Neutron activation analysis of Mediterranean volcanic rocks – An analytical database for archaeological stratigraphy

Pumice has been used as a serviceable abrasive or religious artifact since antiquity and has therefore been an object of trade. By analyzing pumice samples from archaeological excavations and comparing the results to an analytical database, it is possible to establish the origin of the sample and thereby get information on the maximum age and the transport route of the pumice sample. In addition, the deposition of primary tephra deposits can be used as time markers, and place constraints on the ages of archaeological materials.Neutron activation analysis (NAA) was applied to determine the concentrations of 25 elements (As, Ba, Ce, Co, Cr, Cs, Eu, Fe, Hf, K, La, Lu, Na, Nd, Rb, Sb, Sc, Sm, Ta, Tb, Th, U, Yb, Zn and Zr) in pumice samples from the Mediterranean region: Milos, Santorini, Kos, Giali and Nisyros (Greece), Lipari (Italy) and Cappadokia (Turkey). It was found that eruption products like pumice or volcanic ash can be correlated in many cases to their volcanic sources by comparison of the typical main- and trace-elemental concentration patterns (“chemical fingerprint”). Such a distinction is possible if the volcanic rocks are homogenous enough with respect to the concentrations of geochemically relevant elements. Using only the pure glass fraction of tephra, a sample size of 5 mg is sufficient for identification by NAA.