Collaborative Research: Holocene Geomagnetic Field Variability from the High-Latitude Southern Hemisphere

目前，南半球大部分地区在过去3000年之前没有详细的定向PSV记录，南半球只有一个详细的全新世（近12000年）古强度记录。这一关键的数据缺口阻碍了开发史前时间间隔的球谐模型，以更好地了解地球深层内部的发电机源，甚至正确解释北半球的PSV记录。ODP Leg 202站点1233、1234、1235和邻近智利南部边缘的站点调查核心为解决这一数据缺口提供了绝佳的机会。在本项目中，研究人员打算：(1)从智利南部大陆边缘（35°S-50°S）附近收集的深海沉积物岩心中恢复4个跨越全新世的定向PSV记录。(2)从这些岩心中恢复至少2个复制的古强度记录。(3)对所有沉积物进行仔细的岩石磁研究（磁矿物学、ARM、IRM、CHI，加上选定的AMS和迟滞测量），以评估环境影响可能对方向或古强度数据产生偏倚的地方。(4)对该地区所有全新世PSV记录进行区域比对，评估数据质量，并将其整合到现有的全新世PSV数据库中，为未来的建模研究提供依据。这一建议的结果将极大地帮助地球全新世磁场变异性的球谐模型的发展，并提供一个更好的整体空间/时间变异性的视角。需要这样的观测和模型来正确评估在地核内作用的发电机过程的性质。更广泛的影响：该项目将指导至少一名高中生，一名本科生和一名付费研究生。最终的古磁学数据集将在PI的网站（http://earth.usc.edu/~slund）上提供，并作为对其他数据库计划的贡献转发。

There are currently no detailed directional PSV records from most of the Southern Hemisphere prior to the last 3000 years and only one detailed Holocene (last 12,000 years) paleointensity record from anywhere in the Southern Hemisphere. This critical data gap precludes developing spherical harmonic models for prehistoric time intervals to better understand dynamo sources in the Earth's deep interior or to even properly interpret PSV records in the Northern Hemisphere. ODP Leg 202 Sites 1233, 1234, 1235 and Site Survey cores adjacent to the southern Chilean margin provide an exceptional opportunity to address this data gap. In this project, the investigators intend to: (1) Recover four replicate directional PSV records spanning the Holocene from deep-sea sediment cores collected adjacent to the southern Chilean continental margin (35 degrees S-50 degrees S). (2) Recover at least two replicate paleointensity records from these same cores. (3) Carry out a careful rock magnetic study of all sediments (magnetic mineralogy, ARM, IRM, CHI, plus selected AMS and hysteresis measurements) to assess where environmental effects might be biasing the directional or paleointensity data. (4) Carry out a regional inter-comparison of all Holocene PSV records from this region to assess data quality and integrate them into an existing Holocene PSV database for future modeling studies. Results from this proposal will significantly aid development of spherical harmonic models of the Earth's Holocene field variability and provide a much better view of the overall space/time variability of the field. Such observations and models are required to properly assess the nature of dynamo processes acting within the Earth's core. Broader Impacts: This project will mentor at least one high school student, one undergraduate student and a paid graduate student. Final paleomagnetic datasets will be made available on the PI's website (http://earth.usc.edu/~slund) and forwarded as a contribution to other database initiatives.