Roadium
| 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 Roadium the lower stratigraphic level (or age in geochronology ) of Mittelperm or Guadalupium - series . Expressed in absolute terms, the level ranges from about 272.3 million years to about 268.8 million years. The roadium follows the kungurium and is overlaid by the wordium .
Naming and history
Walter William Nassichuk established in 1964 that a further level can be eliminated between the Wordium and the Russian Artinskium. William Madison Furnish and Brian F. Glenister then introduced the Roadium in 1968 as the basal chronostratigraphic lower level of their, then still regional level of the Guadalupian. It is named after the basal unit of the Word formation , the Road Canyon Member, whose type locality is in Brewster County ( Texas ). In 2001 the Roadium was ratified by the IUGS as a global chronostratigraphic stage .
Definition and GSSP
The basis of the roadium is defined by the first appearance of the conodont species Jinogondolella nanginkensis . The stage ends with the first appearance of the conodont species Jinogondolella aserrata . The reference profile ( GSSP ) of Roadiums located in Stratotype Canyon in the southern Guadalupe Mountains in Texas , USA (31 ° 52 '36.1 "N, 104 ° 52' 36.5" W).
literature
- Felix Gradstein, Jim Ogg, Jim & Alan Smith: A Geologic timescale. Cambridge University Press 2005, ISBN 9780521786737
- Brian F. Glenister, Bruce R. Wardlaw, Lance L. Lambert, Claude Spinosa, SA Bowring, DH Erwin, Manfred Menning and Garner L. Wilde: Proposal of Guadalupian and Component Roadian, Wordian and Capitanian Stages as International Standards for the Middle Permian Series. Permophiles, 34: 3-11, 1999 PDF; 3.46 MB
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)