THE ROLE OF THE HYDROGEOCHEMICAL METHOD IN THE STUDY OF THE KOLYVAN–TOMSK FOLD ZONE

P. A. UDODOV, P. N. PARSHIN

(Presented by the scientific seminar of the Research Institute of Hydrogeology)

In the central industrial part of Western Siberia lies the Kolyvan–Tomsk fold zone. It belongs to semi-covered geological structures and therefore, until recently, has remained poorly studied in geological and metallogenic terms. However, geological-survey materials of the Novosibirsk and West Siberian geological administrations, thematic studies of SNIIGGiMS [1, 2, 4] and of the Academy of Sciences of the USSR [3] provide data that positively assess its prospects for various—primarily polymetallic—types of mineralization.

All the works cited contain an insufficient amount of data both on the metallogeny of the region as a whole and on areas deserving special attention in the conduct of targeted prospecting work.

The results of hydrogeochemical studies carried out by the Tomsk Polytechnic Institute in the northern part of this region [6] showed the effectiveness of the hydrogeochemical prospecting method under conditions of semi-covered structures and confirmed the prospects of the structures studied with respect to ore minerals.

All this, taken together, served as the basis for undertaking regional integrated hydrogeochemical investigations over the entire area of the Kolyvan–Tomsk zone. These works were carried out by the Tomsk Polytechnic Institute during 1964–1967. Heavy metals in waters were determined by the TPI method [5], which is now provided for by the 1965 instruction on geochemical methods for prospecting ore deposits.

The hydrogeochemical investigations were integrated in character. In the course of field and laboratory work, geologists and hydrogeologists of various specializations, chemists, and microbiologists took part in them. The investigations carried out revealed the advantages of a rational integration of geological and hydrogeochemical work. They made it possible to illuminate a whole series of questions in regional geology, mineral resources, geochemistry, hydrogeology, soil science, and others. A significant portion of these questions was reflected at the All-Union conferences on hydrogeochemistry and paleohydrogeology (Tomsk, 1965); on the application of microcomponents in agriculture (Irkutsk, 1966); on paleohydrogeology (Ashkhabad, 1966); on groundwater of Siberia and the Far East (Tyumen, 1967); and at the regional conference on the protection—

and use of soils, air and water bodies, and groundwater of Tomsk Oblast (Tomsk, 1966).

The comprehensive nature of the studies was designed to provide a more complete substantiation of the hydrogeochemical anomalies being identified. Promising areas for various useful minerals were established on the basis of a set of geological-geochemical criteria. The experience of the studies carried out showed that false hydrogeochemical anomalies do not exist in nature if they are distinguished with consideration of all geological factors.

The data obtained made it possible to distinguish four structural-metallogenic zones for the region.

1. Within the geoanticlinal structures (Bugotak, Mitrofanovka, and Podlomskaya), a group of areas has been distinguished that are promising for polymetallic and, possibly, nickel-cobalt mineralization. In this zone the most promising are: the Shcherbak-Omutninsky area in the north, the Mikhailovsky and Permsky areas in the south, and the Baranovo-Mitrofanovsky area in the central part of the district.

2. In the area of the structures of the geosynclinal trough, the following areas have been distinguished: Semiluzhensky, Tugozhakovsky, Sosnovsky, Izdrevsky, and the Verkh-Suzun group—promising for polymetallic, locally antimony-mercury, and quartz-gold ore mineralization.

3. Within the junction of the Hercynides of the Kolyvan-Tomsk folded zone with Caledonian structures, areas promising for polymetallic mineralization have been distinguished: Ognevo-Zaimsky, Romanovsky in the south, and Turuntaevsky in the north.

4. In the area of manifestation of the Priobsky deep fault, where a marginal complex of intrusions is developed, areas promising for rare-metal and, possibly, polymetallic mineralization have been distinguished.

We consider the following areas the most promising for the initiation of prospecting and exploration work: for polymetallic mineralization—the Turuntaevsky area (with prospecting work being developed to the southwest of the ore occurrence discovered here in 1964), Shcherbak-Omutninsky, Dubrovsky, Baranovo-Mitrofanovsky, and Ognevo-Zaimsky. For antimony-mercury mineralization: the structural elements of the northeastern part of the Tomsk overthrust, the Tugozhakovsky area, and especially the Sosnovsky area.

