Linking site formation processes to magnetic properties. Rock- and archeomagnetic analysis of the combustion levels at Riparo Gaban (Italy)

This study focuses on archeomagnetic directional data that are obtained from combustion levels in the Riparo Gaban rock shelter (northern Italy) in order to assess the degree of disturbance in the sediments and to provide new information to evaluate evolution of the geomagnetic field in the mid-Holocene. Combustion levels consist of ash, rubefied levels, or partially burned material and mixtures of these, or polygenic material. Rock magnetic investigations show that superparamagnetic to single-domain magnetite is the main carrier of the remanent magnetization, but small amounts of hematite and maghemite may also be present in the different materials. Rock magnetic parameters, e.g., the Koenigsberger ratio Q or the reversibility of thermomagnetic can be related to the degree of burning, and the dispersion parameter k to the degree of preservation. The grouping of archeomagnetic directions of a specific level is strongly dependent on the degree of physical disturbances. Directional means from thirteen levels can be compared with reference curves for paleosecular variation based on geomagnetic field models and other archeomagnetic data. The data from this study are in agreement with other archeomagnetic data from the Balkans in the time period 4900 BC to 4600 BC.