TIN-BEARING STREAM SEDIMENTS SPATIALLY ASSOCIATED WITH BRONZE AGE SETTLEMENTS IN WESTERN SERBIA

The Mt. Cer pluton of western Serbia is composed predominantly of two-mica granite and biotite-hornblende granodiorite. It intrudes Devonian to Carboniferous sedimentary strata and is overlain by Miocene sedimentary rocks in the southern margin of the Pannonian basin. Based on unpublished industry and government reports, archeologists have referred to the presence of cassiterite in the Cernica and Lesnica rivers, immediately south of the Mt. Cer pluton.

To confirm and further document the occurrence of tin mineralization in the area, approximately 250 samples were taken from sand bars in streams that drain the south side of Mt. Cer. Preliminary analysis of these samples involved separation into four size fractions, each of which was analyzed using a hand-held x-ray fluorescence apparatus (150 ppm detection limit for Sn). Only three samples (<0.4mm fraction) yielded tin values above the detection limit of the instrument. Accordingly, a subset of samples was selected for heavy mineral separation to amplify the tin signal in order to confirm the presence or absence of cassiterite in each tributary.

Following reanalysis, samples from five tributaries were found to be tin-bearing: the eastern-most tributaries of the Cernica (Plocnik, Cavinac, and Lipovac), and the western-most tributaries of the Lesnica (Milinska Reka and Kamenica). This indicates that a bedrock tin source lies in the east-central portion of the Mt. Cer pluton. Accordingly, the largest placer accumulations would be expected to be found in the headwaters of the Lesnica and the Cernica. Preliminary archeological survey of the area indicates that prehistoric settlements are concentrated at the mouths of the tin-bearing tributaries, whereas barren streams appear to lack similar settlements. This correlation suggests that the settlements were situated to exploit the placer tin resources.