GEOCHEMISTRY OF THE EARLY DIAGENESIS OF LIMNE-GLACIAL DEPOSITS ON THE EXAMPLE OF LAKES OF THE NORILO-PYASINSKAYA WATER SYSTEM (RUSSIAN ARCTIC)

For the first time, some features of the early diagenesis of bottom sediments of glacial lakes in the Arctic zone of Russia (Pyasino and Melkoe) were studied using long drilling cores. For the first time, the chemical composition of pore waters for the entire thickness of bottom sediments was determined for the lakes of the Russian Arctic. The enrichment of pore waters with biogenic compounds NO3 –, PO4 3– and dissolved organic carbon (DOC) is shown to be a consequence of microbiological destruction of organic matter (OM), as a result of which the labilest components of OM pass into the pore water, and reducing environment arises in the sediments. An increase in Fe, Mn, Al, As, B, Ba, Co, Mo, Ni, Si, Sr, V, Y concentrations in pore waters was found in comparison with supra-bottom water due to the diagenesis of bottom sediments. The role of OM in changes concerned with mineral composition of sediments and formation of authigenic minerals (pyrite, calcite) was shown. Sediments poor in OM are characterized by low concentrations of reduced forms of S (sulphur in the composition of Fe sulphides, H2S, thiosulphfates, etc.), which indicates a low intensity of bacterial sulfate reduction processes.