High northern palaeolatitude Jurassic-Cretaceous palaeotemperature variation: new data from Kong Karls Land, Svalbard

The traditional view of warm equable global climates in the Mesozoic with weakly developed latitudinal temperature gradients has been challenged by several recent studies. However, reliable high palaeolatitude palaeotemperature data is still rare. In this study palaeotemperature data, based on oxygen stable isotope palaeothermometry of well preserved mid Jurassic to Lower Cretaceous belemnites from Kong Karls Land, Svalbard, are presented. These data show cool high latitude marine isotopic palaeotemperatures for endemic species during the Lower to mid Valanginian (7.7°C), which may be compatible with the formation of high latitude ice. Middle Bathonian to Kimmeridgian samples give warmer isotopic palaeotemperatures (9.4°C), whilst samples from the Aalenian to Bajocian give isotopic palaeotemperatures which are warmer still (12.7°C). Comparison of the Callovian temperatures with those from a mid-latitude location shows them to be warmer than would be expected if previous latitudinal temperature gradients are correct. This may be due to the ameliorating effect of oceanic heat transport pole-wards from the Panthalassa Ocean via the South Anyui Ocean.