Chaartash Formation

Chaartash Fm

Period:

Jurassic

Age Interval:

Middle Jurassic (Aalenian – Bajocian), F1, F2, F7

Province:
Fergana

Type Locality and Naming

Along the Chaartash Pass, Fergana Range. V.N. Ognev, 1946 (336, p.25). Stratotype along the Chaartash section, Fergana Range.

Synonym: Chaartash Suite, Чаартасская св.

Lithology and Thickness

Conglomerates with lenses of sandstones (central part of the Fergana Range); interbedding of conglomerates, sandstones, siltstone (aleurolites) with coal lenses in the lower part. Thickness 130-700m.

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

Transgressively overlies the Tuyuk Fm or Paleozoic

Upper contact

Transgressively overlain by the Zindan Fm. E.A. Repman. Strat. sl. (446).

Regional extent

Central and southeastern parts of the Fergana Range, its western spurs, and the Fergana Depression.

GeoJSON

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Fossils

Contains large plant remains - Neocalamites carrerei Zeill., Clathropteris obovata Oishi, Coniopteris hymanophylloides (Brongn.) Sew., Cladophlebis nabbensis (Brondh.) Wath., etc.

Age

At the Samarkand Conference (383, table 5, l3) the Aalenian - Bajocian age of the suite was accepted by V.N. Ognev (336, p.25) and at the Tashkent Conference (382, table 13) it was assigned to the Early Jurassic.

Age Span:

Beginning stage:

Aalenian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

174.70

Ending stage:

Bajocian

Fraction up in the ending stage:

0.1

Ending date (Ma):

170.63

Depositional setting

Depositional pattern:

Additional Information

Compiler:

V.V. Kurbatov – In: GeoGPT translation of: ”Abduazimova, Z.M. (Ed.), 2001. Stratigraphic Dictionary of Uzbekistan. IMR (Institute of Mineral Resources), Tashkent, 580 pp. (In Russian)"