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

Shavaz Formation

Shavaz Fm

Period:

Devonian, Carboniferous

Age Interval:

Emsian-Bashkirian, N4

Province:
Nuratau

Type Locality and Naming

Along the village of Shavaz, right bank of the Yamchisay, N. Nuratau Ridge. O.I. Kim, O.A. Starcev et al., 1976. Lectostratotype in the lower-middle course of the Yamchisay.

Synonym: Shavaz Suite, Шавазская св.

Lithology and Thickness

The suite is divided into three parts.

Upper - interbedding of slates, sandstones, gravels, cherts, limestones

Middle - monotonous thickness of basaltoids - amygdaloidal spilites, basaltic porphyrites, diabases, hyaloclastite lavas.

Lower - amygdaloidal spilites with horizons of flaggy cherts with conodonts

Total thickness 600-800 m.

Lithology Pattern:

Volcanics

Relationships and Distribution

Lower contact

Contacts with surrounding deposits are everywhere tectonic. According to R.S. Khan (1998), the Shavaz Fm overlies the Bolosay Fm

Upper contact

Contacts with surrounding deposits are everywhere tectonic. V.V. Mikhailov believes that in the Orta-Kishlak area, it is transgressively overlain by the Farish Fm.

Regional extent

Low foothill part of the northern slope of the North Nuratau ridge.

GeoJSON

null

Fossils

Upper – With ammonites - Prolecanites sp., Stenopronorites sp. and conodonts - Idiognathoides sinuatus Har. et Hol., I. asiaticus Nig. et Nem. - of early Bashkirian age.

Middle – At the top of the suite - rare lenticular bodies of limestones with conodonts - Gnathodus bilineatus (Round.), Lochrica mononodosa (R.A. et D.) - of Visean and Serpukhovian age.

Lower – Conodonts - Palmatolepis gracilis sigmoidalis Zieg., Polygnathus extra lobatus Schafer of the Famennian age. In carbonate lenses along the southern boundary of the suite's distribution area, tabulates - Favosites cf. interatinotus Regnell., Thamnopora cf. aliena aliena Yanet. of the Emsian age of the early Devonian.

Age

The age of the suite is interpreted differently depending on the view of the section structure. Proponents of the allochthonous position of faunistic bodies considered the age of the suite, as a rule, within the middle Carboniferous (165; 460); I.M. Nigmadzhanov et al. consider these bodies as syngenetic interlayers and lenses, determining the age in a wider range from early Devonian to middle Carboniferous of early Bashkirian. P.N. Podkopaev et al. (1964) mapped these deposits as the Chimkurgan suite (Chimkuragan Fm) of the upper Namurian; O.I. Kim, O.A. Startsev (1976) separated the Shavaz Fm from the Chimkurgan suite and assigned it to the Cambrian-Ordovician; R.R. Usmanov et al. (1984) considered the age of the Sh. suite to be late Devonian-early Carboniferous; A.K. Bukharin et al. (1990) middle Carboniferous (Moscovian epoch); V.P. Vashchenko et al. (1992) middle Carboniferous; V.S. Korsakov et al. (1993) - middle Carboniferous (Bashkirian epoch); in the monograph (165) and V.V. Mikhailov (460) assign it to the middle Carboniferous.Put as Base Emsian for graphic purposes - "Lower Devonian-Middle Carboniferous -- Emsian stage to Bashkirian stage. Debated age; but placed here according to possible above/below

Age Span:

Beginning stage:

Emsian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

410.51

Ending stage:

Emsian

Fraction up in the ending stage:

1.0

Ending date (Ma):

394.30

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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