Beshtor Fm
Type Locality and Naming
Along the Beshter River, a left tributary of the Pskem River, Pskem Ridge. Named by A.F. Stepanenko as an independent subdivision from the Sandalashskaya suite, and designated by I.D. Doronkin (475, p.22). Stratotype on the Beshter River.
Synonym: Beshteorskaya Suite, Beshkent suite, Бешторская св.
Lithology and Thickness
At the base of the lower part - low-power lenses of basal conglomerates, overlain by a horizon of reefogenic limestones; above - clayey, carbonate-clayey slates, polymictic siltstones, sandstones, organogenic limestones with interlayers and lenses of slates, dolomites. Thickness: 100-250 m. In the upper part - carbonaceous-siliceous, clayey-siliceous slates, siltstones, sandstones, interlayers of ferruginous-carbonate-siliceous jasper-like, manganese-bearing siliceous slates, dolomites, gravels, lenses of small-pebble conglomerates. In the basin of the Badak River, there are bodies of amygdaloidal diabases and tuffs of basic and intermediate composition. Thickness: 200-550m.
Relationships and Distribution
Lower contact
Along some, it sometimes lies with erosion on the Sandalash Fm or Severo-Chatkal Fm, predominantly conformably, locally with erosion or slight angular unconformity
Upper contact
It is overlain by the Ayutor Fm.
Regional extent
Pskem and Sandalash Ridges. M.A. Akhmedjanov et al. (72) considered the B. suite as a series, identifying two suites within it: Koksubahin Fm and Chiral'min Fm
GeoJSON
Fossils
Trilobites - Cyclopyge cf. rediviva (Barr.), Symphyhos aff. armatus Barr., Bronteus sp., Ampyx sp., Nileus tengriensis Web., Holotrachelus punctillosus Törnq., Illaenus aff. triangularis Lis, and others; brachiopods - Sowerbyella ex gr. sericea Sow., Spirigerina sp. and others; graptolites - Climacograptus pusillus Hall., C. micromacoris Keller., C. matutinus (Chal.), Rectograptus apiculatus Elles and Wood.; corals Paratetradium costatula Kim., Pragnellia sp., Catenipora sp. (165; 441).
Age
Depositional setting
Additional Information