Sheinwoodium

from Wikipedia, the free encyclopedia
system series step ≈ age ( mya )
higher higher higher younger
Silurian Pridolium 419.2
⬍
423
Ludlow Ludfordium 423
⬍
425.6
Gorstium 425.6
⬍
427.4
Wenlock Homerium 427.4
⬍
430.5
Sheinwoodium 430.5
⬍
433.4
Llandovery Telychium 433.4
⬍
438.5
Aeronium 438.5
⬍
440.8
Rhuddanium 440.8
⬍
443.4
deeper deeper deeper older

The Sheinwoodium is the lower chronostratigraphic stage of the Wenlock series of the Silurian in geological history . The stage can be geochronologically dated to the period from about 433.4 to about 430.5 million years. The degree follows the Telychium , above it the Homerium .

Naming and history

The Sheinwoodium is named after the Sheinwood farm north of Much Wenlock , Shropshire ( England ). A group of English geologists ( Michael G. Bassett et al.) Suggested the name in 1975.

Definition and GSSP

The basis has so far only been determined imprecisely. It is located between the base of acritarchs -Biozone 5 and the extinction of conodonts -Art Pterospathodus amorphognathoides . The boundary is probably also near the base of the Cyrtograptus centrifugus - graptolite zone. The end of the stage is defined by the first appearance of the graptolite species Cyrtograptus lundgreni . The official reference profile (GSSP = Global Stratotype Section and Point) for the Sheinwoodium is located in the Hughely Creek, 200 m southeast of the few houses of Leasows and 500 m northeast of the Church of Hughely, Apedale (Shropshire, England).

literature

  • Felix Gradstein, Jim Ogg, Jim & Alan Smith: A Geologic timescale. Cambridge University Press 2004, ISBN 978-0-521-78673-7 .
  • MG Basset, LRM Cooks, CH Holland, RB Rickards and PT Warren: The type Wenlock series. In: Report of the Institute of Geological Sciences. 75/13: 1-19, London 1975, ISSN  0073-9359
  • MG Bassett: The Wenlock Series in the Wenlock Area. In: CH Holland and MG Bassett (eds.): A global standard for the Silurian System. In: National Museum of Wales, Geological Series. 9: 51-73, Cardiff 1989 ZDB -ID & key = zdb 995874-5 .

Web links