INNSJØAVSETNING

This report presents a review of previous work on the use of the chemistry of lake bottom sediments in geochemical exploration for ore deposits in some of the glaciated terrains of the world. The conclusions derived and the methods adopted, based on the philosophy that lake sediments can in fact be used for the geochemical exploration for ore deposits in glaciated areas at reconnais- sance level, are described. The report also includes the results of some of the more important limnological investigations carried out in Scandinavia. A proposed plan of research for the study of lake bottom sediments in Norway during 1975-76, dealing with the selection of sites, access to the area, method of sampling, treatment of samples. processing of data and preparation of reports is described in some detail. Some of the different samplers used for sampling lake bottom sediments, together with a new sampler devised in the workshop of the Geological Survey of Norway for sampling lake bottom sediments for abovementioned proposed project are described and illustrated in the appendix.

This report documents the geochemical and microbiological data on water samples collected during field expeditions during the summers of 1999 and 2000 to the Republic of Khakassia (Russian Federation) in southern Siberia. Data have been obtained from groundwater (boreholes, springs, wells) rivers and lakes and a preliminary interpretation suggests an evolutionary pathway from groundwater to surface waters and lakes involving up-concentration og highly soluble solutes (sodium, sulphate, chloride, boron, magnesium), and removal of silicon and calcium by precipitation of mineral phases. There is also a tendency to elevated pH and alkalinity in surface waters, which has yet to be satisfactorily understood. It is believed that this observation forms the key to understanding hydrochemicaql evolution in the study area and it will be the focus of subsequent interpretation. Mineral samples from lake/marsh areas have been analysed by XRD, which analyses confirm the formation of thin secondary evaporite crusts around lakes, comprising thenardite, calcite, dolomite and halite. In single cases, gypsum and mirabilite were detected. Analyses also suggest that grounwaters in villages have a tendency towards elevated nitrate levels and bacterical counts, possibly resulting from contamination from latrines. Analyses were also made of mine waters from coal mines in the Abakanchernogorsk syncline and from metalliferous mines at Abaza and Vershina Tyei. These mine waters had relatively high pH and low metals contents, due to the buffering nature of ambient groundwater and ore host roch.