GEOL 1001 Chapter : Chapter 4
Document Summary
Melting and crystallization: reverse processes: crystalline structure vibrates, vibrations increase with temperature, structure expands, melting= breaking of chemical bonds. Crystal structure loses order: crystallization= reverse of melting. Liquid cools, ions pack close together, chemical binds form. Igneous rocks form from solidification of liquid rock (magma) in several different ways. Igneous processes within the earth produce intrusive(plutonic) idneous rock. Igneous processes on or near earths surface produce extrusive(volcanic) rock. How do we know a rock is igneous: directly observe the formation of molten rocks, cross cutting the country rocks and truncation of structures, contact metamorphic effects (baking, textures such as glasses and vesicles. Intermediate igneous rocks: mafic igneous rocks, ultramafic igneous rocks. Each group has different characteristics: compositions, mineral content, melt temperature, viscosity (ad explosive nature, felsic/granitic: mostly quartz and feldspar, about 10% dark, silica rich, continental crust, mafic/basaltic. Intermediate/andesitic > 25% dark silicates, plagioclase, volcanic activity at continental margins: ultramafic: rare surface, peridotite (upper mantle)
