Sima (geology)

Sima is a term used in geology to describe the layer of the Earth's crust that is rich in silicate and magnesium minerals. It is an abbreviation derived from "silicate" and "magnesium." Sima primarily constitutes the oceanic crust and is generally found beneath the oceanic lithosphere, where it is composed mostly of basalt and gabbro. In contrast to sima, a term "sial" refers to the continental crust, which is rich in silica and aluminum.