中文摘要：

黄土高原风尘沉积序列厚度大、地层连续,是高分辨率古地磁研究和古气候研究的理想材料.然而,缺少精确年龄控制点制约了黄土古气候信息的区域对比和海陆对比研究.地磁极性漂移是地球磁场长期变化过程中的基本行为之一,全球同步性使其成为古气候研究可靠的年龄控制点.布容正极性时记录了多次极性漂移事件,为高分辨率黄土古气候学提供的新的途径.通过回顾近年来的研究成果可知,黄土沉积物广泛记录了Laschamp和Blake地磁极性漂移事件,且部分剖面中存在Mono Lake事件的报道.此外尚未明确限定的倾角变负波动不断提出,极大地拓展了黄土沉积物极性漂移事件研究的深度和广度.然而,部分高沉积速率黄土剖面存在极性事件缺失现象对黄土沉积物可以稳定记录地磁极性漂移事件提出了质疑.目前对这一现象的解释有剩磁获得机制、Lock-in效应、沉积间断和气候响应等.然而,热退磁可有效去除化学剩磁（CRM）的影响,与CRM密切相关的剩磁获得机制无法解释相近区域内极性事件记录的差异.黄土沉积物较浅的Lock-in效应否定了其会普遍引起极性事件记录的缺失.黄土高原内部低沉积速率（小于10 cm/Ka）地区千年尺度极性事件和地磁场长期变化的记录否定了黄土沉积存在千年尺度的沉积间断.本文通过分析已有研究成果,认为极性漂移期间地磁场稳定性较差,导致磁性颗粒记录的磁场信息存在差异,可能是极性事件记录缺失的主要原因.

英文摘要：

The thick and continuous aeolian loess sequences from Chinese Loess Plateau （CLP） were ideal research materials for paleomagnetic study and paleoclimate research. For the lack of precise age point, uncertainty occurs in regional comparisons and land-ocean comparisons. Magnetic excursion is one of the basic behave in secular variation of the Earth＇ s magnetic field. The global synchronism makes it become the reliable age control tie in the paleoclimate study. The Brunhes ehron remarks much times of the magnetic excursions, which provide new way for high resolution loess paleoclimate research. Through the past successes of magnetic excursion research in loess sediments in Brunhes chron, we know that the loess deposition recorded the Laschamp and Blake excursion excellently in different areas in Chinese Loess Plateau （CLP）. And the Mono Lake excursion record could be detected in some loess profile. It made the studies of magnetic excursions in loess sediments receives much concern in recent years. However, the absence of excursions in some loess section with high sediment rate caused a suspicion that the Chinese loess could not record the magnetic excursions reliably. To explain this annoyance, much factors like magnetic remanenee mechanism, lock-in effect, depositional break and climate response in loess deposition had been discussed. But these could be debated for： 1 ） Thermal treatment could remove the chimerical remanence efficaciously. 2） The lock- in effect in loess deposition should be shallow （less than 5-10 cm）. 3 ） Chinese loess deposition could record short lived magnetic excursion and millennial secular variation in magnetic field in low sediment rate area in the CLP internal. And we discussed the directional abnormality cmTelated with low field intensity during the presence of magnetic excursion would be the most important cause for the absence of excursions in some magnetic studies in CLP. The future study of magnetic excursions in loess deposition in CLP would be based on high re