Pictographs sampling

Given typically only 0.1 mg carbon is extracted from pictograph samples as CO2, we realized that we should be able to obtain non-destructive radiocarbon dates and stable isotopic carbon analyses on many perishable archaeological artifacts. Currently, for radiocarbon dating, subgram samples are removed from artifacts and destroyed during combustion extraction of CO2. Plasma extraction does not require the removal of material from an object for destructive analysis. The characteristics of plasma extraction have great potential for the study of artifacts associated with burials, where the least intrusive techniques are especially critical. Museum artifacts such as basketry,... 

Although pictographs and petroglyphs have withstood hundreds, perhaps thousands of years of exposure, modem pollutants and vandalism, coupled with natural elements, have accelerated their destruction. Recently, scientists have used microscopic mineral sampling to measure the types of chemical elements found in picto-graph pigments. Additionally, studies have included the use of diversional watersheds, shelters, and application of protective adhesives to prevent rock art erosion. The continuing study of chemical compositions and rates of panel decay could one day lead to the discovery of a proper means by which to preserve these features indefinitely. 

The radiocarbon results for organic matter extracted from five different pictograph paint samples taken from Toca do Serrote da Bastiana, including the -20 cm tall red anthropomorph, are shown in Table II. The red paints contain iron ochre and the black ones are charcoal. The high uncertainty associated with 4BR312 is due to small sample size (--0.020 mg of carbon). We would not normally report a radiocarbon age on such a small sample, but the measurement is consist with the other radiocarbon results and shows that the age of the pictograph is certainly not 30,000-40,000 years old. Typically, >0.050 mg of carbon is necessary to obtain a viable radiocarbon age. 

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