Taranchi Fm

Period:

Permian

Age Interval:

late-Early Permian

Province:
Zaisan (Zaysan) Basin - East, Zaisan (Zaysan) Basin - Central

Type Locality and Naming

Synonym: Taranchiskaya, P1tr

Lithology and Thickness

In borehole Sarybulak C-1, it is described as ca. 200 m. The most typical rocks are claystone with thin-laminated texture oftenbituminiferous (combustible shales). Rare interbeds of polymictic aleurotite (silt) and sandstones of porosity 18-20% and specific resistance of 80-100 om/m. In the reference borehole at 3153-3160 m, the bitumen in the joints is present in the form of fellicle (definition?).

In Well X-II, Primanrack Depression, it is "200 m-thick, mainly composed of mudstones and oil shales. Siltstones are of subordinate importance. Sandstones are almost absent, but contain degraded oil at a depth of 3153–3160 m." and in Kenderlyk Trough (southern margin) it is " Up to 500 m-thick, mainly composed of mudstones and oil shales intercalated with thin layers of siltstones and fine- grained sandstones. Dolomitic limestone intercalations occur in the lower part. The formation is intruded by a 20 m-thick, 12 km- long diabase dike." (Nurbekova et al., 2023)

Lithology Pattern:

Claystone

Relationships and Distribution

Lower contact

Overlies the Karaungur Fm

Upper contact

Underlies the Maychat Fm (Michat Fm)

Regional extent

Originally throughout the entire basin; but later tectonics and erosion during uplifts implies that the main surface exposures of the Late Carboniferous-Permian succession is a 2-km-thick succession in the Kenderlyk Trough in the southern part of the Zaisan (Zaysan) basin (Nurbekova et al., 2023).

GeoJSON

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Fossils

Age

late-Early Permian (Kungurian?)

Age Span:

Beginning stage:

Kungurian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

283.30

Ending stage:

Kungurian

Fraction up in the ending stage:

1.0

Ending date (Ma):

274.37

Depositional setting

"The Tarancha Fm is likely to be shallow-marine or lacustrine" (Nurbekova et al., 2023)

Depositional pattern:

Additional Information

Compiler:

Information provided by Nariman Jamikeshev from Kazakh-language sources and from other publications (e.g., Nurbekova et al., 2023. High-quality source rocks in an unexplored basin: The upper Carboniferous-Permian succession in the Zaysan Basin (Kazakhstan). Internat. Jour. Coal Geology, 272, article 104264.