EPS Colloquium – Roger Fu, Harvard University

Understanding conditions on early Earth and Mars using high-resolution paleomagnetism

Plate tectonics and a magnetic core dynamo represent two fundamental links between the interior dynamics of a planet and its surface environment. Paleomagnetic studies have documented these processes over most of Earth history, but the sparse rock record severely limits our understanding at ages greater than about 3 billion-years-ago (Ga). I will discuss how recent advances in magnetic field sensing have enabled new ways to retrieve and verify ancient magnetic signals preserved in complex samples, including early Earth rocks and martian meteorites. Our studies have demonstrated the existence of mobile-lid plate tectonics and a reversing geodynamo on Earth as early as 3.5 Ga, implying remarkable stability in the Earth’s internal processes throughout much of its history. Applying these techniques to Martian meteorites suggests that the martian core dynamo persisted until at least 3.9 Ga, approaching the time of active hydrology in the late Noachian.

To be added to the EPS colloquium mailing list, please contact Caroline Carr at carolinecarr@fas.harvard.edu.

Roger Fu is enthusiastic about old rocks and optics, among other things. He holds a PhD in planetary sciences from MIT after a Harvard undergraduate degree in Earth science and astronomy and a short interlude studying ethnoastronomy. Since 2017, he has headed the Paleomagnetics Lab at Harvard University.