Introducing tectonics, rock structures and mountain belts / Знакомство с тектоникой, горными структурами и горными поясами

Meaning and scope of the terms ‘tectonic’ and ‘structure’ The adjective ‘tectonic’ merely means ‘structural’, i.e. applying to a structure. However, in geological usage it has come to be applied particularly to large-scale structures – thus ‘tectonic plate’. In order to explain rock structures, it is necessary to understand the forces operating within and on the crust that are responsible for creating them, and to do this, we need to investigate the Earth-scale processes known collectively as plate tectonics. The term ‘structure’ in everyday usage refers normally to a building or other artificial construction, but in geological terms it has come to mean a body of rock whose shape can be defined geometrically and which has originated by a geological process. The most obvious and best known types of geological structure are folds and faults, which have been produced by the action of geological forces within the Earth’s crust and which can give us an insight into the magnitude of these forces and how they operate. Another group of structures is typical of deep-seated metamorphic rocks where crustal forces have effected thoroughgoing changes in the rock, producing new textures through recrystallisation; the structure produced by such changes is known as the fabric. A fourth category of geological structures consists of igneous intrusions. Such bodies are influenced by the forces acting within the crust during their emplacement and the igneous bodies themselves may cause structural changes in the host rocks. <...>