Text on this page is printable and can be used according to our Terms of Service. solid and pinstriped B) amount of space available for crystals to fill E. crystal settling. The Rights Holder for media is the person or group credited. A) granite As a magma cools below 1300C, minerals start to crystallize within it. Magma that has cooled into a solid is called igneous rock. What two factors determine what type of rock a magma will form?-One is the composition of the magma. Comments Salt Lake Community College via OpenGeology. A magma chamber is a large underground reservoir of molten rock. D. Heavier crystals float on the top of the magma in the magma chamber producing a layered igneous rock upon complete solidification. The densest magma sinks near the bottom of the chamber. This page titled 5.1: Classification of Igneous Rocks is shared under a CC BY-NC-SA license and was authored, remixed, and/or curated by Chris Johnson, Matthew D. Affolter, Paul Inkenbrandt, & Cam Mosher (OpenGeology) . 4. glassy. What does it mean if a rock has a coarse texture? It is found in its namesake, the Andes Mountains as well as the Henry and Abajo mountains of Utah. A) rhyolitic Rock formed from large deposits of tephra fragments is called tuff. These groups refer to differing amounts of silica, iron, and magnesium found in the minerals that make up the rocks. Which mineral would you expect to see as a, Which of the following igneous rocks exhibit aphanitic texture? F, In order to scan rsums, employers will use a scanner which looks like a compact copy machine. Visible quartz and potassium feldspar grains are the main constituents in a. D. ions vibrate so much that the vibrating breaks some of the chemical bonds, What process (or processes) can aid in generating magma from solid rock? An extreme version of scoria occurs when volatile-rich lava is very quickly quenched and becomes a meringue-like froth of glass called pumice. D) If the magma has no crystals or gases within it, it is called "lava." Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. 3. diorite Arndt, N. T. Chapter 1 Archean Komatiites. A) mafic - very fluid magma makes for passive (fluid) eruptions They are typically more than 100 km2 in area, associated with subduction zones, and mostly felsic in composition. E. All of these. The process by which the same magma may produce different composition igneous rocks. An igneous rock with large crystals embedded in a matrix of much finer crystals is indicative of a two-stage cooling process, and the texture is porphyritic (Figure 3.3.7). The composition of the original magma is critical to magma crystallization because it determines how far the reaction process can continue before all of the silica is used up. light colored, less dense and more viscous (sticky) Parts of a volcano. Rhyolite refers to the volcanic and felsic igneous rocks and granite refer to intrusive and felsic igneous rocks. A rock that chiefly consists of pegmatitic texture is known as a pegmatite. These tiny crystals can be viewed under a petrographic microscope [1]. 5. gabbro A. Inflammation of the lymph vessels is known as________. d. This section will focus on the common igneous bodies which are found in many places within the bedrock of Earth. This reduction in overlying pressure, or decompression, enables the mantle rock to melt and form magma. On the figure above, the top row has both plutonic and volcanic igneous rocks arranged in a continuous spectrum from felsic on the left to intermediate, mafic, and ultramafic toward the right. D) Temperature of the environment - higher T = slower magma cooling. To give an example of how large these crystals can get, transparent cleavage sheets of pegmatitic muscovite mica were used as windows during the Middle Ages. C) granite Which of the following minerals crystallize early in Bowen's reaction series? If the magma cools slowly underground, the product will be gabbro; if it cools quickly at the surface, the product will be basalt (Figure 3.3.5). Lava cools to form volcanic rock as well as volcanic glass. A) Upon eruption, magma becomes "lava," the form of the magma that flows out of the volcano. Chemical data for four rock samples are shown in the following table. K.C. This occurs when calcium-rich early-forming plagioclase crystals become coated with progressively more sodium-rich plagioclase as the magma cools. A) Intrusive magma is cooler because it is well insulated by the surrounding rock. Cooling history is also related to changes that can occur to the composition of igneous rocks. 1. 4. andesite Are plutons assembled over. All magmas contain gases dissolved in a solution called volatiles. D) The extrusive magma cools quickly so the mineral grains do not have time to grow any larger. It can be found in the right below a or within the . E. phaneritic texture, relatively high silica content St. Helens. Many volcanoes sit over magma chambers. C) rate of cooling Sills are another type of intrusive structure. The Hawaiian volcano Kilauea, on the "Big Island" of Hawaii, has erupted with enough molten lava to pave a road around the Earth three times. D. consist of very coarse grained crystals of potassium feldspar, muscovite and quartz __________ is a volcanic rock that is extremely vesicular and glassy. This type of magma has a low gas content and low viscosity, or resistance to flow. There are three main types of rocks: sedimentary, igneous, and metamorphic. The individual crystals in phaneritic texture are readily visible to the unaided eye. