Baysuntau Gr

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

Baysuntau Gr

Period:

Proterozoic

Age Interval:

Lower Proterozoic (?), B1a

Province:
Bukhara-SW Gissar

Type Locality and Naming

V.A. Khokhlov, 1970 (432, 24c); I.M. Mirkhodzhaev, V.A. Khokhlov et al., 1977 (307, pp. 60-73).

Synonym: Baysuntau Series, Байсунтауская сер.

Lithology and Thickness

Forms the cores of large geoanticlines. Includes the upward succession of the Karatash Fm, Khodzha-Buzbak Fm, Aylangar Fm, and Shatut Fm.

More than 90% of the thickness is composed of gneisses and crystalline schists, of which more than half are aluminous varieties (cordierite- and sillimanite-bearing). About 12% of the rocks are orthogneisses, with about 4% being derivatives of basic magmatism (amphibolites, amphibole and amphibole-biotite gneisses), and about 8% being products of acidic magmatism and granitization. About 10% are quartzites. The rocks are metamorphosed predominantly in the amphibolite and epidote-amphibolite facies of regional metamorphism. Thickness 7040m.

Lithology Pattern:

Gneiss

Relationships and Distribution

Lower contact

Schematic stratigraphic column indicates the lower contact as Shatut Fm

Upper contact

Schematic stratigraphic column indicates the upper contact as Vakhshar Fm

Regional extent

Baysuntau and Susyztau ridges, South-Western Gissar.

GeoJSON

null

Fossils

Age

The Precambrian age of the Baysuntau Gr is established based on the discovery of their pebbles in Early Paleozoic conglomerates and numerous dating results indicating the timing of metamorphic stages of the rocks in the range from 288 ± 18–480 to 1239–1465 million years (73). The age is conditionally lower Proterozoic - based on its position in the section and the similarity of deeply metamorphosed rocks of the series to the complex of similar formations of Karategin (Garm block of Tajikistan), for which the absolute age is determined by the lead-isochron method as 2.4-2.9 billion years (307). M.A. Akhmedjanov et al. (75) date the B. series conditionally to the late Archean, A.V. Pokrovsky (349) to the Riphean-early Paleozoic; I.M. Mirkhodzhaev, V.A. Khokhlov (307) to the early-middle Proterozoic; A.K. Bukharin et al. (122) consider the series and all suites included in it within the early Paleozoic-early Silurian; in the Strat. sl. (442) the series is accepted as conditionally Archean; O.N. Nikitina et al. (1993f.) as early-late Proterozoic; in the monograph (165) it is conditionally referred to the late Archean-early Proterozoic, on the State Geol. Map-500 of Uzbekistan (460) the B. series is conditionally lower Proterozoic.

Age Span:

Beginning stage:

Tonian

Fraction up in beginning stage:

0.15

Beginning date (Ma):

958.00

Ending stage:

Tonian

Fraction up in the ending stage:

0.8

Ending date (Ma):

776.00

Depositional setting

Depositional pattern:

Additional Information

Compiler:

R.N. Abdullaev, 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)”