Aeronium
system | series | step | ≈ age ( mya ) |
---|---|---|---|
higher | higher | higher | younger |
Silurian | Pridolium | 419.2 ⬍ 423 |
|
Ludlow | Ludfordium | 423 ⬍ 425.6 |
|
Gorstium | 425.6 ⬍ 427.4 |
||
Wenlock | Homerium | 427.4 ⬍ 430.5 |
|
Sheinwoodium | 430.5 ⬍ 433.4 |
||
Llandovery | Telychium | 433.4 ⬍ 438.5 |
|
Aeronium | 438.5 ⬍ 440.8 |
||
Rhuddanium | 440.8 ⬍ 443.4 |
||
deeper | deeper | deeper | older |
The aeronium is the second chronostratigraphic stage of the Llandovery series of the Silurian in the history of the earth . In absolute numbers ( geochronologically ), the stage is roughly in the period from about 440.8 to 438.5 million years. It follows the Rhuddanium and is overlaid by the Telychium .
Naming and history
The stage is named after the Cwm-coed Aeron Farm, near Llandovery , ( Wales ). The stage (and name) was proposed in 1971 by a British geological group under LRM Cocks.
Definition and GSSP
The beginning of the aeronium is defined by the first appearance of the graptolite species Monograptus austerus sequens . The upper limit is above the extinction horizon of the brachiopod species Eocoelia intermedia and below the first appearance of the brachiopod species Eocoelia curtisi . The boundary is also near the base of the Monograptus turriculatus graptolite zone. The official reference profile (GSSP = "Global Stratotype Section and Point") for the Aeronium is the "Transect h" on the Trefawr Forest Trail, north of the Cwm-coed-Aeron Farm, near Llandovery ( Wales ).
literature
- Felix M. Gradstein, James G. Ogg, and Alan G. Smith (Eds.): A Geologic Time Scale 2004 . Cambridge University Press, Cambridge (UK) 2005. ISBN 0-521-78673-8
- LRM Cocks: The Llandovery Series in the Llandovery area. In: CH Holland and MG Bassett (eds.). A global standard for the Silurian System. National Museum of Wales, Geological Series 9: 36–50, Cardiff 1989 ZDB -ID & key = zdb 995874-5 .
Web links
- International Chronostratigraphic Chart 2012 (PDF)
- German Stratigraphic Commission (Ed.): Stratigraphische Tisch von Deutschland 2002 . Potsdam 2002 ISBN 3-00-010197-7 (PDF; 6.57 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)