Bentho-planktonic evidence from the Austrian Alps for a decline in sea-surface carbonate production at the end of the Triassic |
| |
Authors: | Marie-Emilie Clémence Silvia Gardin Annachiara Bartolini Guillaume Paris Valérie Beaumont Jean Guex |
| |
Institution: | 1. Université de Paris VI, CR2P “Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements” CNRS UMR 7207, 4 place Jussieu, 75252, Paris Cedex 05, France 2. Muséum National d’Histoire Naturelle, CR2P “Centre de Recherche sur la Paléobiodiversité et les Paléoenvironnements” CNRS UMR 7207, 8 rue Buffon, 75231, Paris Cedex 05, France 3. Département de Géologie et Géochimie, IFP, 92852, Rueil Malmaison Cedex, France 4. IGP, Quartier UNIL-Dorigny, Batiment Anthropole 3182, 1015, Lausanne, Switzerland
|
| |
Abstract: | A high-resolution micropalaeontological study, combined with geochemical and sedimentological analyses was performed on the
Tiefengraben, Schlossgraben and Eiberg sections (Austrian Alps) in order to characterize sea-surface carbonate production
during the end-Triassic crisis. At the end-Rhaetian, the dominant calcareous nannofossil Prinsiosphaera triassica shows a decrease in abundance and size and this is correlated with a increase in δ18O and a gradual decline in δ13Ccarb values. Simultaneously, benthic foraminiferal assemblages show a decrease in diversity and abundance of calcareous taxa and
a dominance of infaunal agglutinated taxa. The smaller size of calcareous nannofossils disturbed the vertical export balance
of the biological carbon pump towards the sea-bottom, resulting in changes in feeding strategies within the benthic foraminiferal
assemblages from deposit feeders to detritus feeders and bacterial scavengers. These micropalaeontological data combined with
geochemical proxies suggest that changes in seawater chemistry and/or cooling episodes might have occurred in the latest Triassic,
leading to a marked decrease of carbonate production. This in turn culminated in the quasi-absence of calcareous nannofossils
and benthic foraminifers in the latest Triassic. The aftermath (latest Triassic earliest Jurassic) was characterised by abundance
peaks of “disaster” epifaunal agglutinated foraminifera Trochammina on the sea-floor. Central Atlantic Magmatic Province (CAMP) paroxysmal activity, superimposed on a major worldwide regressive
phase, is assumed to be responsible for a deterioration in marine palaeoenvironments. CAMP sulfuric emissions might have been
the trigger for cooling episodes and seawater acidification leading to disturbance of the surface carbonate production at
the very end-Triassic. |
| |
Keywords: | |
本文献已被 SpringerLink 等数据库收录! |
|