ON THE STRATIGRAPHIC POSITION AND AGE OF THE LITVINOVSKAYA PHOSPHORITE-BEARING SEQUENCE (BATENEVSKY RIDGE)

I. I. KOPTEV, A. K. SEMASHKO, V. A. SHIPITSYN

(Presented by the scientific seminar of the Departments of General Geology, Historical Geology, and Mineral Resources)

For the first time, under the name “Litvinovskaya suite,” V. D. Tomashpolskaya distinguished a sequence of dark-gray marbled limestones exposed in the area between the Yuliya mine and Son Station. The age of this sequence was provisionally determined by her as Lower Cambrian, on the basis of finds of Archaeocyatha on the northern margin of the Yuliya mine; the contacts with all other formations were regarded as disjunctive (subsequently it became clear that the limestones containing remains of Archaeocyatha do not belong to the Litvinovskaya sequence). Somewhat later A. B. Gintsinger et al. [1] included the indicated sequence in the Goldzhinskaya suite, assigning it in age to the Upper Precambrian and placing it in the section below the volcanogenic Kulburtstyugskaya (Loshchenkovskaya) suite.

Detailed work by a group of staff members of the Department of General Geology of TPI (G. A. Ivankin and others) made it possible to obtain new geological and paleontological materials, to establish the exact stratigraphic position and relationships of the indicated sequence, and to express an opinion on its stratigraphic significance. These same studies made it possible to establish the widespread elevated phosphatic content of the sequence, in places reaching industrial concentrations (the deposit at Skalisty Creek on the Sukhoi Erbe River). The new materials set forth below make it possible to eliminate the existing disagreements concerning the position and significance of the Litvinovskaya sequence.

Within the area described (Podtemnyi Log—Yuliya mine—Son Station), rocks of the Litvinovskaya suite are mapped as several bands and patches isolated from one another. At the same time, in different areas the suite has a somewhat different composition and a considerably varying thickness; nevertheless, as a whole, the suite is characterized by a predominance of dark-gray, more often massive limestones that include beds and lens-shaped bodies of black and dark-brown, commonly brecciated silicites, which clearly emphasize the internal structure of the sequence.

In the section along Podtemnyi Log (its right side), the suite has a thickness of 380 m and rests, at different horizons, on the underlying volcanogenic formations of the Kulburtstyugskaya suite with a break, having at its base thin ferruginous gravelites and sandstones (20–30 cm). In this area, by composition, the suite is subdivided into two members, of which the lower is limestone–dolomite, and the upper is conglomerate–sandstone–limestone. In the lower member, among organogenic carbonate rocks, V. A. Shipitsyn identified Osagia tenuilamellata

Reitl., O. granulosa Krasn., O. poetaevi Krasn., O. grandis Z. Zhur., O. columnata Reitl., Asterosphaeroides ruminatus Zabr., Volvatella obsolita Nar., V. vadosa Z. Zhur., Vermiculites irregularis Reitl., which make it possible to determine its age as Upper Riphean. In the limestones of the lower and upper members there are lenses of black siliceous rocks of organogenic origin with spherical formations resembling radiolarians. A small area of outcrops of rocks of the Litvinovskaya Formation has been mapped on the northern slope of Mt. Romanovskaya, where the formation is represented by dark-gray bedded limestones with beds and lenses of phosphatic siliceous rocks lying on porphyrites of the Kulbyurstyug Formation. In these areas the Litvinovskaya Formation is overlain, with a break, by light saccharoidal dolomites of the Tarzhul Formation, containing a rich complex of Vendian microphytolites.

In the section along the watershed of the Poperechnyi and B. Kordonnyi ravines (headwaters of the Sukhaia Erba River in the area of the Yuliya mine), the Litvinovskaya Formation has a considerable thickness (about 1200 m) and a uniform composition, being composed of dark-gray and black massive (mainly) limestones. About 20% by volume consists of dolomites of light-gray, yellowish, or bluish shades. In addition, there are members and lenses of gray, brown, and black silicilites, often also occurring as nodules and angular fragments of varying extent and thickness. Some members of silicilites reach a thickness of 120 m. The cherts are often brecciated and distinctly bedded; under the microscope they in many cases contain sponge spicules and spherical formations (radiolarians?). The base of the formation in this section has not been exposed (disjunctive contact); it is overlain with an azimuthal unconformity by basal conglomerates of the overlying dolomitic Tarzhul Formation. The thickness of the conglomerates varies from 30 to 100 m, and their pebbles are represented by all varieties of rocks of the underlying Litvinovskaya Formation. In the dolomites of the Tarzhul Formation in this section, a Vendian complex of organic remains (catagraphs, algae) is also established.

