In this paper,on the basis of high-density particle size analysis on deep-sea sediments at IODP site U1313, North Atlantic,using algorithm of grain size-the standard deviation change, two groups of environmentally sensitive component from the grain-size distribution are extracted; the fine fraction (< 1. 73μm, part Ⅰ) and coarse fraction (>1. 73μm, part Ⅱ) ,the part Ⅱ are divided into part Ⅱa(l. 73~34. 26μm)and Ⅱb(>34. 26μm). We concluded that part Ⅰ , the fine particle fraction, is transported by Westerly jet; part Ⅱ, which represents coarse particle fraction,are transported by ocean currents. Although the part Ⅱb are minor in the grain size distribution,they may indicate occurrence of ice rafted debris. The ratio curves of part Ⅰ/Ⅱ and part Ⅰ /Ⅱa varied significantly, they can be used as the sensitive indicators of past climatic change. Analyzing the part Ⅱ and part Ⅰ /Ⅱ group Ⅱ with the method of EMD, the results show that; during the study period, the earth's orbit cycle of three orbit elements are not obvious, while the millennium cycle of 2ka ( 2. 12ka and 2. 15ka) is one of the main cycle. Analyses of these indexes,the past climatic changes of our study site( 115. 18~69. 93med) can be divided into nine stages during 2415. 60 ~ 1471. 53ka. Stage A( 1471. 53 ~ 1640. 09ka) .corresponding to MIS 49~57 ,in this stage glacial stages and interglacial stages converted rapidly, and the IRD events occurred for many times; Stage B( 1640.09~ 1865. 57ka),corresponding to MIS 58 ~69,in this stage interglacial stages are obvious but glacial stages are not; Stage C ( 1865. 57~1914. 70ka) , corresponding to MIS 70 ~ 72, in this stage glacial stages are obvious but interglacial stages are not obvious; Stage D(1914. 70~2021. 13ka),corresponding to MIS 73~76, in this stage glacial stages are not obvious;Stage E(2021. 13~2092. 21ka) corresponding to MIS 77~78,in this stage glacial stages are obvious and the IRD events occurred for many times;Stage F(2092. 21~2226. 43ka) .corresponding to MIS 79~85, in this stage interglacial stages are obvious; Stage G (2226. 43 ~ 2261. 53ka) , corresponding to MIS 86.in this stage IRD events occurred for many times; Stage H( 2261. 53 ~ 2384. 61 ka) , corresponding to MIS 87~93, in this stage interglacial stages are obvious but glacial stages are not; Stage I (2384.61 -2415. 60ka) ,corresponding to MIS 94~95,in this stage IRD events occurred for many times.%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.
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