Tunguska99 Photos

Location of gravity cores collected from the lake Cheko bottom by the Tunguska99 expedition. Sedimentological, geochemical, mineralogical as well as radiometric and magnetic analyses were carried out on the selected samples shown. The lake’s sediments show a general dark brown-blackish colour, a high content of organic matter, a fine grain size and alternating laminated and massive intervals. Water content is high in all cores. Cores collected from shallow-water areas show laminations throughout their length. The sediment is mainly sandy mud (pelite ranges from 60 to 80% d.w.) with organic matter ranging from 5 to 16 % d.w. The mineralogical composition is rather constant in different cores, showing predominant quartz, plagioclases, K-feldspar and clay minerals, mostly a smectite. Cores from the lake center display a more complex stratigraphy, i.e., two different facies: an upper, laminated and a lower massive units, in agreement with the seismo-stratigraphic observations. Within the upper unit the sandy component is larger (up to 60%). See paper and thesis.

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