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

Ahlberg, Per LU and Terfelt, Fredrik LU (2012) In Geological Magazine 149(6). p.1001-1012
Abstract
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... (More)
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. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
agnostoids, biostratigraphy, correlation, Furongian, Scandinavia
in
Geological Magazine
volume
149
issue
6
pages
1001 - 1012
publisher
Cambridge University Press
external identifiers
  • wos:000311058900004
  • scopus:84869433985
ISSN
0016-7568
DOI
10.1017/S0016756812000167
language
English
LU publication?
yes
id
9d09fbf7-6f44-4ee7-a427-526252e95bef (old id 3244232)
date added to LUP
2012-12-28 09:59:22
date last changed
2017-09-10 03:16:46
@article{9d09fbf7-6f44-4ee7-a427-526252e95bef,
  abstract     = {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.},
  author       = {Ahlberg, Per and Terfelt, Fredrik},
  issn         = {0016-7568},
  keyword      = {agnostoids,biostratigraphy,correlation,Furongian,Scandinavia},
  language     = {eng},
  number       = {6},
  pages        = {1001--1012},
  publisher    = {Cambridge University Press},
  series       = {Geological Magazine},
  title        = {Furongian (Cambrian) agnostoids of Scandinavia and their implications for intercontinental correlation},
  url          = {http://dx.doi.org/10.1017/S0016756812000167},
  volume       = {149},
  year         = {2012},
}