DIPOLE AND NONDIPOLE FIELDS OF THE GEOMAGNETIC FIELD ON THE BASIS OF PALAEOINTENSITIES OF THE BRUNHES VOLCANIC ROCKS.

研制了实验仪器，并在第一年用于测试样品的测量。交变磁场消磁器的最大输出为120mT，具有恒定的增减磁场速率。这个常数是100mT/60sec，因为较高的速率往往会导致较小的ARM。ARM与比较的NRM或TRM并行获取。这样的ARM可以校正NRM或TRM强度的各向异性效应。第一次和第二次加热时，最高温度下的加热时间分别为10min和20min。样品采集于日本大森火山、秘鲁安第斯火山和中国大同单生火山。它们都是在布伦赫斯时代形成的。Shaw法的双重加热使32个样品中的13个样品成功。根据实测的古强度和倾斜度计算的vdm，在以前的报告中显示出在平均vdm周围的分裂分布。这意味着地球动力强度的分布可能比古地磁学家先前提出的更为复杂。利用Matuyama-Brunhes过渡沉积记录的方向研究了非偶极子场和偶极子场的相对强度变化。这些记录来自日本博索海相沉积物。光谱分析表明，在过渡场中，短周期变化（可能为10^2年）是显著的。

The experimental instruments were developed and used in the measurents of the test samples in the first year. The alternating field demagnetiser has a 120mT maximum output with a constant rate of increasing and decreasing fields. This constancy is of 100mT/60sec because the higher rate tends to result in a smaller ARM.The ARM is acquired in parallel to the NRM or TRM which is compared. Such an ARM can correct the NRM or TRM intensity for the anisotropy effects. The heating time at the top temperature is 10min. and 20min. in the first and the second heating, respectively. The samples were collected from Daisen Volcano (Japan), Andean volcanic region (Peru), and Datong monogenetic volcanoes (China). All of them were formed in the Brunhes epoch. Double heating of the Shaw method results in the success of 13 samples out of 32. The VDMs, calculated from the measured palaeointensities and the inclinations, show the splitted distribution around the mean VDMs in the previous reports. This implies the geodynamo intensities may have more complicated distribution than those previously suggested by the palaeomagnetists. The relative intensity change in the nondipople/dipole fields was investigated using the direcions of the sedimentary records of the Matuyama-Brunhes transition. The records were obtained from the Boso marine sediments in Japan. The spectral analyzes suggest that the short-period variations, probably of the order of 10^2 years, are remarkable in the transition field.