CASADIO Silvio Alberto
Latest Cretaceous climatic and environmental change in the South Atlantic region
WOELDERS, L.; VELLEKOOP, J.; KROON, D.; SMIT, J; CASADÍO, S.; PRAMPANO, M; DINARÈS-TURELL, J.; PETERSE, F.; SLUIJS, A.; LENAERTS, J.T.M. ; SPEIJER, R.P.
AMER GEOPHYSICAL UNION
There is continuing debate about the contribution of latest Maastrichtian climate changes, possibly caused by Deccan volcanism, to the Cretaceous-Paleogene (K-Pg) boundary mass extinction (~66 Ma). Here we present an astronomically tuned K-Pg boundary record of δ18O-based Sea Surface Temperature (SST) record from Ocean Drilling Program Site 1262 and a K-Pg boundary TEX86-based SST record from the Bajada del Jagüel (BJ) site in the Neuquén Basin (Argentina). The combination of these inferred temperature records with foraminiferal and organic-walled dinoflagellate cyst (dinocyst) data from BJ allows us to reconstruct environmental changes across this time interval. Our results show that latest Maastrichtian warming of ~2.5-4°C started gradually around 66.7 Ma, culminating in the interval between 450 to 150 kyr before the K-Pg boundary. Benthic foraminiferal and dinocyst assemblage changes indicate that this warming resulted in more humid climate conditions in the Neuquén Basin, causing enhanced runoff and stratification of the water column. A subsequent cooling towards the K-Pg boundary induced again a drier climate in the basin, resulting in reduced salinity stratification.. We conclude that late Maastrichtian climate change caused distinct environmental perturbations in the Neuquén Basin, although it remains uncertain to which extent these climatological changes contributed directly to the K-Pg boundary mass extinction. We speculate that the mechanism resulting in the environmental changes in the Neuquén Basin might have also occurred at other large continents characterized by seasonal, monsoon-like precipitation pulses at mid-latitudes driven by land-sea temperature contrasts and by thermally driven circulation cells.