TissotIndikatrix

The Tissot Indikatrix, also known as the Tissot's indicatrix or indicatrix of deformation, is a graphical representation used in geology and structural geology to describe the strain experienced by a rock body. It was introduced by the Swiss geologist Henri Tissot in 1959. The indicatrix is a graphical tool that helps geologists visualize and quantify the deformation of rocks, such as stretching, shortening, and rotation, that occur due to tectonic forces.

The Tissot Indikatrix is constructed by plotting the deformed positions of a set of points that were initially arranged in a regular grid pattern. The resulting shape of the indicatrix provides information about the type and magnitude of strain experienced by the rock. For example, an ellipse-shaped indicatrix indicates that the rock has undergone differential strain, with different amounts of stretching and shortening in different directions. A circle-shaped indicatrix, on the other hand, indicates that the rock has experienced uniform strain, with equal amounts of stretching and shortening in all directions.

The Tissot Indikatrix is widely used in structural geology to analyze and interpret the deformation history of rocks. It is particularly useful in studying fold and fault structures, as well as in understanding the kinematics of tectonic processes. By examining the shape and orientation of the indicatrix, geologists can gain insights into the stress field that caused the deformation and the resulting strain patterns in the rock. The Tissot Indikatrix is a valuable tool for geologists to unravel the complex history of deformation in the Earth's crust.