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Skeletal carbonate productivity and phosphogenesis at the lower-middle Cambrian transition of Scania, southern Sweden

Javier Alvaro, J.; Ahlberg, Per LU and Axheimer, Niklas LU (2010) In Geological Magazine 147(1). p.59-76
Abstract
The lower-middle Cambrian transitional interval of Scania is largely represented by condensed limestone beds, lithostratigraphically grouped in the Gislov Formation (1-5.7 m thick), and the Forsemolla and Exsulans Limestone beds (lower part of the Alum Shale Formation, up to 4 in thick). The strata display a combination of skeletal carbonate productivity, episodic nucleation of phosphate hardground nodules, and polyphase reworking recorded on a platform bordering the NW corner of Baltica. The shell accumulations can be subdivided into three deepening-upward parasequences, separated by distinct erosive unconformities. The parasequences correspond biostratigraphically to the Holmia kjerulfi, Ornamentaspis? linnarssoni and Ptlychagnostus... (More)
The lower-middle Cambrian transitional interval of Scania is largely represented by condensed limestone beds, lithostratigraphically grouped in the Gislov Formation (1-5.7 m thick), and the Forsemolla and Exsulans Limestone beds (lower part of the Alum Shale Formation, up to 4 in thick). The strata display a combination of skeletal carbonate productivity, episodic nucleation of phosphate hardground nodules, and polyphase reworking recorded on a platform bordering the NW corner of Baltica. The shell accumulations can be subdivided into three deepening-upward parasequences, separated by distinct erosive unconformities. The parasequences correspond biostratigraphically to the Holmia kjerulfi, Ornamentaspis? linnarssoni and Ptlychagnostus gibbus zones, the latter two generally being separated by a stratigraphic gap that includes the middle Cambrian Acadoparadoxides oelandicus Superzone. Except for the Exsulans Limestone, the carbonates reflect development of a prolific epibenthic biota, dominated by filter-feeding nonreefal chancelloriid-echinoderm-sponge meadows, rich in trilobites and brachiopods, and which were subjected to high-energy conditions. The absence of microbial mats or veneers encrusting the erosive surfaces of these event-concentration low-relief shoal complexes may be related to long hiatal episodes resulting in microboring proliferation. High levels of nutrient supply resulted in high primary productivity, eutrophic conditions, glauconite precipitation, phosphogenesis (in some case microbially mediated) and rnicroendolithic infestation. An early-diagenetic mildly reducing environment is suggested by the presence of authigenic (subsequently reworked) pyrite, which contrasts with the syndepositional normal oxygenated conditions reflected by macroburrowing and the abundance of benthic fossils. (Less)
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author
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Baltica, chemostratigraphy, glauconite, carbonate productivity, apatite
in
Geological Magazine
volume
147
issue
1
pages
59 - 76
publisher
Cambridge University Press
external identifiers
  • wos:000274377000005
  • scopus:77953619605
ISSN
0016-7568
DOI
10.1017/S0016756809990021
language
English
LU publication?
yes
id
aedd3ec6-bc1f-4ffe-9e2e-e4647ee3d691 (old id 1568938)
date added to LUP
2010-03-17 11:25:44
date last changed
2018-05-29 12:14:35
@article{aedd3ec6-bc1f-4ffe-9e2e-e4647ee3d691,
  abstract     = {The lower-middle Cambrian transitional interval of Scania is largely represented by condensed limestone beds, lithostratigraphically grouped in the Gislov Formation (1-5.7 m thick), and the Forsemolla and Exsulans Limestone beds (lower part of the Alum Shale Formation, up to 4 in thick). The strata display a combination of skeletal carbonate productivity, episodic nucleation of phosphate hardground nodules, and polyphase reworking recorded on a platform bordering the NW corner of Baltica. The shell accumulations can be subdivided into three deepening-upward parasequences, separated by distinct erosive unconformities. The parasequences correspond biostratigraphically to the Holmia kjerulfi, Ornamentaspis? linnarssoni and Ptlychagnostus gibbus zones, the latter two generally being separated by a stratigraphic gap that includes the middle Cambrian Acadoparadoxides oelandicus Superzone. Except for the Exsulans Limestone, the carbonates reflect development of a prolific epibenthic biota, dominated by filter-feeding nonreefal chancelloriid-echinoderm-sponge meadows, rich in trilobites and brachiopods, and which were subjected to high-energy conditions. The absence of microbial mats or veneers encrusting the erosive surfaces of these event-concentration low-relief shoal complexes may be related to long hiatal episodes resulting in microboring proliferation. High levels of nutrient supply resulted in high primary productivity, eutrophic conditions, glauconite precipitation, phosphogenesis (in some case microbially mediated) and rnicroendolithic infestation. An early-diagenetic mildly reducing environment is suggested by the presence of authigenic (subsequently reworked) pyrite, which contrasts with the syndepositional normal oxygenated conditions reflected by macroburrowing and the abundance of benthic fossils.},
  author       = {Javier Alvaro, J. and Ahlberg, Per and Axheimer, Niklas},
  issn         = {0016-7568},
  keyword      = {Baltica,chemostratigraphy,glauconite,carbonate productivity,apatite},
  language     = {eng},
  number       = {1},
  pages        = {59--76},
  publisher    = {Cambridge University Press},
  series       = {Geological Magazine},
  title        = {Skeletal carbonate productivity and phosphogenesis at the lower-middle Cambrian transition of Scania, southern Sweden},
  url          = {http://dx.doi.org/10.1017/S0016756809990021},
  volume       = {147},
  year         = {2010},
}