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The Calcium Isotope (δ44/40Ca) Record Through Environmental Changes : Insights From the Late Triassic

Kovács, Zsófia LU ; Demangel, Isaline LU orcid ; Baldermann, Andre ; Hippler, Dorothee ; Schmitt, Anne Désirée ; Gangloff, Sophie ; Krystyn, Leopold and Richoz, Sylvain LU (2022) In Geochemistry, Geophysics, Geosystems 23(12).
Abstract

Calcium isotopes (δ44/40Ca) are particularly useful in palaeo-environmental studies due to the key role of carbonate minerals in continental weathering and their formation in seawater. The calcium isotope ratio can provide hints on past changes in the calcium fluxes, environmental shifts, ecological factors and alternatively diagenesis of carbonate rocks. The investigation of the Late Triassic calcium isotope record offers a great opportunity to evaluate such factors in a time interval that witnessed important environmental and ecological turnovers, such as the first appearance of calcareous nannoplankton, ocean acidification and periods of elevated extinction rates. In this study, we present a δ44/40Ca data set... (More)

Calcium isotopes (δ44/40Ca) are particularly useful in palaeo-environmental studies due to the key role of carbonate minerals in continental weathering and their formation in seawater. The calcium isotope ratio can provide hints on past changes in the calcium fluxes, environmental shifts, ecological factors and alternatively diagenesis of carbonate rocks. The investigation of the Late Triassic calcium isotope record offers a great opportunity to evaluate such factors in a time interval that witnessed important environmental and ecological turnovers, such as the first appearance of calcareous nannoplankton, ocean acidification and periods of elevated extinction rates. In this study, we present a δ44/40Ca data set from the upper Norian (Upper Triassic) through the lower Hettangian (Lower Jurassic) interval. The isotope records reveal two globally significant signals: a ∼ 0.20‰ decrease through the early Rhaetian (Upper Triassic) and a small, negative (∼0.14‰) excursion corresponding to the emplacement of the Central Atlantic Magmatic Province, at the end of the Triassic. The possible explanations for these signals are changes in the isotopic ratio of the continental calcium influx to the ocean due to the high chemical weathering rate of carbonates and possibly ocean acidification, respectively. The considerable (∼0.15–0.30‰) offset in δ44/40Ca between study areas is likely the combined result of local differences in lithology and early marine diagenesis. The major evolutionary step represented by the first occurrence of calcareous nannoplankton did not have at this time a determining role on the calcium isotopic signature of the marine carbonates.

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author
; ; ; ; ; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
carbonates, end-Triassic mas extinction, isotope proxy, nannofossils, Rhaetian, Triassic/Jurassic boundary
in
Geochemistry, Geophysics, Geosystems
volume
23
issue
12
article number
e2022GC010405
publisher
American Geophysical Union (AGU)
external identifiers
  • scopus:85145020719
ISSN
1525-2027
DOI
10.1029/2022GC010405
language
English
LU publication?
yes
id
179769f7-6da5-4795-b403-10c422258072
date added to LUP
2023-01-05 10:16:42
date last changed
2024-03-21 17:08:04
@article{179769f7-6da5-4795-b403-10c422258072,
  abstract     = {{<p>Calcium isotopes (δ<sup>44/40</sup>Ca) are particularly useful in palaeo-environmental studies due to the key role of carbonate minerals in continental weathering and their formation in seawater. The calcium isotope ratio can provide hints on past changes in the calcium fluxes, environmental shifts, ecological factors and alternatively diagenesis of carbonate rocks. The investigation of the Late Triassic calcium isotope record offers a great opportunity to evaluate such factors in a time interval that witnessed important environmental and ecological turnovers, such as the first appearance of calcareous nannoplankton, ocean acidification and periods of elevated extinction rates. In this study, we present a δ<sup>44/40</sup>Ca data set from the upper Norian (Upper Triassic) through the lower Hettangian (Lower Jurassic) interval. The isotope records reveal two globally significant signals: a ∼ 0.20‰ decrease through the early Rhaetian (Upper Triassic) and a small, negative (∼0.14‰) excursion corresponding to the emplacement of the Central Atlantic Magmatic Province, at the end of the Triassic. The possible explanations for these signals are changes in the isotopic ratio of the continental calcium influx to the ocean due to the high chemical weathering rate of carbonates and possibly ocean acidification, respectively. The considerable (∼0.15–0.30‰) offset in δ<sup>44/40</sup>Ca between study areas is likely the combined result of local differences in lithology and early marine diagenesis. The major evolutionary step represented by the first occurrence of calcareous nannoplankton did not have at this time a determining role on the calcium isotopic signature of the marine carbonates.</p>}},
  author       = {{Kovács, Zsófia and Demangel, Isaline and Baldermann, Andre and Hippler, Dorothee and Schmitt, Anne Désirée and Gangloff, Sophie and Krystyn, Leopold and Richoz, Sylvain}},
  issn         = {{1525-2027}},
  keywords     = {{carbonates; end-Triassic mas extinction; isotope proxy; nannofossils; Rhaetian; Triassic/Jurassic boundary}},
  language     = {{eng}},
  number       = {{12}},
  publisher    = {{American Geophysical Union (AGU)}},
  series       = {{Geochemistry, Geophysics, Geosystems}},
  title        = {{The Calcium Isotope (δ<sup>44/40</sup>Ca) Record Through Environmental Changes : Insights From the Late Triassic}},
  url          = {{http://dx.doi.org/10.1029/2022GC010405}},
  doi          = {{10.1029/2022GC010405}},
  volume       = {{23}},
  year         = {{2022}},
}