Istemes Gr
Period:
Proterozoic
Age Interval:
Lower Proterozoic (?), U5
Province:
Ustyurt-Sultanuzdag
Type Locality and Naming
Along Lake Istemes, Sultanuizdag Ridge, South Pre-Aral. A.M. Vilensky, 1960 (142, p.582), as an independent massif.
Synonym: Istemesskaya Thickness, Истемесская т.
Lithology and Thickness
Migmatites, micaceous plagiogranites, plagiogranite-gneisses, granite-gneisses with interlayers of quartzites, granite-biotite gneisses, and amphibolites. Thickness 300-350m.
Lithology Pattern:
Gneiss
Relationships and Distribution
Lower contact
Contacts are unknown.
Upper contact
Contacts are unknown.
Regional extent
Central part of the Sultanuizdag Mountains, valley of the Urusay River, Granatovaya Factory area. V.A. Khokhlov, O.I. Kim correlate the I.t. with the rocks of the migmatite-gneiss domes of the Baysuntau Fm (73; 231; 493).
GeoJSON
null
Fossils
Age
According to the data of A.A. Kulesh and others, O.I. Kim, V.A. Khokhlov, radiological data obtained by the K-Ar method and indicating the time of metamorphism are: by amphibole - 776 million years, by granite-gneisses from 218 to 446 million years.
Age Span:
Beginning stage:
Tonian
Fraction up in beginning stage:
0.75
Beginning date (Ma):
790.00
Ending stage:
Tonian
Fraction up in the ending stage:
0.90
Ending date (Ma):
748.00
Depositional setting
Depositional pattern:
Additional Information
Compiler:
R.N. Abdullaev – In: GeoGPT translation of: “Abduazimova, Z.M. (Ed.), 2001. Stratigraphic Dictionary of Uzbekistan. IMR (Institute of Mineral Resources), Tashkent, 580 pp. (In Russian)”