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通过对北大西洋IODP U1313站深海沉积序列高密度取样和粒度分析,利用粒级-标准偏差变化算法和EMD方法提取了对环境敏感粒度组分并探讨了气候变化的周期。本文粒度组分可分为细组分(<1.73μm,组分Ⅰ)和粗组分(>1.73μm,组分Ⅱ),其中粗组分又分为组分Ⅱa(1.73～34.26μm)和组分Ⅱb(>34.26μm)。综合分析认为:组分Ⅰ为西风环流搬运堆积形成,组分Ⅱ为洋流搬运下沉积形成,组分Ⅱb虽然含量较低,但能指示冰漂砾事件的发生。比值曲线组分Ⅰ/组分Ⅱ和组分Ⅰ/组分Ⅱa波动幅度较大,可作为反映古气候冷暖波动的敏感指标。对组分Ⅱ、组分Ⅰ/组分Ⅱ进行EMD分解,结果表明:在本研究时段内,两指标对地球轨道三要素的周期体现均不明显,而2ka(2.12ka和2.15ka)的亚轨道千年周期是主要的周期之一。依据上述多个指标的波动情况,把研究剖面69.93～115.18mcd(1471.53～2415.60ka)分为9个古气候变化阶段:A阶段(1471.53～1640.09ka),对应深海氧同位素阶段(MIS)49～57,冰期和间冰期迅速转换,发生多次IRD事件;B阶段(1640.09～1865.57ka),对应MIS 58～69,间冰期显著而冰期不明显;C阶段(1865.57～1914.70ka),对应MIS 70～72,冰期显著而间冰期不明显;D阶段(1914.70～2021.13ka),对应MIS 73～76,冰期不显著;E阶段(2021.13～2092.21ka),对应MIS 77～78,冰期显著,发生多次IRD事件;F阶段(2092.21～2226.43ka),对应MIS 79～85,间冰期显著;G阶段(2226.43～2261.53ka),对应MIS 86期,发生多次IRD事件;H阶段(2261.53～2384.61ka),对应MIS 87～93,冰期不显著而间冰期显著;Ⅰ阶段(2384.61～2415.60ka),对应MIS 94～95,发生多次IRD事件。
Based on the high-density sampling and particle size analysis of deep-sea sedimentary sequence from IODP U1313 station in North Atlantic Ocean, the environmental-sensitive grain-size components were extracted and the period of climate change was explored by using the particle size-standard deviation variation algorithm and EMD method. Particle size can be divided into fine component (<1.73μm, component Ⅰ) and coarse component (> 1.73μm, component Ⅱ), the crude component is divided into component Ⅱa (1.73 ~ 34.26μm) and Component IIb (> 34.26 μm). The comprehensive analysis shows that component Ⅰ is formed by westerly circulation and sedimentation, while component Ⅱ is formed by ocean current transport. Although component Ⅱb is relatively low, it can indicate the occurrence of ice-boulder events. The ratio curve of component I / component II and component I / component IIa fluctuates widely, which can be used as a sensitive index to reflect the warm and cold fluctuations of palaeoclimate. The results of EMD decomposition of component Ⅱ and component Ⅰ / component Ⅱ show that the periods of the two indices are not obvious to the three elements of the Earth’s orbit during this research period, while the sub-components of 2ka (2.12ka and 2.15ka) Orbital millennium is one of the major cycles. According to the fluctuation of multiple indicators mentioned above, the study section is divided into nine paleoclimate stages from 69.93 to 115.18 mcd (1471.53 to 2415.60 ka): Phase A (1471.53 ~ 1640.09 ka) corresponding to MIS 49 ~ 57, during the glacial and interglacial transitions rapidly, multiple IRD events occurred; in B stage (1640.09 ~ 1865.57ka), corresponding to MIS 58 ~ 69, interglacial was significant but glacial was not obvious; C stage (1865.57 ~ 1914.70ka) ~ 72, the glacial period was significant and the interglacial period was not obvious. In the D stage (1914.70 ~ 2021.13 ka), corresponding to the MIS 73 ~ 76, the glacial period was insignificant. In the E stage (2021.13 ~ 2092.21 ka), corresponding to the MIS 77 ~ 78, (2292.43 ~ 2261.53ka) corresponding to MIS 86, multiple IRD events occurred in the F stage (2092.21-2226.43ka) corresponding to MIS 79-85, and the interglacials were significant. In the H stage (2261.53-2384.61ka) ), Corresponding to MIS 87-93, the glacial period was not significant and the interglacial period was significant. In stage I (2384.61-2415.60ka), corresponding to MIS 94-95, multiple IRD events occurred.