The volume of magma produced is minor in comparison to that generated at oceanic rises and at convergent plate boundaries. Flood basalts are the most common form of occurrence. read more
Convergent plate boundaries Igneous rocks associated with convergent plate boundaries have the greatest diversity. In this case, granite batholiths underlie the great composite volcanoes and consist of rocks ranging from basalt through andesite to dacite and rhyolite. read more
What rocks are present at the other two types of plate boundaries depends on where those boundaries are and what rock types are already present, mostly. At a convergent plate boundary, we find intermediate composition intrusives and volcanics forming due to compression, melting and assimilation of sediments, remelting of existing igneous rock, and subsequent intrusion and volcanism. read more