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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Jax Formation

Jax Fm

Period:

Carboniferous

Age Interval:

Late Serpukhovian (C₁ n), D1

Province:
SW Tajik

Type Locality and Naming

The suites were delineated by N.G. Vlasov and I.V. Pyzyanov (Vlasov, 1961, 1963). Uppermost formation in Namurian Gr.

Synonym: Jaxskaya suite, джакская свита

Reference section:

Lithology and Thickness

Its lower part (1100-1200 m) is composed of thinly banded light green jasper-like tuffaceous rocks.

Here, lenses (10-80 m) of light green plagioclase and pyroxene-plagioclase porphyrites, diabases, and tuffs are also encountered. The upper part of this suite (600-700 m) contains interbedded tuffs, plagioclase porphyrites, and tuff breccias.

Lithology Pattern:

Volcanic_ash

Relationships and Distribution

Lower contact

N. G. Vlasov considers the contact between the Ushkharv Fm and Jax Fm (считает контакт ушхарвскойи джакской свит) to be conformable. I. V. Pyzyanov (1964) supposes that the Jax Fm unconformably overlies the Ushkharv Fm.

Upper contact

Namurian Gr. I. V. Pyzyanov (1964) supposes, it is in turn conformably overlain by limestones of the upper substage of the Moscow stage.

Regional extent

They are distributed in the territory of Darvaz.

GeoJSON

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Fossils

The presence in the Jax Fm of redeposited fragments of limestones with Visean-Namurian foraminifera and brachiopods.

Age

The Jax Fm (джакская свита) caps the Serpukhovian stage. N.G. Vlasov conditionally considers its age as Late Serpukhovian. Taking into account I. V. Pyzyanov (1964) conclusions, as well as the presence in the Jax Fm of redeposited fragments of limestones with Visean-Namurian foraminifera and brachiopods, I. V. Pyzyanov refers the Jax Fm to the Middle Carboniferous, considering it synchronous with the Upper Bashkirian - Lower Moscovian Vozgin Fm.

Age Span:

Beginning stage:

Serpukhovian

Fraction up in beginning stage:

0.5

Beginning date (Ma):

326.87

Ending stage:

Serpukhovian

Fraction up in the ending stage:

1.0

Ending date (Ma):

323.40

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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