Bajocium

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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 Bajocium (seldom shortened to Bajoc , also Bajocien) is the second chronostratigraphic level of the Middle Jurassic series in the Jura . The Bajocian began geochronologically about 170.3 million years ago and ended about 168.3 million years ago.

Naming and history

The original type locality is near Bayeux ( Calvados department , France). The stage is named after the Gallo-Roman city name Bajocae for Bayeux. The stage and name were introduced by Alcide Dessalines d'Orbigny in 1842.

Definition and GSSP

The beginning of the stage is defined by the first appearance of the ammonite genus Hyperlioceras . The GSSP (= type locality and type profile) that determines this is at Murtinheira on Cabo Mondego in Portugal . The end is marked by the first appearance of the ammonite species Parkinsonia convergens .

Subdivision of the Bajocium

The Bajocium is subdivided into seven ammonite biozones in the Tethyalen area:

The Bajocium in turn is divided into the Lower Bajocian and Upper Bajocian , with the first appearance of the ammonite Strenoceras niortense determining the beginning of the Upper Bajocian .

literature

  • Giulio Pavia and Raymon Enay: Definition of the Aalenian-Bajocian Stage boundary. Episodes, 20 (1): 16-22, Beijing 1997 PDF
  • Felix Gradstein, Jim Ogg, Jim & Alan Smith: A Geologic timescale. Cambridge University Press 2005, ISBN 978-0-521-78673-7
  • Hans Murawski & Wilhelm Meyer: Geological dictionary . 10., rework. u. exp. Ed., 278, Enke Verlag, Stuttgart 1998, ISBN 3-432-84100-0 .
  • Alcide d´Orbigny: Paléontologie française. 1. Terrains oolitiques or jurassiques. 642 pp., Bertrand, Paris 1842

Web links