Unusually Large Subsidence and Sea-Level Events during Middle Paleozoic Time - New Evidence Supporting Mantle Convection Models for Supercontinent Assembly

New evidence from basin modeling documents a nearly synchronous episode of rapid subsidence between Middle Devonian and earliest Mississippian time in almost all preexisting margins and interior basins of North America. The subsidence events appear to have been accompanied by a large sea-level rise relative to the stable cratonic platform. Herein we suggest that the timing and magnitude of basin subsidence and sea-level change are compatible with predictions by recent mantle-convection models for the assembly of supercontinents. If so, the sea-level and subsidence events were consequences of the onset of accretion of Pangea above a major zone of mantle downwelling.