This relates to the cooling history of the molten magma from which it came. light colored, more dense and less viscous (not sticky), What type of composition would result in a magma if equal amounts of basaltic and granitic magma were mixed? C. Mt. Dark, dense volcanic rock from the lower part of the magma chamber may be released later. Intrusive rocks, forming underground with larger, stronger crystals, are more likely to last. if((replacementValue > 0) && (replacementValue < limit)). Because felsic lavas are less mobile, it is less common than granite. A) striped and dotted; Extrusive or volcanic rocks crystallize from lava at the earth's surface. 1. granite St. Helens volcano, and why? E) None of these. A. D) Each vesicle is filled by air and water. 20/3 B. olivine The path of rising magma is called a diapir. Andesite is a fine crystalline intermediate extrusive rock. 4. volatiles, A heated crystalline solid most likely melts when ________. The individual crystals in phaneritic texture are readily visible to the unaided eye. Therefore, most landforms and rock groups that owe their origin to igneous rocks are intrusive bodies. C) number of ions B) gabbro Which of the following is the likely cause of a vesicular texture (open cavities in a rock)? C) the magma in the magma chamber before eruption 3. diorite National Geographic Society is a 501 (c)(3) organization. D) dark colored, less dense and more viscous (sticky); Typical felsic rocks are granite and rhyolite (Figure 3.3.5). Laccoliths bulge upwards; a similar downward-bulging intrusion is called a lopolith. Texture describes the physical characteristics of the minerals, such as grain size. Intrusive or plutonic rocks crystallize from magma beneath the earth's surface. [Hint] Which of the following best describes an aphanitic texture? Differences in temperature, pressure, and structural formations in the mantle and crust cause magma to form in different ways. In some cases, however, partially cooled but still liquid magma, with crystals in it, will either move farther up into a cooler part of the crust, or all the way to the surface during a volcanic eruption. It is the source of all igneous rock. As cooling continues, the various reactions on the discontinuous branch will proceed because silica is abundant, the plagioclase will become increasingly sodium-rich, and eventually potassium feldspar and quartz will form. C) andesitic A) the lava after it erupted from a crystallizing magma chamber A rock that chiefly consists of pegmatitic texture is known as a pegmatite. A. crystal settling Batholiths are found in the cores of many mountain ranges, including the granite formations of Yosemite National Park in the Sierra Nevada of California. D. Heavier crystals float on the top of the magma in the magma chamber producing a layered igneous rock upon complete solidification. 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. Basalt is the main rock which is formed at mid-ocean ridges, and is therefore the most common rock on the Earths surface, making up the entirety of the ocean floor (except where covered by sediment). E) rhyolite: extrusive rock that formed from cooling of relatively low silica magma Rock formed from large deposits of tephra fragments is called tuff. Felsic magmas, on the other hand, have much more SiO2 (65% to 75%) and Na2O + K2O (around 10%) and much less FeO and MgO plus CaO (about 5%). E. phaneritic texture, relatively high silica content The minerals present will be olivine, pyroxene, and calcium-rich plagioclase. Condie) 11, 1144 (Elsevier, 1994). B. komatiite As the magma rises to the surface, the drop in pressure causes the dissolved volatiles to come bubbling out of solution, like the fizz in an opened bottle of soda. If magma cools slowly, deep within the crust, the resulting rock is called intrusive or plutonic. A) The rock is crystalline, but mineral grains are of distinctly different sizes. When lava is extruded onto the surface, or intruded into shallow fissures near the surface and cools, the resulting igneous rock is called extrusive or volcanic. D) The extrusive magma cools quickly so the mineral grains do not have time to grow any larger. 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). The dikes may be intruding over millions of years, but since they may be made of similar material, they would be appearing to be formed at the same time. D) texture and mineral composition 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. 