Data on the content and distribution of trace and rare-earth elements (SIMS method) in sectors and growth zones of a large zircon crystal from miaskite pegmatites of the Vishnegogorsky massif are presented. The morphology of the zircon crystal is a combination of a dipyramid {111} and prism {010}. It has been established that the growth sector of dipyramid {111} is characterized by almost one order of magnitude higher contents of Y, Nb, REE, Th; higher Th/U and Eu/Eu* values; REE distribution spectra are flatter compared to prism {010} growth sector. A regular decrease in the content of trace and rare-earth elements in the direction from the central zone to the marginal zone of crystal growth was revealed. A smooth regression of zircon crystallization temperature of zircon from 960 °C in the central zone to 740 °C in the marginal zone of the dipyramid sector and 700-650 °C in the prism sector has been revealed, which may be a reflection of thermal evolution of the crystallization process. It is assumed that crystallization of the central zone of zircon occurred at early stages from a relatively trace-еlement-rich melt. The crystallization was completed at lower temperatures, probably, simultaneously with the formation of REE-concentrating minerals, which resulted in natural decrease of content of trace and rare-earth elements in the melt and, consequently, in zircon crystallizing from it.
A radioisotope instrument for separate oil, water and gas determination in multiphase multicomponent borehole liquid flows calibration is described in the article. An instrument calibration methods on static experimental test bench is given. Possible errors for the calibration methods are assayed.
The article deals with a radioisotope instrument for measuring the density and phase composition of flows in main oil pipelines. The instrument uses direct radiation and a gamma radiation beam scattered in space to obtain information on the flow composition (presence of free gas, water, clots and solid impurities) in the entire cross-section of the pipeline. The procedure of modeling such radiation beams by Monte Carlo method is described: the assumptions adopted in modeling and the sequence of operations. Further expected results of the work determination of the spatial distribution of the scattered radiation in the pipeline and the distribution of the registered radiation by energies.
