COMPARING MAGNETIC PROPERTIES AND GEOCHEMICAL MEASUREMENTS OF OBSIDIAN

The magnetic properties of obsidian flows vary significantly and hold great promise as a tool for discriminating between groups of obsidian specimens and correlating archaeological artifacts to specific volcanic sources. Typically such provenance studies utilize compositional (usually trace-element concentrations) and geochronologic data. In this context, magnetic measurements are seen as a complementary approach that is nondestructive, quick and inexpensive. This study compares magnetic measurements from 430 individual obsidian specimens to elemental concentrations (20 major and trace elements) collected from the same specimens using electron microprobe analysis. The geographic focus of this study is southwest Asia, especially Turkey. Broadly speaking, both the intensity of natural remanent magnetization and values of low-field susceptibility are negatively-correlated with concentrations of FeO, TiO₂, and MnO, and positively-correlated with concentrations of SiO₂ and Al₂O₃. Continuing research will examine relationships among expanded elemental concentrations and geographic ranges, and will also incorporate magnetic hysteresis measurements.