Akkolka Fm
Period:
Permian
Age Interval:
Late Permian
Province:
Zaisan (Zaysan) Basin - East, Zaisan (Zaysan) Basin - Central
Type Locality and Naming
Synonym: Akkolan Fm, Akkolanskaya,
Lithology and Thickness
In borehole Sarybulak C-1, it is described as ca. 300 m with the bottom being small waste rock mass of polymictic and volanomictic components. The main body is coaly claystone and aleurotite (silt), with a downhole increase in the volume of rare sandstone. Heightened compactness and low (5-7%) penetrativeness (porosity?) of the rocks are typical. Bitumen evidence is very rare and slight. Near the base of the formation is a diabase (2300 m in the reference well). Deep system of joints with strongly pronounced glid planes at the angles of 75, 45 and 15 degrees; rarely are the joints horizontal; with sinters and insets of bitumen.
Lithology Pattern:
Siltstone
Relationships and Distribution
Lower contact
Overlies the Maychat Fm (Michat Fm)
Upper contact
Unconformable (Early Triassic is absent) below the Middle Triassic conglomerate of the Akzhai Fm
Regional extent
Originally throughout the entire basin; but later tectonics and erosion during uplifts implies that the main surface exposures of the Late Carboniferous-Permian succession is a 2-km-thick succession in the Kenderlyk Trough in the southern part o the Zaisan (Zaysan) basin (Nurbekova et al., 2023).
GeoJSON
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Fossils
Age
Late Permian (Wuchiapingian-Changhsingian?)
Age Span:
Beginning stage:
Wuchiapingian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
259.55
Ending stage:
Changhsingian
Fraction up in the ending stage:
1.0
Ending date (Ma):
251.90
Depositional setting
Depositional pattern:
Additional Information
Compiler:
Information provided by Nariman Jamikeshev from Kazakh-language sources and from other publications.