Brachiopod biogeochemistry and isotope stratigraphy from the Rhaetian Eiberg section in Austria: Potentials and limitations

Christoph Korte; Nicolas Rudolph Thibault; Clemens Vinzenz Ullmann; Marie-Emilie Clemence; Wolfgang Mette; Troels K. Olsen; Malgorzata Rizzi; Micha Ruhl

doi:10.1127/njgpa/2017/0651

Brachiopod biogeochemistry and isotope stratigraphy from the Rhaetian Eiberg section in Austria: Potentials and limitations

Christoph Korte, Nicolas Rudolph Thibault, Clemens Vinzenz Ullmann, Marie-Emilie Clemence, Wolfgang Mette, Troels K. Olsen, Malgorzata Rizzi, Micha Ruhl

Geology

7 Citations (Scopus)

Abstract

The end-Triassic is characterized by one of the most severe biotic crises of the entire Phanerozoic, with strong carbon cycle perturbations potentially predating the biotic event. In order to improve and test the chemostratigraphic framework for the Rhaetian Stage, which culminated in the end-Triassic extinction, a total of 675 and 108 carbonate δ¹³C and δ¹⁸O values have been measured from bulk rock carbonate and articulate brachiopod samples from the Rhaetian Eiberg quarry succession (Northern Calcareous Alps, Austria) respectively. Both brachiopod and bulk rock oxygen isotope trends are compatible with a sedimentologically-constrained basinal deepening, culminating in unit 3 of the latest Rhaetian Eiberg Member. Brachiopod calcite δ¹⁸O evolving from -1.4 ‰ to -0.5 ‰ V-PDB in this interval is offset to heavier values than bulk carbonates by circa 0.5 9‰, compatible with biomineralization in deeper water than the calcite composing the bulk rock micrite. Significant metabolic disequilibrium effects on brachiopod carbon isotope ratios are suggested by a clear negative correlation between δ¹³C values and Sr/Ca ratios of the samples. Consequently, chemostratigraphy based on brachiopod Δ¹³C data, especially with regard to short-term events, is limited. High-resolution bulk rock Δ¹³C data show a >1 ‰ increasing trend throughout units 3 and 4 of the Hochalm Member, and first two units of the Eiberg Member reaching values of circa +2.5 %. This trend is reversed by a circa 1 % negative shift across the boundary of units 2 and 3 of the Eiberg Member. This latter negative shift, known as the "Late Rhaetian Event", represents an important chemostratigraphic marker in the Eiberg quarry section, but its superregional significance remains to be confirmed.

Original language	English
Journal	Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen
Volume	284
Issue number	2
Pages (from-to)	117-138
Number of pages	22
ISSN	0077-7749
DOIs	https://doi.org/10.1127/njgpa/2017/0651
Publication status	Published - 2017

Keywords

Brachiopods
Carbon isotopes
Isotope stratigraphy
Metabolic effects
Northern calcareous alps
Rhaetian

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10.1127/njgpa/2017/0651

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Brachiopod biogeochemistry and isotope stratigraphy from the Rhaetian Eiberg section in Austria : Potentials and limitations. / Korte, Christoph ; Thibault, Nicolas Rudolph; Ullmann, Clemens Vinzenz et al.

In: Neues Jahrbuch fur Geologie und Palaontologie - Abhandlungen, Vol. 284, No. 2, 2017, p. 117-138.

Research output: Contribution to journal › Journal article › Research › peer-review

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title = "Brachiopod biogeochemistry and isotope stratigraphy from the Rhaetian Eiberg section in Austria: Potentials and limitations",

abstract = "The end-Triassic is characterized by one of the most severe biotic crises of the entire Phanerozoic, with strong carbon cycle perturbations potentially predating the biotic event. In order to improve and test the chemostratigraphic framework for the Rhaetian Stage, which culminated in the end-Triassic extinction, a total of 675 and 108 carbonate δ13C and δ18O values have been measured from bulk rock carbonate and articulate brachiopod samples from the Rhaetian Eiberg quarry succession (Northern Calcareous Alps, Austria) respectively. Both brachiopod and bulk rock oxygen isotope trends are compatible with a sedimentologically-constrained basinal deepening, culminating in unit 3 of the latest Rhaetian Eiberg Member. Brachiopod calcite δ18O evolving from -1.4 ‰ to -0.5 ‰ V-PDB in this interval is offset to heavier values than bulk carbonates by circa 0.5 9‰, compatible with biomineralization in deeper water than the calcite composing the bulk rock micrite. Significant metabolic disequilibrium effects on brachiopod carbon isotope ratios are suggested by a clear negative correlation between δ13C values and Sr/Ca ratios of the samples. Consequently, chemostratigraphy based on brachiopod Δ13C data, especially with regard to short-term events, is limited. High-resolution bulk rock Δ13C data show a >1 ‰ increasing trend throughout units 3 and 4 of the Hochalm Member, and first two units of the Eiberg Member reaching values of circa +2.5 %. This trend is reversed by a circa 1 % negative shift across the boundary of units 2 and 3 of the Eiberg Member. This latter negative shift, known as the {"}Late Rhaetian Event{"}, represents an important chemostratigraphic marker in the Eiberg quarry section, but its superregional significance remains to be confirmed.",

keywords = "Brachiopods, Carbon isotopes, Isotope stratigraphy, Metabolic effects, Northern calcareous alps, Rhaetian",

author = "Christoph Korte and Thibault, {Nicolas Rudolph} and Ullmann, {Clemens Vinzenz} and Marie-Emilie Clemence and Wolfgang Mette and Olsen, {Troels K.} and Malgorzata Rizzi and Micha Ruhl",

