Moving beyond the age-depth model paradigm in deep-sea palaeoclimate archives: dual radiocarbon and stable isotope analysis on single foraminifera

作者：Lougheed Bryan C^*; Metcalfe Brett; Ninnemann Ulysses S; Wacker Lukas

来源：Climate of the Past, 2018, 14(4): 515-526.

DOI：10.5194/cp-14-515-2018

Late-glacial palaeoclimate reconstructions from deep-sea sediment archives provide valuable insight into past rapid changes in ocean chemistry. Unfortunately, only a small proportion of the ocean floor with sufficiently high sediment accumulation rate (SAR) is suitable for such reconstructions using the long-standing age-depth model approach. We employ ultra-small radiocarbon (C-14) dating on single microscopic foraminifera to demonstrate that the long-standing age-depth model method conceals large age uncertainties caused by post-depositional sediment mixing, meaning that existing studies may underestimate total geochronological error. We find that the age-depth distribution of our C-14-dated single foraminifera is in good agreement with existing bioturbation models only after one takes the possibility of Zoophycos burrowing into account. To overcome the problems associated with the age-depth paradigm, we use the first ever dual C-14 and stable isotope (delta O-18 and delta C-13) analysis on single microscopic foraminifera to produce a palaeoclimate time series independent of the age-depth paradigm. This new state of the art essentially decouples single foraminifera from the age-depth paradigm to provide multiple floating, temporal snapshots of ocean chemistry, thus allowing for the successful extraction of temporally accurate palaeoclimate data from low-SAR deep-sea archives. This new method can address large geographical gaps in late-glacial benthic palaeoceanographic reconstructions by opening up vast areas of previously disregarded, low-SAR deep-sea archives to research, which will lead to an improved understanding of the global interaction between oceans and climate.

• 出版日期2018-4-20
• 单位中国地震局