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The results of subaqueous landslide studies at Krasnoyarskiy are given in this paper. The landslide were located at a subaqueous part of the delta of the Selenga River. A multidisciplinary approach ...was applied to the study of the landslide, including seismo-acoustic, lithological, gas-geochemical and geotechnical studies. Data from landslide and surrounding soils allowed us to propose the hypothesis that a key factor in the landslide origin was high gas saturation of soils and that the reason of landslide was an earthquake. The proposed approach to the study of bottom soils in lakes and seas can be applied both in assessing their stability and in searching for focused fluid discharge zones at the bottom in areas associated with hydrocarbon deposits in the sedimentary section. As well, the approach can be applied to mapping of permafrost melting in the Arctic region offshore, where gases often accumulate below it.
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Outcrops of the coal-bearing Tankhoi Formation (Oligocene–Pliocene), traced along the southern shore of Lake Baikal, submerge under its Southern Basin, where several hydrate-bearing zones of the ...focused hydrocarbon fluid discharge have been found. To test the hypothesis that coals of the Tankhoi Formation can be the sources of hydrocarbon gases in these zones, we collected coal samples from the Shakhterskaya Gorka outcrop. Experiment on gas generation from the selected samples was carried out in a special autoclave at a temperature of 90°C for eight months. This paper presents the obtained results, which confirm an important role of the process of gas generation from coals in the formation of fluids in the Kedr mud volcano. The further migration of gases was accompanied by the biodegradation and formation of secondary microbial methane due to CO
2
reduction. This was one of the reasons for the carbon isotopic pattern observed in methane (heavier than –50‰ VPDB) and carbon dioxide (positive values) taken from the near-surface sediments and hydrates of the Kedr mud volcano, as well as for the significant enrichment of authigenic siderites in the heavy
13
C isotope.
