Study of marble provenience in antique artifacts found at Histria and Tomis

The importance of assigning a correct provenience of ancient marble artifacts in detecting forgeries and in associating broken or separated fragments is obvious. The first use of isotopic analysis for marble provenience studies was that of Craig and Craig in 1972. The stable isotopic signature technique uses the deviation ratios for 13 C / 12 C and 18 O / 16 O relative to a conventional standard. This deviation is expressed as δ13 C and δ18 O. By statistical treatment of the data from the data base of some classical Greek and Roman marble quarries it could be possible to locate and to fix the extension of every quarry distribution point (δ13 C, δ18 O) as a scatter plot of these values. The quarry statistical characteristics could be described by a bivariate Gaussian distribution. Some marble artifacts found at Histria and Tomis sites were analyzed to determine their provenience using stable isotopic analysis and petrography. The main petrographic features are accessory mineral content, grain size, structures and texture. Comparison between the isotopic values of the samples and the ancient quarry data base was carried out by statistical methods. This allowed to find for every sample the confidence level of the provenience of any quarry of the data base, or the probability that any random point (13 C/12 C, 18 O/16 O) of a specific quarry falls to a distance greater than that of the measured sample point. (authors)