Asselian

Asselian
Asselian
Chronology
←	Permian-Triassic mass extinction event
←	end-Capitanian extinction event
←	Olson's Extinction
	Subdivision of the Permian according to the ICS, as of 2022.; Vertical axis scale: millions of years ago.;
Etymology
Name formality	Formal
Usage information
Celestial body	Earth
Regional usage	Global (ICS)
Time scale(s) used	ICS Time Scale
Definition
Chronological unit	Age
Stratigraphic unit	Stage
Time span formality	Formal
Lower boundary definition	FAD of the Conodont Streptognathodus isolatus within the morphotype Streptognathodus wabaunsensis chronocline
Lower boundary GSSP	Aidaralash, Ural Mountains, Kazakhstan; 50°14′45″N 57°53′29″E / 50.2458°N 57.8914°E
Lower GSSP ratified	1996
Upper boundary definition	FAD of the Conodont Mesogondolella monstra
Upper boundary GSSP	Usolka section, Southern Urals, Russia.; 53°55′29″N 56°43′43″E / 53.9247°N 56.7287°E
Upper GSSP ratified	2018

In the geologic timescale, the Asselian is the earliest geochronologic age or lowermost chronostratigraphic stage of the Permian. It is a subdivision of the Cisuralian Epoch or Series. The Asselian lasted between 298.9 and 293.52 million years ago (Ma). It was preceded by the Gzhelian (the latest or uppermost subdivision in the Carboniferous) and followed by the Sakmarian.

^ "Chart/Time Scale". www.stratigraphy.org. International Commission on Stratigraphy.
^ Davydov, Vladimir; Glenister, Brian; Spinosa, Claude; Ritter, Scott; Chernykh, V.; Wardlaw, B.; Snyder, W. (March 1998). "Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System" (PDF). Episodes. 21: 11–18. doi:10.18814/epiiugs/1998/v21i1/003. Retrieved 7 December 2020.
^ Shen, Shuzhong (August 2018). "Notes from the SPS Chair" (PDF). Permophile: 4. ISSN 1684-5927. Retrieved 12 December 2020.