Fish tooth δ18O revising Late Cretaceous meridional upper ocean water temperature gradients

Abstract

The oxygen isotope composition of fossil fish teeth, a paleoupper ocean temperature proxy exceptionally resistant to diagenetic alteration, provides new insight on the evolution of the low-to middlelatitude thermal gradient between the middle Cretaceous climatic optimum and the cooler latest Cretaceous period. The new middle Cretaceous low to middle latitude thermal gradient agrees with that previously inferred from planktonic foraminifera 8 ls O recovered from Deep Sea Drilling Project and Ocean Drilling Program drilling sites, although the isotopic temperatures derived from 8 ls O offish teeth are uniformly higher by -3-4 °C. In contrast, our new latest Cretaceous thermal gradient is markedly steeper than those previously published for this period. Fish tooth 8 ls O data demonstrate that low-to middle-latitude thermal gradients of the middle Cretaceous climatic optimum and of the cooler latest Cretaceous are similar to the modern one, despite a cooling of 7 °C between the two periods. Our new results imply that no drastic changes in meridional heat transport are required to explain the Late Cretaceous climate. Based on climate models, such a cooling without any change in the low to middle latitude thermal gradient supports an atmospheric C0 2 decrease as the primary driver of the climatic evolution recorded during the Late Cretaceous.

Exploring the climatic impact of the continental vegetation on the Mezosoic atmospheric CO<sub>2</sub> and climate history

“…The Maastrichtian records a cooling that settles back the temperature to the mean base level of the Early Cretaceous. Fish teeth δ 18 O data gathered by Puceat et al (2007) have already demonstrated that marine temperatures of the climatic optimum of the middle Cretaceous and of the cooler latest Cretaceous were separated by 7 • C on average. Amplitude of the cooling estimated here is of the same order.…”

Tectonic-driven climate change and the diversification of angiosperms

“…1,000 ppm for these periods. For the Cretaceous, comparisons of our simulations with oceanic latitudinal thermal gradients reconstructed from paleoceanographic data (17)(18)(19)(20)(21)(22)(23)(24)(25) show that pCO 2 of 2,240 ppm is required to produce sea surface temperatures comparable with data for the Aptian and Cenomanian, whereas for the Maastrichian, data-derived sea surface temperature gradient is better reproduced at 1,120 ppm (Fig. S2).…”

A GCM Study on Effects of Continental Drift on Tropical Climate at the Early and Late Cretaceous

“…The most recent studies (e.g., Puceat et al 2007), in which the oxygen isotope content of fossil fish teeth was used, show that the low-to-mid-latitude SST gradients in the Cretaceous are very similar to the present-day gradients. The results obtained by Amiot et al (2004) are very similar to those reported by Puceat et al (2007), although the reconstructed temperatures in the study conducte by Amiot et al are the mean air temperatures in coastal lowlands.…”