Wjhat Hapens When Granite Becomes Metamotphic Rock

Gneiss is a foliated metamorphic rock identified by its bands and lenses of varying composition while other bands contain granular minerals with an interlocking texture.

Wjhat hapens when granite becomes metamotphic rock. Consider how granite changes form. Metamorphic rocks arise from the transformation of existing rock types in a process called metamorphism which means change in form. Metamorphic rocks started out as some other type of rock but have been substantially changed from their original igneous sedimentary or earlier metamorphic form. The original rock is subjected to heat temperatures greater than 150 to 200 c and pressure 100 megapascals 1 000 bar or more causing profound physical or chemical change the protolith may be a sedimentary igneous or existing metamorphic rock.

Other bands contain platy or elongate minerals with evidence of preferred orientation. What happens when granite is eroded and deposited a it crystallizes b it melts into magma c it becomes sediment d it becomes metamorphic rock. These rocks primarily consist of quartz feldspar and mica. In order to create metamorphic rock it is vital that the existing rock remain solid and not melt.

The mineral constituents that create these rocks get recycled over time. In the large outcrop of metamorphic rocks in figure 1 the rocks platy appearance is a result of the process metamorphism. Metamorphic rocks form when rocks are subjected to high heat high pressure hot mineral rich fluids or more commonly some combination of these factors. This will result in the formation of an igneous rock not a metamorphic rock.

When granite is metamorphosed it becomes a rock called gneiss. It is this banded appearance and texture rather than composition that define a gneiss. Metamorphism is the addition of heat and or pressure to existing rocks which causes them to change physically and or chemically so that they become a new rock. The rock cycle simply moves from the igneous to metamorphic to sedimentary rocks and the process repeats itself over and over.

The metamorphic rock that granite forms is gneiss. The rock cycle is a continuous process describing the transformation of the rocks through various stages through their lifetime. If there is too much heat or pressure the rock will melt and become magma. All rocks undergo a series of processes called the rock cycle where one type of rock changes into another.