Cretaceous palaeoclimate and palaeoceanography in the Pacific Ocean

在地球历史的大部分时间里，大气中的二氧化碳含量和全球平均气温被认为比现在高得多。这段时间被称为“温室”气候。白垩纪（1.45亿至6500万年前）是温室气候的极端终端成员。那时的气候比现在温暖得多;极地很少或根本没有冰，海平面很高。在极地地区，如阿拉斯加和南极洲，今天很冷，恐龙，鳄鱼和热带植物蓬勃发展。然而，白垩纪海洋的实际温度仍然存在很大争议。现代技术使我们能够利用在古代沉积物中发现的细菌化学残留物来估计过去的海面温度。迄今为止，使用这种技术的大部分工作都集中在大西洋上。然而，在白垩纪，太平洋是最大的海洋环境，因此对那里温度的估计最有可能代表“全球”条件。此外，我们对太平洋白垩纪环境历史的了解很少，因为深海钻探取样的地点很少。该项目将利用综合大洋钻探计划第324次考察西北太平洋沙茨基海隆期间将钻探的新沉积物岩心样本，确定白垩纪海面温度和环境条件。通过量化早白垩世太平洋的海面温度和海洋环境，我们将能够确定温室气候有多温暖;不同海洋盆地之间的温度是否不同;并确定海洋条件如何随时间变化。

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.