Accomplishment Based Renewal: Transforming the paleointensity experiment and application to the paleointensity database

基于成就的更新：将古强度实验和应用转变为古强度数据库

• 批准号: 1547263
• 负责人: Lisa Tauxe
• 金额: $ 39.55万
• 依托单位: University of California-San Diego Scripps Inst of Oceanography
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-02-15 至 2021-01-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1547263&HistoricalAwards=false
• 关键词: Accomplishment; Based; Renewal; Transforming; paleointensity

The geomagnetic field has been dropping rapidly over the past century (8%)leaving some worried that it could collapse into what is known as a 'transitional state' with a strength of ~10% of the present field. Such an event would pose severe danger to the planet's electrical grid and satellites requiring some advanced planning. The likelihood of this happening is presently unknown as human measurements of the magnetic field strength span only the last ~150 years and fundamental questions regarding the average field strength of the geomagnetic field and its variation through time remain despite decades of effort. This project will serve to support the research of several students (both undergraduate and graduate), one of whom is an under-represented minority female. In addition, it will provide funding for a female computer programmer to continue efforts on improving the software supporting online materials including a textbook and a complete software package (PmagPy) that integrates smoothly with the MagIC database, (http://earthref.org/MAGIC/books/Tauxe/Essentials and http://earthref.org/PmagPy/cookbook respectively).The signal of an axial geomagnetic dipole, whereby the field strength doubles from the equator to the poles, is readily apparent in the present field but no such clear dipolar signal exists in the paleointensity database from the last five million years. There are several possible explanations for this troubling failure: 1) combining data from different ages with possibly different average intensities leads to an inappropriate comparison of field states, 2) there is a depression of field strength at high latitude, perhaps reflecting the role of the 'tangent cylinder' or 3) there is noise and/or bias introduced by poor selection criteria or poor experimental design. The latter is a likely explanation as published data from the 1960 flow on Hawaii display the entire range of intensity values observed on the Earth's surface today, yet they should all have one distinct value. The PI has developed new experimental methods, better field strategies and a new approach to data selection that will allow the team to obtain accurate estimates of the ancient field strength to improve our understanding of the intensity behavior in Earth's past. The PI plans a comprehensive field campaign to collect samples targeting the most promising material for paleointensity study. These will be analyzed using the most robust experimental protocol and subjected to rigorous selection criteria proven to reject inaccurate results, leading to both accurate and precise paleointensity estimates. The PI will also complete a long term aging experiment of thermal remanence to investigate the contribution of bias (andnoise) of non-single domain material in the database, with an eye toward improving the experiment and data selection procedures leading to higher accuracy in paleointensity estimates.

过去一个世纪中，地磁场一直在迅速下降（8%），这让一些人担心地磁场可能会崩溃到所谓的“过渡状态”，其强度约为当前磁场的 10%。 此类事件将对地球的电网和卫星构成严重危险，需要一些提前规划。 目前尚不清楚这种情况发生的可能性，因为人类对磁场强度的测量仅持续了大约 150 年，尽管经过了数十年的努力，有关地磁场平均场强及其随时间变化的基本问题仍然存在。 该项目将支持几名学生（本科生和研究生）的研究，其中一名是代表性不足的少数族裔女性。 此外，还将为一名女性计算机程序员提供资金，以继续努力改进支持在线材料的软件，包括一本教科书和一个与MagIC数据库顺利集成的完整软件包（PmagPy），（http://earthref.org/分别为 MAGIC/books/Tauxe/Essentials 和 http://earthref.org/PmagPy/cookbook）。轴向地磁偶极子的信号，场强从赤道到两极加倍，在目前的领域中很明显，但在过去五百万年的古强度数据库中不存在如此清晰的偶极信号。对于这种令人不安的失败，有几种可能的解释：1）将不同年龄的数据与可能不同的平均强度相结合会导致对场状态的不恰当比较，2）高纬度地区场强下降，也许反映了“切线圆柱体”或 3) 由于不良的选择标准或不良的实验设计而引入噪音和/或偏差。后者是一种可能的解释，因为 1960 年夏威夷流的公布数据显示了今天在地球表面观测到的整个强度值范围，但它们都应该有一个不同的值。 PI 开发了新的实验方法、更好的场策略和新的数据选择方法，这将使团队能够获得对古代场强的准确估计，从而提高我们对地球过去强度行为的理解。 PI 计划开展一项全面的实地活动，以收集针对古强度研究最有希望的材料的样本。这些将使用最稳健的实验方案进行分析，并遵循严格的选择标准，经证明可以拒绝不准确的结果，从而获得准确和精确的古强度估计。 PI还将完成热剩磁的长期老化实验，以研究数据库中非单域材料的偏差（和噪声）的贡献，着眼于改进实验和数据选择程序，从而提高古强度估计的准确性。

项目成果

PSV10: A Global Data Set for 0-10 Ma Time-Averaged Field and Paleosecular Variation Studies

PSV10：用于 0-10 Ma 时间平均场和古变化研究的全球数据集

• DOI: 10.1002/2017gc007318
• 发表时间: 2018-05
• 期刊: Geosystems
• 作者: Cromwell, G.;Johnson, C. L.;Tauxe, L.;Constable, C. G.;Jarboe, N. A.
• 通讯作者: Jarboe, N. A.

Domain State Diagnosis in Rock Magnetism: Evaluation of Potential Alternatives to the Day Diagram

岩石磁性中的域状态诊断：日图潜在替代方案的评估

• DOI: 10.1029/2018jb017049
• 发表时间: 2019-06
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: Roberts, Andrew P.;Hu, Pengxiang;Harrison, Richard J.;Heslop, David;Muxworthy, Adrian R.;Oda, Hirokuni;Sato, Tetsuro;Tauxe, Lisa;Zhao, Xiang
• 通讯作者: Zhao, Xiang

A Critical Appraisal of the “Day” Diagram

对“日”图的批判性评价

• DOI: 10.1002/2017jb015247
• 发表时间: 2018-04
• 期刊: Journal of Geophysical Research: Solid Earth
• 作者: Roberts, Andrew P.;Tauxe, Lisa;Heslop, David;Zhao, Xiang;Jiang, Zhaoxia
• 通讯作者: Jiang, Zhaoxia

Thermomagnetic recording fidelity of nanometer-sized iron and implications for planetary magnetism

纳米铁的热磁记录保真度及其对行星磁性的影响

• DOI: 10.1073/pnas.1810797116
• 发表时间: 2019-01-22
• 期刊: Proceedings of the National Academy of Sciences
• 作者: L. Nagy;W. Williams;L. Tauxe;A. Muxworthy;Idenildo Ferreira
• 通讯作者: Idenildo Ferreira

Investigating the Accuracy, Precision, and Cooling Rate Dependence of Laboratory‐Acquired Thermal Remanences During Paleointensity Experiments

研究实验室在古强度实验中获得的剩磁的准确性、精密度和冷却速率依赖性

• DOI: 10.1029/2018gc007946
• 发表时间: 2019-01-01
• 期刊: Geochemistry
• 影响因子: 3.7
• 作者: C. N. Santos;L. Tauxe
• 通讯作者: L. Tauxe