![]() Stresses caused by plates colliding in the process of mountain building. The huge weight of overlying layers of sediments. There are 3 factors that cause an increase in pressure which also causes the formation of metamorphic rocks. The diagram above shows you where metamorphic rock (YELLOW ZONE) can be produced at a subduction zone. When rock melts it is then considered igneous not metamorphic, but the rock next to the melted rock can be changed by the heat and become a metamorphic rock. Some of the descending rock will melt because of this friction. The descending of rock layers at subduction zones causes metamorphism in two ways the shearing effect of the plates sliding past each other causes the rocks coming in contact with the descending rocks to change. The great weight of these layers also causes an increase in pressure, which in turn, causes an increase in temperature. The deeper the layers are buried the hotter the temperatures become. As we descend into the earth the temperature increases about 25 degrees Celsius for every kilometer that we descend. ![]() Temperature increases can be caused by layers of sediments being buried deeper and deeper under the surface of the Earth. Factors that cause an increase in Temperature, Pressure, and Chemical changes are the three agents that we are going to study. There are 3 main agents that cause metamorphism. Solid rock can be changed into a new rock by stresses that cause an increase in heat and pressure. This changing of rock types is called the "Rock Cycle". The diagram above shows you how the rocks on Earth have been changed continually over time from one rock type to another. The word "metamorphic" comes from Greek and means "To Change Form". ![]() The parent rock can be either sedimentary, igneous, or even another metamorphic rock. Metamorphic rocks form from heat and pressure changing the original or parent rock into a completely new rock. Sedimentary rocks are formed from the cementing together of sediments, or from the compaction (squeezing together) of sediments, or from the recrystallization of new mineral grains which are larger than the original crystals. Igneous rocks form when rocks are heated to the melting point which forms magma. Rocks are formed on Earth as igneous, sedimentary, or metamorphic rocks. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |