Ashisuy Formation

Ashisuy Fm

Period:

Carboniferous

Age Interval:

Gzhelian, F9b

Province:
Fergana

Type Locality and Naming

Along the Ashchisu River, Guzan Mountains, South Fergana. M.Sh.Shamsutdinov, 1954 (502, pp. 13-17). Stratotype along the Ashchisu River. F.R.Beni

Synonym: Ashchisuyskaya Suite, Ашисуйская св.

Lithology and Thickness

Volcaniclastic sedimentary sequence. Sandstones, siltstones, argillites, marls, shell limestones, horizons of acidic tuffs and ignimbrites, in the lower part - coal-bearing argillite layers with coal seams. Thickness 560-600m.

Lithology Pattern:

Volcanic_ash

Relationships and Distribution

Lower contact

Underlying deposits are unknown, contact is tectonic

Upper contact

Overlain by the Burganin Fm

Regional extent

South Fergana, northern slope of the Guzan Mountains.

GeoJSON

null

Fossils

Contains a floristic complex - Sphenophyllum ex gr. oblongifolium (Germ. et Kaulf.) Unger, Trizygia radczenkoi Sixt., Calamites gigas Brong., Pecopteris cyathea Schloth., P. candolleana Brogn., Neuropteris sp., Maclaja polymorpha Sav., Taeniopteris sp., Cordaites principalis (Germ.) Gein., Cordaianthus ex gr. penjonii Renault, and others. Upper - Sigillaria sp., Sphenophyllum sp., Annularia ex gr. sphenophylloides (Zenk.) Gutb., Calamostachys ex gr. calathifera Weiss., Pterophyllum sp., Taeniopteris guzanicus Sixt., Guzania ferganica Sav. et Sixt., Cordaites sp.; Upper Carboniferous and Lower Permian gastropods - Goniasma lasallensis (Worth.), G. ferganica Lich., Sphaerodoma veberi Lich., Naticopsis kikeni Jakov., Euphemis carbonaricus (Cox), Triplicatula calamitoides (Grabau et Jin), Bucaniopsis cf. netschaejewi Lich., and others; pelecypods - Astartella adenticata Jakov., A. permocarbonica Tschern., Schizodus wheeleri Swall., Aviculopecten subpapiraceus Vern., Antraconeilo elongata Tschern., Myalina Permiana Swall.; ostracods - Kirkbya sp., Paraparchites cf. humerosus Ulrich et Bassler, P. punctatus Harris et Worrell, Jonesina aff. etherdgei Champ., known from the Lower Permian of Central America (291; 410).

Age

M.Sh.Shamsutdinov (501, 502) assigns it to the Permian based on flora; T.A.Sixtel in early works (410) dates it to the Permian age, the lower part is assigned to the Gzhelian Stage, the upper part to the Permian. The same opinion is held by L.I.Savitskaya and T.A.Iskandarkhojaev (450), thus defining the boundary between the Carboniferous and Permian within the A. suite. F.R.Bensh (107), A.S.Masumov et al. (291), Kh.Ch.Chinikulov (1989) date it to the Gzhelian epoch. The A. suite is paralleled with the lower and, in part, middle Burganian sub-suite and can be considered a facies analog of the lower part of the Burganian suite, expressed to a significant extent by continental-origin rocks. The age of the A. suite is accepted as Late Carboniferous Gzhelian Stage Early Permian. On the State Geological Map-500 of Uzbekistan (460), it is assigned to the Lower Permian. The age-span has ambiguity hence it is considered Gzhelian for schematic stratigraphic representation.

Age Span:

Beginning stage:

Gzhelian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

303.68

Ending stage:

Gzhelian

Fraction up in the ending stage:

0.5

Ending date (Ma):

301.28

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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