Sumsar-Sil Formation

Sumsar-Sil Fm

Period:

Silurian

Age Interval:

Llandovery, CK5a

Province:
Chatkal-Kuramin Region

Type Locality and Naming

Named after the river Sumsar, southern slope of the Chatkal Range. S.V. Litovchak, K.V. Seliverstov et al. in 1984 (460, pp.79-80).

Synonym: Sumsarskaya Topitsa, Сумсарская св.

Lithology and Thickness

Most complete section in the interfluve of Sumsar-Koksar. Polymictic sandstones, interbedded with siltstone (aleurolites), clay slates, phyllites, with rare interlayers and lenses of conglomerates and limestones; in the lower part of the thickness, bodies of andesites and basalts, tuffs of basic composition are encountered. Thickness up to 3000m.

Lithology Pattern:

Volcanic_ash

Relationships and Distribution

Lower contact

The base of the thickness is not exposed

Upper contact

The upper contact is unconformable with the volcanics of the lower Devonian.

Regional extent

Southern part of the Chatkal Range, south of the valley of the river Chirchik, Sumsar and Gavasai districts (459).

GeoJSON

null

Fossils

Contains graptolites of middle-lower Llandovery - Climacograptus medius Turnq., C. normalis Elles. et Wood., Rhapidograptus turnquist (Elles et Wood.), Rastrites linnaei Barr., Oktavites cf. proteus (Barr.), Monograptus halli Barr., Streptograptus exiguus (Nich.); lower Silurian tabulates - Favosites aff. desolatus Klaam. (valley of the river Alabuka) and brachiopods - Tchatcalia unica Nikif., Nuclospira asiatica Nikif. (area of the pass Chanach).

Age

Lower Silurian (middle-lower Llandovery)

Age Span:

Beginning stage:

Rhuddanian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

443.07

Ending stage:

Telychian

Fraction up in the ending stage:

1.0

Ending date (Ma):

432.93

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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