The Calcium Isotope (δ^44/40Ca) Record Through Environmental Changes

Autor(en)

Zsófia Kovács, Isaline Demangel, Andre Baldermann, Dorothee Hippler,  Anne-Désirée Schmitt, Sophie Gangloff, Leopold Krystyn, Sylvain Richoz

Abstrakt

Calcium isotopes (δ 44/40 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 44/40 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 44/40 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.

Organisation(en)

Institut für Paläontologie

Externe Organisation(en)

Université de Strasbourg, Lund University, Karl-Franzens-Universität Graz, Technische Universität Graz

Journal

Geochemistry, Geophysics, Geosystems

Band

23

Seiten

1-16

Anzahl der Seiten

16

ISSN

1525-2027

DOI

https://doi.org/10.1029/2022GC010405

Publikationsdatum

12-2022

Peer-reviewed

Ja

ÖFOS 2012

105118 Paläontologie

Schlagwörter

ASJC Scopus Sachgebiete

Geochemistry and Petrology, Geophysics

Sustainable Development Goals

SDG 14 – Leben unter Wasser

Link zum Portal

https://ucrisportal.univie.ac.at/de/publications/f2248fdf-2e69-44ec-a2c7-b07d3204ff6c