Earth's Internal Heat Sources PDF

**Module 2: Earth's Internal Heat Sources** identify the sources of the internal heat of the Earth; and explain the process of the production of internal heat of Earth. Heat is needed in order for organisms to survive. This heat may come from internal and external sources. The Earth\'s internal h...

**Module 2: Earth's Internal Heat Sources** identify the sources of the internal heat of the Earth; and explain the process of the production of internal heat of Earth. Heat is needed in order for organisms to survive. This heat may come from internal and external sources. The Earth\'s internal heat provides the heat and energy which supplies the force for natural phenomena such as earthquakes and volcanic eruptions. It also provides energy for the movement of the plates. However, despite the large amount of heat that the Earth possesses, its internal energy is greater during its early stages. Earth was formed about 4.6 billion years ago and continue to serve as habitat to diverse organisms. Its biotic components remain alive due to proper regulation of internal heat. It has massive amount of heat that varies from its layer. The heat increases from the crust down to the inner core due to several reasons. This internal heat comes from the following sources. 1. Primordial heat of the planet remains from its early stage. The Earth was formed from the process of accretion wherein gasses and dust of cloud was attracted by gravitational energy. When these masses compacted it formed planetisimals. In the process, due to the collision of these masses, heat was generated. This process formed the earliest stage of planet Earth which is molten in state and heat is trapped in the core of the planet. Eventually, the accrued heat did not vanish. It took a long time for heat to move from the internal part of the planet going to its surface. There had been the convective transport of heat within the core to the mantle of the earth. While conductive transport of heat occurs through different plate boundary layers. This resulted in the preservation of some amount the primordial heat in the interior earth. 2. Heat from the decay of radioactive elements. Earth is considered as thermal engine since its main source of internal heat come from the produced decay of some naturally occurring isotopes from its interior. This process is known as radioactive decay by which the spontaneous breakdown of an atomic nucleus causes the release of energy and matter from the nucleus. Some of the isotopes are potassium -- 40, Uranium - 235, Uranium - 238 and Thorium - 232. There are other radioactive isotopes that are also present in the Earth however they play a minor role in the production of heat due to its small abundance and low heat capacity. This process of radioactive decay which emits heat energy as one of the products prevents the Earth from completely cooling off. 3. Gravitational pressure The more a person descend into Earth's interior, the amount of pressure increases due to the force pressing on an area caused by the weight of an overlying rocks. The pressure near the center is considered to be 3 to 4 million times the pressure of atmosphere at sea level. Again, because rocks are good insulators, the escape of heat from Earth's surface is less than the heat generated from internal gravitational attraction or squeezing of rock, so heat builds up within. At high temperature, the material beneath will melt towards the central part of the earth. This molten material under tremendous pressure conditions acquires the property of a solid and is probably in a plastic state. 4. Dense core material in the center of the planet. Due to increase in pressure and presence of heavier materials towards the earth's center, the density of earth's layers also increases. Obviously, the materials of the innermost part of the earth are very dense. The inner core as the inner most layer is composed primarily of iron and nickel which contributes to the density in the core that ranges between 12,600-13,000 kg/m3. This suggests that there must be other heavy elements such as gold, platinum, palladium, silver and tungsten that are present in the core. Like in the descent of the dense iron-rich material that makes up the core of the planet to the center that produce heating in about 2,000 kelvins. The inner core's intense pressure prevents the iron and other minimal amount of some elements from melting. The pressure and density are simply too great for the iron atoms to move into a liquid state. Thus, this contributes to the intense heat in the interior of the planet. **Module 3: Endogenic Processes: Plutonism and Volcanism** We know that the Earth transmits seismic waves that the bulk of the planet is solid for thousands of kilometers down to the core-mantle boundary. The evidence of volcanic eruptions, however, tells us that there must be liquid regions where magma originate. In the previous module, you learned primordial heat, spontaneous radioactive decay, gravitational pressure and dense core materials are the reasons why Earth's interior is hot. These Earth's internal heat fueled different endogenic activities that enables the planet to sustain life. Meanwhile, in this new lesson, you will learn information about magmatism as one of the endogenic processes. Specifically, you will understand concepts on composition of magma, how it is formed and what happens after it's formed. An endogenic process is a geological process that was formed, originated, and located below the surface of the earth. It involves geologic activities such as tectonic movements, metamorphism, seismic activities and magmatism. How is magma formed? Magma is formed under certain circumstances in special location deep in the crust or in the upper mantle. Magma forms from partial melting of mantle rocks. Rocks undergo partial melting because the minerals that compose them melt at different temperature. Partial