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T1 - Brachiopod biogeochemistry and isotope stratigraphy from the Rhaetian Eiberg section in Austria

T2 - Potentials and limitations

AU - Korte, Christoph

AU - Thibault, Nicolas Rudolph

AU - Ullmann, Clemens Vinzenz

AU - Clemence, Marie-Emilie

AU - Mette, Wolfgang

AU - Olsen, Troels K.

AU - Rizzi, Malgorzata

AU - Ruhl, Micha

PY - 2017

Y1 - 2017

N2 - The end-Triassic is characterized by one of the most severe biotic crises of the entire Phanerozoic, with strong carbon cycle perturbations potentially predating the biotic event. In order to improve and test the chemostratigraphic framework for the Rhaetian Stage, which culminated in the end-Triassic extinction, a total of 675 and 108 carbonate δ13C and δ18O values have been measured from bulk rock carbonate and articulate brachiopod samples from the Rhaetian Eiberg quarry succession (Northern Calcareous Alps, Austria) respectively. Both brachiopod and bulk rock oxygen isotope trends are compatible with a sedimentologically-constrained basinal deepening, culminating in unit 3 of the latest Rhaetian Eiberg Member. Brachiopod calcite δ18O evolving from -1.4 ‰ to -0.5 ‰ V-PDB in this interval is offset to heavier values than bulk carbonates by circa 0.5 9‰, compatible with biomineralization in deeper water than the calcite composing the bulk rock micrite. Significant metabolic disequilibrium effects on brachiopod carbon isotope ratios are suggested by a clear negative correlation between δ13C values and Sr/Ca ratios of the samples. Consequently, chemostratigraphy based on brachiopod Δ13C data, especially with regard to short-term events, is limited. High-resolution bulk rock Δ13C data show a >1 ‰ increasing trend throughout units 3 and 4 of the Hochalm Member, and first two units of the Eiberg Member reaching values of circa +2.5 %. This trend is reversed by a circa 1 % negative shift across the boundary of units 2 and 3 of the Eiberg Member. This latter negative shift, known as the "Late Rhaetian Event", represents an important chemostratigraphic marker in the Eiberg quarry section, but its superregional significance remains to be confirmed.

AB - The end-Triassic is characterized by one of the most severe biotic crises of the entire Phanerozoic, with strong carbon cycle perturbations potentially predating the biotic event. In order to improve and test the chemostratigraphic framework for the Rhaetian Stage, which culminated in the end-Triassic extinction, a total of 675 and 108 carbonate δ13C and δ18O values have been measured from bulk rock carbonate and articulate brachiopod samples from the Rhaetian Eiberg quarry succession (Northern Calcareous Alps, Austria) respectively. Both brachiopod and bulk rock oxygen isotope trends are compatible with a sedimentologically-constrained basinal deepening, culminating in unit 3 of the latest Rhaetian Eiberg Member. Brachiopod calcite δ18O evolving from -1.4 ‰ to -0.5 ‰ V-PDB in this interval is offset to heavier values than bulk carbonates by circa 0.5 9‰, compatible with biomineralization in deeper water than the calcite composing the bulk rock micrite. Significant metabolic disequilibrium effects on brachiopod carbon isotope ratios are suggested by a clear negative correlation between δ13C values and Sr/Ca ratios of the samples. Consequently, chemostratigraphy based on brachiopod Δ13C data, especially with regard to short-term events, is limited. High-resolution bulk rock Δ13C data show a >1 ‰ increasing trend throughout units 3 and 4 of the Hochalm Member, and first two units of the Eiberg Member reaching values of circa +2.5 %. This trend is reversed by a circa 1 % negative shift across the boundary of units 2 and 3 of the Eiberg Member. This latter negative shift, known as the "Late Rhaetian Event", represents an important chemostratigraphic marker in the Eiberg quarry section, but its superregional significance remains to be confirmed.

KW - Brachiopods

KW - Carbon isotopes

KW - Isotope stratigraphy

KW - Metabolic effects

KW - Northern calcareous alps

KW - Rhaetian

U2 - 10.1127/njgpa/2017/0651

DO - 10.1127/njgpa/2017/0651

M3 - Journal article

AN - SCOPUS:85019145526

SN - 0077-7749

VL - 284

SP - 117

EP - 138

JO - Neues Jahrbuch für Geologie und Paläontologie

JF - Neues Jahrbuch für Geologie und Paläontologie

IS - 2

ER -

Brachiopod biogeochemistry and isotope stratigraphy from the Rhaetian Eiberg section in Austria: Potentials and limitations

Abstract

Keywords

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