Indicator Isotope–Geochemical Characteristics of Sulfides from the Satka Magnesite Ore Field (South Urals Province)

The stable enrichment of pyrite from magnesite ores in δ³⁴S isotope (from 5.4 to 6.9‰) compared with pyrite from the host (sedimentary and igneous) rocks was established in the classical Satka sparry magnesite ore field. Concretionary segregations of fine-grained pyrite in dolomite are depleted in the heavy sulfur isotope (δ³⁴S, from–9.1 to–5.8‰). Pyrite from dolerite is characterized by δ³⁴S values (–1.1 and 1.7‰) close to the meteorite sulfur. The δ³⁴S values in barite from the underlying dolomite horizon vary in the range of 32.3–41.4‰. The high degree of homogeneity of the sulfur isotope composition in pyrite from magnesite is a result of thermochemical sulfate reduction during the syngenetic crystallization of pyrite and magnesite from epigenetic brines, formed during dissolution of evaporite sulfate minerals at the stage of early catagenesis of the Riphean deposits.

     

Geochemical Features of Carbonaceous Rocks on the Western Slope of the Southern Urals

Based on the study of rocks in fault zones on the western slope of the southern Urals, it is shown that carbonaceous rocks are confined to the most dislocated parts of the sections and spatially associated with magmatic rocks. They are characterized by specific geochemical features with anomalous contents of gold and platinum group elements (PGE) and native tin mineralization that is atypical of terrigenous rocks. Transformation of these rocks is mainly governed by reduced mantle fluids penetrating into upper levels of the Earths crust at early stages of tectonomagmatic activation. The subsequent inversion of the fluids in the Earths crust leads to the formation of carbonaceous rocks with atypical mineralization and high PGE content.__________Translated from Litologiya i Poleznye Iskopaemye, No. 3, 2005, pp. 281–291.Original Russian Text Copyright © 2005 by Kovalev, Michurin.     

TRANSMISSION AND PROCESSING OF INFRARED SATELLITE IMAGERY IN OCEANOGRAPHIC STUDIES

A methodology for transmitting satellite information from shipboard receiving stations to onshore image processing centers is described, developed for the purpose of increasing the accuracy of water temperature and other oceanographic measurements taken by infrared scanning radiometers and promoting wider utilization of computers in image processing. Signals are recorded on magnetic tape, modulated, amplified to the normal operational range of a digital-analog signal transformer, and transformed into a sequence of eight-digit binary-decimal numbers, which pass through a photoelectric counter into computer memory. Infrared signals are isolated by an envelope demodulator in an early stage of the process. Translated from: Vestnik Leningradskogo Universiteta, 1985, No. 14, pp. 93-95.     

Effective algorithms for sourcewise approximation of geopotential fields

A specialized class of fast algorithms for sourcewise approximation of potential fields, which is intended for mass use in the applications associated with handling large and extralarge measurement data, is developed. Pursuing the objective of the work, we included two informal requirements in the set of the criteria to be met by our algorithms: they should have a sufficiently simple mathematical structure which is transparent for the geophysicist and they should be quite easy to program. Both these requirements are dictated by the present-day practice existing in geology, when the absence of the centralized provision of program products by the geological organizations makes the interpreter create the necessary software themselves. Among the distinguishing features of the three suggested algorithms is the fact that the dimensionality of the approximating construction is not specified a priori but is determined a posteriori. Due to this, it turned out to be helpful to combine one of these algorithms with the fast wavelet transform, which enables the dimension of the future sourcewise approximation and the amount of computing resources required for the implementation of the main algorithm to be estimated a priori. The examples of the practical application of these technologies are presented. The promising paths for the future development of the algorithms for sourcewise approximation of the potential fields are outlined.     

Formation Conditions of Ferromagnesian Metasomatic Carbonates in the Lower Riphean Terrigenous–Carbonate Rocks of the Southern Urals

Lithology and Mineral Resources - Ferromagnesian carbonate metasomatites in limestones of the Lower Riphean Suran Formation in the Avzyan ore region (Bashkir meganticlinorium) are represented by...