CSEDI: Collaborative Research: Paleomagnetism, the Geodynamo and Core-Mantle Interactions

Bloxham Constable建议开展一项关于地幔对地球发电机影响的合作研究，将地球动力学、地球发电机模型和古地磁学结合起来，重点放在三个时间尺度上。首先，通过观察过去500万年，我们将考察发电机在一段时间内的长时间尺度行为，在这段时间内，时间平均场和古分子变化都可以用古地磁来确定。此外，在这个时间尺度上，最低地幔与使用地震层析成像的地幔基本上没有变化，因此可以使用地幔的现代层析图像。其次，将研究从白垩纪正常超时至今的反转频率的变化，包括地幔底部的热柱形成对磁场中反向磁通斑块的出现的影响。第三，将对磁场在数亿年时间尺度上发生的非常长期的变化进行初步调查。这项工作将涉及对现有的古地磁测量进行统计重新分析，以评估什么样的地球发电机实验将与理解这种长期变化有关。发电机模拟和地球动力学模拟将在哈佛大学进行；该提案的古地磁方面，包括数据汇编、分析和野外模拟将在斯克里普斯海洋研究所进行。这项工作将主要通过电子手段协调两所院校之间的工作，并辅之以两所院校之间的访问和短期学生交流。

Bloxham Constable It is proposed to undertake a collaborative study of mantle influences on the geodynamo, combining geodynamics, geodynamo modeling and paleomagnetism, focusing on three timescales. First, by looking at the last 5 million years the long timescale behavior of the dynamo over a period for which both the time averaged field and the paleosecular variation can be determined paleomagnetically will be examined. Furthermore, on this timescale the lowermost mantle is essentially unchanged from that which is imaged using seismic tomography, so modern tomographic images of the mantle can be used. Second, changes in reversal frequency, concentrating on the period from the Cretaceous Normal Superchron to the present day will be examined, including the effect of plume formation at the base of the mantle on the occurrence of reverse flux patches in the magnetic field. Third, preliminary investigations will be conducted on the very long-term changes in the magnetic field occurring over timescales of several hundred million years. This work will involve a statistical re-analysis of the available paleomagnetic measurements to assess what kinds of geodynamo experiments will be relevant to understanding such long-term changes. The dynamo modeling and geodynamical modeling will be performed at Harvard; the paleomagnetic aspects of the proposal, involving data compilation, analysis, and field modeling will be performed at Scripps Institution of Oceanography. The work will be coordinated between the two institutions primarily by electronic means, supplemented by visits and short-term exchange of students between the institutions.