The tectonic evolution of the Labrador-Baffin Seaway began with Early Cretaceous extension between Greenland and North America, resulting in the development of basins infilled with nonmarine and shallow-marine clastic strata. The Late Cretaceous was a time of continued rifting and local subsidence, with deposition of widespread deeper water marine mud and localized sand deposits. Seafloor spreading began in the south in the Latest Cretaceous and propagated throughout the seaway by the Early Paleocene. Regional seafloor spreading coincided with the onset of significant volcanism in the Davis Strait to central West Greenland region, as well as a regional regression. A change in the spreading direction around the Paleocene- Eocene boundary, was accompanied by strike-slip motion in the Davis Strait and Baffin Bay, deformation and basin inversion, and development of regional unconformities. After seafloor spreading ceased in the late Eocene, the seaway was filled by upper Paleogene to Recent sediments, with clinoform progradation building the modern-day shelves.