A Mineral Magnetic Approach to Determine Paleo-Firing Temperatures in the Neolithic Settlement Site of Mursalevo-Deveboaz (SW Bulgaria)

Archeological remains from the Neolithic period in SE Europe are characterized by the presence of massive burnt daub relics sintered at high temperatures. These findings raised the hypothesis of deliberate house burning as a strategy for ensuring the survival of place and the development of social memory in Neolithic society. Although highly discussed in the archeological community, analytical data on the ancient firing temperatures achieved during burning Neolithic houses are missing except an empirical study determining firing temperatures according to the color of burned clay. The Neolithic site Mursalevo-Deveboaz (Bulgaria) is one of the largest known settlements consisting of more than 70 houses. Rock-magnetic analyses are applied for characterization of iron oxides produced during firing, and the firing temperatures were estimated using the magnetic susceptibility method. Results on a collection of 445 samples show the presence of very fine grained magnetite/maghemite and hematite. Magnetic data are supported by elemental analysis, reflectance spectroscopy, and scanning electron microscopy. The data suggest an increase in the magnetic grain size from superparamagnetic toward single domain with increasing firing temperature. Firing temperature estimates for 148 samples of different color vary between 680 and 1,140 degrees C. Comparing the magnetic properties of iron oxides identified and literature data on solution-combustion synthesis of iron oxides allowed a mechanism behind the extreme firing of Neolithic houses to be suggested. Our study proposes for the first time that combustion synthesis of iron oxides could explain the extreme house burning in many Neolithic settlements achieved through intentional addition of wood, dung and urine.