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Constraints on the Pleistocene chronology of sediments from the Lomonosov Ridge

机译：罗蒙诺索夫海岭沉积物的更新世年代学约束

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[1] Despite its importance in the global climate system, age-calibrated marine geologic records reflecting the evolution of glacial cycles through the Pleistocene are largely absent from the central Arctic Ocean. This is especially true for sediments older than 200 ka. Three sites cored during the Integrated Ocean Drilling Program's Expedition 302, the Arctic Coring Expedition ( ACEX), provide a 27 m continuous sedimentary section from the Lomonosov Ridge in the central Arctic Ocean. Two key biostratigraphic datums and constraints from the magnetic inclination data are used to anchor the chronology of these sediments back to the base of the Cobb Mountain subchron ( 1215 ka). Beyond 1215 ka, two best fitting geomagnetic models are used to investigate the nature of cyclostratigraphic change. Within this chronology we show that bulk and mineral magnetic properties of the sediments vary on predicted Milankovitch frequencies. These cyclic variations record "glacial'' and "interglacial'' modes of sediment deposition on the Lomonosov Ridge as evident in studies of ice-rafted debris and stable isotopic and faunal assemblages for the last two glacial cycles and were used to tune the age model. Potential errors, which largely arise from uncertainties in the nature of downhole paleomagnetic variability, and the choice of a tuning target are handled by defining an error envelope that is based on the best fitting cyclostratigraphic and geomagnetic solutions.
机译：[1]尽管它在全球气候系统中具有重要意义，但北冰洋中部基本上没有经过年龄校准的海洋地质记录，该记录反映了通过更新世的冰川循环的演变。对于年龄大于200 ka的沉积物尤其如此。在“综合海洋钻探计划”第302号远征队中取芯的三个地点，即北极取心远征队（ACEX），提供了北冰洋中部罗蒙诺索夫海岭连续27 m的沉积剖面。两个关键的生物地层基准面和来自磁倾角数据的限制条件被用于将这些沉积物的年代学锚定回科布山次亚纪（1215 ka）的基础。除了1215 ka以外，还使用了两个最合适的地磁模型来研究旋回地层变化的性质。在这一年表中，我们显示出沉积物的体积和矿物磁性能随米兰米奇维奇预测的频率而变化。这些周期性变化记录了罗蒙诺索夫海岭上沉积物的“冰川”和“冰川间”沉积模式，这在最近两个冰川周期的冰筏碎屑以及稳定的同位素和动物群落的研究中很明显，并用于调整年龄模型。 。潜在的误差主要由井下古磁变率性质的不确定性引起，而调整目标的选择则通过定义基于最佳拟合地层和地磁解决方案的误差包络来处理。

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