Irisuy Formation

Irisuy Fm

Period:

Carboniferous

Age Interval:

Visean, CK3-5, CK6

Province:
Chatkal-Kuramin Region

Type Locality and Naming

Along the Irys River, Duanytau Mountain, western part of the Talas Alatau Range. O.I. Sergun'kova, 1959 (382, p. 53). Stratotype along the Irys River in Duanytau, on the watershed of the Irys and Kazanchukur rivers. Lower formation in Pskem Gr.

Synonym: Irisuyskaya Suite, Iriksuyian, Ирисуйская св.

Lithology and Thickness

Thin- to medium-bedded limestones of gray to black color, detrital-slime, organogenic, intensely silicified with frequent nodules and layers of chert. Thickness 180-400m.

Lithology Pattern:

Limestone

Relationships and Distribution

Lower contact

Conformably overlies the Sargardon Fm (Chatkal region) or the Taldybulak Fm (Talas Alatau).

Upper contact

Conformably overlain by the Kshikanidyan Fm (Tkachev et al., 1992, 1996) (460; 439).

Regional extent

South-western spurs of the Talas Alatau, Ugam, Pskem, Sandalash, Koksuy ranges.

GeoJSON

null

Fossils

Contains brachiopods Orthotetes keokuk Hall., Dictyoclostus deruptus Rom., Spirifer grimesi Hall., Verkhotomia tenisica Litv., foraminifera - Tetrataxis kiselicus Mal., T. perfidus Mal.; conodonts - Gnathodus texanus Roun., G. pseudosemiglaber T. et F., Paragnathodus symmutatus R.A. et D.

Age

Fossil data indicates early Visean age.

Age Span:

Beginning stage:

Visean

Fraction up in beginning stage:

0.1

Beginning date (Ma):

345.09

Ending stage:

Visean

Fraction up in the ending stage:

0.3

Ending date (Ma):

341.81

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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