Mafic The mafic rocks also typically have a higher density than felsic rocks. The term roughly corresponds to the older "basic rock" class. Mafic lava, before cooling, has a low viscosity, in comparison with felsic lava, due to the lower silica content in mafic magma. Water and other volatiles can more easily and gradually escape from mafic lava. As a result, eruptions of volcanoes made of mafic lavas are less explosively violent than felsic-lava eruptions. Most mafic-lava volcanoes are shield volcanoes, like those in Hawaii. Mafic Mafic is an adjective describing a silicate mineral or igneous rock that is rich in
Eoarchean geology highly deformed biotite-hornblende tonalitic to granitic orthogneiss. Subordinate mafic amphibolitic and chloritic elliptical enclaves and inclusions are observed in felsic gneisses.Although the rocks are highly deformed and could not reflect the original field relation between rock units, the chemical composition of the rocks showcases how Eoarchean greenstone-TTG be like. Chemical composition in the mafic inclusion suggests the acasta area was possibly a supra-subduction setting. Dominant felsic rocks are composed of highly deformed tonalitic, granodioritic and granitic gneisses. Inclusion of as early as 4.2 billion years old zircon core are observed in the gneisses. Mafic rocks, i.e. subordinate amphibolite and ultra