The results of the studies are not limited to prospects for the search for ore deposits. Significant resources of fresh and mineral groundwater have been identified here, and an assessment has also been made of the trace-component composition of soils.

At present, prospecting work by the Novosibirsk and West Siberian geological administrations has uncovered sulfide ores, predominantly zinc ores, at the Turuntaevsky and Baranovsky ore occurrences. The prospects of all the other areas are substantiated by a combination of factors: structural-lithological analysis, the presence of ore minerals, spectral and chemical analysis of rocks, the presence of products of hydrothermal activity, specific products of hypergene processes, the behavior of heavy metals in natural waters, and other geochemical criteria.

Thus, the experience of the work carried out makes it possible to consider that hydrogeochemical anomalies are always confirmed by a set of geological factors. However, evaluation of the quantitative aspect of the zones of presumed mineralization is a matter for further prospecting drilling work, during which it is also absolutely necessary to carry out hydrogeochemical studies.

There is now a need to verify all promising areas—

...within the region by geological prospecting and exploration work. The question of checking geochemical anomalies has repeatedly arisen at All-Union hydrogeochemical conferences.

The checking of hydrogeochemical anomalies for rare metals in Gornaya Shoria, for nonferrous metals in Rudny Altai and Norilsk, and for beryllium in Transbaikalia yielded positive results. At all points ores were discovered.

Experience shows the expediency of checking geochemical anomalies jointly with geologists who have outlined promising areas. As an example of such work one may cite the experience gained in the discovery of ores at the Baranovo site. Here, according to hydrogeochemical data, we identified as the most promising the area on the right bank of the Vlaskovo River between the river channel and the Baranovo fault (800 m south of the channel), as well as downstream, including the western part of the village of Baranovo. This made it possible to introduce substantial corrections into the available electrical-prospecting and metallometric materials. The anomalies indicated by the latter tend toward positive landforms (the most intense zones of silicification), located on the flanks of ore zones and containing only rare disseminations of sulfides.

Taking all these data into account enabled engineer V. V. Borodin of the Novosibirsk Geophysical Trust, together with the authors of this report, to plan the locations for drilling the first three prospecting boreholes within the limits of the most contrasting hydrogeochemical anomaly. All these boreholes, drilled by the West Siberian Geological Administration, exposed an ore zone.

A positive result of the investigations carried out is the establishment of the prospectivity for sulfide mineralization of the areas of development of flyschoid sediments of the Upper Devonian and Lower Carboniferous. The localization of sulfides here is associated with zones of crushing in geological formations of different ages. Previously, only the volcanogenic formations of the Middle Devonian, developed within the Bugotak, Mitrofanovka, and Podlomskaya geoanticlinal structures, were considered promising for sulfide mineralization [2, 4].

The integrated investigations made it possible to establish the specific character of the paleohydrogeological conditions of the structures studied, from the Devonian epoch to the present day. On the basis of these data, the genesis of various types of groundwater and the justification for their use for water supply, balneology, and other purposes are more fully revealed.

REFERENCES

1. I. V. Derbikov. Sulfide mineralization in the Kolyvan-Tomsk folded zone in light of two hypotheses of the genesis of hydrothermal polymetallic deposits. Izv. Vost. Fil. AN SSSR, No. 7, 1957.

2. I. V. Derbikov. More on the conditions of formation of pyrite-polymetallic deposits. Geologiya i geofizika, No. 7, 1960.

3. M. M. Konstantinov. Buried ore belts. Izv. AN SSSR, geological series, No. 9, 1962.

4. Yu. A. Nuvar’eva. On the spatial and genetic relation of polymetallic mineralization of the Kolyvan-Tomsk folded zone to Devonian volcanism. In: Geology and Metallogeny of Effusive-Sedimentary Formations. Nedra Publishing House, 1964.

5. P. A. Udodov, I. P. Onufrienok, Yu. S. Parilov. Experience in hydrogeochemical investigations in Siberia. Vysshaya Shkola Publishing House, Moscow, 1962.

6. P. A. Udodov, V. M. Matusevich, N. V. Grigor’ev. Hydrogeochemical prospecting under the conditions of semiconcealed geological structures of the Tom–Yaya interfluve. Tomsk State University Publishing House, Tomsk, 1965.