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Earth Science, Geology, Geography, Physical Geography. Name one advantage and one disadvantage of drug combination therapy. D. muscovite D. extrusion Peacock, M. A. E. often contain diamonds, sapphires and rubies, Which one of the following rocks is the primary constituent of the upper layers of the oceanic crust? If crystal settling does not take place, because the magma is too viscous, then the process of cooling will continue as predicted by the Bowen reaction series. 2. porphyritic andesite D. and c. only The rock will have some relatively large crystals (phenocrysts) of the minerals that crystallized early, and the rest will be very fine grained or even glassy. B) gabbro D. a magnifying glass or microscope is needed to see individual mineral grains D) Each vesicle is filled by air and water. C) intermediate - the intermediate range composition magma makes for strato volcanoes that are mostly passive erupting What is the name of the process by which minerals crystallize and settle out of a melt? molten rock below Earths surface 7. obsidian, Which of the following is characteristic of pegmatites? If no button appears, you cannot download or save the media. MAGMA - molten material and dissolved gas (in the subsurface). A) diorite; intrusive rock that formed from the cooling of relatively intermediate silica magma . Its mean temperature ranges from 800o to 1000o Celsius (1472o to 1832o Fahrenheit). Transfer of heat often happens at convergent boundaries, where tectonic plates are crashing together. 30-45 seconds Tephra fragments are named based on sizeash (<2 mm), lapilli (2-64 mm), and bombs or blocks (>64 mm). In fact, magma has only been discovered three times in its natural habitat deep in Earths crust. The layers of magma may be documented by the type of eruption material the volcano emits. D. Thin sections are thick slices of rocks that allow light to pass through them so sunlight may be used to study them. B) gabbroic, rhyolitic The slow cooling process allows crystals to grow large, giving the intrusive igneous rock a coarse-grained or phaneritic texture. As a magma cools below 1300C, minerals start to crystallize within it. Types of MagmaAll magma contains gases and a mixture of simple elements. E) The presence or absence of volatiles (gases) - less gases = slower magma cooling. The rifting movement causes the buoyant magma below to rise and fill the space of lower pressure. Rhyolite is commonly pink and will often have glassy quartz phenocrysts. in, Chris Johnson, Matthew D. Affolter, Paul Inkenbrandt, & Cam Mosher, status page at https://status.libretexts.org. The crystals that settle might either form an olivine-rich layer near the bottom of the magma chamber, or they might remelt because the lower part is likely to be hotter than the upper part (remember, from Chapter 1, that temperatures increase steadily with depth in Earth because of the geothermal gradient). National Geographic Society is a 501 (c)(3) organization. America. The pool of magma in a magma chamber is layered. Rhyolite is a fine-crystalline felsic extrusive rock. The type of volcanic rock with common vesicles is called scoria. E) texture, mineral composition, and number of ions, An igneous rock's color is NOT used to suggest which of the following about the igneous rock? Why do all magmas create dominantly silicate minerals upon cooling? What is magma? Andesite and diorite likewise refer to extrusive and intrusive intermediate rocks (with dacite and granodiorite applying to those rocks with composition between felsic and intermediate). C. high silica, low iron and magnesium, phaneritic texture Andesite is the name of a family of fine-grained, extrusive igneous rocks that are usually light to dark gray in color. B. the upper mantle Thin sections are thick cuts of rocks that allow light and liquids to pass through them so that a microscope may be employed. D. ocean ridge volcanoes Young, emerging subvolcanic intrusion cutting through older one, Xenolith (solid rock of high melting temperature which has been transported within the magma from deep below) or roof pendant (fragment of the roof of the magma chamber that has detached from the roof and sunk into the melt), Contact metamorphism in the country rock adjacent to the magma chamber (caused by the heat of the magma), Uplift at the surface due to laccolith emplacement in the near sub-ground, Active magma chamber (called pluton when cooled and entirely crystallized; a batholith is a large rock body composed of several plutonic intrusions), Old pegmatite (late-magmatic dyke formed by aggressive and highly mobile residual melts of a magma chamber). Felsic magmas tend to be cooler than mafic magmas when crystallization begins (because they dont have to be as hot to remain liquid), and so they may start out crystallizing pyroxene (not olivine) and plagioclase. Many xenoliths are crystals torn from inside the Earth and embedded in magma while the magma