocarbon Dating: Naturally Mummified Infant Bundle from SW Texas

“…The primary advantage of this process is that the low temperatures of the plasma gas (50-150ºC depending upon our operating conditions) are below the decomposition temperatures of carboncontaining minerals. This allows the plasma to selectively remove only organic carbon from a sample and leave accompanying carbonates and oxalates intact (Chaffee et al 1994;Russ et al 1992). …”

Radiocarbon Dating of Ancient Rock Paintings

“…Our dates are compared with materials of known age ( Figure 3) to ensure that this criterion is met. [16][17][18][19][20] Extraction of the organic carbon must not introduce significant mass fractionation, and, as seen in Figure 2, one needs to be able to separate the organic matter from the paint sample without contamination from limestone or calcium oxalate, either of which would nullify a date. Our measurements of δ 13 C indicate that plasma chemical extraction does not introduce significant fractionation of the carbon isotopes.…”