What metamorphic rocks are contact?
Contact Metamorphism (often called thermal metamorphism) happens when rock is heated up by an intrusion of hot magma. In this photo, the dark grey rock is an intrusion (a sill) between layers of a paler grey limestone. Just above and below the intrusion, the limestone has been altered to form white marble.
Where are contact metamorphic rocks found?
Contact metamorphism is usually restricted to relatively shallow depths (low pressure) in the Earth because it is only at shallow depths where there will be a large contrast in temperature between the intruding magma and the surrounding country rock.
What are the minerals found in metamorphic rock?
Metamorphic minerals Examples include sillimanite, kyanite, staurolite, andalusite, and some garnet. Other minerals, such as olivines, pyroxenes, hornblende, micas, feldspars, and quartz, may be found in metamorphic rocks, but are not necessarily the result of the process of metamorphism.
What is an example of contact metamorphism?
An example of contact metamorphism is the metamorphic rock marble. Marble is created from limestone that has been subjected to heat. Regional metamorphism by contrast takes place over large areas and is high-grade metamorphism.
How is contact metamorphism produced?
Contact metamorphism. This is metamorphism produced by intrusion of magma. Heat and fluids from the crystallizing magma cause chemical and mineralogical changes in the rocks being intruded.
What are the main factors of contact metamorphism?
Contact metamorphism occurs due to heating, with or without burial, of rocks that lie close to a magma intrusion. It is characterized by low P/T gradients, as strong thermal gradients between an intruding magma and adjacent country rock are best established at shallow crustal levels.
How do you identify contact metamorphism?
Contact metamorphism does not involve directed pressure that deforms or squashes the rocks, so contact metamorphic rocks don’t usually have foliated textures like textures found in regionally metamorphosed rocks. The non-foliated appearance of rocks like marble and quartzite are often described as granular or sugary.
What is the difference between regional and contact metamorphism?
Contact metamorphism is a type of metamorphism where rock minerals and texture are changed, mainly by heat, due to contact with magma. Regional metamorphism is a type of metamorphism where rock minerals and texture are changed by heat and pressure over a wide area or region.
What is the effect of contact metamorphism?
reconstituted through the processes of contact metamorphism, in which heat and fluids cause mineralogic and chemical changes in the parent rock of the xenolith; a study of these changes can give information on the temperature and composition of the magmatic body.
What is the major source of heat for contact metamorphism?
Contact metamorphism is a process of changing the physical form of a solid rock or mineral by exposure to high temperatures and pressure. The major source of heat for contact metamorphism is the sun.
What does contact metamorphism create?
Heat is important in contact metamorphism, but pressure is not a key factor, so contact metamorphism produces non-foliated metamorphic rocks such as hornfels, marble, and quartzite. Any type of magma body can lead to contact metamorphism, from a thin dyke to a large stock.
In which setting might contact metamorphism be most likely to occur?
Most regional metamorphism takes place within continental crust. While rocks can be metamorphosed at depth in most areas, the potential for metamorphism is greatest in the roots of mountain ranges where there is a strong likelihood for burial of relatively young sedimentary rock to great depths.