What is the difference between regional metamorphism and contact

Regional metamorphism occurs as a result of convergent tectonic activity and is usually characterised by low temperature and high pressure conditions. Thus this type of metamorphism is often associated with orogenic events and over a large area causes metamorphism. Under regional metamorphic conditions, Barrovian zone sequences and structures such as folds are formed. Conversely, contact metamorphism usually occurs under higher temperature conditions associated with ignorant intrusions on a smaller scale.

The formed rocks are usually called hornfels. Contact Metamorphism occurs when magma comes into contact with an existing rock body. When this happens, the temperature of the existing rocks rises and is also infiltrated with the magma fluid. The area affected by magma contact is usually small, ranging from 1 km to 10 km. Contact metamorphism produces rocks like marble, quartzite, and horns that are non-foliated rocks without any cleavage. Regional metamorphism takes place over a much wider area.

This metamorphism creates rocks like gneiss and schist. Regional metamorphism, as its name suggests, works over much larger areas. Each type of metamorphism generates distinct rock types. Contact processes work by raising the local temperature and producing hornfels. This is contact metamorphism. Note: Even if formed during regional metamorphism, quartzite and marble do not necessarily exhibit foliation because their minerals quartz and calcite respectively do not tend to show alignment.

See also:. Classification of Metamorphic Rocks. What is a metamorhpic rock and how are they formed? How is foliation formed in metamorphic rocks and what can it tell you about the conditions of How are metamorphic rocks classified? What are the characteristics of foliated and non-foliated metamorphic rocks?