Question

explain the formation of metamorphic rocks with examples​

Answer 1

Answer:

Explanation:

Metamorphic rocks are formed when igneous rock or sedimentary rock are changed by

great heat and/or pressure. There are three thypes of metamorphic rock, which are

thermal, dynamic and regional.

Thermal metamorphism is when rocks are changed as a result of great heat. Thermal

metamorphism occurs when heat from volcanic activity changes the rock. In Ireland,

quartzite in the Sugar Loaf, Co. Wicklow was formed as a result of this thermal

metamorphism. Here magma came in contact with the surrounding sandstone rock as the

magma upwelled into a fold mountain. The heat from this magma body within the fold

mountain changed the sandstone to quartzite. As a result of weathering on the peaks of this

fold mountain, the quartizite was revealed. Marble is another example of a metamorphic

rock, this time as a result of the thermal metamorphism of limestone.

Dynamic metamorphism occurs when convection currents cause plates to slide past

eachother at passive plate boundaries or collide with eachother. Along fault lines at passive

plate boundaries, the fault line intself can be changed into a ‘fault gouge’ (fine, sticky

powder). Shale is a sedimentary rock which can be put under huge dynamic pressure at

destructive plate boundaries. As a result of this pressure the shale is compressed forming

slate which can be used for roof tiling.

Regional metamorphism is caused when heat and pressure occur over a large area at, for

example, subduction zones. The majority of Ireland’s metamorphic rocks were formed in

this way 450 million years ago during the Caledonian orogenic (see fold mt. answer) period

when the North American and European plates collided. The collision of the plates caused

the rocks to fold and magma rose into the buckled rock. This was at the same time that the

Leinster Batholith was forming. Mudstone in County Wicklow was changed to schist in this

way.

Finally, as a result of metamorphism, mineral crystals within the original rock can be

rearranged to form foliated metamorphic rocks such as slate. Here, the minerals are

flattened into parallel layers.

Answer 2

Answer:

Metamorphic rocks are created by the physical or chemical alteration by heat and pressure of an existing igneous or sedimentary material into a denser form. ... As the Earth's plates move over geologic time, a plate containing igneous or sedimentary rock may become subducted under another plate.

Examples

Common metamorphic rocks include phyllite, schist, gneiss, quartzite and marble. Foliated Metamorphic Rocks: Some kinds of metamorphic rocks -- granite gneiss and biotite schist are two examples -- are strongly banded or foliated.