Opening of the North Atlantic Ocean
The opening of the North Atlantic Ocean is a geological event that has occurred over millions of years, during which the supercontinent Pangea broke up. As modern-day Europe (Eurasian plate) and North America (North American Plate) separated during the final breakup of Pangea in the early Cenozoic Era,[1] they formed the North Atlantic Ocean. Geologists believe the breakup occurred either due to primary processes of the Iceland plume or secondary processes of lithospheric extension from plate tectonics.
Active vs. passive plates[edit]
Active rifting, such as is formed by the Iceland plume, is driven by hotspot or mantle plume activity. From deep within the Earth, hot mantle rises to force doming of the crust.[10] This causes thinning of the crust and lithosphere, then melting and underplating occur.[10] Finally, there is rifting at the crest of the domed crust and volcanism occurs.[10] In passive rifting, driven by plate tectonics, the crust and lithosphere extend as a result of plate boundary forces such as slab pull.[10] Far field stresses thin the crust and lithospheric mantle, and hot asthenospheric mantle passively enters the thinned area.[10] The upwelling of asthenosphere is not involved in the actual rifting process. The upward flow of the asthenosphere results in decompression melting, magmatic underplating and some volcanism that may occur in the rift area.[10]