simatic

In this process the sial is squeezed out laterally and forms the nuclei of continents, while the subsided region becomes an ocean basin. Thereafter the low-lying basins. which are comprised of solid basic or simatic material. continue to attract basic volcanism because the basic lavas are lighter than their solid counterparts. On the other hand. the high-standing sialic continents largely prevent the extrusion of basic lavas on their surfaces because they are less dense on the average than the basic magmas. By these mechanisms the continents and ocean basins are preserved and continue to grow.

1977, Robert F. Mueller & Surendra K. Saxena, Chemical Petrology: with applications to The Terrestrial Planets and Meteorites, Springer-Verlag, →DOI, →ISBN, page 110