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The appearance of magmatic rocks on the surface or near it is the result of a certain chain of processes, a list of which might look like the following: (a) a partial or complete melting of the upper mantle and the formation of a primary magmatic emulsion; (b) rise of the primary magmatic emulsion; (c) isolation of basaltic asthenoliths; (d) rising of asthenoliths; (e) a change in composition of the primary magma as a result of differentiation, assimilation and contamination; (f) heating of the crust, regional metamorphism, melting of rocks of the crust, gneissification and granitization.
This paper aims to give a brief survey of the probable nature of the processes mentioned above from the viewpoint of the tectonic environment in which they occur. This is the view of a tectonist concerning magmatism. The survey is confined to the continents.
