Cenozoic

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

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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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Kochusu Formation

Kochusu Fm

Period:

Permian

Age Interval:

mid-Early Permian (P₁), M1-M3d

Province:
SE Tajik (SE Pamir)

Type Locality and Naming

Includes in SE Murghab district (Mynkhadjr type), SE Murghab district (Istyk type (Dunkeldyk area), SE Murghab district (Gurdumdin type), SE Murghab district (Gurdumdin type Kastanatdjilga, Buryukurmes rivers), SE Murghab district (Gurdumdin type Shin and Igrymiyu rivers), SE Murghab district (Gurdumdin type Gurumd and Kattamardzhana rivers).

Formerly (?) it was the lower part of the Shindy Fm (Shindy series).

Synonym:

Lithology and Thickness

“The Kochusu Formation consists of 12–60 m of silty limestones, locally bioclastic, overlain by siltstones with few and thin intercalations of marly limestones. … Microfacies analysis of the limestones at the base of the Kutal 2 section shows that they are bioclastic packstones with foraminifers, algae, brachiopods and bivalves.”

Lithology Pattern:

Sandy limestone

Relationships and Distribution

Lower contact

“The Kochusu Fm unconformably covers the Tashkazyk Fm (upper Bazardara Gr) above an emersion surface. “ However, “Outcrops of the Kochusu Formation in the Kuristyk and Kastenat Djilga Valleys are few and mostly covered. We were not able to observe the laterite at its base, reported by Grunt and Dmitriev (1973) and Leonova and Dmitriev (1989), because it is usually covered by talus or the contact with the formation below is tectonized.” (Angiolini et al., 2015). Angiolini et al. (2015) indicate the hiatus (erosion and/or non-deposition) spans the entire Artinskian.

Upper contact

The Shindy Fm conformably overlays the Kochusu Fm and laterally replaces it.

Regional extent

It is widespread in the Southeast Pamir.

GeoJSON

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Fossils

“The Kochusu Fm contains fusulinids [Monodiexodina shiptoni (Dunbar) and species of Chalaroschwagerina, Darvasites, and Leeina), smaller foraminifers (Multidiscus sp.), algae, brachiopods, ammonoids, rare rugosa, corals, and conodonts.” (Angiolini et al., 2015)

Age

Mid-Early Permian. Represent the second type of Kuberkandinsky - Pamir horizons in the South-East Pamir. E. Ya. Leven (1967) believed the [base] Shindy suite (now lower part separated as the Kochusu Fm) to be coeval only with the top of the Bazardarin Fm. B. M. Gushchin (1973) established that the [top] Shindy suite is synchronous with the bottom of the Kubergandin Fm.“According to several authors (Leonova and Dmitriev, 1989; Leven et al., 1989; Reimers, 1999; Kozur, 1994), ammonoids and conodonts suggest a Bolorian (latest Early Permian) age for the Shindy Fm and Kochusu Fm, correlatable to the Kungurian of the International (Global) Scale.” (Angiolini et al., 2015) [For graphics, Kochusa Fm put as late Artinskian portion (after early Artinskian emersion surface), and Shindy Fm as the earliest Kungurian portion.

Age Span:

Beginning stage:

Artinskian

Fraction up in beginning stage:

0.5

Beginning date (Ma):

286.91

Ending stage:

Kungurian

Fraction up in the ending stage:

0.0

Ending date (Ma):

283.30

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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

Angiolini, L., et al. (11 authors) (2015) From rift to drift in South Pamir (Tajikistan): Permian evolution of a Cimmerian terrane. Jour. Asian Earth Sciences, 102: 146-169. http://dx.doi.org/10.1016/j.jseaes.2014.08.001