Estudio experimental de las transformaciones en la mineralogía magnética en fuegos prehistóricos y sus implicaciones en Arqueomagnetismo

Abstract

We present here the rock-magnetic results obtained from the experimental recreation of prehistoric fires. By using a system of thermocouples that allows the control of temperatures and heat penetration with depth, magnetic minerals transformations are studied over a clayey substrate. Different rock-magnetic analyses (thermomagnetic curves, IRM acquisition curves and their 3-axes thermal demagnetization, hysteresis loops, FORC diagrams, magnetic susceptibility and demagnetization of the natural remanent magnetisation, among others) show the creation of post-fire magnetite, likely from prefire haemite, thus promoting a magnetic enhancement. The most noticeable mineralogical changes happen in the upper 2 cm of the central area of the hearth, where single-domain magnetite has been created. The implications of these results for archaeomagnetic studies and their utility for the detection of fire in archaeological sites are discussed.