Episodic Vertical Movements of Supposedly Stable Cratons

Cratons are generally held to be stable, but stability means different things to different specialities. A key characteristic of cratons is the scarcity of cover rocks on Precambrian basement. This property has led many to assume—explicitly or indirectly—that the gap in the stratigraphic record represented by the lack of Phanerozoic cover implies tectonic stability over millions of years. Here we show that supposedly stable cratons have experienced multiple episodes of subsidence and uplift at the scale of kilometres, involving deposition and removal of sedimentary covers. These episodes affect regions at a continental scale, including cratons as well as continental margins.We present a series of case studies based on observations of regional landscapes in relation to stratigraphic constraints and thermal histories derived from apatite fission-track analysis. Evidence of former covers is commonly dismissed as unrealistic, but evidence of vertical movements of cratons has been known for decades, so we question why this is not widely accepted. Some may consider kmscale movements to be insignificant or choose to assume stability based on conventional thinking, while others dismiss the evidence due to the lack of an accepted mechanism by which such covers could have been deposited and removed. To counter that argument, we suggest a variety of lithospheric and sub-lithospheric processes that may explain the observations presented here. It is time to reject the paradigm of cratonic stability and accept that cratons have undergone positive and negative, km-scale vertical motions over geological timescales.