The origin of different kinds of igneous rocks can be understood in terms of their tectonic setting, and by way of the isotope compositions of strontium, neodymium, and lead. This book explains the petrogenesis of igneous rocks as a consequence of tectonic processes resulting from interactions between asthenopheric plumes and the overlying lithospheric mantle. The relevant principles of isotope geochemistry are explained in the first chapter, making it accessible for university students as well as professionals. The relevant isotopic data is presented in diagrammatic form. The book contains more than 400 original drawings.