Emsium
| system | series | step | ≈ age ( mya ) |
|---|---|---|---|
| higher | higher | higher | younger |
| Devon | Upper Devonian | Family | 358.9 ⬍ 372.2 |
| Frasnium | 372.2 ⬍ 382.7 |
||
| Middle Devon | Givetium | 382.7 ⬍ 387.7 |
|
| Eifelium | 387.7 ⬍ 393.3 |
||
| Lower Devon | Emsium | 393.3 ⬍ 407.6 |
|
| Pragium | 407.6 ⬍ 410.8 |
||
| Lochkovium | 410.8 ⬍ 419.2 |
||
| deeper | deeper | deeper | older |
The Emsium (usually shortened to Ems in German) is the highest chronostratigraphic level of the Lower Devonian series of the ( Devonian ) in geological history . Geochronologically, the stage covers the period from about 407.6 million to about 393.3 million years. The stage follows the Pragium (Devonian) and is overlaid by the Eifelium .
Naming and history
The step is named after Bad Ems in the northwest of the Taunus , where the historical type region is located. The level and name were introduced into scientific literature in 1900 by Henry de Dorlodot .
Definition and GSSP
The lower limit of the level is the first appearance of the conodont species Polygnathus kitabicus (= Polygnathus dehiscens ). The fixed and the International Commission on Stratigraphy 1996 ratified official reference profile ( english global boundary stratotype section and point , GSSP) for the base of Emsiums is the Zinzil'ban Canyon, 170 kilometers southeast of Samarkand , Uzbekistan . The upper limit of the level is defined by the first appearance of the conodont species Polygnathus costatus partitus .
Breakdown
The emsium is subdivided into five conodont biozones:
- Polygnaths gronbergi / Polygnatus inversus / Polygnathus kitabicus zone
- Polygnaths inversus / Polygnaths laticostatus zone
- Polygnath's notoperbonus zone
- Polygnaths patulus zone
- Polygnaths serotinus zone
Individual evidence
- ↑ Evgeny A. Yolkin, AI Kim, Karsten Weddige, Jim A. Talent, Michael R. House: Definition of the Pragian / Emsian Stage boundary. Episodes. Vol. 20, No. 4, 1997, pp. 235–240 ( PDF 1.0 MB)
literature
- Felix Gradstein, Jim Ogg & Alan Smith: A Geologic timescale. Cambridge University Press 2004, ISBN 978-0-521-78673-7 .
- Hans Murawski & Wilhelm Meyer: Geological dictionary . 10., rework. u. exp. Ed., 278 pages, Enke Verlag, Stuttgart 1998, ISBN 3-432-84100-0 .
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)
- The basal Emsian GSSP in Zinzil'ban Gorge, Uzbekistan (Abstract)