Crystal Chemistry of Clay Minerals in Bottom Sediments of the Sea of Okhotsk as a Paleoclimatic Indicator. N. A. Pal'chika, E. P. Solotchinaa, E. L. Gol'dbergb, ...
ISSN 0036-0236, Russian Journal of Inorganic Chemistry, 2008, Vol. 53, No. 6, pp. 867–874. © Pleiades Publishing, Ltd., 2008. Original Russian Text © N.A. Pal’chik, E.P. Solotchina, E.L. Gol’dberg, V.N. Stolpovskaya, S.A. Gorbarenko, 2008, published in Zhurnal Neorganicheskoi Khimii, 2008, Vol. 53, No. 6, pp. 938–946.
SYNTHESIS AND PROPERTIES OF INORGANIC COMPOUNDS
Crystal Chemistry of Clay Minerals in Bottom Sediments of the Sea of Okhotsk as a Paleoclimatic Indicator N. A. Pal’chika, E. P. Solotchinaa, E. L. Gol’dbergb, V. N. Stolpovskayaa, and S. A. Gorbarenkoc a
Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia b Limnological Institute, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia c Pacific Oceanology Institute, Far East Division, Russian Academy of Sciences, Vladivostok, Russia Received October 5, 2006
Abstract—X-ray diffraction and infrared spectroscopy were used to study the mineral composition of bottom sediments of the Sea of Okhotsk with ages ranging from Holocene (10 My ago) to Pleistocene (10 to ~74 My ago). The concentrations of nonlayered minerals (quartz, plagioclase, carbonates, and biogenic silica) were determined from IR spectra, which made it possible to estimate the actual abundance of the clay component in test samples. Calibration curves used in the calculation were plots of the optical density in the maximum of the analytical absorption band of the analyzed component versus its concentration in the sample. These curves were constructed for standard mixtures of known compositions. The crystal-chemical parameters and quantitative ratios of clay minerals were elucidated by the computer simulation of X-ray diffraction profiles; clear correlations were found between these parameters and paleoclimatic changes. Our results show that the clay minerals from the bottom sediments of the Sea of Okhotsk can serve to search for paleoclimatic events in the North-Eastern Asia. DOI: 10.1134/S0036023608060090
The creation of global and regional models of climatic and environmental evolution is an important line of research over the world. This became a challenge because of the uncertainty of both short-term and longterm planetary climate predictions and the perceivable lack of reliable data about the ancient climate. During several last decades, which are called the golden age of marine geology [1], long continuous annuals were obtained on the basis of investigations of marine sediments. A clear correlation between the warming and cooling epochs on the Earth, on one hand, and the Earth’s position on the orbit and its ecliptic angle was derived on the basis of variations in the oxygen isotope abundances in organic carbonate oceanic oozes. The situation with the understanding of the reasons for rapid and abrupt global climatic changes is much worse. The recognition of climate-governing mechanisms is a very important scientific and economical problem of the present times. Studies of the terrigenous part of the marine sediments, mainly the assemblage of clay minerals, their composition and structural and crystalchemical parameters, are an important part of the complex approach to the reconstructions of rapid changes of the paleoenvironment and paleoclimate. The latest studies of sediments of the Sea of Okhotsk revealed regions with very high sedimentation rates (1–1.5 m/My), which made climatic reconstructions possible on the scale from hundreds of years to several decades [2, 3]. In earlier research [4–7], on the basis of the detailed investigations of the crystal chemistry, structure, and quantitative relations of clay miner-
als in lacustrine sediments of the Inner Asia, intervals were revealed in which the signatures of chemical weathering of the continental material are maximal and these intervals were matched with global and short warming and cooling periods in the region [4–7]. In this work, we analyze the crystal-chemical features of clay minerals in sediments of the Sea of Okhotsk and search for their response to climatic changes in the Far-East Region. EXPERIMENTAL We studied the core material disclosed by deep-sea drilling (core LV 28-40-5) in the central part of the Sea of Okhotsk near the Sakhalin Island during the cruise of the R/V “Akademik M.A. Lavrentiev” in the fulfillment of the Russian–German project KOMEX. The station was situated at 51°20.045N, 147°10.613E, and 1312 m deep. The core length was 805 m. Samples from the upper portion of the column were built of oozes, which were dominated by biogenic silica, namely BioSiO2. This BioSiO2 consisted of diatom valves (diatom oozes). The range 180–220 cm was represented by clayey ooze (with particle sizes of 0.01–0.1 mm) with subordinate fine shell fragments. The range 220–805 cm consisted of a finegrained sedimentary rock (
