Explore the fascinating world of basalts and their role in understanding Earth's mantle composition and structure in this comprehensive geology lecture. Delve into the two main types of basalts, learn to interpret the basalt tetrahedron, and discover the key differences between alkaline and tholeiitic basalts. Examine the nepheline-quartz phase diagram and its relationship to basalt categories. Uncover four main methods for determining mantle composition and structure, and gain insights into Earth's interior layers. Investigate the processes that induce partial melting of the mantle and the resulting magma compositions. Consider the ongoing debate about the source of alkali and tholeiitic basalts, and explore four types of magma-generating environments. Enhance your understanding of igneous petrology and Earth's deep processes through this informative geological exploration.