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

Dzhazbulak Formation

Dzhazbulak Fm

Period:

Silurian

Age Interval:

upper Llandovery, N7

Province:
Nuratau

Type Locality and Naming

Along the Dzhazbulak valley, N. Nuratau ridge. N.R. Asatullaev et al. (1970f.), volume, age, and distribution clarified by R.R. Usmanov et al. (1984f., 1989f.), R.S. Khan et al. (1989f.), Z.M. Abdouazimova et al. (11) (165, p.46). Stratotype in Jazbulaksa (Dzhazbulak).

Synonym: Dzhazbulakskaya Suite, Джазбулакская св., Jazbulak Fm

Lithology and Thickness

Quartzose greenish-gray siltstone (aleurolites), interbedded with dark, yellowish-gray claystone (argillites), quartz-schistose slates, and less frequently polymictic, poorly sorted sandstones. Thickness 100-110 m.

In the siltstone (aleurolites), horizontal and wavy bedding is observed; traces of erosion of underlying clayey layers are often seen. Among the terrigenous rocks, there are layers of tuffs of basic composition and lenticular bodies of dolerite-basalts. Here, according to V.V. Mikhailov, there are sill-like deposits, dikes, and stocks of diabases, gabbro-diabases, and apodiabase porphyrites (460).

Lithology Pattern:

Volcanics

Relationships and Distribution

Lower contact

According to the stratigraphic position, it lies conformably on the Nakrut Fm

Upper contact

It is conformably overlain by the Naukatsay Fm.

Regional extent

Southern slope of the North Nuratau Ridge - basin of the Jilandy, Baypurshly, Jazbulak, and Sanzar rivers; and South Nuratau - basin of the Aktapa-Tusun to the eastern end of Karakchatay; Gobduntay Mountains. In South Nuratau, the Dzhazbulak Fm was distinguished by R.S. Khan et al. (1989) from the composition of the Alanguz Fm, Tusun Fm, and Mullamalin Fm, as understood by I.A. Pyanovskaya et al. (371); and from the Kutangbulak Fm, Sartbulak Fm, and Buratbulak Fm, as understood by Yu.I. Loshkin et al. (1963, 1965, 1967, 271).

GeoJSON

null

Fossils

In the argillites and siltstone (aleurolites), graptolites of the Late Llandovery - Oktavites spiralis (Geinitz.), Monoclimacis griestonensis (Nicol.), M. alaica Obut., M. asiatica Obut., Monograptus priodon Bronn., Stomatograptus grandis(Suess.), Retiolites geinitzianus Barr., R. angustidens (Elles.); chitinozoa - Margochitina margaritana (Eis.), Cingulochitina cingulata (Eis.), Eisenackitina sp.

Age

In the Stratigraphic Lexicon (443), it is dated to the early Silurian (late Llandovery-early Wenlock).

Age Span:

Beginning stage:

Telychian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

438.59

Ending stage:

Telychian

Fraction up in the ending stage:

1.0

Ending date (Ma):

432.93

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)”