Dzhaksan-Dev Fm
Type Locality and Naming
Along the Say Dzhaksan, N. Tamdytau, Central Kyzylkum. A. I. Kim et al. (1974f). Basin of the Say Dzhengeldy, Kosbulak, Koskuduk, Dzhaksan, being a stratotype locality. The stratigraphic name has limited application.
Synonym: Dzhaksan Suite, Джаксанская св.
Lithology and Thickness
The upper part (thickness about 65m) - siltstone (aleurolites), sandstones, organogenic-clastic and sandy limestones, containing lenses (?) of conglomerate-breccias.
According to A.A., the lower part of the suite (thickness 120-150m) consists of basal conglomerate-breccias at the base. Above - crinoidal and crinoidal-algal limestones, alternating with several horizons of conglomerate-breccias, sandy platy limestones, gravelites, sandstones, and siltstone (aleurolites). Total formation thickness 185-215m.
Relationships and Distribution
Lower contact
The lower contact is stratigraphically discordant (?) with the Koskuduk Fm
Upper contact
The upper contact is not established.
Regional extent
Central Kyzylkum, in the form of tectonic scales, blocks in N. Tamdytau
GeoJSON
Fossils
The upper part - in limestones, corals - Spongophyllum halysitoides Ether., S. sedgwicki M.E. et Haime. and others; brachiopods - Gypidula rara Nikif., Karpinskia konjugula Tschern. and others
The lower part - in the fragments of breccia, corals and brachiopods of the upper Silurian are present. In the pebbles of coarse-clastic rocks, re-deposited fauna of the lower and upper Silurian, in limestones early Devonian tabulates - Favosites interstinctus Miron., F. socialis Sok., Squameofavosites sokolovi Chekh.; rugosans - Spongophyllum saumaensis Schur. and others; brachiopods - Spirigerina supramarginalis Khod., Cumostrophia costatula Barr. and others, characteristic of the lower part of the lower Devonian.
Age
Depositional setting
Additional Information