Wenlock (geology)
| 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 Wenlock (very rarely also called Wenlockium ) is a chronostratigraphic series of the Silurian in the history of the earth . It began geochronologically about 433.4 million years ago and ended about 427.4 million years ago. It replaces the Llandovery series and is followed by the Ludlow series.
Naming and history
The Wenlock is named after Wenlock Edge , a geological outcrop near Much Wenlock in the central English county of Shropshire . The name goes back to Roderick Murchison , who proposed it in 1833.
Definition and GSSP
The inexactly determined base lies between the base of the acritarch biozone 5 and the extinction of the conodont species Pterospathodus amorphognathoides . The boundary is probably also near the base of the Cyrtograptus centrifugus - graptolite zone. The end of the series is also imprecise; it lies near the base of the Saetograptus leintwardinensis graptolite zone. The reference profile ( GSSP = "Global Stratotype Section and Point") for the Sheinwoodium is in the Hughely Creek, 200 m southeast of the few houses of Leasows and 500 m northeast of the Church of Hughely, Apedale ( Shropshire , England).
Breakdown
The Wenlock series is divided into two geological tiers:
-
System : Silurian (443.4–419.2 mya )
- Series : Pridolium (423–419.2 mya) (not subdivided into further stages)
- Series: Ludlow (427.4–423 mya)
- Series: Wenlock (433.4–427.4 mya)
- Level: Homerium (430.5–427.4 mya)
- Level: Sheinwoodium (433.4-430.5 mya)
- Series: Llandovery (443.4-433.4 mya)
Geological situation at the time of Wenlock
This series is characterized by the clash of the continents Laurentia , Baltica and Avalonia , and the resulting Caledonian orogeny .
literature
- Felix Gradstein, Jim Ogg & Alan Smith: A Geologic timescale. Cambridge University Press 2004 ISBN 978-0-521-78673-7
- MG Bassett: The Wenlock Series in the Wenlock Area. In: CH Holland and MG Bassett (eds.): A global standard for the Silurian System. National Museum of Wales, Geological Series, 9: 51–73, Cardiff 1989 ZDB -ID & key = zdb 995874-5 .
Web links
- International Chronostratigraphic Chart 2012 (PDF)
- 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 (large)