The Nature of the Mid-Archean Geomagnetic Field

晚太古宙/早元古代(约270万至250万年)的古地磁和古地磁强度数据显示了过去2亿年来地磁场的许多特征。然而，在此之前，我们对该地区的情况尚不清楚，因为即使是保存最好的岩石，也可能经历了长期的低级变质条件。一种新的CO2激光/超导量子干涉装置(SQUID)磁强计方法首次提供了分析单个定向硅酸盐颗粒的古地磁和古强度特征的机会。这些颗粒含有微小的磁性包裹体，应该能保留原始的磁化作用。将开展一项联合实验室和实地计划，重点是分析Kaapva al Craton(南部非洲)的太古代深成岩。研究早期地球和内核的广泛科学家以及参与行星发电机数值模拟和实验模拟的科学家将对太古代地磁场性质的定义感兴趣。这项工作将通过开发二氧化碳激光/SQUID磁强计系统，为科学基础设施和教育事业做出贡献。本科生和研究生将参与与该项目有关的所有活动，包括实地考察、设备开发和实验室分析。

Paleomagnetic and paleointensity data of late Archean/early Proterozoicage (approximately 2.7 to 2.5 million years old) show many of thehallmarks of the geomagnetic field of the last 200 million years. Ourpicture of the field prior to this time, however, is unclear becauseeven the best-preserved rocks have likely seen prolonged low-grademetamorphic conditions. A new CO2 laser/superconducting quantum interferencedevice (SQUID) magnetometer approach affords the opportunity to analyzefor the first time paleomagnetic and paleointensity signatures of single,oriented silicate grains. These grains contain minute magnetic inclusionsthat should preserve original magnetizations. A joint laboratory and fieldplan will be pursued, focused on the analysis of Archean plutonic rocks ofthe Kaapvaal Craton (southern Africa).The definition of the nature of the Archean geomagnetic fieldwill be of interest to a broad range of scientists studyingthe early Earth and inner core, as well as those involvedin numerical and experimental simulations of planetary dynamos. The workwill contribute to scientific infrastructure, through the development ofthe CO2 laser/SQUID magnetometer system, and to education. Undergraduateand graduate students will be involved in the full range of activitiesassociated with the project, including field studies, equipmentdevelopment and laboratory analyses.