The Kasimovian is a geochronologic

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or chronostratigraphic stage in the ICS

geologic timescale The geologic time scale or geological time scale (GTS) is a representation of time based on the rock record of Earth. It is a system of chronological dating that uses chronostratigraphy (the process of relating strata to time) and geochron ...

. It is the third stage in the Pennsylvanian (late

Carboniferous The Carboniferous ( ) is a Geologic time scale, geologic period and System (stratigraphy), system of the Paleozoic era (geology), era that spans 60 million years, from the end of the Devonian Period Ma (million years ago) to the beginning of the ...

), lasting from to Ma.; 2004: ''A Geologic Time Scale 2004'',

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Press. The Kasimovian Stage follows the Moscovian and is followed by the Gzhelian. The Kasimovian saw an extinction event which occurred around 305 mya, referred to as the

Carboniferous Rainforest Collapse The Carboniferous rainforest collapse (CRC) was a minor extinction event that occurred around 305 million years ago in the Carboniferous period. The event occurred at the end of the Moscovian and continued into the early Kasimovian stages of th ...

. It roughly corresponds to the Missourian in North American geochronology and the Stephanian in western European geochronology.

Name and definition

The Kasimovian is named after the

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n city of Kasimov. The stage was split from the Moscovian in 1926 by Boris Dan'shin (1891-1941), who gave it the name ''Teguliferina horizon''. The name was posthumously changed to ''Kasimov horizon'' by Dan'shin in 1947. The name Kasimovian was introduced by Georgy Teodorovich in 1949. The base of the Kasimovian Stage is at the base of the fusulinid biozone of ''Obsoletes obsoletes'' and ''Protriticites pseudomontiparus'' or with the first appearance of the

ammonite Ammonoids are extinct, (typically) coiled-shelled cephalopods comprising the subclass Ammonoidea. They are more closely related to living octopuses, squid, and cuttlefish (which comprise the clade Coleoidea) than they are to nautiluses (family N ...

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''Parashumardites''. The top of the stage is close to the first appearances of the fusulinid genera ''Daixina'', ''Jigulites'' and ''Rugosofusulina'' or the first appearance of the conodont '' Streptognathodus zethus''.

Biozones

The Kasimovian is subdivided into three conodont biozones: *'' Idiognathodus toretzianus'' Zone *''Idiognathodus sagittatus'' Zone *''Streptognathodus excelsus'' and ''Streptognathodus makhlinae'' Zone

References

Literature

*; 1947: ''Geology and Mineral Resources of Moscow and its Surroundings'', Izdat. Moskov. Obshch. Isp. Prir., Moscow, 308 pp. . *; 2006: ''Global time scale and regional stratigraphic reference scales of Central and West Europe, East Europe, Tethys, South China, and North America as used in the Devonian–Carboniferous–Permian Correlation Chart 2003 (DCP 2003)'', Palaeogeography, Palaeoclimatology, Palaeoecology 240(1-2): pp 318–372. *

External links

Carboniferous timescale
at the website of the Norwegian network of offshore records of geology and stratigraphy

{{Geological history, p, p, state=collapsed Pennsylvanian geochronology Geological ages