北京地区史期地磁場及其变化的研究

本文利用考古地磁法,对北京地区汉、三国、唐、宋、金、元、明、清各朝代的古砖标本进行了研究,测定了标本的剩余磁性,并做了逐步加热的实验,从而推算出上述各时期北京地区的磁倾角值和磁埸强度值。结果表明,北京地区近两千午来磁倾角是在51°—66°之间变化,并且有循环性特征,其周期为一千余年;而地磁埸强度则是逐渐减小的,汉、三国、唐、宋、元、清各时期的地磁场强度分别为现代地磁埸强度1.57,1.41,1.42,1.29,1.21,1.12倍。

THE GEOMAGNETIC FIELD IN PEKING REGION AND ITS SECULAR VARIATION DURING THE LAST 2000 YEARS

The results of the archaeomagnetic study of the geomagnetic field in Peking region and its secular variation during the last 2000 years are presented. The authors have measured the intensity of the natural magnetization of a number of ancient brick samples of known ages collected in Peking region for the last 2000 years. From these measurements the geomagnetic inclinations are deduced. The total intensities of the geomagnetic field are determined by means of Thellier's method of heating step by step. The results clearly show that the inclination in Peking varies between 51°—66° during the last 2000 years,and has a cyclic variation,the period of which is about 1000 years. The total intensities F at the epoch of Han （206 B.C.—219 A.D.）,San-Kuo （220—280 A.D.）,T'ang （618—905 A.D.）,Sung （960—1276 A.D.）,Yuan （1280—1360 A.D.）,Ch'ing （1644—1911 A.D.） are respectively 1.57,1.41,1.42,1.29,1.21,1.12 times of that of the present field in Peking,the F decreases gradually with time during this period.