Eifelium

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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 Eifelium is a chronostratigraphic stage of the Devonian in the history of the earth . It forms the lowest level of the Middle Devonian . Geochronologically, the Eifelium represents a time interval beginning about 393.3 million years ago and lasting up to 387.7 million years. It is covered by the emsium and the givetium .

Naming and history

The step is named after the Eifel , a part of the Rhenish Slate Mountains on the left bank of the Rhine . The Eifelium as a stratigraphic unit goes back directly to the "Eifeler Kalkstein" which Heinrich Ernst Beyrich spun off in 1837 between the "Rheinische Grauwacke" and the "Stringocephalen-Kalk". The term "Eifel level" competed for a long time with the Ardennes Couvinien (Couvin level) as the name and content definition of the lower part of a two-part middle Devonian . During the second Düsseldorf "International Directional Section Conference" in May 1937, it was decided to create a directional cut in the vicinity of the current stratotype in order to collect further lithographic and biostratigraphic data on the Lower / Middle Devonian border. In 1982, the international "Sub-Commission for Devonstratigraphy" recommended the adoption of the lower limit of the Eifel region, which had meanwhile paralleled the appearance of the conodont Polygnathus patulus partitus, as the beginning of the Middle Devonian. Thus, the original demarcation in the sense of Ernst Beyrich had prevailed over the somewhat lower-lying Couvin stage, which was distinguished by the onset of the distinctive orbignyanus-cultrijugatus-alatiformis faun society. During the geological congress in Moscow in 1984, this demarcation was ratified through the final choice of the current stratotype by resolution of the International Union of Geosciences (IUGS).

Definition and GSSP

The GSSP (global calibration point and stratotype ) of the Eifelium base is the Wetteldorfer directional cut , which is located approx. 650 m southeast of the center of Schönecken-Wetteldorf in the Prümer Kalkmulde ( Eifel ). The boundary point is 21.25 meters above the profile base in the upper part of the Heisdorf Formation, just under two meters below the base of the Leek Formation. The Eifelium base there is, worldwide binding, marked by the first occurrence ( English first appearance date , FAD) of the Conodonten Polygnathus costatus partitus (so-called partitus boundary ). Just above is the FAD of the conodont Icriodus corniger retrodepressus . The Prastav quarry in the southern Prague suburb of Holyně in the Czech Republic is regarded as the “parastratotype” for the Eifelium base or the partitus boundary . The border is there in the upper part of the Třebotov limestone, 2.8 meters below the base of the Choteč limestone.

The end of the step, or rather the base of the givetium , is indicated by the FAD of the Conodont Polygnathus hemiansatus .

Breakdown

The Eifelium is divided into five conodont biozones:

  • Polygnatus xylus ensensis zone
  • Tortodus kockelianus zone
  • Tortodus australis zone
  • Polygnathus costatus costatus zone
  • Polygnathus costatus partitus zone

Individual evidence

  1. ↑ Ernst Beyrich (1837): Contributions to the knowledge of the fossils of the Rhenish transition mountains. 44 p., Berlin (F. Dümmler).
  2. ^ Rudolf Richter (1942): History and task of the Wetteldorfer directional cut. In: Senckenbergiana. Vol. 25 (4/6): 357-361; Frankfurt am Main.
  3. ^ R. Werner & Willi Ziegler (1982): Proposal of a Boundary Stratotype for the Lower / Middle Devonian Boundary ( partitus -Boundary). In: W. Ziegler & R. Werner [Eds.]: On Devonian Stratigraphy and Palaeontology of the Ardenno-Rhenish Mountains and related Devonian Matters. In: Courier Research Institute Senckenberg. Vol. 55: 13-84, 17 illustrations, 2 plates; Frankfurt am Main.
  4. ^ Wolfgang Struve (1982): The Eifelian within the Devonian frame, history, boundaries, definitions. - In: Willi Ziegler & R. Werner [Eds.]: On Devonian Stratigraphy and Palaeontology of the Ardenno-Rhenish Mountains and related Devonian Matters. Courier Research Institute Senckenberg, Vol. 55: 401-432, 6 fig .; Frankfurt am Main.
  5. ^ A b Willi Ziegler and G. Klapper (1985): Stages of the Devonian System. IN: Episodes. Vol. 8 (2): 104-109, 9 fig .; Ottawa.
  6. ^ R. Werner (1990): Refuge above the border stratotype Lower / Middle Devon in Schönecken-Wetteldorf / Eifel. In: Nature and Museum. Vol. 120 (5): 160-163, 3 illustrations; Frankfurt am Main.

literature

  • DSK [German Stratigraphic Commission] [Hrsg.] (2002): Stratigraphic table of Germany 2002. Potsdam (Center for Geo-Research). [= STD 2002]
  • Felix M. Gradstein, James G. Ogg and Alan G. Smith: A Geologic Time Scale 2004 . Cambridge University Press, 2004 ISBN 9780521786737

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