The role of deformation on the thermal regime in thrustbelts can be divided into three areas of control:

1. the velocity at which different thrust sheets are emplaced on top of each other, which controls the rate at which their thermal regimes affect each other;

2. the heating provided by the internal deformation of the thrust sheet material; and

3. the heating provided by the friction along the décollement and major thrust faults.

Role of the shortening rate

Shortening brings a hanging wall from depth to rest on top of the footwall, causing warming of the footwall by increased burial and cooling of the hanging wall by placing it into a cooler thermal regime. This concept can be illustrated by petrological data from footwall rocks, which reflect pressure and temperature increase during thrusting, and from hanging wall rocks, which record retrograde reactions (Karabinos, 1984a, b; Chamberlain and Zeitler, 1986; Trzcienski, 1986).

In order to discuss the effect of the velocity at which different thrust sheets are emplaced on top of each other, a set of finite-element models has been designed for various types of thrustbelt structures (Henk and Nemčok, 2000). Because the report in which the results have been described has restricted circulation, they will be discussed here in detail.

Because the shortening rate affects the duration of the heat transfer between thrust sheets moving on top of each other, it is extremely important to understand which rates are realistic for natural cases.While a rate of centimetres per year is appropriate for plate movements, typical shortening rates for local structures in active thrustbelts are in millimetres per year (Table 9.3a).