Archaeomagnetic dating of a vitrified wall at the Late Bronze Age settlement of Misericordia (Serpa, Portugal)

The age of cooling of a vitrified wall at the Late Bronze/Second Iron Age settlement of Misericordia (Serpa, Portugal) has been determined using archaeomagnetic dating. Vitrification occurred in the Late Bronze Age (842–652 BC), in agreement with archaeological constraints based on the style of the potteries recovered at the site. This demonstrates the suitability of vitrified structures for archaeomagnetic dating and the potential for developing absolute chronologies for similar structures in Iberia and across Europe as a whole. Magnetite, low Ti-content titanomagnetite and, to a lesser extent, metallic Fe carry the archaeomagnetic signal, thus representing phases formed during the heating event. Native Fe was preserved due to it being isolated within the glassy matrix. The vitrified structure underwent at least one strong heating event which led to partial melting of the rocks used in its construction. Both microprobe and archaeomagnetic data support a single heating event, although multiple heating to temperatures >600–800 °C cannot be excluded on archaeomagnetic grounds.