Characterisation of sediments of the Tarn flat lake (Antartica)

XRD, INAA and 57Fe Mossbauer data for a sedimentary core of the small lake of Tam Flat in the region of Terra Nova Bay are reported and discussed. The lake sediments consist of quartz, muscovite, feldspars, calcite, fluorite and chlorite. Iron is present as Fe(II) in chlorite for about 16%, as Fe(III) up to 74% and in ferrihydrite for the remaining 10% of the total iron content. The specimens from the border of the Tarn Flat lake contain amphiboles in addition to the silicates found in the sediment but less calcite and fluorite. Their iron chemistry differs from that of the sediment, in particular for the lower Fe(lII) content. The specimens from the borders of other lakes present in the region of Terra Nova do not contain calcite or fluorite and differ substantially for silicate composition. The sediments of the Tam Flat lake derive from local materials, modified in silicate fraction and enriched in calcite and fluorite.