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
Archean felsic volcanic rocks these felsic sequences and dating their time of formation, stratigraphic units of different locations can be correlated despite the obstacles or discontinuity in between felsic volcanic units. The geochronology of Archean events strongly relies on U-Pb dating and Lu-Hf dating. Since mafic rocks (contain low silica content, such as basalt) are lack of zircon, only the age of felsic rocks can be dated among the volcanic rocks in greenstone belts. As felsic volcanic rocks are episodically deposited in between mafic layers, the age range of a particular mafic layer can be constrained by the upper and lower felsic volcanic layers.