melting takes place because rocks are not pure materials. As temperature rises, some minerals melt and others remain solid. If the same conditions are maintained at any given temperature, the same mixture of solid and melted rock is maintained. To visualize the partial melt, think of how chocolate chip cookies would look if you heated it to the point at which chocolate chips melted while the main part of the cookie stayed solid. The chips represent the partial melt or magma. To understand melting, pressure is also considered. Pressure increases with depth as a result of the increased weight of overlying rock. Geologist found out that as they melted rocks under various pressures, higher pressure led to higher melting points. The two main mechanisms through which rocks melt are decompression melting and flux melting. Decompression melting takes place within Earth when a body of rock is held at approximately the same temperature but the pressure is reduced. This happens because the rock is being moved toward the surface, either at a mantle plume (a.k.a., hot spot), or in the upwelling part of a mantle convection cell. If a rock that is hot enough to be close to its melting point is moved toward the surface, the pressure is reduced, and the rock can pass to the liquid side of its melting curve. At this point, partial melting starts to take place. Flux melting happens if a rock is close to its melting point and some water or carbon dioxide is added to the rock, the melting temperature is reduced and partial melting starts. As the magma moves toward the surface, and especially when it moves from the mantle into the lower crust, it interacts with the surrounding rock. This typically leads to partial melting of the surrounding rock because most such magmas are hotter than the melting temperature of crustal rock. At very high temperatures (over 1300°C), most magma are entirely liquid because there is too much energy for the atoms to bond together. As the temperature drops, usually because the magma is slowly moving upward, things start to change. Silicon and oxygen combine to form silica tetrahedra, and then, as cooling continues, the tetrahedra start to link together to make chains (polymerize). These silica chains have the important effect of making the magma more viscous (less runny), and magma viscosity has significant implications for volcanic eruptions. As the magma continues to cool, crystals start to form. What happens after magma is formed? Magma escaped in two forms: intrusion and extrusion. An intrusion is magma that moves up into a volcano without erupting. Like a balloon, this causes the volcano grows on the inside. What is meant by the intrusion of magma is the inclusion of the rock layers forming the earth\'s crust (magma does not get out). Plutonism Plutonism refers to all sorts of igneous geological activities taking place below the Earth\'s surface. In cases where magma infiltrates the Earth\'s crust but fails to make it to the surface, the process of magma differentiation gives birth to ideal conditions for metallogenesis and that is a kind of Plutonism. This is the exact process that gives birth to magma, when the presence of various oxides, fluorine, sulfur, and chlorine compounds that are necessary for the creation of magma is guaranteed. The solidification and crystallization of magma takes place mainly inside the Earth\'s interior. When the process of crystallization takes place inside the crust, the magmatic rocks produced are called plutonites, which is another major category of igneous rock formation. Plutonites are igneous rock formations that are created when the process of crystallization and solidification of magma takes places below the Earth\'s surface and particularly in the crust. An extrusion is an eruption of magmatic materials that causes land formation on the surface of the Earth. Magma extrusion causes the formation of volcanoes when the gas pressure is strong enough and there are cracks in the earth\'s crust. Magma that came out to the surface of the earth is called the eruption. Magma that came to the surface of the earth is called lava. Magma can move up because of a high pressure exerted by magma and gases. In the lithosphere magma occupies a bag which is called magma chamber. The depth of the magma chamber causes the differences in the strength of volcanic eruptions. In general, the deeper the magma chamber, the stronger the explosion. Volcanism Volcanism is used to describe all geological phenomena that occur on the natural terrestrial surface, such as the creation of volcanoes and hot springs. It refers to all sorts of geological activities correlated with the flow and transportation of igneous material from the planet\'s interior towards the natural terrestrial surface. This motion takes place inside cracks that are known among geologists as natural pipes that infiltrate the upper mantle. In many cases, the mantle allows massive quantities of liquids and gases to reach the upper layers of the planet and in various cases, even the natural terrestrial surface. Volcanoes are created and formed when energy generated by inductive currents flowing from the Earth\'s core towards the surface hits the upper layers in the form of pressure and smashes the overlaying rock formations. The presence of dilated water vapor plays an important role in the creation of craters by assisting the flow of magma towards the surface. This also explains why massive amounts of water vapor concentration in magmatic gases with an average value of 80% are emitted into the atmosphere during volcanic eruptions. Molten material in the form of lava that undergoes the process of crystallization on the natural terrestrial surface gives birth to rock formations known as volcanites. These are one of the major categories of igneous rock formations. Volcanites are composed of gray, dull pink colored trakibasaltic lava with large phenocrystal and pyroclastic.