EAR-PF: Mesozoic Geomagnetic Field Behavior: Exploring Mesozoic core dynamics by tuning numerical geodynamo simulations to paleomagnetic observations

EAR-PF：中生代地磁场行为：通过调整数值地球发电机模拟到古地磁观测来探索中生代核心动力学

基本信息

批准号：
1725798
负责人：
Margaret Avery
金额：
$ 10.86万
依托单位：
Avery Margaret S
依托单位国家：
美国
项目类别：
Fellowship Award
财政年份：
2017
资助国家：
美国
起止时间：
2017-11-01 至 2020-04-30
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1725798&HistoricalAwards=false
关键词：
EAR PF Mesozoic Geomagnetic Field

项目摘要

Dr. Margaret S. Avery has been granted an NSF EAR Postdoctoral Fellowship to carry out research and education activities at the University of California - Berkeley. The investigation focuses on building an updated compilation of paleomagnetic datasets for rocks from the Mesozoic area (251 - 65.5 million years ago) and running numerical geodynamo simulations. Using the geomagnetic field strength data measured from igneous rocks, Dr. Avery explores the relationship between polarity reversal rate and paleomagnetic field strength. This research links advanced geodynamo simulations with expanded paleomagnetic observations to enable better understanding of core dynamics and core-mantle boundary conditions during an important period of Earth evolution. For the education activities, Dr. Avery is developing and teaching a "Data Science Connector" course focused on geophysical data, specifically geomagnetism. In addition, she mentors an undergraduate student through the UC Berkeley's Society of Women in the Physical Sciences, and participates outreach activities, like the Expanding Your Horizons conference that introduces 5th-8th grade girls to careers in STEM fields.The Earth's magnetic field varies on a broad range of timescales. It is to first order dipolar in structure, but the dipole varies is strength and polarity. The rate of polarity reversals varies on time-scales of tens of millions of years. For example, the magnetic field has reversed ~4 times per million years over the past 20 Myr, whereas no polarity reversals occurred for 38 Myr during the Cretaceous normal-polarity superchron. During the Jurassic, the reversal rate was much higher than the present rate (up to 14 reversals per million years). These drastic changes in reversal rate occur on such long periods that they likely are related to slow changes in the mantle that modulate the outer-core flow, providing information about Earth's thermal evolution. During times when the field strength was higher on average the reversal rate was low; in contrast, during times when the field strength was lower on average there was a high rate of reversals. Dr. Avery uses improved observational constraints and a new suite of numerical geodynamo numerical simulations. The geodynamo software Calypso is used to explore core dynamics and core-mantle interactions that could cause these differing geomagnetic field behaviors, and to test the hypothetical positive correlation between polarity reversal rate and paleointensity.

Margaret S. Avery 博士已获得 NSF EAR 博士后奖学金，在加州大学伯克利分校开展研究和教育活动。该调查的重点是建立中生代地区（251 - 6550 万年前）岩石古地磁数据集的更新汇编，并运行数值地球发电机模拟。艾弗里博士利用从火成岩测量的地磁场强度数据，探索了极性反转率与古磁场强度之间的关系。这项研究将先进的地球发电机模拟与扩展的古地磁观测联系起来，以便更好地了解地球演化重要时期的核心动力学和核心-地幔边界条件。对于教育活动，艾弗里博士正在开发和教授“数据科学连接器”课程，重点关注地球物理数据，特别是地磁数据。此外，她还通过加州大学伯克利分校物理科学女性协会指导一名本科生，并参加外展活动，例如向 5 至 8 年级女孩介绍 STEM 领域职业的扩展视野会议。广泛的时间尺度。它在结构上是一阶偶极子，但偶极子的强度和极性不同。极性反转的速率在数千万年的时间尺度上变化。例如，在过去 20 Myr 中，磁场每百万年反转约 4 次，而在白垩纪正常极性超纪元期间，38 Myr 没有发生极性反转。侏罗纪时期，逆转率远高于现在的逆转率（高达每百万年 14 次逆转）。反转率的剧烈变化发生在如此长的时期内，很可能与调节外核流动的地幔缓慢变化有关，从而提供了有关地球热演化的信息。当场强平均较高时，反转率较低；相反，在平均场强较低的时期，反转率很高。艾弗里博士使用改进的观测约束和一套新的数值地球发电机数值模拟。地球发电机软件 Calypso 用于探索可能导致这些不同地磁场行为的岩心动力学和岩心-地幔相互作用，并测试极性反转率与古强度之间假设的正相关性。