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Since the knowledge of heavy metal concentrations allows the decision of several scientific tasks in oceanology, the study of slurries and sediments is of great importance in oceanological research. Here some of the abovementioned tasks should be listed: (i) description of geochemistry of the oceanic sedimentary process that allows one to create geochemical model of the modern ocean; (ii) development of a basis for comparative lithological study for modern and ancient oceanic sedimentary formations; (iii) creation of a general scheme for the ore formation in the ocean since new mineral deposits are one of the criteria by which one can judge about the features of a particular type of lithogenesis; (iv) monitoring the amount of trace elements because many of them are of interest to their industrial mining (for example, rare-earth elements) [1]. The main markers to search for ore deposits within pelagic sediments are often the ratios of main components, e.g. the ratio of iron to manganese in ferromanganese nodules (FMN) samples. This value is used to determine the age of the sample that is related to its price as time accumulates rare-earth metals in the nodules [2, 3]. Another important ratio is calcium to strontium, which can be used for identifying Sr-rich (aragonite) carbonate layers in cold seep sediments [4]. Palaeo-climate investigations are also dependent on Ca to Sr ratio that helps create the climatic model of our planet at ancient times [5]. In this work, the possibility of semi-quantitative determination of basic components ratios (Fe/Mn from 0.2 to 5.1, Ca/Sr from 18.4 to 33.3) in iron-manganese nodules samples by laser-induced breakdown spectroscopy (LIBS) is demonstrated. Comparison between results obtained with expensive gated detector and cheap non-gated one as well as between LIBS and reference methods (ICP-OES and X-ray fluorescence) has been performed. The results show possibility to develop a new method of express and direct elemental analysis of FMN that might be necessary during oceanological expeditions related, in general, to search and sampling of sediments. Literature 1. Демина Л.Л. Формы миграции тяжелых металлов в океане (на ранних стадиях океанского осадкообразования). М.: Наука. 1982. 2. Hein J.R., Koschinsky A., Halbach P., Manheim F.T., Bau M., Jung-Keuk K., Lubick N. Iron and manganese oxide mineralization in the Pacific // Geochemistry and Mineralogy of Terrestrial and Marine Deposits. 1997, V.119, P.123–138. 3. Балашов Ю.А. Геохимия редкоземельных элементов. М.: Наука. 1976. 4. Bayon G., Pierre C., Etoubleau J., Voisset M., Cauquil E., Marsset T., Sultan N., Le Drezen E., Fouquet Y. Sr/Ca and Mg/Ca ratios in Niger Delta sediments: Implications for authigenic carbonate genesis in cold seep environments // Marine Geology. 2007, V.241, P.93–109. 5. Hutton J. T., Dixon J. C. The chemistry and mineralogy of some South Australian calcretes and associated soft carbonates and their dolomitisation // Journal of the Geological Society of Australia 1981, V.28, P.71–79.