Arashan Formation

Arashan Fm

Period:

Neogene

Age Interval:

Lower-Middle Miocene, CK10

Province:
Chatkal-Kuramin Region

Type Locality and Naming

Along the Arashan River, Angren Plateau. L.D. Anpleeva, A.A. Bukharina in 1977, on the Angren Plateau in the interfluve of the Tashsai and Arashan rivers (Koloyarov et al., 1977f.), G.Yu. Alferov et al. (61, p. 38), volume clarified by B.I. Pinhasov (145). The stratotype is taken as the reference Tashsai section, described by L.D. Anpleeva (Koloyarov et al., 1977f.).

Synonym: Arashan Suite, Арашанская св.

Lithology and Thickness

From the composition of the Arashan Fm, L.D. Anpleeva, B.I. Pinhasov excluded the upper part of the section, represented by a thickness of pale-pink carbonate weathering crusts, and distinguished it as an independent Irtash suite. The Arashan Fm consists of siltstone (aleurolites), clays, sandstones, gravelites, and conglomerates of red-brown, brick-red colors. There are many carbonate concretions in the loams. Thickness 180m.

Lithology Pattern:

Siltstone

Relationships and Distribution

Lower contact

With erosion, it lies on the Tashsay Fm

Upper contact

It is also overlain with erosion by the Irtash Fm

Regional extent

Angren Plateau, Angren Depression, valleys of the Chirchik and Aksakaty rivers, Chatkal Depression, along the Sandalash River.

GeoJSON

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Fossils

Contains ostracods - Меdiocypris aff. plumbeg Bod., M. sp., Kassinina beliaevskyi Mand., Eucypris sp., E. glabra Bod., E. aff. numulis Schn., E. grandis Bod., Cyprinotus aff. novellus Bod., Gravicypris sp., Potamocypris sp., Herpetocypris sp., Candoniella marcida Mand. Cb.

Age

Age, according to A.A., Middle Miocene - Tarhan, Chokrak (61). According to B.I. Pinhasov, - Lower-Middle Miocene

Age Span:

Beginning stage:

Serravallian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

13.82

Ending stage:

Serravallian

Fraction up in the ending stage:

1.0

Ending date (Ma):

11.63

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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