The Kasimovian is an geochronologic

Geochronology

Geochronology is the science of determining the age of rocks, fossils, and sediments, within a certain degree of uncertainty inherent to the method used. A variety of dating methods are used by geologists to achieve this, and schemes of classification and terminology have been proposed...

 age or chronostratigraphic

Chronostratigraphy

Chronostratigraphy is the branch of stratigraphy that studies the age of rock strata in relation to time.The ultimate aim of chronostratigraphy is to arrange the sequence of deposition and the time of deposition of all rocks within a geological region, and eventually, the entire geologic record of...

 stage in the ICS

International Commission on Stratigraphy

The International Commission on Stratigraphy , sometimes referred to by the unofficial "International Stratigraphic Commission" is a daughter or major subcommittee grade scientific daughter organization that concerns itself with stratigraphy, geological, and geochronological matters on a global...

 geologic timescale. It is the third stage in the Pennsylvanian

Pennsylvanian

The Pennsylvanian is, in the ICS geologic timescale, the younger of two subperiods of the Carboniferous Period. It lasted from roughly . As with most other geochronologic units, the rock beds that define the Pennsylvanian are well identified, but the exact date of the start and end are uncertain...

 (late Carboniferous

Carboniferous

The Carboniferous is a geologic period and system that extends from the end of the Devonian Period, about 359.2 ± 2.5 Mya , to the beginning of the Permian Period, about 299.0 ± 0.8 Mya . The name is derived from the Latin word for coal, carbo. Carboniferous means "coal-bearing"...

), lasting from 306.5 ± 1.0 to 303.9 ± 0.9 Ma. The Kasimovian stage follows the Moscovian

Moscovian

Moscovian, deriving from Moscow, the capital of Russia, can have the following meanings:*An inhabitant of Moscow.*In stratigraphy:**Moscovian , an ICS stage in the Carboniferous;**Moscovian , a regional stage in the Pleistocene....

 and is followed by the Gzhelian

Gzhelian

The Gzhelian is an age in the ICS geologic timescale or a stage in the stratigraphic column. It is the youngest stage of the Pennsylvanian, the youngest subsystem of the Carboniferous. The Gzhelian lasted from 303.9 ± 0.9 to 299.0 ± 0.8 Ma...

.

Name and definition

The Kasimovian is named after the Russia

Russia

Russia or , officially known as both Russia and the Russian Federation , is a country in northern Eurasia. It is a federal semi-presidential republic, comprising 83 federal subjects...

n city of Kasimov

Kasimov

Kasimov is a town in Ryazan Oblast, Russia, which serves as the administrative center of Kasimovsky District . The town is situated on the left bank of the Oka River...

. 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 in Kasimov horizon by Dan'shin in 1947. The name Kasimovian was introduced by Georgy Teodorovich in 1949.

The base of the Kasomovian stage is at the base of the fusulinid

Fusulinid

The Fusulinida is an extinct order within the Foraminifera in which the tests are composed of tightly packed, secreted microgranular calcite. In advanced forms the test wall is differentiated into two or more layers...

 biozone

Biozone

Biostratigraphic units or Biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa....

 of Obsoletes obsoletes and Protriticites pseudomontiparus or with the first appearance of the ammonite

Ammonite

Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct subclass within the Molluscan class Cephalopoda which are more closely related to living coleoids Ammonite, as a zoological or paleontological term, refers to any member of the Ammonoidea an extinct...

 genus

Genus

In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 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

Conodont

Conodonts are extinct chordates resembling eels, classified in the class Conodonta. For many years, they were known only from tooth-like microfossils now called conodont elements, found in isolation. Knowledge about soft tissues remains relatively sparse to this day...

 Streptognathodus zethus. The golden spike

Golden spike

The "Golden Spike" is the ceremonial final spike driven by Leland Stanford to join the rails of the First Transcontinental Railroad across the United States connecting the Central Pacific and Union Pacific railroads on May 10, 1869, at Promontory Summit, Utah Territory...

 for the Kasimovian stage has not yet been assigned (in 2008).

Biozones

The Kasimovian is subdivided into three conodont biozone

Biozone

Biostratigraphic units or Biozones are intervals of geological strata that are defined on the basis of their characteristic fossil taxa....

s:

• Idiognathodus toretzianus Zone
• Idiognathodus sagittatus Zone
• Streptognathodus excelsus and Streptognathodus makhlinae Zone

Literature

; 1947: Geology and Mineral Resources of Moscow and its Surroundings, Izdat. Moskov. Obshch. Isp. Prir., Moscow, 308 pp. .; 2004: A Geologic Time Scale 2004, Cambridge University Press.; 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
• Kasimovian, GeoWhen Database