13 - Development of the passive margin of Eastern North America: Mesozoic rifting, igneous activity, and breakup

Abstract

Field, seismic, and drill hole data constrain the tectonic processes associated with rifting, breakup, and the early stages of seafloor spreading for the passive margin of eastern North America. The onset of rifting, occurring by Late Triassic time, was approximately synchronous along the entire margin. The cessation of rifting (and presumably the onset of drifting) was diachronous, occurring first in the southeastern United States (latest Triassic), then in the northeastern United States and southeastern Canada (Early Jurassic), and finally in the Grand Banks (Early Cretaceous). Magmatism of the Central Atlantic Magmatic Province developed simultaneously (earliest Jurassic, ~200 Ma) throughout the region; it occurred after rifting in the southeastern United States and during rifting in the northeastern United States and maritime Canada. The deformational regime changed after rifting: post-rift shortening (inversion) replaced syn-rift extension. Detached structures associated with salt movement also developed after rifting, especially on the Scotian shelf and Grand Banks.