Nd and Sr isotopic composition of ancient iron-made artifacts and ores from northwest Russia

摘要

Iron-made artifacts from northwest Russia, including nails, arrowheads, and brackets used in the 13th-19th centuries, have a wide range of Sr and Nd isotopic composition (Sr-87/Sr-86=0.710-0.737 and Nd-143/Nd-144=0.5115-0.5124). Authigenic iron ore sites mined in the region from 10th to 19th centuries preserve a similar range of isotopic compositions, suggesting artifacts retain the Sr and Nd signatures of their parent ores. Analyses of the ores also reveal two broad regions distinguished by their isotopic compositions, with the Precambrian Baltic craton in the northern part of the region having very radiogenic Sr and unradiogenic Nd isotopic compositions (Sr-87/Sr-86 >0.7177 and Nd-143/Nd-144 <0.5119) compared with ores from the Paleozoic sedimentary cover of the East European platform to the south. The recognition of distinct geochemical provinces permits identification of the broad regions from which the various ores were mined, and demonstrates the utility of applying radiogenic isotopic analyses to artifacts and their potential geologic sources.