Borehole Carbonate Formation

Borehole Carbonate Fm

Period:

Cretaceous

Age Interval:

Santonian–Maastrichtian, U4

Province:
Ustyurt-Sultanuzdag

Type Locality and Naming

Predominance of carbonate rocks, Southern Aral region. I.M. Abdouazimov in 1996.

Synonym: Carbonate Topitsa, Карбонатная т.

Lithology and Thickness

Divided into three subunits.

Upper - marls, sandy, clayey limestones with interlayers of calcareous clays, with phosphorite pebbles at the base. Thickness up to 100m. Lies with erosion on the middle subunit.

Middle - marls, limestones with interlayers of calcareous clays with pyrite, at the base - phosphorite pebbles. Thickness 26-153m. Lies with erosion on the lower subunit.

Lower - marls with clay and chalk-like limestone interlayers, at the base - sandstone with phosphorite pebbles. Thickness 7-47m.

Lithology Pattern:

Shallow-marine marl

Relationships and Distribution

Lower contact

Lower subunit - Lies with erosion on the Muynak Fm.

Upper contact

Schematic stratigraphic column indicates Kipchak Fm with erosion.

Regional extent

Wells. E. Ustyurt, Southern Aral region. Used in the legend of the Aral subseries for geological maps of the 1: 200000 scale, 1998.

GeoJSON

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Fossils

Upper – Contains foraminifera Gavelinella danica (Brotz.), Hanzawia ekblomi (Brotz.), Cibicidoides bembix (Marss.), Bolivina incrassata incrassata (Reuss), B. incrassata crassa Vass., Reussella minuta (Marss.).

Middle - Contains foraminifera - Gavelinella clementiana laevigata (Marie), G. clementiana (Orb.), Cibicidoides temirensis (Vass.), C. voltzianus (Orb.), Bolivinoides decoratus Jones.

Lower - Contains foraminifera - Gavelinella infrasantonica (Balakhm.), G. stelligera (Marie).

Age

Upper – Belongs to the Maastrichtian. Middle - Belongs to the Campanian. Lower - Belongs to the Santonian.

Age Span:

Beginning stage:

Santonian

Fraction up in beginning stage:

0.3

Beginning date (Ma):

85.09

Ending stage:

Maastrichtian

Fraction up in the ending stage:

1.0

Ending date (Ma):

66.04

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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