5000a　B．P．以来地磁场要素时空变化特征及其与环境变化关系的讨论

Discussion about Characteristics of Geomagnettc Field Element's Spatio-temporal Changes and Their Relations to Environmental Changes since 5000a B. P.

通过渤海ＱＤ－３１３４孔位连续沉积岩芯所记录的５０００ａＢ．Ｐ．以来地磁场要素（主要是Ｄ和Ｉ及磁场相对强度）的系统测量分析结果表明，其时空变化特征与黄河中－下游区域考古地磁的测量分析结果相吻合。由变化特征显示出：Ｉ及地磁场相对强度的明显变化界线位于２５００ａＢ．Ｐ．左右，此界线与该区域孢粉及有孔虫分析显示出的组合明显变化界线相一致。Ｄ的明显变化界线位于２０００ａＢ．Ｐ．左右，此界线与竺可桢等统计分析的中国北方５０００ａＢ．Ｐ．以来的气候的明显变化界线相一致。这种变化的相关性进一步分析显示出，自龙山文化期以来，Ｉ由高值向低值变化及Ｄ由酉偏转向东偏，与气候温湿特征对应，Ｉ由低值向高值变化及Ｄ由东偏转向西偏，与温干气候特征相对应；Ｉ及Ｄ突变时期与灾害气候环境变化相对应。

Through a systematic measurment and analysis of the records of geomagnetic field elements (mainly D, I and magnetic field relative intensity) derived from the Bobal Sea post continuous sediment cores, the results suggest the time and space characteristics of its changes are identical with the measured and analysed archaeomagnetic results deny6d from the region of the middle and lower reachal of the Yellow River. The characteristics of the changes indicate:the boundary of the apparent change I and the geomagnetic field relative intensity are identical, and D is located at around 2500 a B. P. the boundary is consistent with the combination apparent change boudary indicated by the region's palynological and foraminiferal analyses,D's apparent change boudary is located at around 2000 a B. P., and is consistent with the apparent change boundary of the climate change of North China since 5000 a B. P. as shown by Kezhen Zhu et al'sstatistical indicates: since the Longshan culture peeriod,I has change from higher value to lower value and D has rotated from west to east, these two chanses correspond to warm and wet climatic features; I has changed from lower value to hisher value and D rotated from east to west, which correstpond to warm and dry climatic features; I and D sudden change periods correspond to the change of disastrous climatic environment.