TY - JOUR
T1 - The end-Cretaceous in the southwestern Tethys (Elles, Tunisia)
T2 - orbital calibration of paleoenvironmental events before the mass extinction
AU - Thibault, Nicolas Rudolph
AU - Galbrun, Bruno
AU - Gardin, Silvia
AU - Minoletti, Fabrice
AU - Le Callonnec, Laurence
PY - 2016
Y1 - 2016
N2 - An integrated study of magnetic mass susceptibility (MS), bulk stable isotopes and calcareous nannofossil paleoecological changes is undertaken on the late Maastrichtian of the Elles section, Tunisia, spanning the last ca. 1 Myr of the Cretaceous. A cyclostratigraphic analysis reveals the presence of Milankovitch frequencies and is used for proposal of two distinct orbital age models and to provide ages of important stratigraphic horizons, relative to the age of the Cretaceous–Paleogene boundary (K–PgB). Principal component analysis (PCA) performed on the nannofossil assemblage reveal two main factors, PCA1, mostly representing fluctuations of D. rotatorius, P. stoveri, Lithraphidites spp., Retecapsa spp., Staurolithites spp., Micula spp., and PCA2, mostly representing fluctuations of A. regularis, C. ehrenbergii, Micula spp., Rhagodiscus spp., W. barnesiae and Zeugrhabdotus spp. Variations in PCA1 and PCA2 match changes in bulk δ13C and δ18O, respectively, and suggest changes in surface-water fertility and temperatures and associated stress. The variations in abundances of high-latitude taxa and the warm-water species Micula murus and in bulk δ18O delineate fast changes in sea-surface paleotemperatures. As in many other sites, an end-Maastrichtian greenhouse warming is highlighted, followed by a short cooling and an additional warm pulse in the last 30 kyr of the Maastrichtian which has rarely been documented so far. Orbital tuning of the delineated climatic events is proposed following the two different age models. Calcareous nannofossil assemblages highlight a decrease in surface-water nutriency, but their species richness remains high through the latest Maastrichtian, indicating, in Tunisia, a weak impact of Deccan volcanism on calcareous nannoplankton diversity before the mass extinction.
AB - An integrated study of magnetic mass susceptibility (MS), bulk stable isotopes and calcareous nannofossil paleoecological changes is undertaken on the late Maastrichtian of the Elles section, Tunisia, spanning the last ca. 1 Myr of the Cretaceous. A cyclostratigraphic analysis reveals the presence of Milankovitch frequencies and is used for proposal of two distinct orbital age models and to provide ages of important stratigraphic horizons, relative to the age of the Cretaceous–Paleogene boundary (K–PgB). Principal component analysis (PCA) performed on the nannofossil assemblage reveal two main factors, PCA1, mostly representing fluctuations of D. rotatorius, P. stoveri, Lithraphidites spp., Retecapsa spp., Staurolithites spp., Micula spp., and PCA2, mostly representing fluctuations of A. regularis, C. ehrenbergii, Micula spp., Rhagodiscus spp., W. barnesiae and Zeugrhabdotus spp. Variations in PCA1 and PCA2 match changes in bulk δ13C and δ18O, respectively, and suggest changes in surface-water fertility and temperatures and associated stress. The variations in abundances of high-latitude taxa and the warm-water species Micula murus and in bulk δ18O delineate fast changes in sea-surface paleotemperatures. As in many other sites, an end-Maastrichtian greenhouse warming is highlighted, followed by a short cooling and an additional warm pulse in the last 30 kyr of the Maastrichtian which has rarely been documented so far. Orbital tuning of the delineated climatic events is proposed following the two different age models. Calcareous nannofossil assemblages highlight a decrease in surface-water nutriency, but their species richness remains high through the latest Maastrichtian, indicating, in Tunisia, a weak impact of Deccan volcanism on calcareous nannoplankton diversity before the mass extinction.
KW - Calcareous nannofossils
KW - Cyclostratigraphy
KW - Late Maastrichtian
KW - Paleoecology
KW - Stable isotopes
U2 - 10.1007/s00531-015-1192-0
DO - 10.1007/s00531-015-1192-0
M3 - Journal article
AN - SCOPUS:84929688382
SN - 1437-3254
VL - 105
SP - 771
EP - 795
JO - International Journal of Earth Sciences
JF - International Journal of Earth Sciences
IS - 3
ER -