Clay minerals of the Rubtsovsk deposit

Pavlovskaya A.V.

Tomsk State University, Tomsk, Russia

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The Rubtsovsk pyrites-polymetallic deposit(Rudnyi Altai) is characterized by the wide occurrence of clay formations throughout the whole deposit. The clay minerals are permanent components both of the sulfide primary ores and of oxidized ores of the deposit. Entering into the composition of the sulfide primary ores aggregates, they can influence, depending on the concrete type, the technological properties and sometimes deteriorate the quality of ores [5]. Besides, as good adsorbents, the clay minerals may have admixtures, including those industrially significant, in their composition. In the ores beneficationprocess, they will be removed together with clay minerals, resulting in their inevitable loss not to be prevented by usual methods. This defines the actuality of the study on the composition of the clayey formations.

In the process of the complex investigation, the type composition of clayey formations has been established, as well as the principal items connected with conditions of their forming. The complexity of the investigation on clayey formations consists in common presence of diverse minerals in the same aggregate and problems in extracting monofractions.

The clay minerals of the Rubtsovsk deposit are practically indistinguishable macroscopically: they are coloured white, sometimes with a grey tint, and differ in only that some of them are incoherentand others are dense. In the present studies, modern investigational techniques have been applied in a certain order: the roenthgeno-phase analysis (RPA), raster-electron microscopy (REM), emission spectral analysis (ESA), roenthgeno-fluorescent analysis and thermal analysis.

The clayey formations from the sulfide primary ores zone are the constituents of argillizites, that are among the earliest manifestations of wall-rock alterations of enclosing rocks [3]. The forming of the clay minerals of the primary ores zone of the Rubtsovsk deposit is a low-temperatural hypogenic process, but not hypergene. This is evidenced by these minerals presence not only in the upper part of the metasomatic column, but also as a relics at the deeper horizons; besides, this is indicated by the presence of their sulfide mineralization. Moreover, the argillization process is known to go on actively in the regions with active volcanism, to which the Rubtsovsk ore region was confined in the Devonian [8]. That is why the endogenous genesis of these argillizites is beyond doubt. As a process, the argillization represents a metasomatic replacement of rock-forming alumosilicates (feldspars, muskovites, chlorites and others) with minerals of the kaolinite group, such as kaolinite, dickite, nakrite, halloysite and others. The hypogenic argillization is known to be mostly connected with the moderate- and low-temperature processes preceding the disengagement of the polymetallic mineralization. The argillization can take place both in alkaline-neutral and neutral-acidic media. The formation of kaolinite, quartz, sometimes aluniteis characteristic for the acidic medium, the formation of hydromica, montmorillonite, chlorite, feldspar for the alkaline or neutral media [4].

The clay minerals of the sulfide primary ores zone are represented by kaolinite, dickite and illite [2, 6, 7].

The definite data on the formation conditions of clay minerals can be obtained in studying the set of isomorphic admixtures. Kaolinites from the sulfide primary ores and oxidized zones are similar in their composition and the quantity of admixtures. This makes possible the conclusion that kaolinite of the oxidized zone is relic. In illite distinguished from samples of the sulfide primary ores zone, the composition of admixtures differs widely from that of illite of the oxidized zone. This suggests that illite from the oxidized zone is neogenic. Hence, illite of the deposit is represented by two generations: endogenetic and supergene.

The results of the performed studies are as follows:

– in the composition of the studied clay formations of the Rubtsovsk deposit, kaolinite and dickite have been distinguished assigned to the kandites subfamily and illite referred to hydromicas;

– all three mineral species have been established in the composition of the sulfide primary ores, while only kaolinite and illite have been revealed from the oxidized zone;

– all clay minerals are depleted in trace elements, and that is why the loss in the ore-forming components cannot be associated with them;

– the results of spectral analysis suggests that kaolinite is relic in the oxidized zone while illite is neogenic;

– the further investigation will surely extend the list of clay minerals existing in ores of the Rubtsovsk deposit.

References:

1. Kotelnikov D.D., Konyukhov A.I. Clay minerals of sedimentary rocks. – M.: Nedra, 1986. 247 pp.

2. Betekhtin A.G. A course of mineralogy: manual. – М.: BHU, 2008. 721 pp.

3. Chekvaidze V.B. Near-ore metasomatites of pyrites-polymetallic deposits and their prospecting significance. – M.: Nedra, 1981. 240 pp.

4. Petrographic dictionary. Eds.V.P. Petrov et al. – M.: Nedra, 1981. 496 pp.

5. Shakhov F.N. Morphological characteristics of oxidized zones. – Transactions of IGG SB AS of the USSR, 1960, iss. 4. P. 3-42.

6. Godovikov A.A. Mineralogy. – M.: Nedra, 1975. 520 pp.

7. Mikheyev V.I. Roenthgenometric mineral determinator. – M.: Nedra, 1957. 863 pp.

8. Doronin A.Ya., Chinakov I.G. Report on the geological prospecting works at the Rubtsovsk polymetallic deposit during 1970-1974. – Novokuznetsk, 1975.

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