报告题目：A view on the long-term history of dipole moment through the Mesozoic from the analysis of the updated global paleointensity database
报告人：Prof. Alexsey Smirnov
报告人简介：
Smirnov教授是美国密歇根技术大学地球物理系教授，是该校古地磁学实验室主任，同时是美国地质学会会士。他在古地磁学、磁性地层学与环境磁学综合研究工作中取得了一系列成果，在国际上有很高的知名度。Smirnov教授也是一位活跃的大洋钻探科学家，曾担任IODP科学评估工作组成员，参加过IODP航次，积累了丰富经验。在此次报告中，他将综述有关地磁场古强度测量、地球磁场起因和地球热演化历史的最新研究进展。
报告内容简介：
Data on the long-term evolution of Earth’s magnetic field are crucial for understanding the mechanisms of the geodynamo and planetary evolution. However, there has been a controversy regarding whether the long-term variations of geomagnetic polarity reversal frequency, secular variation and field strength have been intrinsically coupled, or they have varied independently throughout the geological history. Many geodynamo models predict an anti-correlation between reversal frequency and field strength but the majority of the paleointensity data fails to confirm this relationship. The paleointensity record in rocks, however, may be adversely affected by a plethora of physical processes which must be taken into account when analyzing the paleointensity database. If not accounted for, these processes may lead to significant under- or overestimates of paleointensity. These effects have not been fully understood yet and require extensive experimental and theoretical rock magnetic, mineralogical and petrological studies. However, failure to recognize them may lead to some apparent paradoxes in the large-scale picture of geodynamo evolution derived from statistical treatments of the global paleointensity database. In particular, the presence of non-ideal carriers of magnetic remanence in rocks may have resulted in a pervasive low-field bias affecting most paleointensity data in the global database. Such a bias offers a feasible explanation for the discrepancy between the experimental data and numerical models, and thus supports an inverse relationship between the reversal rate and field strength as a fundamental property of the geodynamo. Other fundamental challenges and perspectives of paleointensity determination will be discussed in the context of current models of the long-term geomagnetic and thermal evolution of our planet.
报告时间：2019年9月6日（周五）10:00-11:30
报告地点：海洋楼一楼报告厅
邀请人：赵西西 研究员
欢迎大家参加！