Scripps Institution of Oceanography
2020-2021 Distinguished Lecturer
Hunting the magnetic field through ocean drilling
Earth’s magnetic field has been the target of scientific investigation for over four centuries yet the basic fact that the field switches polarities, though suspected for over a century was not proven until the early sixties. This fact was key to the plate tectonic revolution and part of the rationale to begin drilling the ocean floor with the Deep Sea Drilling Project over fifty years ago. And the study of the Earth’s magnetic field has remained an integral part of ocean drilling throughout the history of endeavor.
In addition to flipping polarity, the Earth’s magnetic field changes both direction and strength on time scales from decades to millennia. Human observations of field directions provide constraints for field behavior since the age of maritime exploration starting in the fifteenth century but field strength measurements only started in the 19th century, so understanding of the geomagnetic field requires the use of “accidental” records such as sediments and igneous rocks. Because 70% of the surface of the Earth is covered by ocean, marine records are essential to get a global view of history of the Earth’s magnetic field and records beyond a few million years require ocean drilling.
The International Ocean Discovery Program maintains cores from fifty years of drilling. Magnetic measurements on these cores continue to provide clues as to the timing and nature of magnetic reversals, attempted reversals (excursions), and the rise and fall in field strength since the Jurassic. Prof. Tauxe will share paleomagnetic results not only from her most recent experience on IODP Expedition 382 to the “Iceberg Alley” in the Scotia Sea but also from previous expeditions since DSDP Leg 73.
Dr. Lisa Tauxe is Distinguished Professor of Geophysics at the Scripps Institution of Oceanography, University of California, San Diego. She received her PhD from Columbia University and participated in her first expedition (Leg 73) while a graduate student. She has sailed on a total of five expeditions (Legs 73, 108 and Expeditions 318, 355 and 382).