Lower Ordovician Fm
Period:
Ordovician
Age Interval:
Lower Ordovician, S2
Province:
North Tajik
Type Locality and Naming
Synonym: Lower Division
Reference section:
Lithology and Thickness
Clayey limestone. In the Turkestan region (basin of the Robut River), brownish-gray claystones and clay slates with interlayers of limestones, rarely conglomerates, have been referred to the Lower Ordovician by V.T. Vashurov and A.S. Shadshiniev. Their incomplete thickness is 250 m.
Lithology Pattern:
Clayey limestone
Relationships and Distribution
Lower contact
They conformably overlie the Upper Cambrian
Upper contact
Overlying sediments are absent.
Regional extent
Known in the Turkestan region and on the Pamir.
GeoJSON
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Fossils
Remains of Tremadocian trilobites Paraceratopyge sp. have been found.
Age
Lower Ordovician
Age Span:
Beginning stage:
Tremadocian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
486.85
Ending stage:
Floian
Fraction up in the ending stage:
1.0
Ending date (Ma):
471.26
Depositional setting
Depositional pattern:
Additional Information
Compiler:
Extracted from Baratov, R. B. (1976). Subdivisions of stratified and intrusive rocks of Tajikistan. Donish, Dushanbe, 276.