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. Classification of Igneous Rock Series. Decompression melting also occurs at mantle plumes, columns of hot rock that rise from Earths high-pressure core to its lower-pressure crust. G. both olivine and pyroxene, Which two minerals are characteristic of lower crystallization temperatures, and are absent in basalt and gabbro? = 2 1/4. What is "magmatic differentiation"? Rocks labeled as granite in laymen applications can be several other rocks, including syenite, tonalite, and monzonite. The most abundant elements are oxygen and silicon, followed by aluminum, iron, calcium, sodium, magnesium, and potassium. F. olivine National Geographic Headquarters 1145 17th Street NW Washington, DC 20036. Note that these 8 elements make up about 99 percent of the Earth's crust. Name one advantage and one disadvantage of drug combination therapy. If magma cools slowly, deep within the crust, the resulting rock is called intrusive or plutonic. F) Both c. and d. a. D) The glass is formed mostly when lava cools in contact with water whereas phaneritic rocks cool deep beneath the surface. If a media asset is downloadable, a download button appears in the corner of the media viewer. Some igneous rocks have a mix of coarse-grained minerals surrounded by a matrix of fine-grained material in a texture called porphyritic. A significant exception to this is active volcanoes, which are discussed in a later section on volcanism. A __________ texture would be most UNLIKELY to occur in an extrusive igneous rock. Magma is extremely hotbetween 700 and 1,300 Celsius (1,292 and 2,372 Fahrenheit). C. heat expansion of the chemical bonds causes them to break E. pyroxene, Which one of the following rock types is most likely to contain calcium-rich feldspar? Examples of rhyolite include several lava flows in Yellowstone National Park and the altered rhyolite that makes up the Grand Canyon of the Yellowstone. E. granite, According to Bowen's reaction series for cooling magma, which mineral(s) is/are likely to form a phenocryst in porphyritic basalt? Magma is molten rock inside the earth. Basalt is a fine-grained mafic igneous rock. D. muscovite and quartz, According to Bowen's reaction series, which is the proper sequence of ferromagnesian silicate minerals crystallizing from a cooling magma? There are 3 main agents that cause metamorphism. _________ is the dominant feldspar in basalt. flowing rock above Earths surface, When your rsum is first reviewed, a potential employer looks at it for approximately _____. D) pressure. Igneous rocks are classified based on texture and composition. In order to scan resumes, employers will use a scanner which looks like a compact copy machine. Peacock, M. A. A) Each vesicle was filled by a gas bubble when the lava was still mainly liquid. A xenolith is a piece of rock trapped in another type of rock. TRUE. a. There are three main types of rocks: sedimentary, igneous, and metamorphic. Some pumice is so full of vesicles that the density of the rock drops low enough that it will float. B) the first crystals to form when the magma was in the magma chamber Classification of Igneous Rock Series. A magma consists mostly of liquid rock matter, but may contain crystals of various minerals, and may contain a gas phase that may be dissolved in the liquid or may be present as a separate gas phase. These tiny crystals can be viewed under a petrographic microscope [1]. When it cools to solid rock, this intrusion is often called a pluton. 3. In the discontinuous branch, olivine is typically the first mineral to form (at just below 1300C). Igneous rocks are classified based on texture and composition. Plutons can have irregular shapes, but can often be somewhat round. Because the earth was largely molten at its origin, magma may be considered the beginning of the rock cycle. The presence of quartz is a good indicator of granite. Magma is hot, molten rock that exists beneath the Earth's surface. What is a likely reason for this phaneritic texture? Are plutons assembled over. The minerals that make up igneous rocks crystallize at a range of different temperatures. Pyroclastic texture is usually recognized by the chaotic mix of crystals, angular glass shards, and rock fragments. Lava that cools extremely quickly may not form crystals at all, even microscopic ones. This explains why a cooling magma can have some crystals within it and yet remain predominantly liquid. B. magma mixing Factors that cause an increase in Temperature, Pressure, and Chemical changes are the three agents that we are going to study. D) considered "volcanic" rocks because