Raukas, A., Koch, R., Jüriado, K., Järvelill, J.-I.
Anomalous radioactivity level and high concentrations of
heavy minerals in Lemme area, South-West Estonia
As early as in the 1960s, extensive heavy-mineral
concentrations containing zircon, monazite, and xenotime were discovered in the
Lemme region of south-western Estonia. These concentrations contribute to the
elevated radioactivity levels of the enclosing sediments. The near shore sands
of the Litorina Sea contain up to 10-cm-thick interlayers with a heavy mineral
content of up to 80%. These anomalous layers were formed during the
transgressive phase and result from a complicated cross- and alongshore migration
of sedimentary material, derived mainly from local Devonian bedrock.
Radioactivity level in the study area is higher relative to the majority of the
Devonian plateau. The Lemmeoja buried soil has 13 radiocarbon dates in an area
of renewed interest for the investigation of the Baltic Sea history.