Acta Musei Moraviae

Geochemistry of Sošůvka cave sediments in Moravian Karst

Cave sediment geochemistry is still quite omitted discipline in the cave sediment research. The study of 25 samples from Šošůvka cave in Moravian Karst performed within the frame of retrieval archeological-paleontological research proved that the very useful information can be extracted even from the basic evaluation of geochemical data. According to the sediment chemical composition Šošůvka cave can be divided into two parts despite of sample position in sediment layer and ratio of its sand/clay content. First one can be characterized by relatively low content of SiO₂ (around 55 wt. %) and higher content of CO₂ (even more than 10 wt. %), both with high variability. Second part contains cave sediments with higher Si02 concentration (65 wt. %), low concentration CO₂ (around 5 wt. %) and relatively uniform distribution. Some other main components follow the trend of SiO₂ (Al₂O₃, K₂O, Na₂O, partly MgO). This is probably caused by their common binding in clay minerals. Ferrous iron, ferric iron and manganese do not show any difference between the two parts, but has good correlation each other. The special behavior showed phosphorus with extreme high content in some samples (more than 10 wt. % of P₂O5). Source of phosphorus can be ascribed to the previously found fossil bones. Content of CaO shows much higher correlation to the P₂O₅ content than to CO₂, This indicates that major amount of calcium is included in hydroxyapatite and only minor amount come from calcium carbonate (calcite, aragonite). Despite of the fact that the both previously defined parts forms one uniform cave space without distinct differences the cave sediment geochemistry indicate their different evolution.