Burganin Fm

Along Burgané, eastern part of the Guzan Mountains, South Fergana. M.Sh.Shamsutdinov, 1954 (502, pp.13-17).

Synonym: Burganin Suite, Бурганинская св.

Sandy-slate formation. F.R.Bensh (107, 291) and Kh.Ch.Chinikulov (1989) divide it into three subformations. Lower (thickness 218-260m) - coarse-grained, poorly sorted sandstones, sometimes tuffogenic, transitioning into gravellites and small-pebble conglomerates, with interlayers of carbonaceous argillites. Middle (thickness 234-380m) - monotonous alternation of fine-grained sandstones, siltstone (aleurolites), and argillites with rare interlayers of clayey and sandy limestones. Upper (thickness 380-414m) - at the base, sandstones (thickness about 100 m), higher up, a package of interbedded sandstones with argillites and siltstone (aleurolites), containing interlayers of clayey limestones, higher up - sandstones with interlayers of siltstone (aleurolites).

The thickness of the formation varies significantly due to the substitution of its lower subformation by the sedimentary-volcanogenic Ashisu Fm, as well as the absence of the upper subformation in the central part of the northern slope of the mountains. The most complete Thickness 1092-1272m. - on the southern slope of the mountains along the left bank of the Ashisu River.

Lower with plant remains (left bank of the Ashisu River), bivalve mollusks, and limestones with foraminifers - Triticites ex gr. rossicus (Schel.), Rugosofusulina procera Bensh, R. praevia orientale Bensh, Daixina minima Bensh, D. asiatica Bensh. Along foraminifers, the subformation belongs to the Jigulites corpulentus-Daixina asiatica zone (middle zone of the Dastar horizon Gzhelian stage). Middle (thickness 234-380m) - foraminifers and brachiopods. On the right bank of the Ashisu River, at the base of the subformation - a layer (thickness 25-38m) of tuffs of quartz porphyry. Contains foraminifers - Triticites vulgaris M.-Macl., Rugosofusulina procera Bensh., Schagonella implexa (Bensh), Pseudofusulina ferganensis (Dutk.), P. olgae M.-Macl., P. (?) vesiculosa Bensh. The subformation belongs to the Pseudofusulina ferganensis zone (upper zone of the Dastar horizon Gzhelian stage). Upper - in the limestones, foraminifers - Rugosofusulina ex gr. stabilis Raus., Kahlerella ex gr. alpina (Schel.), Dutkevitchia tachygrada (Bensh), D. bimorpha (Bensh), D. ruzhenzevi (Raus.), Pseudofusulina ferganensis (Dutk.), P. ex gr. olgae M.Macl., P. subcylindrica Bensh, P. cf. parasolida Bensh, Pseudofusulinoides cf. parasecalicus (Chang), Pseudochusenella pseudopointeli (Raus.), Occidentoschwagerina sp.

The absence of the most important Asselian genera (Schwagerina, Pseudoschwagerina) is apparently due to unfavorable facies conditions (107).

Brachiopods in the upper part of the middle and upper subformations are represented by forms with a wide vertical distribution, most commonly found in the Upper Carboniferous and Lower Permian - Dictyoclostus gruewaldti (Krot.), Marginifera pusilla Schel., Echinoconchus komischani (Lich.), Linoproductus simensis (Tschern.), Avonia echidniformis (Grab. et Chao), Isogramma paotechowensis (Grab. et Chao), Neospirifer fasciger (Keys.), Choristites fritschi ferganensis (Lich.), Neophricocothyris asiatica (Chao).