695 ISSN 1028-334X, Doklady Earth Sciences, 2009, Vol. 426, No. 4, pp. 695–698. © Pleiades Publishing, Ltd., 2009. Original Russian Text © A.A. Tomilenko, S.V. Kovyazin, L.N. Pokhilenko, N.V. Sobolev, 2009, published in Doklady Akademii Nauk, 2009, Vol. 426, No. 4, pp. 533–536. In recent years, considerable attention has been given to study fluid and redox regimes of the upper mantle [1–3]; however, direct evidence on the fluid composition has been insignificant until now. Of spe- cial interest is the study of fluid and melt inclusions in minerals of mantle xenoliths from kimberlite pipes, which provide direct data on the composition and behavior of fluid in the upper mantle. Despite great interest in such investigations, data on fluid and melt inclusions in minerals of mantle xenoliths are severely limited [4–10]. This study describes new results of microthermom- etry and micro Raman and infrared (IR) spectroscopy of primary fluid and syngenetic crystalline inclusions and quartz paramorph after coesite in garnet of the dia- mondiferous eclogite xenolith from the Udachnaya kimberlite pipe, Yakutia (table). This pipe, the largest diamond deposit, is widely known due to systematic investigation of the mantle xenoliths, among which more than 150 xenoliths of diamondiferous eclogite were studied [11]. Measurements were taken by means of an OMARS 89 Raman microspectrometer and VERTEX 70 FTIR spectrometer at the Institute of Geology and Mineral- ogy, Siberian Branch, Russian Academy of Sciences, Novosibirsk. All fluid inclusions ranging from a few to 20 μm in size were partially decrepitated, which is indicated by a halo of tiny daughter inclusions around them. The inclusions are commonly irregularly distributed in the garnet grain; however, compact clusters of fluid and crystalline inclusions are abundant in the grain cores. After freezing the liquid phase of fluid inclusions, the formed solid phases were melted at –40°C and the last solid phase disappeared at –33°C (Fig. 1). In the IR spectra of the matter of these inclusions in the region 3000–2800 cm –1 , there are strong absorption bands at 2950, 2925, 2870, and 2857 cm –1 , which correspond to C–H stretching vibrations of the CH 2 and CH 3 groups (Fig. 2). According to the phase transformation and melting temperature of solid phases formed at freezing and IR data, these phases are composed of a mixture of high-molecular hydrocarbons. Primary Hydrocarbon Inclusions in Garnet of Diamondiferous Eclogite from the Udachanaya Kimberlite Pipe, Yakutia A. A. Tomilenko, S. V. Kovyazin, L. N. Pokhilenko, and Academician N. V. Sobolev Received December 12, 2008 DOI: 10.1134/S1028334X09040412 Institute of Geology and Mineralogy, Siberian Branch, Russian Academy of Sciences, pr. Akademika Koptyuga 3, Novosibirsk, 630090 Russia GEOCHEMISTRY Corresponding author: A.A. Tomilenko. E-mail: tomilen@uiggm.nsc.ru Chemical composition (wt %) of minerals in eclogite xeno- lith from the Udachnaya kimberlite pipe, sample Uv-464/86 Component Garnet Clinopyroxene SiO 2 39.0 54.7 TiO 2 0.46 0.3 FeO* 22.4 7.4 Al 2 O 3 21.0 6.4 Cr 2 O 3 0.05 0.41 MgO 6.9 10.1 MnO 0.42 0.06 CaO 9.3 16.2 Na 2 O 0.16 4.2 K 2 O 0.01 0.03 Total 99.7 99.8 Mg# 35.1 69.3 Ca# 24.5 44.7 * All Fe as FeO.