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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Tashdzhilga Formation

Tashdzhilga Fm

Period:

Triassic

Age Interval:

Anisian – Carnian (T_2-3), M3a

Province:
SE Tajik (SE Pamir)

Type Locality and Naming

Includes in SE Murghab district (Gurdumdin type section), also belong to the Tashdzhilginsk type of Triassic section.

Synonym: Tashdzhilginskaya Suite, ташджилгинская, Bashgumbez Suite

Reference section:

Lithology and Thickness

Tashdzhilgin Fm (Ташджилrинская толща) (100-1000 m) consists of gray and colorful, predominantly limestone gravel conglomerates, gravels, and sandstones with interlayers and lenses of light massive and coarse-bedded, partly reef limestone. Limestones prevail in the upper part of the section of the layer. In the lower part, there are interlayers and lenses of colorful acidic volcanics of the Irikyak type.

Chatyrtash Fm (Чатырташсkая толща) (1000 - 1500 m) is composed of dark green amphibolitized diabases, basalts, spilites, and their volcanoclastic varieties;
Murzabek Fm (500-1000 m) - greenish-gray quartz albitephires, passing into granophires. The layer is saturated with plagio-granite material and is cut by a system of dikes and stock-like masses of plagio-granites.

The Irikyak Fm (100 - 500 m) is composed of colorful liparites, quartz porphyries, quartz albitephires, their tuffs, and tuff conglomerates.

In general, the Chatyrtashskaya, Murzabekskaya, and Irikyakskaya layers (чатырташская, мурзабекская и ирикякс,кая толщи) form a single powerful (1600-3000 m) series of volcanic rocks, which it is proposed to name Bashgumbez.

Lithology Pattern:

Volcanics

Relationships and Distribution

Lower contact

They lie with an unclear contact on the formations of the conditionally Riphean North Alay Gr

Upper contact

They are overlain by a conditionally Norian Janbulak Fm with visible conformity.

Regional extent

It is widespread in the eastern part of the South Alay (Pamir) ridge, in the basins of the Bashgumbez, Irikyak, Sedek, Tashdzhilga, Kuldzhilga, Janbulak rivers.

GeoJSON

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Fossils

In the clasts of the conglomerates, limestones prevail, including with abundant remains of Permian foraminifera and corals: Staffella sp., Palaeofusulina sp., Geinitzina sp., Reichellina sp., Gal-lowainella sp., Nodosaria sp., Waagenophyllum ex gr. kueichowense Huang, W. cf. virgalense Waag. et Wentz.

Age

The age of the Tashdjilgin layer (ташджилгинской толщи) is determined by the findings in the interlayers and lenses of limestones among conglomerates of remains of Carnian corals Conophyllia boletiformis (Münst.), Thecosmilia? subdichotoma (Münst.), T.? sublaevis (Münst.). In the Chatyrtash, Murzabek, and Irikyak layers, no remnants of fauna have been found, and they are conditionally assigned to the middle-upper Triassic, based on the conformable deposition beneath the faunistic characterized Tashdjilgin layer and by comparison with the Kattamardjanai suite, which is substantiated by remains of fauna. At the same time, possible erosion at the boundary of the Irikyak and Tashdjilgin layers does not exclude a more ancient age of the volcanics. Hence considered Middle Triassic – Carnian for schematic stratigraphic representation purpose.

Age Span:

Beginning stage:

Anisian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

246.70

Ending stage:

Carnian

Fraction up in the ending stage:

1.0

Ending date (Ma):

227.30

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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