Sagdor Fm
Type Locality and Naming
Along the Sagdor River, south slope of the Gissar Range. E.M. Golovin et al. in 1941 (460, p. 185). Stratotype in the basin of the Kshut River.
Synonym: Sagdorskaya Suite, Сагдорская св.
Lithology and Thickness
Rhythmically interbedded sandstones, siltstone (aleurolites), claystone (argillites) with layers of conglomerates, limestones, gravellites, tuff-sandstones, locally tuffs of acidic and intermediate composition. According to F.R. Ben (457), in the stratotype of the suite along the rivers Kshut, Sisan, and Sagdor, the lower part of the section is not exposed. D.A. Rubanov (385) indicates at the base of the suite the presence of tuffoconglomerate-breccias (thickness 5 m). Total thickness of Fm 760m.
In the northern part of Baysuntau (r. Aksu - left tributary of r. Sangardak) the rocks of the suite are metamorphosed under the influence of a granitic intrusion, terrigenous layers are transformed into banded hornfels, and limestones are strongly recrystallized and often marbled. Total thickness of the suite is about 2000m.
In the south of Surkhantau (watershed of rivers Aksu-Vakhshivar) the suite consists of two parts.
Upper part - sandy-aleurolitic (thickness about 300m) - sandstones, siltstone (aleurolites), argillites, often alternating.
Lower part - coarse-clastic (thickness 450-500m) conglomerates, gravellites, coarse-grained sandstones. Sandstones and conglomerates are massive and thick-bedded, greenish-gray due to fragments of acidic and basic volcanogenic rocks from the Vakhshivar Fm and Suffin-Carb Fm.
Relationships and Distribution
Lower contact
The nature of the relationship of the Sagdor Fm with underlying deposits on the southern slope of the Gissar Range is unknown, as everywhere it is separated from the Karatag Fm and Suffin-Carb Fm by faults. In the northern Baysuntau, the S. suite is gradually transitional from the underlying Suffin-Carb (?) suite. In Surkhantau, the S. suite lies unconformably on the Suffin-Carb Fm and Khodzhirbulak Fm.
Upper contact
It is overlain with angular stratigraphic unconformity by the Alyachapan Fm (460).
Regional extent
Southern slope of the Gissar Range, basin of the Kshut River, to the west in the basins of the Irgaylik, Shilkhazor rivers, and to the east on the territory of Tajikistan (rivers Shirkent, Karatag, basin of the Khanaki River). On the territory of Uzbekistan - in Baysuntau (r. Aksu, basin of r. Sangardak and upper reaches of r. Kayrak) and Surkhantau (watershed of rivers Aksu-Vakhshivar).
GeoJSON
Fossils
In the lower part of the section (thickness 75m) foraminifers of the upper Bashkirian substage are found: Asteroarchaediscus baschkiricus (Krest. et Theod.), Endothyra ex gr. bradyi (Mich.), Mediocris breviscula (Gan.), Eostaffella postmosquensis acutiformis Kir., E. pseudostruvei angusta Raus., E. ex gr. acuta Grozd. et Leb., Millerella cf. variabilis Raus., Seminovella carbonica Grozd. et Leb., Pseudostaffella antiqua (Dutk.), P. antiqua grandis (Schlyk.), Ozawainella cf. pararhomboidalis Man., Staffellaeformis staffellaeformis (Kir.), Profusulinella parva Lee et Chen. The overlying layers (thickness 440m) contain foraminifers of the lower Moscovian substage: Pseudostaffella gorskyi (Dutk.), Ozawainella sp., Profusulinella pseudorhomboides (Putrja), Ovatella constans (Saf.), Depratina prisca (Depr.), Aljutovella ex gr aljutovica (Raus.), Hemifusulina ? sp., Eofusulina ? sp.
Age
Depositional setting
Additional Information