was cooling. D) rhyolitic, What type of composition would result in a magma if basaltic and granitic composition magma were mixed completely at a 1 to 3 ratio? Residual molten material expelled from igneous intrusions may form veins or masses containing very large crystals of minerals like feldspar, quartz, beryl, tourmaline, and mica. A) basaltic, gabbroic An active volcano always has a magma chamber beneath the cone. D) solid + crystal. C. biotite If solid, obsidian. If that magma is then involved in a volcanic eruption, the rest of the liquid will cool quickly to form a porphyritic texture. [Hint] in, Chris Johnson, Matthew D. Affolter, Paul Inkenbrandt, & Cam Mosher, status page at https://status.libretexts.org. A) Mafic is a magma/rock that is rich in feldspar and silica (quartz), whereas felsic refers to that which is rich in Fe and Mg. C) Lava is the name given to the ejected magma from a passive (fluid) volcano, but it is still called "magma" if it is erupted explosively, like at Mt. Rhyolite is commonly pink and will often have glassy quartz phenocrysts. What is "magmatic differentiation"? A rock that chiefly consists of pegmatitic texture is known as a pegmatite. Intrusive rocks, forming underground with larger, stronger crystals, are more likely to last. B. mineral grains are roughly equal size and coarse enough to be seen without the aid of a microscope or magnifying lens 2. pressure When located beneath the ocean, these plumes, also known as hot spots, push magma onto the seafloor. A. phaneritic texture, relatively low silica content User: 3/4 16/9 Weegy: 3/4 ? In the discontinuous branch, olivine is typically the first mineral to form (at just below 1300C). Nature rarely has sharp boundaries and the classification and naming of rocks often impose what appears to be sharp boundary names onto a continuous spectrum. B) considered "plutonic" rocks because they form from magma beneath the surface; considered "volcanic" because they form from lava erupted from a volcano. Pyro, meaning fire, refers to the igneous source of the tephra and clastic refers to the rock fragments. This answer has been confirmed as correct and helpful. Magma is a molten and semi- molten rock mixture found under the surface of the Earth. = 45/20 C. Amphibole - pyroxene - biotite - olivine Sills are another type of intrusive structure. A. chemical bonds melt B) dark colored, more dense and less viscous (not sticky); Gabbro is a major component of the lower oceanic crust. Basalt is a fine-grained mafic igneous rock. B) the magma stays the same temperature, causing ions to slow down and form crystals, mostly Si-O tetrahedra Rocks that solidify from lava flows are typically finer grained than those that crystallize intrusively. G) All of these. The cracks, called fissures or vents, are tell-tale signs of a volcano. If you have questions about how to cite anything on our website in your project or classroom presentation, please contact your teacher. Laccoliths are blister-like, concordant intrusions of magma that form between sedimentary layers. Basalt and gabbro are the extrusive and intrusive names for mafic igneous rocks, and peridotite is ultramafic, with komatiite as the fine-grained extrusive equivalent. Composition refers to the rock's specific mineralogy and chemical composition. Classification of Igneous Rock Series. A. Pyroxene - amphibole - olivine - biotite A) texture User: She worked really hard on the project. Diorite is identifiable by its Dalmatian-like appearance of black hornblende and biotite and white plagioclase feldspar. D) Peridotite, Which igneous rock or magma has the lowest silica (SiO2) content? This heat makes magma a very fluid and dynamic substance, able to create new landforms and engage physical and chemical transformations in a variety of different environments. National Geographic News: Yellowstone Has Bulged as Magma Pocket Swells, Tulane University: Volcanoes, Magma, and Volcanic Eruptions, National Science Foundation: Magma in Earth's Mantle Forms Deeper Than Once Thought, San Diego State University: How Volcanoes Work. When many plutons merge together in an extensive single feature, it is called a batholith. D. gabbro Granite is a good approximation for the continental crust, both in density and composition. Mafic magmas have 45% to 55% SiO2, about 25% total of FeO and MgO plus CaO, and about 5% Na2O + K2O. Magma is extremely hotbetween 700 and 1,300 Celsius (1,292 and 2,372 Fahrenheit). A sill is a concordant intrusion that runs parallel to the sedimentary layers in the country rock. In some cases, individual plagioclase crystals can be zoned from calcium-rich in the centre to more sodium-rich around the outside. Much like hot fudge being poured over cold ice cream, this transfer of heat is able to melt the surrounding rock (the ice cream) into magma. in Developments in Precambrian Geology (ed. A significant exception to this is active volcanoes, which are discussed in a later section on volcanism. These eight elements . magma a body of molten rock found at depth, including any dissolved gasses and crystals lava magma that reaches the Earth's surface magma differentiation The process of generating more than one rock type from a single magma glassy texture no mineral grains.