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In this reading:how Igneous Rocks type Igneous Rocks and also Plate limits Igneous Rocks and also Minerals That space Mineral sources (Table) Metamorphic Rocks Metamorphic Rocks and Plate Boundaries an ext about Igneous task and Hydrothermal Fluids steel Sulfide Minerals and Acid Mine Drainage Glossary
How Igneous Rocks Form
There is no liquid layer that magma waiting below the Earth's surface. Instead, rocks in some parts of the reduced crust and/or top mantle have to melt in bespeak to do magma. When magma forms, the will try to increase from higher-pressure areas (deeper in the crust) to reduced pressure areas (near Earth's surface), because magma is less dense than solid rock. Together magma rises, that cools. Many often, the cools and also hardens (the magma crystallizes, an interpretation that crystals
By the way, rocks will obviously melt as soon as heated over their melt temperature. However most rocks in reality melt due to the fact that something lowers your melting temperature, not due to the fact that they are heated. There room two ways that the melt temperature have the right to be lowered. First, pressure squeezes atoms together, into a solid. If push is reduced, atoms can move apart, probably far enough to come to be liquid. So, lowering press will minimize melting temperature. Second, mixtures of substances normally melt at reduced temperatures than pure substances. So, adding something to a rock will lower its melting temperature. This is what happens when we put salt on ice. The salt go not warm the ice; fairly it causes the ice cream to melt in ~ a lower temperature. In the earth, the most typical thing that is included to rock the lowers its melting temperature is water. Individual water molecule can enter a mineral's structure (only if the mineral is pretty warm already) and lower the mineral's melting temperature.
Concept map reflecting the basics of just how igneous rocks form. Ide map created by pleasure Branlund, Southwestern Illinois College
Concept map showing just how metamorphic rocks form. Principle map produced by delight Branlund, Southwestern Illinois College
Provenance: ide map by happiness Branlund, Southwestern Illinois College.Reuse: This item is readily available under a an innovative Commons Attribution-NonCommercial-ShareAlike license http://creativecommons.org/licenses/by-nc-sa/3.0/ You might reuse this item for non-commercial functions as lengthy as you administer attribution and also offer any kind of derivative functions under a comparable license.
The ide map come the best shows how metamorphic rocks form. The blue boxes show substances, and all various other boxes either present forces or areas in which metamorphic rocks form.
Unlike sedimentary and igneous rocks, metamorphic rocks room made directly from an existing rock. The original rock is heated, squeezed, or exposed come hot, reactive fluids, and also these factors serve come squeeze minerals into alignment and remove the pores, allow the mineral in the rock come grow, and/or the atoms in those minerals to move around and make new minerals. Hence, the rock changes (metamorphoses) right into a new rock. Through the way, the hot, reactive fluids are also called hydrothermal fluids (see below).
Mineral resources developed by metamorphic procedures include:marble (rock) and also other building stones---used in buildings, sculpture, etc. Talc (mineral)---used in an individual care items, ceramics, chewing gum, etc. Asbestos (mineral)---mining is banned in the unified States, but it is still used in imported items such as brake pads, and also was once heavily used in structure materials.
Metamorphic Rocks and also Plate Boundaries
Like igneous rocks, metamorphic rocks kind almost exclusively at plate boundaries.
Metamorphic rocks that kind because they space exposed to warmth from magma kind at the very same plate limits igneous rocks form: divergent, ocean--ocean convergent, and ocean--continent convergent boundaries. These species of metamorphic rocks can also kind at hot spots.
Metamorphic rocks created when rocks are buried to depths v high temperature and also pressure are discovered where rocks are squeezed and crumpled into mountains---that is, at convergent key boundaries.
The warm fluids mostly type when water flows near magma. And this brings united state to the next topic.
More around Igneous activity and Hydrothermal Fluids
Magma heats increase water and other fluids through which it comes in contact. The fluid can come from the magma chin (magma release water and also chlorine, hydrogen sulfide, sulfur dioxide, carbon dioxide, fluorine, etc.) or indigenous rainwater, groundwater, or seawater. These hot fluids are called hydrothermal fluids. The hydrothermal fluids can also contain metallic ion such together copper, nickel, lead, zinc, silver, gold, and platinum. These elements do not get in rock-forming minerals together the magma crystallizes, for this reason they stay in the fluid.
In addition, hydrothermal fluids likewise react with minerals in the bordering rocks, and also metal ion from those mineral can go into the fluid.
