Do meteorite impacts the geomagnetic field and can meteorites retain the record of planetary magnetic fields?

陨石是否会影响地磁场？陨石能否保留行星磁场的记录？

• 批准号: 169945988
• 负责人: Professor Dr. Stuart Alan Gilder
• 金额: --
• 依托单位: Department of Earth, Atmospheric, and Planetary Sciences
• 依托单位国家: 德国
• 项目类别: Priority Programmes
• 财政年份: 2010
• 资助国家: 德国
• 起止时间: 2009-12-31 至 2016-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/169945988?language=en
• 关键词: Do; meteorite; impacts; geomagnetic; field

Meteorite impacts have profoundly influenced the evolution of planets in our solar system. The kinetic energy involved in impact events is released as a shock wave, with instantaneous pressures sometimes >100 GPa spread over hundreds of square kilometers. Seismic waves generated by the shock can potentially influence the geodynamo when reaching the Earth s core. Cessation of the Martian dynamo may have also been caused by a large meteorite impact. We propose to carry out detailed, systematic paleomagnetic studies of several terrestrial impact craters to test whether the geomagnetic field was perturbed by the impacts. If impact events strongly influenced the geodynamo, then the effects should be evident in the paleomagnetic data, either as swings in magnetic field direction or as fluctuations in intensity. We intend to track these changes in the cooling record of the rocks that were melted by the impact. We also will conduct studies on rocks shocked by the impacts in order to determine how their rock magnetic properties were modified and overprinted by the impact process. Moreover, we will conduct paleomagnetic studies of meteorites to constrain the intensities of early magnetic fields of the Moon, Mars, and planetesimals. The paleomagnetism of meteorites and impact craters are linked in that one of the key proposed field sources of the former is impact-generated plasmas on the parent body. It is critical to develop an understanding of the effects of shock waves on rock magnetic properties given that nearly all meteorite samples were shocked during ejectionfrom their parent bodies.

陨石撞击深刻地影响了我们太阳系行星的演化。撞击事件中涉及的动能以冲击波的形式释放，瞬时压力有时会扩散到数百平方公里。地震产生的地震波在到达S地核时可能会影响地球发电机。火星发电机的停止也可能是由大型陨石撞击造成的。我们建议对几个陆地撞击坑进行详细、系统的古地磁研究，以测试地球磁场是否受到撞击的扰动。如果撞击事件强烈地影响了地球发电机，那么这种影响在古地磁数据中应该是明显的，要么是磁场方向的摆动，要么是强度的波动。我们打算追踪在撞击中熔化的岩石的冷却记录的这些变化。我们还将对受到撞击的岩石进行研究，以确定它们的岩石磁性是如何在撞击过程中被修改和叠加的。此外，我们将对陨石进行古地磁研究，以限制月球、火星和小行星早期磁场的强度。陨石和陨石坑的古地磁联系在一起，因为前者的主要场源之一是撞击母体上产生的等离子体。考虑到几乎所有的陨石样品在从母体弹射时都受到了冲击，了解冲击波对岩石磁性的影响是至关重要的。