An age-calibrated record of upper Campanian – Maastrichtian climate change in the Boreal Realm

TY - ABST

T1 - An age-calibrated record of upper Campanian – Maastrichtian climate change in the Boreal Realm

AU - Thibault, Nicolas Rudolph

AU - Schovsbo, Niels

AU - Harlou, Rikke

AU - Stemmerik, Lars

AU - Surlyk, Finn

N1 - SAO/NASA ADS Physics Abstract Service

PY - 2011

Y1 - 2011

N2 - The latest Cretaceous climate of the Boreal Realm was recorded through high-resolution bulk carbon- and oxygen-stable isotopes and a nannofossil temperature index (NTI) on the Stevns-1 core (Denmark) which recovered 456 m of upper Campanian to basal Danian chalk with ~100% recovery and an excellent continuity. Carbon isotope stratigraphy and nannofossil biostratigraphy were used to correlate Stevns-1 to two sites that bear an excellent magnetostratigraphic record: DSDP Site 525A and ODP Site 762C. The correlation of d13C trends between the three sites and the use of the recent astronomical calibration of upper Campanian – Maastrichtian magnetochrons (Husson et al., 2011; K-Pg boundary at 66 Ma) led to the establishment of a precise age-model for Stevns-1. The good correlation between bulk d18O and the NTI (R=-0.81) allows the use of oxygen stable isotopes to estimate past variations of sea surface temperatures (SSTs) in the Boreal Realm. Three warming events punctuate the overall cooling trend of the latest Cretaceous: (1) the late Campanian climatic optimum (73.9–71.6 Ma) is characterized by maximum SSTs of 20°C, (2) the mid-Maastrichtian warming (69.7–68 Ma) is characterized by stable SSTs around 17°C and (3) the end-Maastrichtian warming (66.37–66.03) is characterized by increasing SSTs up to 18°C. The two cooling events of the early (71.6–69.7 Ma) and late Maastrichtian (68–66.37 Ma) are both characterized by stable SSTs around 16°C. This Boreal record of SSTs derived from the d18O of bulk nannofossil chalk is in agreement with planktic biotic events of the latest Cretaceous and matches well with climatic trends of intermediate- and deep-waters from other oceanic basins recorded through benthic foraminiferal d18O (Barrera and Savin, 1999). However, most planktic foraminiferal d18O data do not record well the mid- and end-Maastrichtian warmings. This suggests that the influence of changes in seawater pH and depth habitats of Campanian–Maastrichtian planktonic foraminifer species have to be reconsidered before deriving past SSTs from planktic foraminiferal d18O data in this time interval.

AB - The latest Cretaceous climate of the Boreal Realm was recorded through high-resolution bulk carbon- and oxygen-stable isotopes and a nannofossil temperature index (NTI) on the Stevns-1 core (Denmark) which recovered 456 m of upper Campanian to basal Danian chalk with ~100% recovery and an excellent continuity. Carbon isotope stratigraphy and nannofossil biostratigraphy were used to correlate Stevns-1 to two sites that bear an excellent magnetostratigraphic record: DSDP Site 525A and ODP Site 762C. The correlation of d13C trends between the three sites and the use of the recent astronomical calibration of upper Campanian – Maastrichtian magnetochrons (Husson et al., 2011; K-Pg boundary at 66 Ma) led to the establishment of a precise age-model for Stevns-1. The good correlation between bulk d18O and the NTI (R=-0.81) allows the use of oxygen stable isotopes to estimate past variations of sea surface temperatures (SSTs) in the Boreal Realm. Three warming events punctuate the overall cooling trend of the latest Cretaceous: (1) the late Campanian climatic optimum (73.9–71.6 Ma) is characterized by maximum SSTs of 20°C, (2) the mid-Maastrichtian warming (69.7–68 Ma) is characterized by stable SSTs around 17°C and (3) the end-Maastrichtian warming (66.37–66.03) is characterized by increasing SSTs up to 18°C. The two cooling events of the early (71.6–69.7 Ma) and late Maastrichtian (68–66.37 Ma) are both characterized by stable SSTs around 16°C. This Boreal record of SSTs derived from the d18O of bulk nannofossil chalk is in agreement with planktic biotic events of the latest Cretaceous and matches well with climatic trends of intermediate- and deep-waters from other oceanic basins recorded through benthic foraminiferal d18O (Barrera and Savin, 1999). However, most planktic foraminiferal d18O data do not record well the mid- and end-Maastrichtian warmings. This suggests that the influence of changes in seawater pH and depth habitats of Campanian–Maastrichtian planktonic foraminifer species have to be reconsidered before deriving past SSTs from planktic foraminiferal d18O data in this time interval.

M3 - Conference abstract for conference

T2 - AGU Fall meeting 2011

Y2 - 5 December 2011

ER -