Cenozoic oxygen isotopic values for benthic foraminifera from DSDP and ODP low and high latitude marine sediment cores@en

The climate during the Cenozoic era changed in several steps from ice-free poles and warm conditions to ice-covered poles and cold conditions. Since the 1950s, a body of information on ice volume and temperature changes has been built up predominantly on the basis of measurements of the oxygen isotopic composition of shells of benthic foraminifera collected from marine sediment cores. The statistical methodology of time series analysis has also evolved, allowing more information to be extracted from these records. Here we provide a comprehensive view of Cenozoic climate evolution by means of a coherent and systematic application of time series analytical tools to each record from a compilation spanning the interval from 4 to 61 Myr ago. We quantitatively describe several prominent features of the oxygen isotope record, taking into account the various sources of uncertainty (including measurement, proxy noise, and dating errors). The estimated transition times and amplitudes allow us to assess causal climatological-tectonic influences on the following known features of the Cenozoic oxygen isotopic record: Paleocene-Eocene Thermal Maximum, Eocene-Oligocene Transition, Oligocene-Miocene Boundary, and the Middle Miocene Climate Optimum. We further describe and causally interpret the following features: Paleocene-Eocene warming trend, the two-step, long-term Eocene cooling, and the changes within the most recent interval (Miocene-Pliocene). We review the scope and methods of constructing Cenozoic stacks of benthic oxygen isotope records and present two new latitudinal stacks, which capture besides global ice volume also bottom water temperatures at low (less than 30°) and high latitudes. This review concludes with an identification of future directions for data collection, statistical method development, and climate modeling.新生代（Cenozoic era）的气候经历了多阶段演变，从两极无冰的温暖状态逐步过渡至两极被冰盖覆盖的寒冷状态。自20世纪50年代起，学界主要通过对取自海洋沉积物岩芯的底栖有孔虫（benthic foraminifera）壳体的氧同位素组成开展测量，积累了大量关于冰量与温度变化的研究资料。时间序列分析的统计方法亦不断发展，使得我们能够从这些气候记录中提取更多有效信息。本研究针对一套覆盖4至61百万年前的全球海洋沉积物记录集合，通过一致性且系统性的时间序列分析工具应用，全面展现了新生代的气候演化历程。我们定量描述了氧同位素记录中的多项显著特征，并综合考量了各类不确定性来源（包括测量误差、代用指标噪声及测年误差）。通过估算得到的气候转型时间与转型幅度，我们得以评估气候-构造成因对新生代氧同位素记录中下述已知特征的影响：古新世-始新世极热事件（Paleocene-Eocene Thermal Maximum）、始新世-渐新世过渡、渐新世-中新世界线，以及中新世中期气候适宜期（Middle Miocene Climate Optimum）。我们进一步对下述特征进行了成因解析与描述：古新世-始新世的升温趋势、两阶段的长期始新世降温过程，以及最新地质时段（中新世-上新世）内的气候变迁。本文回顾了构建底栖氧同位素记录纬向堆叠序列的研究范畴与方法，并提出两套全新的纬向堆叠序列，其不仅能够反映全球冰量变化，还可分别记录低纬度（30°以下）与高纬度区域的底层海水温度。本综述最后指明了未来在数据采集、统计方法研发以及气候模拟领域的研究方向。