Late Cretaceous seasonal ocean variability from the Arctic

摘要: Palaeoclimate records for the Arctic Ocean and its environs in late Cretaceous 'greenhouse' era, 65–99 million years ago, are sparse. Using electron microscope techniques applied to cores of shallow buried laminated sediments from Alpha ridge Ocean, Davies et al. have obtained a seasonally resolved sediment record that permits reconstruction annual cycle marine productivity flux sediment. They find period was characterized by seasonal diatom stratified ocean with possible winter sea ice cover. Although modern is regarded as barometer global change an amplifier warming, little known about state greenhouse Late epoch (65–99 ago). Here, sedimentary presented; evidence suggests The warming1 therefore past critical palaeoclimate reconstruction. Little (65–99 million ago), yet such times may yield important clues behaviour near-future warmer climates. Here we present Ocean. This palaeo-sediment trap provides new insight into workings biological carbon pump. Seasonal primary production dominated algae but not related upwelling previously hypothesized2. Rather, occurred within water column, involving specially adapted species blooms resembling those North Pacific subtropical gyre3, or indicated Mediterranean sapropels4. With increased CO2 levels warming currently driving stratification ocean5, this style become more widespread. Our testify ice-free summer, thin accumulations terrigenous ooze consistent presence intermittent winter, supporting wide body low temperatures Ocean6,7,8, rather than recent suggestions 15 °C mean temperature at time9.