One of the major uses of seismic data is to identify sub-surface structures in sedimentary rocks. Sedimentary rocks are normally laid down in horizontal layers, and so any dip, cracks or bends that can be seen are the products of deformation. These changes to the rocks are caused by tectonic forces exerting stresses on the rocks that lead to permanent strain.
Deformation is divided into two main groups according to the behaviour of the rocks:
- Brittle deformation: the rock breaks when subjected to stress
- Ductile deformation: the rock bends or flows when subjected to stress
There are many excellent resources in books and the internet explaining the different types of deformation, the structures they produce and the tectonic forces involved.
Rather than repeat the information already available, this part of Sub-surf Rocks! provides an opportunity to apply knowledge of deformation to a series of images and exercises that illustrate various structures using seismic data.
It is strongly recommended that you are familiar with the basic concepts of deformation before you attempt the exercises.