Gidzhal Formation

Gidzhal Fm

Period:

Neogene

Age Interval:

Upper Pliocene, CK10

Province:
Chatkal-Kuramin Region

Type Locality and Naming

Along the Gidjalsay, tributary of the Aksakat River. L.D. Anpleeva, A.A.Bukharina, 1977 (Koloyarov et al., 1977), G. Yu. Alferov et al., 1981 (61, p.40). Stratotype along the Gidzhalsay, a right tributary of the Aksakata River.

Synonym: Gidzhal Formation, Гиджалская св.

Lithology and Thickness

Forms the lower part of the section of the alluvial-proluvial brown-colored molasse formation of the upper Tien Shan series. In the valleys of the Chirchik and Aksakata rivers, it is represented by brown, brownish, and light brown siltstone (aleurolites) and clays with subordinate pinkish-brown and gray sandstones, gravelites, and conglomerates. In the Chatkal depression, at the bottom, there are brownish-gray conglomerates, sandstones, marls, and siltstone (aleurolites); at the top - greenish-gray sandstones and siltstone (aleurolites). Thickness up to 1547m.

Lithology Pattern:

Siltstone

Relationships and Distribution

Lower contact

Lies with erosion on the Irtash Fm, red-colored molasse formation, Miocene, and all older formations, up to the Paleozoic

Upper contact

With erosion overlain by the Kandyrsay Fm

Regional extent

Mountainous part of the Pre-Tashkent district: Angren plateau, valleys of the Angren and Chirchik rivers, Chatkal depression. Corresponds to the Chatkal Fm, Bogustan Fm, and Beldersay Fm. In the submerged part of the Pre-Tashkent district, it is correlated with the Pskent Fm, and in the Fergana depression with the Akchop Fm. Accepted in the Chatkal-Kuramin series of sheets m-1:50000, 1998.

GeoJSON

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Fossils

Contains ostracods - Candona praelustris Bod., Candoniella marcida Mand., Potamocypris aff. longisetosa Bron., Cypris mandelstamina Liib., C. subglobosa (Sow.), Cyprinotus arasensis Bod., Ilyocypris manasensis Mand. In the valley of the Aksakata River, the suite is associated with the Gidzhal and Beldersay localities of mammal remains, and in the valley of the Pskem River - the Beshkayragach locality (193; 145), where, along with Miocene-Pliocene vertebrates - Chilotherium cf. schlosseri (Weber.), Paleotragus sp., Ictitherium cf. wongi Zdansky., I. Chilotherium cf. schlosseri (Weber.), Paleotragus sp., Ictitherium cf. wongi Zdansky., I. cf. hipparionum (Gervais), Gazella sp., Hipparion sp., there are clearly Upper Pliocene Anancus arvernensis (Cr. et Job.).

Age

Age of the suite, according to A.A., late Miocene - middle Pliocene. Based on the fossil finds and the position in the general section of the Late Cenozoic molasses, the suite is attributed to the Upper Pliocene. It is not excluded that the lower boundary may be somewhat older. Overall, the formation of the suite, like the entire brown-colored molasse formation, is associated with the global Late Pliocene cooling and humidification of the climate and the emergence of a permanently active hydrographic network. In the intermountain depressions of Tien Shan, brown-colored molasses is characterized by the Upper Pliocene Ilyisk and Eopleistocene Khorgos complexes of fauna and lie on the lacustrine - salt-gypsum formation of the Middle Tien Shan series with the richest remains of the Upper Miocene-Lower Pliocene complex of mammals (145).

Age Span:

Beginning stage:

Gelasian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

2.58

Ending stage:

Gelasian

Fraction up in the ending stage:

0.5

Ending date (Ma):

2.19

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)”