Cretaceous palaeoclimate and palaeoceanography in the Pacific Ocean

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For much of Earth history atmospheric CO2 levels and average global temperatures are thought to have been much higher than present. These periods of time are known as 'greenhouse' climates. The Cretaceous (145 to 65 million years ago) was an extreme end-member of a greenhouse climate. Then the climate was much warmer than it is today; there was little or no polar ice and sea-levels were high. In polar areas, like Alaska and Antarctica, which are cold today, dinosaurs, crocodiles and tropical plants flourished. However, what the actual temperature of the ocean was during the Cretaceous is still much debated. Modern techniques allow us to use the chemical remains of bacteria found in ancient sediments to estimate what sea-surface temperatures were like in the past. To date, much of the work using this technique has focused on the Atlantic Ocean. However, during the Cretaceous the Pacific Ocean was the largest marine environment and thus estimates of temperature from there are most likely to represent 'global' conditions. Furthermore our knowledge of the environmental history of the Pacific Ocean during the Cretaceous is poor due to the small number of localities that have been sampled by deep-sea drilling. This project will determine Cretaceous sea-surface temperatures and environmental conditions by using samples from new sediment cores that will be drilled during Expedition 324 of the Integrated Ocean Drilling Program to Shatsky Rise in the northwest Pacific. By quantifying sea-surafce temperatures and oceanic environments in the Pacific Ocean during the Early Cretaceous we will be able to determine how warm the greenhouse climate was; whether temperatures varied between different ocean basins; and establish how oceanographic conditions varied through time.