Associate Program Material History of Rock Worksheet Write a 500- to 750-word explanation regarding the role of plate tectonics in the origin of igneous rocks.
| Plate tectonics play a major role in the origin of igneous rocks. Igneous rocks are called fire rocks and are formed either| |underground or above ground. Underground, they are formed when the melted rock, called magma, deep within the earth becomes trapped| |in small pockets. As these pockets of magma cool slowly underground,the magma becomes igneous rocks. Igneous rocks are also formed | |when volcanoes erupt, causing the magma to rise above the earth’s surface.When magma appears above the earth, it is called lava. | |Igneous rocks are formed as the lava cools above ground. Rock formed of lava is called extrusive, rock from shallow magma is called| |intrusive and rock from deep magma is called plutonic.
Igneous rocks form in three main places. They form where lithospheric plates| |pull apart at mid-ocean ridges, where plates come together at subduction zones and where continental crust is pushed together, | |making it thicker and allowing it to heat to melting. | |Most magmas are associated with plate tectonics.Basaltic and ultramafic magmas form along the divergent mid oceanic ridges and | |are major components of new oceanic crust. More felsic magmas, such as andesites and rhyolites, are associated with the edges of | |continental crust at subduction zones along converging plate boundaries. Whether a magma is intermediate or felsic may depend on | |the relative amounts of oceanic crust and continental crust in the subduction zone that melt to form the magma. The great abundance| |of granitic intrusions in continental crust is thought to be related to the partial melting of the lower continental crust.Plate | |tectonics is the study of how the Earth’s plates are driven and shaped by geological forces that keep them in constant motion.
The | |outermost crust of the Earth is cracked into several large pieces called plates that average 50 miles thick. These plates float on | |a partially molten mantle beneath the Earth’s surface. Powered by forces originating in Earth’s radioactive, solid iron inner core,| |these tectonic plates move ponderously about at varying speeds and in different directions atop a layer of much hotter, softer, | |more malleable rock called the athenosphere.Because of the high temperatures and immense pressures found here, the top part of the| |athenosphere is deformed and flows almost plastically just beneath the Earth’s surface. When mantle rocks near the radioactive core| |become hot, they become less dense than the cooler, top mantle rocks.
These warmer rocks rise while the cooler rocks sink, creating| |slow, vertical currents within the mantle. This action makes these convection currents move mantle rocks a few centimeters a year. | |This movement of hot and cold mantle rocks, creates pockets of circulation within the mantle called convection cells.
The | |circulation of these convection cells could very well be the driving force behind the movement of tectonic plates over the | |athenosphere. | | | | | | | Write a 500- to 750-word explanation regarding the role of plate tectonics in the origin of metamorphic rocks. |Metamorphic rocks are rocks that have “morphed” into another kind of rock.These rocks were once igneous or sedimentary rocks. The | |rocks are under tons and tons of pressure, which makes heat build up, and this causes them to change.
If you exam metamorphic rock | |samples closely, you’ll discover how flattened some of the grains in the rock are. The word “Metamorphism” comes from the Greek | |word Meta which means change and Morph which means form, metamorphism means to change form. In geology this refers to the | |changes in mineral assemblage and texture that result from subjecting a rock to pressures and temperatures different from those | |under which the rock originally formed.Metamorphism, therefore occurs at temperatures and pressures higher than normal Rocks can | |be subjected to these higher temperatures and pressures as they become buried deeper in the Earth. Such burial usually takes place | |as a result of tectonic processes such as continental collisions or subduction. In most cases, the overall chemistry of the | |metamorphic rock is very similar to that of the parent rock. A quartz sandstone, for example, will metamorphose into a rock that | |contains a high percentage of silica.A calcite-rich rock such as limestone can metamorphose only into a calcium-rich metamorphic | |rock.
A quartz sandstone cannot metamorphose into a calcium-rich rockMetamorphic rocks result from the forces active during plate | |tectonic processes. The collision of plates, subduction, and the sliding of plates along transform faults create differential | |stress, friction, shearing, compressive stress, folding, faulting, and increased heat flow. The tectonic forces deform and break | |the rock, creating openings, cracks, faults, breccias, and zones of weakness along which magmas can rise.Generally speaking, the | |greater the tectonic forces, the higher the pressures and temperatures affecting a rock mass and the greater the amount of | |resulting structural deformation and metamorphism. Nicole Baker | |Some information from: | |Corina Fiore | |Cliffs notes | |Stephen A.Nelson | |Rock hounds | ———————– Igneous rocks host important mineral deposits (ores): for example, tungsten, tin, and uranium are commonly associated with granites and diorites, whereas ores of chromium and platinum are commonly associated with gabbros.Igneous rocks host important mineral deposits (ores): for example, tungsten, tin, and uranium are commonly associated with granites and diorites, whereas ores of chromium and platinum are commonly associated with gabbros. Igneous rocks host important mineral deposits (ores): for example, tungsten, tin, and uranium are commonly associated with granites and diorites, whereas ores of chromium and platinum are commonly associated with gabbros.
These temperature changes must be hot enough to reorganize matter within the rock but not hot enough to melt it.Hot magma pushes itself to the surface at both divergent plate boundaries and convergent plate boundaries. This magma comes in contact with rocks as it rises to the surface. The magma is hot, heating the rocks around it.
As the rocks heat, they change and become metamorphic rocks. This process is called contact metamorphism. Read more: How Does Plate Tectonics Affect the Rock Cycle? Regional metamorphism occurs at convergent plate boundaries, due to intense pressure.
As two plates collide, the Earth’s crust folds and faults.The intense pressure changes large areas of the Earth’s crust into metamorphic rock. Mountain ranges are typically metamorphic rock, due to plate tectonic processes.
Read more: How Does Plate Tectonics Affect the Rock Cycle? Regional metamorphism occurs at convergent plate boundaries, due to intense pressure. As two plates collide, the Earth’s crust folds and faults. The intense pressure changes large areas of the Earth’s crust into metamorphic rock. Mountain ranges are typically metamorphic rock, due to plate tectonic processes.
Read more: How Does Plate Tectonics Affect the Rock Cycle?