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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

Baysun-Jur Formation

Baysun-Jur Fm

Period:

Jurassic

Age Interval:

late Bathonian-lower Callovian, B1-B3

Province:
Bukhara-SW Gissar

Type Locality and Naming

Along the Baysun Mountains, Baysuntau Mountains, Southwest Gissar. Collective authors, 1959 (382, table 13, p.102). Stratotype in the reference section of Kugitanga, Khodzharyz section.

Synonym: Baysun Suite, Байсунская св.

Lithology and Thickness

Divided into two parts:

Lower – claystones (argillites), siltstone (aleurolites), marls, and limestones. Thickness 24-102m;

Upper - in complete sections, marls with subordinate layers of limestones, and in shortened sections - clays, siltstone (aleurolites), limestones, marls, sandstones, and gravelites. Thickness 28-109m.

Total thickness up to 140m.

Lithology Pattern:

Shallow-marine marl

Relationships and Distribution

Lower contact

Transgressively overlies the Tangiduval Fm, Sandzhar Fm, or Paleozoic

Upper contact

It is conformably overlain by the Zarmas Fm or Tupolang Fm, Kugitang Gr.

Regional extent

Southwest Gissar, its southern slope, Mechetli Mountains, Pitnyak uplift, Khorezm, Bukhara-Karshinsky regions, and border regions of Turkmenistan. In the sections of South Baysuntau (Derbent, Tuda), a facies replacement of the upper part of the Baysun-Jur Fm with limestones of the Zarmass Fm formation is established. The facies and age analogue is the Kafaklin Fm. It is part of the Baysun-Jur Horizon.

GeoJSON

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Fossils

In the lower part, Upper Bathonian ammonites of the Oppelia aspidoides and Clydoniceras discus zones and determined; foraminifers - Epistomina vandobensis Kurb. sp. n., Haplophragmium conostomum myahensis Kurb. and others; marine bivalve mollusks - Pholadomya murchisoni morphotype alfa Pak sp.n., Pteria inornata Rep. and others; brachiopods - Sphaeroidothyris globata (Sow.), Lophothyris curyptycha (Kitch.) and others; corals - Montlivaltia cornutiformis Gregory, M. caryophyllata Lamour., sea urchins - Pygaster laganoides Agas., Chinobrissus orbicularis (Phillips). (339; 383, table 4).

The upper part is characterized by Lower Callovian ammonites of the Macrocephalites macrocephalus zone and foraminifers - Epistomina rasilis Kurb., Praekaraisella vandobensis Kurb. and others; marine bivalve mollusks - Pholadomya murchisoni morphotype belta Pak sp. n., Ceratomya calloviensis Kas. and others; brachiopods - Burmirhycha rodunda Buckm., Septaliphoria levizkii Moiss. (339; 383, table 4).

Age

The lower part of the formation is dated to the late Bathonian, and the upper part to the early Callovian. The boundary between the Bathonian and Callovian is drawn at the top of the 6-8m oolitic-detrital limestone

Age Span:

Beginning stage:

Bathonian

Fraction up in beginning stage:

0.7

Beginning date (Ma):

166.15

Ending stage:

Bathonian

Fraction up in the ending stage:

1.0

Ending date (Ma):

165.29

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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