Middle Jurassic

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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 Middle Jurassic (or Middle Jurassic ) is the middle stratigraphic series of Jura in Earth's history. In the older literature, partly also in the popular scientific literature, this series is often referred to as Dogger or Brauner Jura ( Braunjura ). In the southern German Jurathe term Brown Jura is used in the context of the lithostratigraphic structure (in the sense of a group of formations). The term Dogger is also still used for the lithostratigraphic subdivision of the North German Jura. The series of the Middle Jura is underlain by the series of the Lower Jura and overlaid by the Upper Jura. It roughly corresponds to the period from 174.1 million to 163.5 million years.

Older names

In older scientific works, but above all in popular scientific literature (partly still today), this period of geological history is usually referred to as the Brauner Jura (Braunjura) or Dogger. However, this is not correct, as two different stratigraphic classifications (chronostratigraphy and lithostratigraphy) are mixed up here. The lithostratigraphic unit of the Brown Jura in southern Germany is primarily characterized by iron-bearing brown sandstones and clays. Since the deposits of the Brown Jura set in regionally before the beginning of the Middle Jura and extend well into the Upper Jura in large areas of the South German Jura, the lithostratigraphic term Brown Jura is not exactly synonymous with the chronostratigraphic Middle Jura series .

The term Dogger is also still used frequently for the Middle Jura series. The name Dogger comes from the English quarry industry. Today it is provisionally reserved in the form of Norddeutscher Dogger for a lithostratigraphic group in the Central Jura of Northern Germany. However, a final decision has not yet been made on the demarcation and use of the lithostratigraphic unit of North German Dogger in central and northern Germany.

Breakdown

The series of the Middle Jurassic is subdivided into the following chronostratigraphic levels :

Fauns

The Middle Jura had a warm climate, and ammonites , as in the entire Jura, are important key fossils , on the basis of which the further biostratigraphic subdivision of the levels takes place. The first lizards appeared in the Middle and Upper Jurassic .

literature

  • Friedrich August Quenstedt: The Jura. Laupp Publishing House, Tübingen 1856–57.
  • On the Upper Bathonium (Middle Jura) in the Hildesheim area, northwest Germany - mega- and micropalaeontology, biostratigraphy. In: Geological Yearbook Series A, issue 121. Hannover 1990.
  • Gert Bloos, Gerd Dietl & Günter Schweigert: The Jura of Southern Germany in the Stratigraphic Table of Germany 2002. Newsletters on Stratigraphy, 41 (1-3): 263-277, Stuttgart 2005 ISSN  0078-0421
  • Günter Schweigert (Ed.): The Braunjura at the foot of the Swabian Alb. (= Fossils special edition 2013). Quelle & Meyer Verlag, Wiebelsheim 2013, ISBN 978-3-494-01548-4
  • Felix Gradstein, Jim Ogg, Jim & Alan Smith: A Geologic timescale. Cambridge University Press 2005 ISBN 978-0-521-78673-7

Individual evidence

  1. ↑ Eckhard Mönnig: The Jura of Northern Germany in the Stratigraphic Table of Germany 2002. Newsletters on Stratigraphy, 41 (1-3): 253-261, Stuttgart 2005

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