Paleomagnetic detection of relative plate motions and an infrequently reversing core dynamo at 3.5 Ga

# Paleomagnetic detection of relative plate motions and an infrequently reversing core dynamo at 3.5 Ga *Published: 2026 Mar 19* Whether early Earth had a mobile lithosphere and plate tectonics is debated. We present paleomagnetic data quantifying differential motion between lithospheric blocks at ~3.48 billion years ago (Ga). This manifested as [Formula: see text]centimeters per year latitudinal motion of the East Pilbara Craton (Western Australia) across high latitudes, whereas the Barberton Greenstone Belt (South Africa) was stationary at low latitudes. Comparison of this plate motion with candidate analogs suggests either rapid collisional plate tectonics (i.e., an "active-lid") or an episodically mobile lithosphere. We also document the oldest known geomagnetic reversal at ~3.46 Ga, consistent with an axial dipolar dynamo that reversed less frequently than today's. The existence and rates of these surface and core geophysical phenomena provide geodynamic context to Earth's early geophysical and biological evolution. DOI: 10.1126/science.adw9250