Genesis
Silica-undersaturated igneous rocks typically are formed by low degrees of partial melting in the Earth's mantle. Carbon dioxide may dominate over water in source regions. Magmas of such rocks are formed in a variety of environments, including continental rifts, ocean islands, and supra-subduction positions in subduction zones. Nepheline syenite and phonolite may be derived by crystal fractionation from more mafic silica-undersaturated mantle-derived melts, or as partial melts of such rocks. Igneous rocks with nepheline in their normative mineralogy commonly are associated with other unusual igneous rocks such as carbonatite.
Read more about this topic: Nepheline Syenite
Famous quotes containing the word genesis:
“If only he would not pity us so much,
Weaken our fate, relieve us of woe both great
And small, a constant fellow of destiny,
A too, too human god, self-pity’s kin
And uncourageous genesis . . .”
—Wallace Stevens (1879–1955)
“Nature centres into balls,
And her proud ephemerals,
Fast to surface and outside,
Scan the profile of the sphere;
Knew they what that signified,
A new genesis were here.”
—Ralph Waldo Emerson (1803–1882)
“Power is, in nature, the essential measure of right. Nature suffers nothing to remain in her kingdoms which cannot help itself. The genesis and maturation of a planet, its poise and orbit, the bended tree recovering itself from the strong wind, the vital resources of every animal and vegetable, are demonstrations of the self-sufficing and therefore self-relying soul.”
—Ralph Waldo Emerson (1803–1882)