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| Titel |
Boron isotopes in brachiopods during the end-Permian mass extinction: constraints on pH evolution and seawater chemistry |
| VerfasserIn |
Hana Jurikova, Marcus Gutjahr, Volker Liebetrau, Uwe Brand, Renato Posenato, Claudio Garbelli, Lucia Angiolini, Anton Eisenhauer |
| Konferenz |
EGU General Assembly 2017
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| Medientyp |
Artikel
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| Sprache |
en
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 19 (2017) |
| Datensatznummer |
250147027
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| Publikation (Nr.) |
 EGU/EGU2017-11121.pdf |
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| Zusammenfassung |
| The global biogeochemical cycling of carbon is fundamental for life on Earth with the
ocean playing a key role as the largest and dynamically evolving CO2 reservoir.
The boron isotope composition (commonly expressed in δ11B) of marine calcium
carbonate is considered to be one of the most reliable paleo-pH proxies, potentially
enabling us to reconstruct past ocean pH changes and understand carbon cycle
perturbations along Earth’s geological record (e.g. Foster et al., 2008; Clarkson et al.,
2015). Brachiopods present an advantageous and largely underutilised archive for
Phanerozoic carbon cycle reconstructions considering their high abundance in the
geological record and its origin dating back to the early Cambrian. Moreover, their shell
made of low-magnesium calcite makes these marine calcifiers more resistant to
post-depositional diagenetic alteration of primary chemical signals. We have investigated
the δ11B using MC-ICP-MS (Neptune Plus) and B/Ca and other elemental ratios
(Mg/Ca, Sr/Ca, Al/Ca, Li/Ca, Ba/Ca, Na/Ca and Fe/Ca) using ICP-MS-Quadrupole
(Agilent 7500cx) from the same specimens in pristine brachiopod shells from two
sections from northern Italy during the Late Permian. These sections cover the
δ13C excursion in excess of ∼4 ‰ (Brand et al., 2012) and are associated with
major climate and environmental perturbations that lead to the mass extinction
event at the Permian-Triassic boundary. Particular emphasis will be placed on the
implications of our new paleo-pH estimates on the seawater chemistry during the Late
Permian.
Brand, U., Posenato, R., Came, R., Affek, H., Angiolini, L., Azmy, K. and Farabegoli,
E.: The end-Permian mass extinction: A rapid volcanic CO2 and CH4-climatic
catastrophe, Chemical Geology 323, 121-144, doi:10.1016/j.chemgeo.2012.06.015,
2012.
Clarkson, M.O., Kasemann, S.A., Wood, R.A., Lenton, T.M., Daines, S.J., Richoz, S.,
Ohnemueller, F., Meixner, A., Poulton, S.W. and Tipper, E.T.: Ocean acidification and the
Permo-Triassic mass extinction. Science 348, 229-232, doi: 10.1126/science.aaa0193,
2015.
Foster, G.L.: Seawater pH, pCO2 and [CO32−] variations in the Caribbean Sea over the
last 130 kyr: A boron isotope and B/Ca study of planktic foraminifera. Earth and
Planetary Science Letters 271, 254-266. doi:10.1016/j.epsl.2008.04.015, 2008. |
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