The Nature of the Mid-Archean Geomagnetic Field

点击翻译按钮获取中文摘要

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.