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Mollusk maxima and marine events in the Middle Ordovician of Baltoscandia

Lindskog, Anders LU ; Eriksson, Mats LU ; Tell, Carsten LU ; Terfelt, Fredrik LU ; Martin, Ellinor LU ; Ahlberg, Per LU ; Schmitz, Birger LU and Marone, Federica (2015) In Palaeogeography, Palaeoclimatology, Palaeoecology 440. p.53-65
Abstract
Except for the scattered cephalopod conchs that have given the rock type its name, mollusk fossils are relatively rare in the Middle Ordovician 'orthoceratite limestone' of Sweden. However, an interval in the Darnwilian stands out as being unusually rich in various types of mollusks. Throughout southern Sweden, gastropods became relatively abundant close to the Volkhov-Kunda Baltoscandian Stage boundary, and their numbers increase significantly in the Kundan. This increase is most apparent in the microscopic realm. A distinct peak in abundance is seen toward the middle Kundan, across the boundary between the regionally recognized Asaphus expansus and Asaphus raniceps trilobite zones, close to the Lenodus variabilis-Yangtzeplacognathus... (More)
Except for the scattered cephalopod conchs that have given the rock type its name, mollusk fossils are relatively rare in the Middle Ordovician 'orthoceratite limestone' of Sweden. However, an interval in the Darnwilian stands out as being unusually rich in various types of mollusks. Throughout southern Sweden, gastropods became relatively abundant close to the Volkhov-Kunda Baltoscandian Stage boundary, and their numbers increase significantly in the Kundan. This increase is most apparent in the microscopic realm. A distinct peak in abundance is seen toward the middle Kundan, across the boundary between the regionally recognized Asaphus expansus and Asaphus raniceps trilobite zones, close to the Lenodus variabilis-Yangtzeplacognathus crassus conodont Zone boundary (Dw1-Dw2 transition). Hyoliths, which are otherwise exceptionally rare, are also more common in these beds, as are putative bivalves. Moreover, macroscopic cephalopod conchs occur in unusually high numbers. Gastropods and other small mollusks become relatively rare again in the upper half of the Kundan, but cephalopods are concentrated in some beds. The mollusk-rich intervals coincide with diverse assemblages and multiple morphotypes were distinguished. Point counting of skeletal grains in thin sections showed that the relative abundance of gastropods fluctuates in a pulse-like (cyclic?) manner throughout the studied succession. The concurrent paleontologic and sedimentologic development suggests a correlation to sea level, and thus that gastropod abundance can be used as a paleobathymetric proxy. Abundance peaks are associated with inferred lowstand intervals. Closely similar abundance patterns throughout southern Sweden suggest that the increase in mollusks was a geographically widespread phenomenon, perhaps even global in extent. (C) 2015 Elsevier B.V. All rights reserved. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
keywords
Darriwilian, Kunda, 'Orthoceratite limestone', Mollusks, Gastropods, Hyoliths, Kinnekulle, Killerod
in
Palaeogeography, Palaeoclimatology, Palaeoecology
volume
440
pages
53 - 65
publisher
Elsevier
external identifiers
  • wos:000366539700005
  • scopus:84942061276
ISSN
1872-616X
DOI
10.1016/j.palaeo.2015.08.018
language
English
LU publication?
yes
id
638e80f4-76ad-4344-a9d0-6dd64b1d0113 (old id 8767502)
date added to LUP
2016-02-22 11:13:45
date last changed
2017-10-08 03:10:57
@article{638e80f4-76ad-4344-a9d0-6dd64b1d0113,
  abstract     = {Except for the scattered cephalopod conchs that have given the rock type its name, mollusk fossils are relatively rare in the Middle Ordovician 'orthoceratite limestone' of Sweden. However, an interval in the Darnwilian stands out as being unusually rich in various types of mollusks. Throughout southern Sweden, gastropods became relatively abundant close to the Volkhov-Kunda Baltoscandian Stage boundary, and their numbers increase significantly in the Kundan. This increase is most apparent in the microscopic realm. A distinct peak in abundance is seen toward the middle Kundan, across the boundary between the regionally recognized Asaphus expansus and Asaphus raniceps trilobite zones, close to the Lenodus variabilis-Yangtzeplacognathus crassus conodont Zone boundary (Dw1-Dw2 transition). Hyoliths, which are otherwise exceptionally rare, are also more common in these beds, as are putative bivalves. Moreover, macroscopic cephalopod conchs occur in unusually high numbers. Gastropods and other small mollusks become relatively rare again in the upper half of the Kundan, but cephalopods are concentrated in some beds. The mollusk-rich intervals coincide with diverse assemblages and multiple morphotypes were distinguished. Point counting of skeletal grains in thin sections showed that the relative abundance of gastropods fluctuates in a pulse-like (cyclic?) manner throughout the studied succession. The concurrent paleontologic and sedimentologic development suggests a correlation to sea level, and thus that gastropod abundance can be used as a paleobathymetric proxy. Abundance peaks are associated with inferred lowstand intervals. Closely similar abundance patterns throughout southern Sweden suggest that the increase in mollusks was a geographically widespread phenomenon, perhaps even global in extent. (C) 2015 Elsevier B.V. All rights reserved.},
  author       = {Lindskog, Anders and Eriksson, Mats and Tell, Carsten and Terfelt, Fredrik and Martin, Ellinor and Ahlberg, Per and Schmitz, Birger and Marone, Federica},
  issn         = {1872-616X},
  keyword      = {Darriwilian,Kunda,'Orthoceratite limestone',Mollusks,Gastropods,Hyoliths,Kinnekulle,Killerod},
  language     = {eng},
  pages        = {53--65},
  publisher    = {Elsevier},
  series       = {Palaeogeography, Palaeoclimatology, Palaeoecology},
  title        = {Mollusk maxima and marine events in the Middle Ordovician of Baltoscandia},
  url          = {http://dx.doi.org/10.1016/j.palaeo.2015.08.018},
  volume       = {440},
  year         = {2015},
}