Shakhpakhtin Formation

Shakhpakhtin Fm

Period:

Cretaceous

Age Interval:

Berriasian, U3

Province:
Ustyurt-Sultanuzdag

Type Locality and Naming

Along the well of Shakhpakhty, N. Turkmenistan. I.N. Shebueva in 1966 (192, p.26). Shakhpakhtin Horizon Fm - along the Shakhpakhtin Fm, well of Shakhpakhty, S. Turkmenistan. V.V. Kurbatov, V.N. Polyakov, E.A. Repman et al., 1978 (252, p.91) used the name Shakhpakhtinskaya suite (horizon), proposed by I.N. Shebueva in 1966 (192, p.26).

Synonym: Shakhpakhtinskaya Suite, Шахнахтинская св, Shakhpakhtinsky Horizon, Шахнахтинский гор.

Lithology and Thickness

Organogenic, oolitic limestones, dolomites, clays, marls, interlayers of anhydrites. Thickness up to 106m.

Shakhpakhtin Horizon Fm: Alternation of sulfate-carbonate and red-colored terrigenous layers. Thickness in the stratotype up to 106m. Includes Shahpaxtin Fm, Sharaaplin Fm (446), and cover anhydrites of the Gaurdak Fm.

Lithology Pattern:

Oolitic limestone

Relationships and Distribution

Lower contact

It lies with erosion on the Shordzhin Fm, Aginish Fm or Nikolayev Fm

Shakhpakhtin Horizon Fm - Overlies transgressively the Kugitang Horizon (Aginysh or Shordzhin series) or with erosion on the Gaurdak mountain (Nikolaev series or upper salt series).

Upper contact

It is overlain by the Aybugir Fm or Karabilskian Fm.

Shakhpakhtin Horizon Fm – Overlain transgressively by a red-colored analogue of the Karabil series (Assakeudan, Ismail) or Aibugir series.

Regional extent

Well of S. Mangyshlak, SN Turkmenistan, South Ustyurt, Takhatakir district, right bank of the Amudarya River, S. Pre-Aral. Stratotype - section of the well of the Shakhpakhty plateau.

Shakhpakhtin Horizon Fm – Shahpaxtin, Sharaaplin, and Gaurdak series of the Mangyshlak, South Turkmenistan, Ustyurt, Takhtakair district, and South Aral regions.

GeoJSON

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Fossils

Contains marine bivalve mollusks Buchia sp.; brachiopods - Rhynchonella rollieri eltonica Makr., Russielia eichwaldi Lehm.

Shakhpakhtin Horizon Fm – Contains marine bivalve mollusks (see Shahpaxtin series) and brachiopods.

Age

In the Strat. Sl. (446) it is attributed to the Kimmeridgian-Tithonian; according to T.T. Radushkina, - to the Berriasian and Valanginian (91). In recent years, V.A. Prozorovsky (364) believes that the Shakhpakhtin Fm, in the east, completes the Malm, and in the west, begins the Neocomian formation complexes and, based on the clearly transgressive position, correlates it with the lower part of the Berriasian deposits of Mangyshlak. V.I. Troitsky et al. (165) consider the Shakhpakhtin Fm to be early Cretaceous (Berriasian - Valanginian), and the suite of cover anhydrites of the Gaurdak series and the Sharaplin Fm as its age and facies analogs.Age of the Shakhpakhtin Horizon is accepted as Berriasian. Tithonian is used for schematic stratigraphic column cause of the debation of Malm.

Age Span:

Beginning stage:

Tithonian

Fraction up in beginning stage:

0.5

Beginning date (Ma):

146.17

Ending stage:

Berriasian

Fraction up in the ending stage:

0.5

Ending date (Ma):

140.40

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)”