ESR STUDY OF THERMAL HISTORY AND DATING OF A STONE TOOL

Electron spin resonance (ESR) of Fe3+ ions and of radiation-induced ce nters in quartz (E', peroxy and Al centers) was studied to distinguish between burnt and unburnt stone tools and to determine their age. The yellow stone tool with a reddish edge discovered at the paleolithic s ite in Kamitakamori, northern Japan, was investigated. The ESR spectru m intensity of Fe3+ ions around g = 4.3 and the color of the material changed at 600 degrees C and 240 degrees C, respectively, which indica tes that the red part was heated at 240-600 degrees C. The E' center i n the red part was used for dating because isochronal annealing experi ments showed low thermal stability of the Al center and overlap of bro ad signals at g = 2.0086 onto the peroxy center. Assuming the same eff iciency of defect formation in the red part as of that in the laborato ry-heated material at 450 degrees C, the obtained age of 520-770 ka is in concordance with the ages of the tephra layers at the site.