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High-resolution δ13Corg chemostratigraphy links the Decorah impact structure and Winneshiek Konservat-Lagerstätte to the Darriwilian (Middle Ordovician) global peak influx of meteorites

Bergstrom, Stig M.; Schmitz, Birger LU ; Liu, Huaibao P.; Terfelt, Fredrik LU and Mckay, Robert M. (2018) In Lethaia 51(4). p.504-512
Abstract

The precise age of the Winneshiek Shale, a recently discovered Konservat-Lagerstätte located in a very unusual depositional setting inside the Decorah impact structure, has remained uncertain in the absence of biostratigraphically highly diagnostic fossils. This chemostratigraphical study, based on δ13Corg data from 36 drill core samples through the shale, shows that the age ranges from the upper part of a small unnamed δ13C excursion in the Dw1 Stage Slice of the Darriwilian Global Stage to the lower part of the MDICE excursion in Stage Slice Dw2 of the same stage. This Dw1-Dw2 interval has an isotopic age of ~464-467 Ma. The gradational contact between the Winneshiek Shale and the underlying, rapidly... (More)

The precise age of the Winneshiek Shale, a recently discovered Konservat-Lagerstätte located in a very unusual depositional setting inside the Decorah impact structure, has remained uncertain in the absence of biostratigraphically highly diagnostic fossils. This chemostratigraphical study, based on δ13Corg data from 36 drill core samples through the shale, shows that the age ranges from the upper part of a small unnamed δ13C excursion in the Dw1 Stage Slice of the Darriwilian Global Stage to the lower part of the MDICE excursion in Stage Slice Dw2 of the same stage. This Dw1-Dw2 interval has an isotopic age of ~464-467 Ma. The gradational contact between the Winneshiek Shale and the underlying, rapidly deposited, impact breccia indicates minimal time difference between the impact event and the Winneshiek Shale. New age data show that the Decorah impact event was coeval with the early Darriwilian abnormally high influx of micrometeorites and meteorites recorded in sections in Baltoscandia, Russia and China and that the Decorah crater can be included among the unusually large number of meteorite craters formed during Middle and early Late Ordovician time. As is commonly the case in black shale deposits, the partly uniquely preserved Winneshiek Shale crater fauna is impoverished taxonomically and adds numerically relatively little to the conspicuous and much discussed Darriwilian global biodiversification increase.

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author
organization
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type
Contribution to journal
publication status
published
subject
keywords
Chemostratigraphy, Darriwilian, Decorah impact structure, Ordovician, The Great Ordovician Meteorite Shower, Winneshiek Konservat-Lagerstätte
in
Lethaia
volume
51
issue
4
pages
504 - 512
publisher
Taylor & Francis
external identifiers
  • scopus:85046792894
ISSN
0024-1164
DOI
10.1111/let.12269
language
English
LU publication?
yes
id
ef877c10-99c5-4c1a-80c2-4cbfc7b01bb2
date added to LUP
2018-05-25 14:36:25
date last changed
2019-04-10 04:09:02
@article{ef877c10-99c5-4c1a-80c2-4cbfc7b01bb2,
  abstract     = {<p>The precise age of the Winneshiek Shale, a recently discovered Konservat-Lagerstätte located in a very unusual depositional setting inside the Decorah impact structure, has remained uncertain in the absence of biostratigraphically highly diagnostic fossils. This chemostratigraphical study, based on δ<sup>13</sup>C<sub>org</sub> data from 36 drill core samples through the shale, shows that the age ranges from the upper part of a small unnamed δ<sup>13</sup>C excursion in the Dw1 Stage Slice of the Darriwilian Global Stage to the lower part of the MDICE excursion in Stage Slice Dw2 of the same stage. This Dw1-Dw2 interval has an isotopic age of ~464-467 Ma. The gradational contact between the Winneshiek Shale and the underlying, rapidly deposited, impact breccia indicates minimal time difference between the impact event and the Winneshiek Shale. New age data show that the Decorah impact event was coeval with the early Darriwilian abnormally high influx of micrometeorites and meteorites recorded in sections in Baltoscandia, Russia and China and that the Decorah crater can be included among the unusually large number of meteorite craters formed during Middle and early Late Ordovician time. As is commonly the case in black shale deposits, the partly uniquely preserved Winneshiek Shale crater fauna is impoverished taxonomically and adds numerically relatively little to the conspicuous and much discussed Darriwilian global biodiversification increase.</p>},
  author       = {Bergstrom, Stig M. and Schmitz, Birger and Liu, Huaibao P. and Terfelt, Fredrik and Mckay, Robert M.},
  issn         = {0024-1164},
  keyword      = {Chemostratigraphy,Darriwilian,Decorah impact structure,Ordovician,The Great Ordovician Meteorite Shower,Winneshiek Konservat-Lagerstätte},
  language     = {eng},
  month        = {01},
  number       = {4},
  pages        = {504--512},
  publisher    = {Taylor & Francis},
  series       = {Lethaia},
  title        = {High-resolution δ<sup>13</sup>C<sub>org</sub> chemostratigraphy links the Decorah impact structure and Winneshiek Konservat-Lagerstätte to the Darriwilian (Middle Ordovician) global peak influx of meteorites},
  url          = {http://dx.doi.org/10.1111/let.12269},
  volume       = {51},
  year         = {2018},
}