The passive margin of the U.S.A.

Abstract

The E coast of the USA is the archetypal passive margin. Draped over the basement are sedimentary rocks of Middle Jurassic to Holocene age, thickest in five major basins that dominate the structure. The US Atlantic margin broke apart during the Middle Jurassic at roughly the same time as the Gulf of Mexico. Both areas underwent a shift in major spreading center a few million years after break-up, leaving an extinct spreading center and oceanic crust north of Florida and an unusually wide transitional crust under the Blake-Bahamas region.-Author Dept. Geol. Sci., Rutgers Univ., New Brunswick, NJ 08903, USA.