Bokteken Formation

Bokteken Fm

Period:

Cambrian, Ordovician

Age Interval:

Upper Cambrian-Lower Ordovician, K2

Province:
Kyzylkum Region

Type Locality and Naming

Along the Bokteken column, South Bukantau, Central Kyzylkum. Ya.B.Aysanov et al. in 1984 (1986). Lectostratotype south of the city of Irlyr.

Synonym: Bokteken Formation, Боктекенская св.

Lithology and Thickness

Pelitomorphic limestones, thin- and medium-bedded, light and dark gray (pale yellow on the surface), greenish and bluish-gray, parallel-, cross-, and lenticular-bedded, rhythmically interbedded with claystones and calcareous mica and siliceous-mica slates, dark gray and greenish-gray with subordinate layers and lenses of organogenic-clastic limestones and black quartz-siliceous rock. Thickness not more than 110m.

Lithology Pattern:

Clayey limestone

Relationships and Distribution

Lower contact

Lower contact is tectonic

Upper contact

The upper contact is presumably conformable with the Telibay Fm.

Regional extent

West and east parts of South Bukantau, south of the Irlyr Devonian-Carboniferous carbonate ridge and in Jetymtau II, mainly in tectonic blocks.

GeoJSON

null

Fossils

Contains trilobites in the lower part - Pseudagnostus sp., Onchonetellus sp., Olentella (?) sp., hyoliths - Orthothecidae; cyanobacteria Stereophycus schochycus Pjan., found in Upper Cambrian deposits; in the upper part - trilobites - Dalmanitidae, Proctidae; inarticulate brachiopods; gastropods - Lesucurilla sp.; conodonts - Cordylodus cf. rotundatus Pand., Acodus (?) sp., Oneotodus sp.

Age

Fossil data indicates Upper Cambrian-early beginning of middle Ordovician. On the geological map of the Central Kyzylkum massif 1: 100000 (Aysanov et al., 1986), the suite is dated to the Cambrian-early Ordovician. A.K. Bukharin et al. (1990) assigned it to the middle Cambrian-early Ordovician. On the geological map of the Kyzylkum geodynamic polygon (Savchuk et al., 1993), the State Geological Map-500 of Uzbekistan (460), and in the monograph (165), it is dated to the late Cambrian-early Ordovician.

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:

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)”