Angren Formation

Angren Fm

Period:

Jurassic

Age Interval:

Middle Jurassic (Aalenian–Bathonian), CK12

Province:
Chatkal-Kuramin Region

Type Locality and Naming

Along the Angren River, Prishchekent District, Collective of authors, 1959 (382, table 13). Stratotype by boreholes: 2091, 2097, 2076 in the Angren River valley (367, Appendix 16).

Synonym: Angrenskaya Formation, Ангренская св.

Lithology and Thickness

Interbedding of gravelites, sandstones, clays, and brown coals. Thickness up to 230 m.

Lithology Pattern:

Sandstone

Relationships and Distribution

Lower contact

Angren Fm transgressively overlies the Paleozoic, primary weathering crust, or Changan Fm.

Upper contact

With apparent conformity, it is overlain by the Dzhigiristan Fm

Regional extent

GeoJSON

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Fossils

Contains large plant remains - Haysmannia leeiana Sze, Marattia müensteri Goepp., Coniopteris ferganensis Pryn., etc., spores, and pollen: from the lower part of the section Coniopteris hymenophylloides (Brongn.), Sew., Marattiopsis muensteri (Goepp.), Phlebopteris polypodioides Brongn., Hausmannia leeiana Sze, Lygodium volubiliopsis Kuz., Protoconiferus funarius (Naum.) Bolch., Bennettites sp., B. modius Bolch., Cecrus aristata Zauer.; from the middle part of the section - Coniopteris hymenophylloides (Brongn.), Sew., Hausmannia leeiana Sze, Osmundopsis angrenica Sixt., Bennettites dilucidus (Bolch.), Ginkgo parva Bolch., Protopinus pergrandis Bolch., Pinus sp.; from the upper part of the section - Coniopteris hymenophylloides (Brongn.), Sew., Phlebopteris polypodioides Brongn., Hausmannia leeiana Sze, Klukisporites variegatus Couper, Plicifera delicata (Bolch.) Bolch., Bennettites ailucidus Bolch., Cycas glabra Bolch., Podocarpus unicus (Bolch.), Classopollis sp. (367, Appendix 16).

Age

The lists of organic remains do not contradict the Aalenian-Bajocian age of the enclosing deposits. T.A. Sixtel, Yu.M. Kuzichkina (382, Table 13; 383, Table 5, p.2) attributed A.sv. to the upper Jurassic - Bajocian; N.P. Gomolitsky and A.V. Lobanova (175); V.V. Kurbatov, V.I. Troitsky, et al. (165) - to the Middle Jurassic.

Age Span:

Beginning stage:

Aalenian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

174.70

Ending stage:

Bathonian

Fraction up in the ending stage:

0.8

Ending date (Ma):

165.87

Depositional setting

Depositional pattern:

Additional Information

Compiler:

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