Webbläsaren som du använder stöds inte av denna webbplats. Alla versioner av Internet Explorer stöds inte längre, av oss eller Microsoft (läs mer här: * https://www.microsoft.com/en-us/microsoft-365/windows/end-of-ie-support).

Var god och använd en modern webbläsare för att ta del av denna webbplats, som t.ex. nyaste versioner av Edge, Chrome, Firefox eller Safari osv.

Per Ahlberg, Skottland 2013

Per Ahlberg

Professor emeritus

Per Ahlberg, Skottland 2013

Furongian (Cambrian) agnostoids of Scandinavia and their implications for intercontinental correlation

Författare

  • Per Ahlberg
  • Fredrik Terfelt

Summary, in English

Out of the 14 agnostoid species/subspecies so far recorded from the Furongian of Scandinavia, seven are excellent biostratigraphical indices and important for correlation between Baltica and other palaeocontinents. Glyptagnostus reticulatus, Aspidagnostus lunulosus and Agnostus (Homagnostus) obesus first appear at the base of the G. reticulatus Zone, allowing a precise correlation of the base of the Paibian Stage into Scandinavia. Tomagnostella orientalis and Psettdagnostus cyclopyge appear near the base of the Parabolina brevispina Zone, suggesting a correlation with the uppermost Paibian through the lowermost Jiangshanian stages. Lotagnostus americanus and Pseudagnostus rugosus have an intercontinental distribution and their first appearance in Scandinavia allows for a correlation with one of the most favourable levels for defining the base of Cambrian provisional Stage 10. In the Furongian of Scandinavia, agnostoids are conspicuously assembled in three different intervals: the lower Glyptagnostus reticulatus Zone, the lower Psettdagnostus cyclopyge Zone and the Lotagnostus americanus through lower Trilobagnostus holmi zones. The agnostoid-barren and largely unfossiliferous succession separating the lower and middle agnostoid-bearing intervals can be explained by means of subsequent dissolution of the calcareous fauna and/or a hostile environment. The middle agnostoid-bearing interval is succeeded by an anomalous succession dominated by the orthide brachiopod Orusia lenticularis, reflecting a regressive event coupled with increasing levels of oxygen at the sediment/water interface. This shallowing evidently resulted in unfavourable conditions for agnostoids.

Avdelning/ar

  • Berggrundsgeologi

Publiceringsår

2012

Språk

Engelska

Sidor

1001-1012

Publikation/Tidskrift/Serie

Geological Magazine

Volym

149

Issue

6

Dokumenttyp

Artikel i tidskrift

Förlag

Cambridge University Press

Ämne

  • Geology

Nyckelord

  • agnostoids
  • biostratigraphy
  • correlation
  • Furongian
  • Scandinavia

Status

Published

ISBN/ISSN/Övrigt

  • ISSN: 0016-7568