Essentials of igneous and metamorphic petrology / Основы магматической и метаморфической петрологии

Petrology, from the Greek words petra , meaning rock, and logos, meaning knowledge, is the study of rocks and the conditions in which they form. It includes igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together because both disciplines depend on the use of chemistry and phase diagrams. In contrast, sedimentary petrology is oft en combined with stratigraphy because both of these sciences depend on understanding the physical processes that accompany the deposition of sediments. Igneous and metamorphic petrology share common foundations; for example, both use phase diagrams to understand the conditions that control the crystallization of various minerals. However, there are important diff erences between the disciplines. In igneous petrology, the bulk composition of the rock is important because it gives clues to the tectonic environment in which it formed. Metamorphic petrology is not so much concerned with the bulk chemistry of the rocks as with the use of mineral assemblages to determine the conditions under which the rock crystallized. Because igneous rocks may later be transformed into metamorphic rocks, this book begins with igneous petrology and takes up metamorphic petrology second.