Plate Tectonics

This chapter explains how pressure and density vary with depth and how they together control the different elevations of continental and oceanic regions, and reviews the fundamental concept of isostasy, the principle of flotation, where the lithospheric plates float on hot underlying mantle. It discusses Airy and Pratt models for isostasy and how and when high surface topography is compensated by a crustal root. The fundamental role of temperature is demonstrated in terms of the geotherm, heat production in the lithosphere, mantle and core, and how the Earth loses heat to the atmosphere through plate tectonic processes. The latter point also relates to how the geotherm varies through the upper crust, which again relates to geothermal energy exploitation. Temperature and pressure variations also control melting and magmatism, and this chapter covers the fundamental principles and characteristics of melting and magma crystallization. Also covered is metamorphic rocks and the metamorphic processes that occur in response to plate tectonic processes. Finally different kinds of sedimentary basins and their formation and classification according to plate tectonics are briefly reviewed.