Research On Millennial-scale Climate Change In North Atlantic During Early Pleistocene Based On Period Analysis

North Atlantic is recognized universally as the sensitive area of climatic change and it is also the driver of the global climate change. North Atlantic is the source areas of the global climate change, which is the most active area of sea circulation. The original research of millennial-scale climate change is carried out in North Atlantic firstly. The sediment from North Atlantic contains much information of palaeoclimate and Palaeoenvironment, and it is enough for thorough analysis the mechanism of palaeoclimate.In this thesis, grain size analysis have been done with the core sediment of 2.415 Ma～1.471 Ma which obtained in prior from Integrated Ocean Drilling Program (IODP) and drilled in North Atlantic IRD(Ice Rafted Debris) region (Site U1313), the palaeoenvironment in North Atlantic area in Early Pleistocene and the variation of terrigenous clastic deposition flux have been reconstruct..The terrigenous deposits in North Atlantic in Early Pleistocene mainly compose of clay and extremely fine silt, and the sorting is worse. The palaeoenvironmen can be divided into three stages:StageⅠ(2.415Ma～1.901Ma), climate vary frequently.StageⅡ(1.901 Ma～1.634 Ma), the climate tends to stable, vary gently.StageⅢ(1.634Ma～1.471 Ma), the climate vary intensify once more.We did MTM spectral analysis and Wavelet Analysis using the grain size data, and the result reflect the timescale of climatic change vary in North Atlantic in Early Pleistocene.In SageⅠ, the climate has orbital scale cycle of 170Ka,93Ka,40Ka,26Ka,17.5Ka and the sub-orbital scale cycle of 4.93Ka to 2.38Ka.In stageⅡ, the climate has orbital scale cycle of 187.8Ka.109.6Ka,42K,16Ka and the sub-orbital scale cycle of 3.5Ka to 2.85Ka.In stageⅢ, the climate has orbital scale cycle of 97.4Ka,90.4Ka,76.4Ka,67.6Ka,30Ka.13Ka, and sub-orbital scale cycle of 2 to 1Ka has been detected with the grain size data.On the whole, the climate change is reflected by both orbital scale cycle and. sub-orbital scale cycle change from 2～5Ka (2.415 Ma-1.634Ma) to 1～2Ka (1.634Ma～1.471 Ma). Therefore we infer that the period during 1.901 Ma-1.634 Ma is the stage when the climate cycle transformed. Hereafter the typical millennial scale climatic change cycle of about 1500yr appeared in 1.634Ma～1.471Ma.