Among the organic remains in the rocks of the Litvinovskaya Formation collected in this area at several points, V. A. Shipitsyn identified: Osagia tenuilamellata Reitl., O. granulosa Krasn. Southeast of the described area, on the watershed of the Sukhaia and Sredniaia Erba rivers, another belt of outcrops of rocks of the Litvinovskaya Formation has been mapped; it is bounded on the southeast by a disjunctive, and on the northwest is overlain either by light limestones with the Obruchev complex of archaeocyaths and trilobites, or by terrigenous rocks of the Sladkokorenevskaya Formation [4]. In this area the rocks of the Litvinovskaya Formation are also represented mainly by black and dark-gray limestones, silicilites, and gray dolomites, and are distinguished by the highest phosphatic content (in 1965–1966 exploration was conducted here for a phosphorite deposit on the northern slope of Mt. Skalistaya). In this belt, at several points, V. A. Shipitsyn collected and identified: Osagia tenuilamellata Reitl., Tunicatella maritima Korol., Vermiculites angularis Reitl., V. maracus f. nov., Asterosphaeroides serratus Reitl., A. palmatus f. nov., Osagia monolamellosa Z. Zhur., O. grandis Z. Zhur., O. composita Z. Zhur., O. crispa Zhur., indicating the Upper Riphean age of the deposits containing them.

A significant field of distribution of rocks of the Litvinovskaya Formation is the belt of outcrops traced from the Sredniaia Erba River, 5 km above Zverosovkhoz, across the watershed to the Bolshaia Erba River, where these rocks were included by V. A. Borisov in the Sosnovskaya Formation. To the southwest this belt is cut off by the northern margin of the Uibat intrusive massif; to the southeast it borders on the effusives of the Kulbyurstyug Formation, overlying the latter, and to the northwest is overlain—

is replaced by light-gray dolomites, probably belonging to the Tarzhul Formation. In this area the formation is also represented by dark-gray, for the most part massive limestones, silicilites, and dolomites. Its rocks here are also easily recognized by their increased phosphatic content. In small quantities, in the upper part of the formation, gray calcareous siltstones, sandstones, and conglomerates occur as separate beds and lenses up to the first tens of meters thick, which, among other things, increases the similarity of the formation in this area to its rocks in the section along Podtemnyi Log. Separate small outcrops of rocks of the formation are observed northeast of the Yuliya mine and near the settlement of Zverosovkhoz, but they are of no substantial significance for establishing the stratigraphic position of the formation because of complex disjunctive tectonics.

Thus, from the materials presented above, the following conclusions may be drawn:

1. The unit of massive dark-gray limestones with silicilites and dolomites, distinguished everywhere by increased phosphatic content, has independent stratigraphic significance; it is bounded below and above by breaks and should be distinguished at the rank of a formation under the name “Litvinovskaya” (in accordance with the principle of priority).

2. The Litvinovskaya Formation lies above the volcanogenic Kulbyurstorg (Loshchenkovskaya) Formation and is overlain by the Tarzhul, predominantly dolomitic, Formation, which is of Vendian age.

3. On the basis of the assemblage of organic remains and its stratigraphic position, the age of the Litvinovskaya Formation is determined as Upper Riphean.

With regard to the question of the distribution of the rocks of the formation in other areas, it should be noted that in the Kommunarovsky, Saralinsky, Tyurim-Efremkinsky, Amarsky, and Tamalyksky districts it is not represented, and this interval corresponds to a break that is clearly established at the base of the Tarzhul Formation. It is quite evident that the Litvinovskaya Formation has its analogues in other parts of the Kuznetsk Alatau, in particular on the Azyr-Tal Ridge, but at present there are few data for making an exact correlation of the section described with the section of the Azyr-Tal Ridge. It is clear that the Litvinovskaya Formation corresponds to all or some part of the Yenisei Series of the section along the Kuten-Buluk valley (which is not contradicted by paleontological data); the great similarity in rock composition and the increased phosphatic content of the Litvinovskaya and Sorninskaya formations are striking, but it is still premature to draw firm conclusions about correlation of these sections.

In conclusion, it should be noted that the conclusions of some researchers concerning the inclusion of the rocks of the Litvinovskaya Formation in the Goldzhinskaya (Poludennaya and Tyurimskaya) Formation are unfounded. The distinctive features of the Litvinovskaya and Tyurimskaya formations are: the absence of dolomites in the Tyurimskaya Formation; completely different organic remains (Saralinskia and Newlandia, on the one hand, and predominantly oncolites on the other); the abundance of silicilites in the Litvinovskaya Formation and their small amount in the Tyurimskaya; occurrence beneath the effusives of the Kulbyurstorg Formation and above them (Litvinovskaya); and, finally, different degrees of metamorphism (schistosity).

REFERENCES

1. A. B. Ginzinger, M. K. Vinkman, V. A. Astashkin, V. A. Tarasenko, B. G. Kraevsky, A. G. Postelov. Sections of the Precambrian and Lower Paleozoic of the western part of the Altai-Sayan folded region. Transactions of SNIIGGiMS, Krasnoyarsk, 1969.

2. I. I. Yuttev, V. E. Nomokonov, A. K. Semashko, V. A. Shi-

[[unclear: beginning of reference]] on the stratigraphy of ancient sequences in the area of the upper course of the Sukhoi Yerba River. Izv. TPI, vol. 218, 1971.

1. A. F. Senakolis, I. I. Koptev, V. A. Shpitsin. New data on the stratigraphy and lithology of the Upper Precambrian and Lower Cambrian deposits of the Batenevsky Ridge. Izv. TPI, vol. 151, 1966.

2. V. A. Shpitsin, G. A. Ivankin, I. I. Koptev. Manganese content of the Middle Cambrian in the eastern part of the Kuznetsk Alatau. In: Problems of the Geology of Exogenous Mineral Raw Materials of Krasnoyarsk Krai. Krasnoyarsk, 1970.