Neogene

Paleogene

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Neoproterozoic

Mesoproterozoic

Paleoproterozoic

Main source = Abduazimova, Z.M. (Ed.), 2001. Stratigraphic Dictionary of Uzbekistan. IMR (Institute of Mineral Resources), Tashkent, 580 pp. (In Russian) Translated to English by the GeoGPT group, Zhejiang Lab, Hangzhou, China--see About

Vakhshar Formation

Vakhshar Fm

Period:

Carboniferous

Age Interval:

Visean upper substage - Serpukhovian, B1a, B2

Province:
Bukhara-SW Gissar

Type Locality and Naming

By the village of Vakhshivar, southern slope of the Gissar Ridge. F.R. Bensh, 1965 (457, p.234); (106, p.8). Stratotype in the upper reaches of the Vakhshivar River.

Synonym: Vakhshivar Suite, Вахшайская св.

Lithology and Thickness

At the base, basal layers of conglomerates, gravels, sandstones, siltstone (aleurolites) (up to 140m). Above - acid volcanic rocks: rhyolites, rhyodacites, dacites, their tuffs and ignimbrites, with interlayers of limestones, sandstones, siltstone (aleurolites), less frequently gravels, conglomerates, jaspers, cherts, argillites. Reef limestone structures are characteristic. Thickness 500-2000 m.

Lithology Pattern:

Volcanics

Relationships and Distribution

Lower contact

Transgressively overlies the Obizarang Fm and Zoy Fm

Upper contact

conformably overlain by the Suffin-Carb Fm.

Regional extent

Kugitangtau, Susyztau, Baysuntau, Surkhantau, Yakkabag, rarely southern slopes of the Gissar Range.

GeoJSON

null

Fossils

Numerous remains of foraminifera - Asteroarchaediscus ex gr. baschkiricus Krest. et Theod., Globoendothyra ishimica Raus., Howchinia Gibba Moell., Valvulinella tchotchiai Grozd. et Leb., Eostaffella parva Moell., E. parva decurta Raus. and others, brachiopods - Gigantoproductus giganteus Mart., G. superior Jan., G. superbus Sar., Spirifer postriatus Nik., corals - Lithostrotion irregulare Phill., L. junceum Flem., L. caespitosum Mart. and others; conodonts - Gnathodus cf. girtyi Hass., Goniatites and others.

Age

Radiological age of rhyolites, quartz porphyries, and ignimbrites of the V. sv. 316-310 +/- 9 million years (K-Ar method) (187). Dated to the early Carboniferous, late Visean-Serpukhovian epoch. (165; 439; 460).

Age Span:

Beginning stage:

Visean

Fraction up in beginning stage:

0.5

Beginning date (Ma):

338.54

Ending stage:

Serpukhovian

Fraction up in the ending stage:

1.0

Ending date (Ma):

323.40

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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