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

Obizarang Formation

Obizarang Fm

Period:

Cambrian, Ordovician

Age Interval:

Cambrian-middle Ordovician, B2

Province:
Bukhara-SW Gissar

Type Locality and Naming

Along the Obizirang River, Gissar Range. E.M. Golovin in 1933. Stratotype in the basin of the Obizirang River.

Synonym: Obizarang Suite, Обизарангская св.

Lithology and Thickness

Crystalline, quartzitic, carbonaceous, and phyllitic slates, quartzites, marbles, gneisses, actinolites, orthoschists, gneisses, and amphibolites over acid and basic volcanites with layers of meta-siltstones (meta-aleurites) and meta-sandstones. Thickness 1000-1900m

Lithology Pattern:

Sandy_claystone

Relationships and Distribution

Lower contact

The lower contact is tectonic, but Along data from Z.A. Yudalevich, F.R. Divaev, in some outcrops it is conformable on the Mastavat Fm.

Upper contact

It is unconformably overlain by the Vakhshvar Fm.

Regional extent

South slope of the Gissar Range, Yakkabag and Mechetli Mountains.

GeoJSON

null

Fossils

Age established by microfossil complexes: in the lower part - Protoleiosphaeridium conglutinatum Tim., Leioligotriletes crassus (Naum.) Tim., Mycteroligotriletes marmoratus Tim., Trachyoligotriletes inrassatus (Naum.) Tim., etc., no younger than early Cambrian; higher up - Baltisphaeridium crassus (Naum.), Leiominuscula minuta Naum., L. rugosa Naum., Lophosphaeridium laculatum N.Umn., Margominuscula minor Naum., etc., of late Cambrian-early Ordovician age; chitinozoa - Conochitina sp., Desmochitina sp., Lagenochitina sp. (?) - no older than the Ordovician (460).

Age

V.V. Mikhailov, considering the high degree of metamorphism of the rocks, where the preservation of organic remains is highly questionable, considers the Obizirang Fm to be Proterozoic. The Obizirang Fm slates were conditionally considered pre-Cambrian in 1956-1958 by S.K. Ovchinnikov and A.T. Tarasenko; the decision of the stratigraphic conference in 1959 (382); V.A. Khokhlov (492); A.V. Pokrovsky (349).

Age Span:

Beginning stage:

Paibian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

497.00

Ending stage:

Tremadocian

Fraction up in the ending stage:

1.0

Ending date (Ma):

477.08

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)”