Lochkovium
| 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 Lochkovium (also Lochkov , Lochkovien ); is the oldest chronostratigraphic stage of the Lower Devonian . The Lochkovian represents geochronologically a time interval in the history of the earth that began about 419.2 million years ago and ended about 410.8 million years ago . It replaces the Upper Silurian Pridolium and is followed by the younger Pragium .
Naming and history
The step is named after the district of Lochkov in the southwest of Prague . In 1958 the Lochkovium was defined in the "Prager Arbeitstagung" as a level corresponding to the Lochkov-Kalk and assigned to the uppermost Silurian. During the 24th Geological Congress in Montreal, the Lochkovium was internationally accepted as the oldest part of the Devonian.
Definition and GSSP
The base of the Lochkovium and thus the beginning of the Devonian is defined in the Prager Mulde southwest of the Czech capital. Lochkovium begins with bank 20 on the Klonk slope about 35 kilometers southwest of Prague. There is the so-called GSSP ( G lobal S tratotype S ection and P oint (Global calibration point for stratotypes ) ). The graptolite Monograptus uniformis appears for the first time in bank 20 .
Breakdown
The Lochkovium is subdivided into four conodont biozones:
- Pedavis pesavis zone
- Ozarkodina delta zone
- Ozarkodina eurekaensis zone
- Icriodus woschmidti / Icriodus postwoschmidti zone
literature
- Ivo Chlupáč and Z. Kukal: The boundary stratotype at Klonk. The Silurian-Devonian Boundary. IUGS Series, A5: 96-109, Berlin 1977 ISSN 0374-8480
- Ivo Chlupac: The Bohemian Lower Devonian stages. Courier Forschungsinstitut Senckenberg, 55: 345-400, Frankfurt am Main 1982 ISSN 0341-4116
- Ivo Chlupác and Frantisek Vacek: Thirty years of the first international stratotype: The Silurian-Devonian boundary at Klonk and its present status. Episodes, 26 (3): 10-15, Beijing 2003 ISSN 0705-3797
- Felix Gradstein, Jim Ogg & Alan Smith: A Geologic timescale. Cambridge University Press 2004 ISBN 978-0-521-78673-7
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)
Individual evidence
- ↑ Chlupac 1982: 347-352