Asselium
| system | series | step | ≈ age ( mya ) |
|---|---|---|---|
| higher | higher | higher | younger |
| Perm | Lopingium | Changhsingium | 251.9 ⬍ 254.2 |
| Wuchiapingium | 254.2 ⬍ 259.9 |
||
| Guadalupium | Capitanium | 259.9 ⬍ 265.1 |
|
| Wordium | 265.1 ⬍ 268.8 |
||
| Roadium | 268.8 ⬍ 272.3 |
||
| Cisuralium | Kungurium | 272.3 ⬍ 279.3 |
|
| Artinskium | 279.3 ⬍ 290.1 |
||
| Sacmarium | 290.1 ⬍ 295.5 |
||
| Asselium | 295.5 ⬍ 298.9 |
||
| deeper | deeper | deeper | older |
The Asselium is the lowest chronostratigraphic level of the Unterperm or the Cisuralium in the history of the earth . The level ranges in absolute numbers ( geochronologically ) from about 298.9 million years to about 295.5 million years. The Asselium follows the Gzhelium , the uppermost level of the Carboniferous, and is replaced by the Sacmarium .
Naming and history
The stage was separated and named in 1954 from the formerly more comprehensive Sakmar stage ( Sakmarium ) by the Soviet paleontologist, malacologist and geologist Vasily Yermolajewitsch Rushenzew ( Russian Василий Ермолаевич Руженцев , 1899–1978). The Asselium is named after the Russian-Kazakh border river Assel in the southern Urals .
Definition and GSSP
The beginning of the Asselium (and the Cisuralium ) is defined by the first appearance of the conodont species Streptognathodus isolatus . The end of the stage is reached with the first appearance of the conodont species Streptognathodus postfusus . The globally valid type locality ( GSSP = Global Stratotype Section and Point) established by the IUGS is located in the Aidaralash valley, near the city of Aqtöbe (Russian Aktyubinsk) in the southern Urals ( Kazakhstan ).
Breakdown
The Asselium can be divided into five conodont biozones:
- Streptognathodus barskovi zone
- Streptognathodus postfusus zone
- Streptognathodus fusus zone
- Streptognathodus constrictus zone
- Streptognathodus isolatus zone
literature
- Felix Gradstein, Jim Ogg, Jim & Alan Smith: A Geologic timescale. Cambridge University Press 2004, ISBN 978-0-521-78673-7
- Vladimir I. Davydov, Brian F. Glenister, Claude Spinosa, Scott M. Ritter, VV Chernykh, BR Wardlaw and WS Snyder: Proposal of Aidaralash as Global Stratotype Section and Point (GSSP) for base of the Permian System . In: Episodes. 21 (1): 11-18, Beijing 1998 ISSN 0705-3797 PDF
Web links
- German Stratigraphic Commission, Manfred Menning (Hrsg.): Stratigraphische Tisch von Deutschland 2002 . Potsdam 2002, ISBN 3-00-010197-7 (1 sheet, Stratigraphie.de [PDF; 6.6 MB ]).
- Commission for the paleontological and stratigraphic research of Austria of the Austrian Academy of Sciences (Ed.) : The Stratigraphic Table of Austria (sedimentary layer sequences). Vienna, 2004 (PDF; 376 kB)
- International Chronostratigraphic Chart 2012 (PDF)