High Resolution Study of Major Middle-Late Cenozoic Paleoceanographic Changes in the South and Equatorial Pacific

在地球历史的大部分时间里，气候是温暖和相对均匀的。向现在的冰期和间冰期的变化并不是统一进行的。它们的特点是离散和突然的冷凝，这与海洋环流的变化有关。大约3800万年前有一次显著的变化，随后是1400万年前、600万年前和300万年前的冷却。这些间隔由稳定性高得多的时间分隔，尽管已经定义了波动。自三年前提交上一份提案以来，已有大量来自太平洋的晚渐新世至新近纪高质量水力活塞岩心沉积序列可供详细分析，其中一些地点是在DSDP-iPod第90和89段期间钻探的；它们形成了从赤道延伸到南太平洋亚南极的前所未有的高质量纬向断面。这些沉积剖面具有重要的古海洋学价值。该项目希望进一步扩大对中低纬度地区中、晚新生代沉积层序的古海洋学研究，并与其他地方发现的事件进行对比；主要目标是：继续进行古海洋学历史的时间序列分析；研究中新世末期、中新世中晚期和上新世晚期的事件；确定保存在浮游/底栖有孔虫中的主要数量变化。

During much of the earth's history the climate was warm and relatively uniform. The change to the present glacial and interglacial periods did not proceed uniformly. These were marked by discrete and sudden coolings which are linked with changes in oceanic circulation. There was a prominent change about 38 million years ago, followed by subsequent coolings 14 million years ago, 6 million years ago, and 3 million years ago. These intervals are separated by times of much higher stability although fluctuations have been defined. Since the last proposal was submitted three years ago, a number of high quality hydraulic piston cored sedimentary sequences of late Oligocene through Neogene age from the Pacific have become available for detailed analysis, some of these sites were drilled during DSDP-IPOD Legs 90 and 89; they form a latitudinal transect of unprecedented quality extending from the equator to the subantarctic in the South Pacific. These sediment sections are of great paleoceanographic value. This project wants to further extend paleoceanographic studies of middle and late Cenozoic sedimentary sequences in middle and low latitudes and to correlate with events found elsewhere; the major objectives are: to continue time-series analysis of paleoceanographic history; to examine events during the terminal Miocene, the middle and late Pliocene; to define the main quantitative changes as they are preserved in planktonic/benthonic foraminifera.