Several varieties of metal ions integrate with sulfur in the hydrothermal fluids to form metallic sulfide minerals. Thus, the hydrothermal fluids concentrate metals, creating mineral reserves referred to as metallic ore deposits.
Metallic ore deposits can form wherever over there is igneous activity, due to either volcanism or plutonism. The metallic ore deposits have the right to be uncovered near website of current igneous task or activity that happened sometime during the geologic past.
The types of steels in the deposit depend on the magma chemistry, which counts on tectonic setup (type of bowl boundary).
Metallic Sulfide Minerals and Acid Mine Drainage
Sulfide minerals chemically weather to make sulfuric acid. Unless there is a neutralizing certified dealer (such as limestone) present, the sulfuric acid rises the mountain of nearby soil and also water. This is referred to as acid rock drainage, or acid mine drainage once the high mountain is specifically attached to mining.
Mining regularly exacerbates mountain rock drainage since it division up (mechanically weathers) the rock, creating much more surface locations on which chemical weathering deserve to act.
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There room several impacts of mountain mine drainage. Numerous organisms have the right to only tolerate particular pH conditions, so raised acidity in surface ar water can damage ecosystems. Also, water with high acidity (pH ≤ 2) have the right to dissolve and also transport heavy metals, such together chromium (Cr), copper (Cu), zinc (Zn), cadmium (Cd), and also lead (Pb), every one of which space toxic at elevated concentrations.
Acid Mine Drainage: an extremely acidic (low pH) water developed mostly once microbes eat sulfide minerals at mine sites. Go back to text
Convergent bowl Boundaries: A region where two tectonic plates relocate toward each other. If one of the key is do of oceanic lithosphere, climate the oceanic plate will certainly sink right into the mantle, creating a subduction zone. Go back to text
Divergent plate Boundaries: A ar where 2 tectonic plates relocate apart. Go back to text
Extrusive Igneous Rocks: A rock formed when magma cools on the surface. These include hardened lava flows but additionally rocks made of volcanic ash or other particles erupted indigenous a volcano. This rocks have invisible crystals, or no crystals at all, since the magma cooled quickly. Go back to text
Felsic: offered to describe magma or igneous absent containing a high (>65%) ratio of silica (SiO2). Return to text
Hot Spots: locations with igneous activity (magma and also volcanoes) that are not on bowl boundaries. Return to text
Hydrothermal Fluid: Hot, reactive water (and various other chemicals) that is typically heated by magma. The water either comes from the surface ar (ocean water or groundwater acquired from precipitation) or native the magma itself. Return to text
Intermediate ingredient of magma/lava: provided to describe magma or igneous absent containing an intermediate (52--65%) proportion of silica (SiO2). Go back to text
Intrusive Igneous Rocks: A rock developed when magma cools below the surface. This rocks often tend to have large, clearly shows crystals because the magma cooled slowly. Return to text
Lava: What geologists speak to magma as soon as it erupts from a volcano. Return to text
Mafic: offered to define magma or igneous rock containing a low (45--51%) relationship of silica (SiO2). Go back to text
Magma: liquid (melted) rock. Return to text
Metamorphic Rocks: Rock created when another rock (a parent rock or protolith) alters (by becoming much more compact, minerals transforming size, brand-new minerals growing, mineral aligning) right into a brand-new rock. This happens when the parent rock is exposed to high pressure, high temperature, and/or hydrothermal fluids. Return to text
Ore Deposit: an additional name for a mineral reserve, a location where geologic procedures have concentrated a mineral resource. Return to text
pH: A measure up of a liquid's mountain or alkalinity. If pH worths are much less than 7, the liquid is acidic (and reduced values are more acidic). If pH worths are greater than 7, the liquid is one alkali (and higher values are stronger alkalis). Go back to text
Plutonic Igneous Rocks: one more name for intrusive igneous rock. Return to text
Subduction: The sinking of one oceanic plate. Go back to text
Subduction Zone: A ar where an oceanic plate sinks into the mantle in ~ a convergent plate boundary. Return to text
Sulfide Minerals: minerals containing the sulfide ion, such together pyrite (FeS2), galena (PbS), chalcopyrite (CuFeS2), sphalerite (ZnS). Sulfides is a mineral team (recall, many minerals space in the silicate mineral group). Go back to text
Volcanic Igneous Rocks: another name because that extrusive igneous rock. Go back to text
Volcano: A place where magma reaches Earth's surface. Some, yet not all, volcanoes are hills or cones. Go back to text