论文部分内容阅读
地球内部磁场的变化时间从数月到数十亿年不等。地磁场是由液态外地核对流产生的,从而受到从地核到地幔底部热流的影响。地磁场的变化在很大程度上被认为是随机的,但是它的长期变化可能与地幔对流过程中的热流变化有关。在过去的500Ma中,古地磁行为与地表过程的联系在始于约180Ma前的中生代中晚期尤为显著。地球发电机模拟表明,侏罗纪中期到白垩纪中期之间发生了磁极快速反转时期到持久稳定时期的转变,这或许是球对称的或者赤道方向的核幔边界热流的减少所触发的。该热流的减少可能与核幔边界处地幔柱顶冠活动的减弱有关,或者与真极移有关,亦或与二者同时有关。
The changing magnetic field inside the Earth varies from months to billions of years. The geomagnetic field is generated by the liquid field countercurrent and is thus affected by the heat flow from the earth’s core to the bottom of the mantle. The change of geomagnetic field is considered to be largely random, but its long-term change may be related to the change of heat flux in the mantle convection. In the past 500 Ma, the association between paleomagnetic behavior and surface processes was especially pronounced in the mid-late Mesozoic before about 180 Ma. The simulation of the geoelectric generator shows that the transition from the period of rapid pole reversal to the period of permanent magnetism occurred between the middle Jurassic and the mid-Cretaceous, which may be triggered by the reduction of the heat flux in the sphere-symmetry or equatorial direction of the mantle. The reduction of this heat flux may be related to the weakening of the crest-cap movement at the mantle and the mantle, either related to true pole displacement or both.