Using the ICP-MS method we have studied the isotope systematics of Sr and Nd as well as trace element composition of a representative collection of kimberlites and related rocks from the Siberian Platform. The summarized literature and our own data suggest that the kimberlites developed within the platform can be divided into several petrochemical and geochemical types, whose origin is related to different mantle sources. The petrochemical classification of kimberlites is based on persistent differences of their composition in mg# and in contents of indicator oxides such as FeOtot, TiO2, and K2O. The recognized geochemical types of kimberlites differ from one another in the level of concentration of incompatible elements as well as in their ratios.
Most of isotope characteristics of kimberlites and related rocks of the Siberian Platform correspond to the earlier studied Type 1 basaltoid kimberlites from different provinces of the world: Points of isotopic compositions are in the field of primitive and weakly depleted mantle. An exception is one sample of the rocks from veins of the Ingashi field (Sayan area), which is characterized by the Sr and Nd isotopic composition corresponding to Type 2 micaceous kimberlites (orangeites).
The most important feature of distribution of isotopic and trace-element compositions (incompatible elements) is their independence of the chemical rock composition. It is shown that the kimberlite formation is connected with, at least, two independent sources, fluid and melt, responsible for the trace-element and chemical compositions of the rock. It is supposed that, when rising through the heterogeneous lithosphere of the mantle, a powerful flow of an asthenosphere-derived fluid provoked the formation of local kimberlite chambers there. Thus, the partial melting of the lithosphere mantle led to the formation of contrasting petrochemical types of kimberlites, while the geochemical specialization of kimberlites is due to the mantle fluid of asthenosphere origin, which drastically dominated in the rare-metal balance of a hybrid magma of the chamber.
The biological activity of chitosan determines its broad application as a biopolymer for non-woven wound dressings fabricated by electrospinning. The electrospinning process is affected by a large number of different factors that complicate its optimization. In the present work, the electrospinning of chitosan lactate was carried out using a needleless technique from water solutions of different compositions. Surface response methodology was used to evaluate the effects of the concentration of chitosan, polyethylene oxide, and ethanol on solution properties, such as viscosity, surface tension, and conductivity, as well as the process characteristics and fiber quality. The viscosity of the spinning solution is determined by the polymer concentration as well as by the interpolymer interactions. The addition of ethanol to the spinning solutions effectively decreases the solution surface tension and conductivity, while increasing the volatility of the solvent, to provide more intense fiber spinning. Atomic force microscopy revealed that the chitosan lactate fibers were obtained without defects and with a narrow thickness distribution. The spinning parameters, voltage, distance between electrodes, and rotation speed of the spinning electrode had insignificant influences on the fiber diameter during needleless electrospinning.
All these minerals can give a reliable age, but each entails one shortcoming or another. Phlogopite is susceptible to secondary alteration. Therefore, only fresh grains should be used. Zircon sometimes occurs in kimberlites as a xenogeneic mineral, taken from the lower continental crust and thus providing a crustal age (Batumike et al., 2007). Perovskite contains significant admixture of common Pb, but that difficulty can be overcome by the correction of analytical data (Cox and Wilton, 2006;Storey et al., 2006).Rutile and titanite can incorporate substantial amounts of U in their respective chemical compositions. Therefore, they are useful for age determination using the U-Pb method. Application of LA-ICP-MS for in situ U-Pb rutile dating is well described in Zack et al. (2011) and methods of titanite dating are described by Storey et al. (2006) and by Amelin (2009).This study analyzed rutile, titanite, and zircon grains obtained from heavy-mineral concentrations of kimberlitic rocks of Amakinskaya and Taezhnaya pipes (Fig. 1) of the Mirny kimberlite field, Siberia. Earlier U-Pb dating of Mirny field kimberlites emplacement age (Davis et al., 1980) for bulk zircon probes showed 361.5 ± 2 and 360 ± 2 Ma for the Mir and International pipes,
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