GRGC: Coll Resc: Climatic & Environmental Responses of the Western Equatorial Pacific to Long- and Short-Term Global Warming in the Late Paleocene and Early Eocene

9405784 Bralower本项目旨在测试几个关于气候动力学以及海洋生物对古新世晚期和始新世早期(即跨越古新世/始新世(P/E)界线)逐渐和突然的全球变暖的响应的假说。我们在865站点的两个洞，即赤道太平洋西部的Allison Guyot顶部，收集了跨越这一边界的紧密间隔的沉积物样本。我们的主要目标是建立晚古新世至中始新世热带海洋表面温度和温跃层结构的变化、碳同位素垂直分布、净生产力、底水氧化还原条件(由底栖有孔虫记录)以及这些变化对微生物进化的影响。为此，我们将以高分辨率重建：1)几种浮游(表层和深层)和底栖有孔虫的碳和氧同位素记录，2)定量的浮游和底栖有孔虫组合记录，3)定量的纳米化石组合记录，4)综合的化学生物地层学记录。我们的总体意图是更好地了解全球快速变暖期间热带海洋的环境动态。我们全面的多参数数据集将整合到现有的中高纬度数据集中，缓解热带太平洋数据的匮乏，并帮助定义全球气候重建和建模的边界条件。我们将调查过去9000万年来最大的全球碳循环扰动的生物和化学后果，以及它对热带气候的影响。通过定义热带海洋在古新世/始新世边界对全球快速变暖的物理、化学和生物响应，我们可以检验与热带海温稳定性有关的假设，并解决在模拟早期始新世气候时的悖论：高纬度变暖(需要从低到高纬度的高热量输送)，在低温度梯度和低总风速(因此没有高热量输送的机制)。

9405784 Bralower This project is designed to test several hypotheses regarding climate dynamics of, and marine biotic response to, gradual and abrupt global warming in the late Paleocene and early Eocene (ie., across the Paleocene/Eocene (P/E) boundary). We have collected closely spaced sediment samples from across this boundary at two holes of site 865, atop Allison Guyot in the western equatorial Pacific Ocean. Our primary objectives are to establish late Paleocene through middle Eocene changes in tropical sea surface temperature and thermocline structure, vertical carbon isotope distributions, net productivity, bottom water redox conditions (as recorded by benthic foraminifera), and the effect of these changes on micro-organism evolution. To this end, we will reconstruct at high resolution: 1) carbon and oxygen isotope records from several species of planktonic (surface and deep dwelling) and benthic foraminifera, 2) quantitative planktonic and benthic foraminiferal assemblage records, 3) quantitative nannofossil assemblage records, and 4) an integrated chemobiostratigraphic record. Our overall intent is to develop a better understanding of the environmental dynamics of the tropical oceans during periods of rapid global warming. Our comprehensive, multi-parameter data set will be integrated in existing data sets from mid and high latitudes, alleviate the lack of data from the tropical Pacific, and help define the boundary conditions for global climate reconstructions and modeling. We will investigate the biological and chemical consequences of the largest disturbance of the global carbon cycle in the last 90 million years, and its affect on tropical climate. By defining the physical, chemical, and biological responses of the tropical ocean to the rapid global warming at the Paleocene/Eocene boundary, we can test hypotheses relating to the stability of tropical SST, and address the paradox in modeling early Eocene climate: warm high latitudes (requiring high heat transport from the low to the high latitudes), at low temperature gradients and low overall wind speeds (thus no mechanism for the high heat transport).