Plate Tectonics

This first of three chapters on orogeny presents a general introduction to mountain belts and further focuses on mountain belts formed by accretion of material onto a convergent plate boundary. The chapter starts out emphasizing some of the many tectonic scenarios that can lead to accretionary orogeny. The first example covered is Taiwan, where the transition from a regular accretionary wedge to an actual orogenic belt created by arc collision can be studied. Slab tear and the flipping of subduction is also covered by this example. The prime example of an accretionary mountain belt is the Andes, which is given special attention in this chapter with several maps and profiles. The Andes mountain chain shows lateral variations in terms of timing of orogenic initiation, orogenic events, arc collisions, magmatism, topographic development, strain and width. The chapter also covers the lateral and temporal variation in subduction zone dip and its implications. It continues by exploring tectonostratigraphic terranes and uses the North American Cordillera as the main example. The growth of western North America through repeated accretionary events is also explored, before exploring implications of accretionary orogeny for surface processes, climate and biodiversity.