Bolgalin Fm
Type Locality and Naming
Along the Chashly River, Karamazar Mountains. A.B. Dzainukov, M.E. Zaprozetov, V.N. Tkachev (V.N. Tkachev et al., 1988). In the territory of Tajikistan - Chashlinskaya, in Uzbekistan - Bolgaliinskaya suite. Stratotype of C. suite - Altyntopkan region, and B. suite - Belyauty region (Tashtepinsky heights on the southwestern subsidence of the Chatkal range).
Synonym: Bolgalinskaya (Chashlinskaya) Suite, Bolgalian, Болгалинская (чашлинская) св.
Lithology and Thickness
Fills volcano-tectonic grabens (Almalyk, Altyntopkan, Kurusay-Jangalik, and Shavaz-Dukent) and is exposed in the form of small fragments at the edges of ring structures (Lashkerek, Kyzylnurin, etc.). V.A. Arapov (64) identifies three subdivisions: lower (only in the Altyntopkan graben) - andesite tuffs, replaced by a layer of interbedded arkosic sandstones, conglomerates, siliceous shales, and rhyolite tuffs. Thickness 140-480m; middle - uniform fine- to medium-porphyritic andesites and trachyandesites, less frequently basalts, andesitic-basalts. Lava flows alternate with tuff layers, locally with conglomerate, sandstone, and siltstone (aleurolite) layers. Along with cover facies, this part of the section is associated with subvolcanic bodies of trachyandesites, monzonitoids. Thickness 120-500m; upper - agglomerate and block tuffs and xenotuffs, higher up – andesitic-dacite lavas. Thickness 145 665m. Total Thickness 1100m.
Relationships and Distribution
Lower contact
Lies on a deeply eroded surface of older formations: Middle Devonian-Lower Carboniferous limestones; Lower-Middle Devonian volcanics; granitoids of the Karamazar Gr
Upper contact
Overlain with erosion by the Akchin Fm and younger formations.
Regional extent
Widely developed in the Kuramin and Chatkal ranges. L.I. Savitskaya et al. (450) describe a plant complex from the sedimentary layer of Kandyrkaya as part of the lower sub-suite of the Nadak Fm. Previously, in the territory of Uzbekistan, it was identified as the lower sub-suite of the Akchin Fm, and in Tajikistan - as the Minbulak Fm or Akchin Fm
GeoJSON
Fossils
Contains plant remains - Lepidodendron ex gr. lycopodioides Sternb., Calamites ex gr. sachsei Stur., Neuropteris heterophylla Brongn., N. ex gr. tenuifolia (Sloth.), Aulacotheca kandyrica Sav., Trigonocarpus sp., Cordaites ex gr. principalis (Germ.), Kandyrica vasilkovskyi (Sixt.), Ranczenkoella kandyrensis (Sixt.), Samoropsis sp., Cordaicarpus sp.
Age
Depositional setting
Additional Information