Stable isotope record, calcium carbonate conentrations, and sea surface temperture reconstructions of sediment cores from the North Atlantic@en

We analyze five high-resolution time series spanning the last 1.65 m.y.: benthic foraminiferal delta18O and delta13O, percent CaCO3, and estimated sea surface temperature (SST) at North Atlantic Deep Sea Drilling Project site 607 and percent CaCO3 at site 609. Each record is a multicore composite verified for continuity by splicing among multiple holes. These climatic indices portray changes in northern hemisphere ice sheet size and in North Atlantic surface and deep circulation. By tuning obliquity and precession components in the delta18O record to orbital variations, we have devised a time scale (TP607) for the entire Pleistocene that agrees in age with all K/Ar-dated magnetic reversals to within 1.5%. The Brunhes time scale is taken from Imbrie et al. [1984], except for differences near the stage 17/16 transition (0.70 to 0.64 Ma). All indicators show a similar evolution from the Matuyama to the Brunhes chrons: orbital eccentricity and precession responses increased in amplitude; those at orbital obliquity decreased. The change in dominance from obliquity to eccentricity occurred over several hundred thousand years, with fastest changes around 0.7 to 0.6 Ma. The coherent, in-phase responses of delta18O, delta13O, CaCO3 and SST at these rhythms indicate that northern hemisphere ice volume changes have controlled most of the North Atlantic surface-ocean and deep-ocean responses for the last 1.6 m.y. The delta13O, percent CaCO3, and SST records at site 607 also show prominent changes at low frequencies, including a prominent long-wavelength oscillation toward glacial conditions that is centered between 0.9 and 0.6 Ma. These changes appear to be associated neither with orbital forcing nor with changes in ice volume.我们对过去165万年的5套高分辨率时间序列数据集展开分析，涵盖北大西洋深海钻探计划（Deep Sea Drilling Project, DSDP）607号站位的底栖有孔虫δ¹⁸O、δ¹³C、碳酸钙（CaCO3）百分含量以及估算得到的海表温度（sea surface temperature, SST），以及609号站位的碳酸钙（CaCO3）百分含量。每套记录均为多岩芯复合样（multicore composite），通过对多个钻孔岩芯进行拼接以验证序列的连续性。这些气候指标可反映北半球冰盖规模以及北大西洋表层与深层环流的变化。通过将δ¹⁸O记录中的轨道倾角（obliquity）与岁差（precession）组分调谐至轨道变率，我们构建了适用于整个更新世（Pleistocene）的年代标尺（TP607），该标尺与所有经钾氩定年（K/Ar-dated）的地磁反转的年龄偏差均不超过1.5%。布容年代标尺（Brunhes time scale）取自Imbrie等人1984年的研究成果，仅在第17/16阶段过渡期（0.70 Ma至0.64 Ma）存在差异。所有指标均展现出从松山世（Matuyama）到布容世（Brunhes）的相似演化特征：轨道偏心率（orbital eccentricity）与岁差响应的振幅逐渐增强，而轨道倾角响应的振幅则逐渐减弱。从轨道倾角主导到轨道偏心率主导的气候转型过程持续了数十万年，在约0.7 Ma至0.6 Ma期间变化速率最快。δ¹⁸O、δ¹³C、碳酸钙（CaCO3）与SST在这些轨道周期上呈现出一致的同相响应，表明过去165万年以来，北半球冰量变化主导了北大西洋表层与深层海洋的绝大多数响应过程。607号站位的δ¹³C、碳酸钙百分含量与SST记录还在低频波段展现出显著变化，其中包括一个以0.9 Ma至0.6 Ma为中心的、向冰期环境演变的长周期振荡。这些变化似乎既与轨道强迫（orbital forcing）无关，也与冰量变化无关。