Sultanbobin Formation

Sultanbobin Fm

Period:

Cretaceous

Age Interval:

upper Aptian - middle Albian, U2

Province:
Ustyurt-Sultanuzdag

Type Locality and Naming

By the Sultanbob cemetery, southern slope of the Sultanuizdag ridge, Southern Pre-Aral. S.S. Shulz (Jr.), 1967 (509, p.13). For Sultanbobin Horizon - I.M. Abdazimova et al., 2001.

Synonym: Sultanbobin Suite, Султанбобинская св, Sultanbobin Horizon, Султанбобинский гор.

Lithology and Thickness

Divided into two subunits.

Upper: sandstones, sands, siltstones (aleurites), clays. Thickness 22-75m.

Lower: black, dark gray clays with interlayers of sandstones, sandy shell rocks. Thickness 7-100m.

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

Upper: Lies on the Lower subunit of the Sultanbobin Fm.

Lower: Lies conformably on the Khodzheilin Fm, transgressively on the Paleozoic, Istemes Fm or Borehole Sandy-siltstone Fm.

Sultanbobin Horizon transgressively overlies the Kaligrekian (Horizon?) The lower boundary here is drawn at the base of the Acanthohoplites nolani zone. Both boundaries are well lithologically expressed. At this level, there is a widespread expansion of the marine basin and its connections with the open sea, evidenced by common species of ammonites of the Acanthohoplites nolani zone and the Western European zone Diadochoceras subnodosocostatum.

On Ustyurt, in South Aral, and in the Sultanuizdag ridge, the base and top are conditionally combined with the boundaries of the Sultanbobin Fm; in Central Kyzylkum, Zirabulak-Ziaetdin uplift, the lower boundary corresponds to the base of the Kalaatinian (base of the A. nolani zone), Azkamar Fm, upper - to the top of the Jamanyar Fm, lower Karaiskaya sub-Fm; in the east, in the Prishashkent and Fergana districts, these boundaries are entirely conditional and the formation corresponds to the Kyzylatinian Fm, most of the Alamyshek Fm, Muyn Fm, Lyakam, Fm, Klavdzin Fm, and Aravan Fm.

Upper contact

With erosion and conformably overlain by the Kyzylkalin Fm and Uzunkuduk-LCret Fm

Sultanbobin Horizon is conformably overlain by the Akkaptchigayian (Horizon?). The upper boundary - at the base of the Semenovites michalsckii zone. Both boundaries are well lithologically expressed.

Regional extent

South, Northeast Pre-Aral, Sultanuizdag Ridge, Pitnyak Uplift. Stratotype Along Kahralsay, on the southern slope of the Sultanuizdag Ridge. Analog of the Kalaatinskaya and Jamanyarskaya Fm of C. Kyzylkumov; Azkamar Fm of Zirabulak-Ziaetdin Mountains; Charsangin Fm and Kallamazar Fm. SW Gissar.

Sultanbobin Horizon - Southwestern Gissar, Bukhara-Khivinsky region, Ustyurt, South Aral, Sultanuizdag, Central Kyzylkum, Zirabulak-Ziaetdin uplift, Pre-Tashkent and Fergana districts. The Sultanbobin Horizon corresponds to the Karakuzian, Derbentian Fm of Yu.N. Andreeva.

GeoJSON

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Fossils

Upper part: contains marine bivalve mollusks Pterotrigonia subpiriformis Sav.; foraminifera - Trochammina albica Zhuk., Evolutinella karatjubensis Mjatl., Gaudryinopsis gissarensis (Zhuk.); spores and pollen.

Lower part: contains ammonites - Hypacanthoplites sp.; marine bivalve mollusks - Leda lineata lata Mordv., Leda numerosa Vinok., Amphidonte arduennensis karatavensis Vinok., Pterotrigonia aliformis (Park), Linotrigonia gissarensis Vinok., Corbula gaultina oblongata Vinok.; foraminifera - Evolutinella formosa Suleim., Verneuilina vinokurovae Zhuk., Trochammina dampelae Dain., T. umiatensis Tapp, Verneuilinoides Borealis Tapp.; wood remains - Tempskya wyomingensis Arnold., Araucarioxylon cf. pichasquensis Tor. et Ral., spores and pollen.

In the Sultanbobin Horizon stratotype, the formation is weakly paleontologically substantiated, with ammonites characterizing its base, where late Aptian forms Acanthohoplites noiani appear. The paleontological substantiation of the formation, where sequentially alternating oryctocenoses of ammonites are observed, was established in Southwestern Gissar along the Kampryekskoye gorge.

The Sultanbobin Horizon includes four ammonite complexes: two lower (Acanthohoplites nolani zone, Hypacanthoplites jacobi zone), belonging to the family Parahoplitidae and typical for the upper Aptian; two upper (with Douvilleiceras, with Hoplites) - to the families Douvilleiceratidae and Hoplitidae, characteristic of the lower and middle Albian. The formation is characterized by rich associations of bivalve mollusks and foraminifers, united in the Nucula longa, Exogyra localis subtypica; Gaugryina gasliensis - Verneuilina vinokurovae, Evolutinella asiatica, Gaudryinopsis gissarensis, G. filiformis - Ammomarginulina, characteristic of the upper Aptian-middle Albian. In western Uzbekistan, the boundaries of the formation are insufficiently paleontologically substantiated.

Age

Belongs to the upper Aptian - middle Albian; according to A., to the upper Aptian (446). The stratigraphic volume of the Sultanbobin Horizon can be quite accurately determined in Southwestern Gissar, where it covers the interval from the Acanthohoplites nolani zone to the Semenovites michalskii zone, i.e., is confined to the upper Aptian-middle Albian.

Age Span:

Beginning stage:

Aptian

Fraction up in beginning stage:

0.65

Beginning date (Ma):

116.07

Ending stage:

Albian

Fraction up in the ending stage:

0.6

Ending date (Ma):

105.58

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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