Geodynamics of the lithosphere. Quantitative description of geological problems / Геодинамика литосферы. Количественное описание геологических проблем

The large scale structure of the earth is caused by geodynamic processes which are explained using energetic, kinematic and dynamic descriptions. While “geodynamic processes” are understood to include a large variety of processes and the term is used quite loosely, the methods of their description involve well defined fields. Energetic descriptions are involved with distribution of energy in our planet, typically expressed in terms of heat and temperature. Kinematic descriptions describe movements using velocities, strains and strain rates. Dynamic descriptions indicate how stresses and forces behave.
In the field, we document only the consequences of geological processes. The underlying causes are much harder to constrain directly. Nevertheless, if we want to explain the tectonic evolution of our planet, we need to interpret these causes or: “driving forces” . For this, we need to find a dynamic description of geological processes that is consistent with our observations. Our descriptions relate causes and consequences - tectonic processes with field observations. In many cases, we will use equations as a concise form to describe processes and observations in nature. As we will be dealing mostly with large scale tectonic questions, the observations that we shall use are also on a large scale. For example, we shall use observations on the elevation (Fig. 1.1) and heat flow of mountain ranges, the thickness of continents and the water depth of the oceans.
As the processes we seek to describe are changing with time or space, many of the descriptive equations will be differential equations. However, it is not the aim of this book to confuse the reader with high level mathematics. Rather it is the aim to introduce field geologists to the beauty and simplicity of descriptions with equations. Thus, all equations will be explained from basic principles so that an intuitive understanding can be achieved. While I prefer the term “description”, many colleagues would refer to the contents of this book as “modeling”. Thus, it appears useful to begin this book with a discussion what we mean when we use the word “model”. <...>