Overbank sediment profiles—evidence of early mining and smelting activities in the Harz mountains, Germany

Two overbank sediment cores to a depth of 5.6 m and 2.3 m respectively from the Uferbach catchment on the western foothills of the Harz mountains, Lower Saxony, Germany, revealed two anomalies of Pb, Zn, and Cu at 30–130 cm and at 204 cm, a Pbsingle bondZn-anomaly at 280 cm and a Pb-anomaly at 410 cm—evidence of four phases of mining and smelting activities in the catchment. The geochemical (major, minor, and trace elements) and mineralogical investigations (microscopy and microprobe analysis of matrix and slag particles) allowed for a broad interpretation of the element behavior (e.g., landuse) and the source region of the processed ore (hydrothermal deposits of the Upper Harz). A simple calculation model, based on14C-data, helped to estimate the time frame for the anomalies. The most likely interpretation requires an increase of the sedimentation rates over time (from 1 to 4 mm a−1) and suggests medieval (1140–1345 A.D.), karolingian (82–890 AD), roman-germanic (425–500 A.D.) and early historic (825–625 B.C.) phases of smelting activities.