Cenozoic

Cretaceous

Jurassic

Triassic

Permian

Carboniferous

Devonian

Silurian

Ordovician

Cambrian

Neoproterozoic

Main source = Baratov, R.B., et al. (1976). Subdivisions of stratified and intrusive rocks of Tajikistan. Publishing House "Donish", Dushanbe, 269 pp. plus tables. Provided by Dr. Jovid Aminov, Nazarbayev University, Astana, Kazakhstan Translated to English by the GeoGPT group, Zhejiang Lab, Hangzhou, China--see About

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Ravat Formation

Ravat Fm

Period:

Triassic

Age Interval:

Norian-Rhaetian (T₃), S4

Province:
North Tajik

Type Locality and Naming

Distinguished by T. A. Systel in 1958

Synonym: Ravatskaya suite, раватскую свиту

Reference section:

Lithology and Thickness

Red-colored bauxite-like clays, gray-colored breccias, coarse-grained quartz sandstones, gravelites, siltstones with rare carbonaceous rocks. The thickness of the suite is 0-40 m.

Lithology Pattern:

Coarse-grained sandstone

Relationships and Distribution

Lower contact

It lies at an angular unconformity on paleozoic rocks of different ages

Upper contact

It is overlain by erosive carboniferous lower-middle Jurassic formations.

Regional extent

Deposits are widespread in the basins of the Fandarya, Yagnob, Zeravshan rivers, where they fill the pre-Permian relief depressions. According to its position in the section, composition, and age, this suite, in the opinion of V. S. Luchnikov, corresponds to the Tashkuttan suite (ташкутанской Свите) of the southern slope of the Gissar Range.

GeoJSON

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Fossils

The known complex of plant remains from it is similar to the Tashkuttan one. Here among the representatives of genera Hausmannia, Phlebopteris, Thaumatopteris, Clathropteris, individual Hissaropteris and Coniopteris, as well as various ginkgo and coniferous trees are found. The presence of Coniopteris allowed A. T. Burakova to raise the age of the complex to Toarcian-Aalenian. However, recently it has been established that the first representatives of the genus Coniopteris appear already in the Lower Lias.

Age

Initially, this suite was tentatively dated to the Triassic (Systel, 1952). Later, the same researcher dated the suite to the Norian-Rhaetian (Decisions..., 1959), or to the Norian stage (Systel, 1960a); and later - to the "upper horizons of the Upper Triassic" (Geol. USSR, vol. 23, 1972). The study of the deposits and plant remains from the Ravatskaya suite allowed the author and R. Z. Genkina to come to the same conclusion: the dating of the Ravatskaya suite formations to the Lower Lias. A. T. Burakova, M. V. Mikulin, V. V. Kurbatov (1973) referred the considered thickness to Toarcian-Aalenian. Thus, to date, there is no consensus on the age of the considered deposits. In the map legend, the Late Triassic age of the Ravat Fm (раватской свиты) is left.

Age Span:

Beginning stage:

Norian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

227.30

Ending stage:

Rhaetian

Fraction up in the ending stage:

1.0

Ending date (Ma):

201.36

Depositional setting

Depositional pattern:

Additional Information

Compiler:

Extracted from Baratov, R. B. (1976). Subdivisions of stratified and intrusive rocks of Tajikistan. Donish, Dushanbe, 276.