how does a metamophic rock form.
http://www.cdli.ca/CITE/rocks_metamorphic.htm
http://gpc.edu/~pgore/Earth&Space/metamorphic-notes.html
Metamorphic rocks are formed when pre-existing rocks, whether sedimentary, igneous, or other metamorphic rocks, undergo a process called metamorphism. This process occurs deep within the Earth's crust, typically at depths below 10 kilometers. Here is a step-by-step explanation of how a metamorphic rock forms:
1. Heat: The primary factor in the formation of metamorphic rocks is an increase in temperature. The heat can come from several sources, including magma intrusion, burial deep beneath the Earth's surface, or tectonic forces causing rocks to be pushed down into the hot mantle.
2. Pressure: Along with heat, pressure plays a crucial role in the formation of metamorphic rocks. Two types of pressure are involved: confining pressure, which is uniform in all directions, and directed pressure, which is applied from a specific direction. Elevated pressure causes the minerals within the rock to recrystallize and reorient themselves to form new minerals and textures.
3. Differential stress: As rocks are subjected to directed pressure, it can result in differential stress. This stress causes the minerals to align in a specific orientation along planes or foliation, giving the rock a layered or banded appearance.
4. Chemical reactions: Under the influence of heat and pressure, the minerals within the rock can chemically react to form new minerals. For example, clay minerals can be transformed into mica minerals, or limestone can be metamorphosed into marble.
5. Recrystallization: As the temperature and pressure increase, the original minerals within the rock can recrystallize into more stable, denser minerals. The new minerals can be larger in size and have a different composition than the original minerals.
6. Regional or contact metamorphism: Metamorphism can occur through regional metamorphism or contact metamorphism. Regional metamorphism occurs over large areas due to tectonic forces, while contact metamorphism happens when rocks come into contact with a high-temperature heat source like magma.
Overall, the transformation of a rock into a metamorphic rock involves the reorganization and alteration of the original mineral composition and texture, resulting in a new rock with different physical and chemical properties.
Metamorphic rocks are formed through a process called metamorphism, which involves changes in temperature, pressure, and chemical composition deep within the Earth's crust. This transformation occurs in response to geological forces such as tectonic activity or when rocks are buried beneath other rocks.
To better understand how metamorphic rocks form, you can follow these steps:
1. Start by researching the basics of metamorphism. Websites that provide information about geology and rocks, such as the ones you mentioned (http://www.cdli.ca/CITE/rocks_metamorphic.htm and http://gpc.edu/~pgore/Earth&Space/metamorphic-notes.html), will have detailed explanations and diagrams to help you visualize the process.
2. Familiarize yourself with the main factors that contribute to metamorphism: heat, pressure, and the presence of fluids. These factors cause changes in the minerals and textures of the original rock, leading to the formation of a metamorphic rock.
3. Study the different types of metamorphism. Regional metamorphism occurs when rocks are subjected to intense heat and pressure over a large area due to tectonic forces. Contact metamorphism occurs when rocks come into direct contact with magma, resulting in localized heating and altering the surrounding rocks.
4. Learn about the different textures and structures found in metamorphic rocks, such as foliation, which is the parallel alignment of minerals within the rock. Other structures include banding, folding, and the presence of index minerals.
5. Explore examples of metamorphic rocks, such as marble, which forms from limestone, and slate, which forms from shale. Understand the processes that occur during the transformation of these original rocks into new metamorphic rocks.
By following these steps, you will gain a deeper understanding of how metamorphic rocks form and the conditions under which they are created. Remember to consult reputable sources for accurate information and continue your research to expand your knowledge further.