Aalenium

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system series step ≈ age ( mya )
higher higher higher younger
law Upper Jurassic Tithonium 145
⬍
152.1
Kimmeridgium 152.1
⬍
157.3
Oxfordium 157.3
⬍
163.5
Middle Jurassic Callovium 163.5
⬍
166.1
Bathonium 166.1
⬍
168.3
Bajocium 168.3
⬍
170.3
Aalenium 170.3
⬍
174.1
Lower Jurassic Toarcium 174.1
⬍
182.7
Pliensbachium 182.7
⬍
190.8
Sinemurium 190.8
⬍
199.3
Hettangium 199.3
⬍
201.3
deeper deeper deeper older

The Aalenian (German shortens Aalen, also Aalenien ) is in the Earth's history , the oldest of the four chronostratigraphic stage of the Middle Jurassic and includes geochronological the period of about 174.1 to 170.3 million years ago. The Toarcium precedes this stage ; it is followed by the Bajocium .

Naming and history

The stage is named after the city of Aalen in Baden-Württemberg . The step and name were first used by Karl Mayer-Eymar in 1864. The first fossil finds were made in the deep tunnel in Aalen. A large part of this is exhibited in the city's Urweltmuseum Aalen .

Definition and GSSP

Partial locality "2Fz" of the GSSP near Fuentelsaz. The base of the Aalenium is pretty much at the level of the outstretched arm of the person furthest up the slope.

The beginning (the base) of the stage is defined by the first appearance of the ammonite genus Leioceras . The first appearance of the ammonite genus Hyperlioceras marks the end of the stage or the base of the subsequent Bajocium. The Global Stratotype Section and Point (GSSP, the type profile of the basal unit boundary ) of the Aalenium is located in an outcrop approx. 500 m north of the village of Fuentelsaz (Guadalajara Province, Spain) in the Iberian Mountains .

Subdivision of the Aalenium

The Aalenian will Tethysbereich in the following ammonite - biozones divided:

Lower level Biozone Index fossil
Oberaalenium concavum Graphoceras concavum
bradfordensis Brasilia bradfordensis
murchisonae Ludwigia murchisonae
Unteraalenium opalinum Leioceras opalinum

literature

  • S. Cresta, A. Goy, S. Ureta, C. Arias, E. Barrón, J. Bernad, ML Canales, F. García-Joral, E. García-Romero, PR Gialanella, JJ Gómez, JA González, C. Herrero, G. Martínez, ML Osete, N. Perilli and JJ Villalaín: The Global Boundary Stratotype Section and Point (GSSP) of the Toarcian-Aalenian Boundary (Lower-Middle Jurassic). Episodes, 24 (3), Beijing 2001, pp. 166-175 PDF .
  • Felix Gradstein, Jim Ogg, Jim Smith, Alan Smith: A Geologic timescale. Cambridge University Press, 2005, ISBN 978-0-521-78673-7 .
  • Karl Mayer-Eymar: Tableau synchronistique des terrains jurassiques. 1 table, Zurich 1864.
  • Hans Murawski, Wilhelm Meyer: Geological dictionary . 10., rework. u. exp. Ed., 278, Enke Verlag, Stuttgart 1998, ISBN 3-432-84100-0 .

Web links

Wiktionary: Aalenium  - explanations of meanings, word origins, synonyms, translations