Beatrice, C.

Ferrara, E.

Miola, F.

Pavesio, E.

Perino, A

Tema, E.

Zanella, E.

English

Institutional Research Information System University of Turin

Geophysical Research AbstractsVol. 20, EGU2018-8760, 2018EGU General Assembly 2018© Author(s) 2018. CC Attribution 4.0 license.Magnetic granulometry as a provenance proxy of archaeological obsidianin the MediterraneanEnzo Ferrara (1), Evdokia Tema (2,3), Elena Zanella (2,3), Cinzia Beatrice (1), Francesca Miola (1), ElenaPavesio (1), and Andrea Perino (1)(1) Istituto Nazionale di Ricerca Metrologica, Divisione Nanoscienze e Materiali, Italy (e.ferrara@inrim.it), (2) CentroInteruniversitario di Magnetismo Naturale – CIMAN, Peveragno, Italy, (3) Dipartimento di Scienze della Terra, Universitàdegli Studi di Torino, ItalyReconstructing the distribution of ancient obsidian tools is a valuable way to trace ancient trade routes during theNeolithic. Such lithic material is in fact suitable for provenance investigations due to the rarity and diversity of vol-canic sources where magma solidified as a vitreous rock. In the magmatic amorphous matrix of obsidian, in fact,crystal grains have variable compositions, distribution, and diameter. As some of them contain iron, their magneticbehavior can highlight changes in the amounts and sizes of the ferrous particles representative of different sources.As magnetic measurements are non-destructive, fast, and cheap, they gain advantage as an interesting alternative tothe conventional trace element analysis. The affordability of magnetic measurements is here explored comparingthe magnetic properties of 39 archaeological obsidians recovered in five Italian Neolithic sites (Brignano Frascata,Cascina Chiappona, Casalnoceto, Garbagna, and Castello D’Annone) spread along the river Tanaro in Piedmontto those of geological samples from Mediterranean islands (Lipari, Sardinia, Palmarola, Pantelleria, and Melos).Several magnetic parameters were investigated, namely: low field (χ) and anhysteretic (χa) susceptibility; satura-tion isothermal remanent magnetization at room (SIRM293) and liquid nitrogen (SIRM77) temperature; remanence(MR) and saturation magnetization (MS) as obtained from hysteresis cycles; anisotropy of low field susceptibility(P ). The latter, P , was functional to discriminate between the sources of Lipari and Sardinia SA, both havinglarge contents of superparamagnetic and single-domain grains, otherwise undistinguishable by standard magneticanalyses. Provenance was then attributed using graphic representations such as χa versus χ, and Qa = χa/χ versusSt = SIRM77/SIRM293, which are affected by the relative amount of single domain (SD) and smaller paramagneticgrains, suitable to identify samples from most of the Mediterranean sites. Furthermore, cluster analysis was appliedto the whole set of parameters, using the Euclidean distance between samples defined by the magnetic vectors af-ter data normalization and establishing correlations with the volcanic sources when geological and archaeologicalsamples fall in the same group. Using this procedure, most of the samples recovered from the Neolithic sites ofPiedmont are attributed to Lipari as the most probable Mediterranean source with very few exceptions, confirmingmagnetic grain-size analysis as a useful approach in sourcing obsidian archaeological items in the Mediterraneanregion.

Magnetic granulometry as a provenance proxy of archaeological obsidian in the Mediterranean.

https://iris.unito.it/bitstream/2318/1681013/1/EGU2018-8760.pdf

Magnetic granulometry as a provenance proxy of archaeological obsidian in the Mediterranean.

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