Waned mantle upwelling contributes to a heavily deformed northern smooth plains on Mercury

Recent discoveries of young contractional landforms and grabens indicate that tectonic activity in Mercury's northern smooth plains (NSP) has persisted into geologically recent times. To investigate the mechanisms sustaining this extended activity, we conduct a comprehensive assessment of contractional strain across the NSP. Our analysis reveals that (1) the NSP exhibits higher strain than other terrane on Mercury, and (2) the surface deformation pattern is spatially correlated with the Northern Rise (NR) at the center of the NSP, suggesting an additional driving force. We hereby propose that this higher strain and its distribution result from waned mantle upwelling induced by deep mantle flows beneath the NR. Sustained variations in dynamic topography likely fueled the long-standing tectonism in the NSP. These findings provide new perspectives on Mercury's evolution and underscore the importance of regional processes in shaping planetary tectonics.