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The longevity of cratons usually implies that the entire cratonic lithosphere remained unchanged over billions of years, which is traditionally attributed to their intrinsically buoyant and strong lithospheric roots. By reviewing relevant studies and recent observational constraints, we show that the present cratonic roots are notably denser than the ambient mantle, with the compositional buoyancy offsetting only one-fifth of the negative thermal buoyancy. In addition, the presence of a weak mid-lithospheric discontinuity could decouple the upper and lower lithosphere upon perturbation, allowing delamination of the lower portion, while most of the delaminated lithosphere would eventually relaminate to the base of the lithosphere after sufficient warming inside the convective mantle. This process generates enduring (>100 Myr) and prominent (>1 km) surface uplifts within continents, a mechanism more compatible with data, especially those reflecting lithospheric deformation, than the model of all continents climbing up a steady region of dynamic uplift. Subsequent lithospheric cooling gradually draws the surface down to below sea level, where the lithospheric mantle density reaches a maximum upon formation of the next supercontinent. We argue that such cratonic deformation has happened repeatedly over supercontinent cycles since the Neoproterozoic and has largely shaped the properties of the present cratonic lithosphere. A few new research directions are also suggested. 

Abstract Extensive Mesozoic rifting along the eastern North American margin formed a series of basins, including the Hartford basin in southern New England. Nearly contemporaneously, the geographically widespread Central Atlantic Magmatic Province (CAMP) was emplaced. The Hartford basin provides an ideal place to investigate the roles of rifting and magmatism in crustal evolution, as the integration of the dense SEISConn array and other seismic networks provides excellent station coverage. Using full‐wave ambient noise tomography, we constructed a detailed crustal model, revealing a low‐velocity (Vs = 3.3–3.6 km/s) midcrust and a high‐velocity (Vs = 4.0–4.5 km/s) lower crust beneath the Hartford basin. The low‐velocity midcrust may correspond to a layer of radial anisotropy due to extension and crustal thinning during rifting. The high‐velocity crustal root likely represents the remnant of magmatic underplating resulting from the CAMP event. Our findings shed light on crustal modification associated with supercontinental breakup, rifting, extension, and magmatism.