Darriwilium

from Wikipedia, the free encyclopedia
system series step ≈ age ( mya )
higher higher higher younger
Ordovician Upper Ordovician Brain antium 443.4
⬍
445.2
Katium 445.2
⬍
453
Sandbium 453
⬍
458.4
Middle Ordovician Darriwilium 458.4
⬍
467.3
Dapingium 467.3
⬍
470
Lower Ordovician Floium 470
⬍
477.7
Tremadocium 477.7
⬍
485.4
deeper deeper deeper older

The Darriwilium is the second chronostratigraphic stage of the middle ordovian series of the ordovician in geological history . Geochronologically, the stage roughly corresponds to the period from about 467.3 to about 458.4 million years. The Darriwilium follows the Dapingium and is in turn replaced by the Sandbium .

Naming and history

The stage is named after the place Darriwil in the County of Grant ( Victoria , Australia ). The name and level were proposed as early as 1899 by Thomas Sergeant Hall (1858–1915). The Darriwilium corresponds to the highest part of the earlier Arenigium series (or stage) and the lower part of the earlier Llanvirnium series (or stage).

Definition and GSSP

The lower limit of the Darriwilium was defined by the first appearance of the graptolite species Undulograptus austrodentatus , the upper limit by the first appearance of the graptolite species Nemagraptus gracilis . As a global reference profile (GSSP = Global Stratotype Section and Point) of the Darriwilium, however, a profile was set at Huangnitang , Changshan County , in the Zhejiang Province in southeastern China .

literature

  • SM Bergström, SC Finney, Xu Chen, C. Pålsson, Zhi-lao Wang and Y. Grahn: A proposed global boundary stratotype for the base of the Upper Series of the Ordovician System: The Fågelsång section, Scania, southern Sweden. Episodes. 23 (3): 102-109, Beijing 2000 ISSN  0705-3797 .
  • Felix Gradstein, Jim Ogg and Alan Smith: A Geologic timescale. Cambridge University Press 2004 ISBN 978-0-521-78673-7 .
  • EE Mitchell, Xu Chen, Stig. M. Bergstroem, Yuan-dong Zhang, Zhi-hao Wang, BD Webby and SC Finney: Definition of a global stratotype for the Darriwilian Stage of the Ordovician System. Episodes, 20 (3): 158-166, Beijing 1997 ISSN  0705-3797 .

Web links