Servantium

from Wikipedia, the free encyclopedia
series step Lower level ≈ age ( mya )
higher higher higher younger
 Lower Triassic  Olenekium   Space 249.2-247.2
 Smithium 251.2-249.2
 Indusium  Servantium 251.6-251.2
 Griesbachium  251.9-251.6
deeper deeper deeper older

Dienerium (Engl. Dienerian, in German usage also only servant or servant level) is the upper lower level of the Indusium , the lowest level of the Triassic in geological history . It follows the Griesbachian , the lower sub-stage of the Indusian, and is replaced by the Smithium , the lower sub-tier of the Olenekian .

Concept history

The Dienerium is named after Diener Creek in the northwestern part of Ellesmere Island . This brook is again named after Carl Diener , an Austrian paleontologist who worked mainly in the Alps and for many years in India. The level and name were proposed by Edward Timothy ("Tim") Tozer in 1965.

Definition, absolute dating, correlation and subdivision

The beginning or the lower limit of the dienerium is defined by the first onset of the ammonite family Gyronitidae. The upper limit is marked by the first appearance of the conodont species Neospathodus waageni and the ammonite genera Flemingites and Euflemingites . It is close to the first appearance of the ammonite species Hedenstroemia hedenstroemi and Meekoceras gracilitatis . This limit is at the same time the lower limit of the Smithium lower level and the Olenekium level and the Middle Triassic series.

The geological time interval of the Dienerium is geochronologically dated to 250.4 to 249.7 +/- 0.7 million years ago.

Tozer already indicated in 1974 that dienerium and smithium are difficult to separate in regions other than the Canadian Arctic. Guex (1978) therefore suggested combining Dienerium and Smithium and introducing a new level for them, Nammalium .

The dienerium is divided into two ammonite zones in the boreal area:

  • Vavilovites sverdrupi
  • Proptychites candidus

In the Tethyalen area there are three ammonite zones

  • Rohillites rohilla
  • Gyronites frequens
  • Pleurygonites planidorsatus

supporting documents

Individual evidence

  1. ^ Frisch, Thomas (2011): Edward Timothy Tozer (1928-2010). Arctic, 64 (3): 388-389, Calgary PDF
  2. ↑ Gradstein et al. (2004: p. 277)
  3. ^ Guex, Jean (1978): Le Trias inférieur des Salt Ranges, Pakistan :problemèmes biochronologiques. Eclogae Geologicae Helvetiae, 71: 105-141, Basel. doi : 10.5169 / seals-164720
  4. ↑ Brühwiler, Thomas, Arnaud Brayard, Hugo Bucher, Kuang Guodun (2008): Griesbachian and Dienerian (Early Triassic) Ammonoid faunaus from northwestern Guangxi and southern Guizhou (South China). Palaeontology, 51 (5): 1151-1180, London doi : 10.1111 / j.1475-4983.2008.00796.x
  5. ↑ a b TimeScale Creator 5.0 download page

literature

  • Tozer, Edward Timothy (1965): Lower Triassic stages and ammonoid zones of Arctic Canada. Geological Survey of Canada Paper, 65-12: 1-14, Ottawa.
  • Tozer, Edward Timothy (1967): A standard for Triassic time. Geological Survey of Canada Bulletin, 156: 1–103, Ottawa.
  • Gradstein, Felix, James Ogg & Alan Smith (2004): A Geologic Time Scale 2004. 589 pp. Cambridge University Press, Cambridge ISBN 0521781426

Web links