Siomin Gr

Cenozoic

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Neoproterozoic

Main source = Baratov, R.B., et al. (1976). Subdivisions of stratified and intrusive rocks of Tajikistan. Publishing House "Donish", Dushanbe, 269 pp. plus tables. Provided by Dr. Jovid Aminov, Nazarbayev University, Astana, Kazakhstan Translated to English by the GeoGPT group, Zhejiang Lab, Hangzhou, China--see About

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Siomin Gr

Period:

Carboniferous

Age Interval:

Visean (C_1-2sm), S4

Province:
North Tajik

Type Locality and Naming

It was identified (as a suite) in 1988 by Yu. A. Sorokin. In this work, it is considered as a series.

Synonym: Siomin series

Reference section:

Lithology and Thickness

It is composed of altered lavas, tuff lavas, lava breccias, clastolavas of quartz and dacite porphyries, albite-phires, liparites, their tuffs, marbleized limestones, polymict and quartz sandstones, claystones, kerogenized shales, siliceous rocks. Volcanics predominate in the lower section, carbonate rocks - in the middle part, and terrigenous - in the upper part of the section. Series thickness 1400-2200 m.

Lithology Pattern:

Volcanic_ash

Relationships and Distribution

Lower contact

The Siomin Gr lies on metamorphosed rocks of the upper Silurian - middle Devonian with erosion, but without visible angular unconformity.

Upper contact

The overlying Paleozoic deposits are unknown.

Regional extent

Developed in the axial part of the Hissar Ridge.

GeoJSON

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Fossils

In the limestones of the middle part of the section series, remains of rugose corals Lithostrotion ex gr. junceum Flem., L. aff. caespitosum (Mart.), L. irregulare Phill., Diphyphyllum aff. ingeus Hill., Lonsdaleia aff. diplicata Mart. foraminifers Plectogyra ex gr. omphalota (Raus. et Reitl.), Archaediscus ex gr. moelleri Raus., A. cf. karreri Brady, Eostaffella cf. parastruvei Raus., Eost. ci. mediocris Viss., Eost. mosquensis Viss., Eost. proikensis Raus.,

Age

The fossil assemblage indicates the Visean age.

Age Span:

Beginning stage:

Visean

Fraction up in beginning stage:

0.2

Beginning date (Ma):

343.45

Ending stage:

Visean

Fraction up in the ending stage:

0.6

Ending date (Ma):

336.90

Depositional setting

Depositional pattern:

Additional Information

D. A. Rubanov (1968) on the southern slope of Mt. Zakakhona in the middle part of the series identified Upper Carboniferous, according to O. I. Sergunykhova, brachiopods. At the same time, D. A. Starshinin collected various organic remains from this section, which overall indicate an early Carboniferous age (Viséan-Namurian) for the host deposits. According to D.A. Starshinina, the upper Carboniferous brachiopods originate from deposits that do not belong to the Siomin series. The presence of Bashkirian and lower sub-series of the Moscow series in the Siomin series is assumed based on the large apparent thickness of the upper part of the series section, not characterized by fauna, and the correlation with the below-described Karatag series. The Siomin series has been poorly studied. It is not excluded that Tournaisian formations may be found in its lower parts.

Compiler:

Extracted from Baratov, R. B. (1976). Subdivisions of stratified and intrusive rocks of Tajikistan. Donish, Dushanbe, 276.