they form from lava extruded at the surface; considered "plutonic" rocks because they form from magma beneath the surface. The Bowen reaction series is one of the results of his work, and even a century later, it is an important basis for our understanding of igneous rocks. A) andesite Therefore, most landforms and rock groups that owe their origin to igneous rocks are intrusive bodies. This continues down the chain, as long as there is still silica left in the liquid. CC BY. Steady and relatively calm lava fountains continue to change and expand the Big Island of Hawaii. C) the composition Granite is a course-crystalline felsic intrusive rock. The presence of quartz is a good indicator of granite. 2. gabbro Gabbro is a coarse-grained mafic igneous rock, made with mainly mafic minerals like pyroxene and only minor plagioclase. T A. convergent plate boundaries A) Basalt The Rights Holder for media is the person or group credited. Examples of rhyolite include several lava flows in Yellowstone National Park and the altered rhyolite that makes up the Grand Canyon of the Yellowstone. The sequence in which minerals crystallize from a magma is known as the Bowen reaction series (Figure 3.3.1 and Figure 3.3.3). All rights reserved. 1. That magma body at depth is normally totally encased by solid rock (perhaps with a zone of broken and partly melted rock measuring a few meters thick; depends on the magma and the host rock and how much time has passed), and that solid rock would be the floor, walls, and ceiling to the magma body. The Journal of Geology 39, 5467 (1931). 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? 2.1 Electrons, Protons, Neutrons, and Atoms, 4.5 Monitoring Volcanoes and Predicting Eruptions, 5.3 The Products of Weathering and Erosion, 6.3 Depositional Environments and Sedimentary Basins, 7.5 Contact Metamorphism and Hydrothermal Processes, 9.1 Understanding Earth Through Seismology, 10.1 Alfred Wegener: The Father of Plate Tectonics, 10.2 Global Geological Models of the Early 20th Century, 10.3 Geological Renaissance of the Mid-20th Century, 10.4 Plate, Plate Motions, and Plate Boundary Processes, 11.5 Forecasting Earthquakes and Minimizing Damage and Casualties, 15.1 Factors That Control Slope Stability, 15.3 Preventing, Delaying, Monitoring, and Mitigating Mass Wasting, 21.2 Western Canada during the Precambrian, 22.2 Forming Planets from the Remnants of Exploding Stars, Appendix 1: List of Geologically Important Elements and the Periodic Table. Most magma chambers sit far beneath the surface of the Earth. C. basalt 2. rhyolite What is magma? cooled rock with large crystals For example, it is not known what happens to the pre-existing country rock as the diapir intrudes. Because of this, dikes are often vertical or at an angle relative to the pre-existing rock layers that they intersect. As the magma rises to the surface, the drop in pressure causes the dissolved volatiles to come bubbling out of solution, like the fizz in an opened bottle of soda. As the liquid rock solidifies, it loses its heat to the surrounding crust. A) considered "volcanic" rocks because they form from magma beneath the surface; considered "plutonic" because they form from lava erupted from a volcano. Igneous rocks contain information about how they originate. 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). 2. Magma originates in the lower part of the Earths crust and in the upper portion of the mantle. Tapping into Magmas PotentialIn 2009, the Icelandic Deep Drilling Project created a well that uses magma to generate geothermal energy. One theory is the overriding rock gets shouldered aside, displaced by the increased volume of magma. Granite: Granite is the intrusive equivalent of rhyolite but has a coarser texture. They are formed when magma exploits a weakness between these layers, shouldering them apart and squeezing between them. Composition refers to the rocks specific mineralogy and chemical composition. At about the point where pyroxene begins to crystallize, plagioclase feldspar also begins to crystallize. A) Pressure of the environment - lower P = slower magma cooling. Match the igneous rock texture and its appropriate description. In a porphyritic volcanic rock, which mineral grains are the last to crystallize? It is poor in silica, in the 40% or less range. C) andesite The fine-grained texture indicates the quickly cooling lava did not have time to grow large crystals. d. B. an increase in heat (high temperature) 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? For a volcano to erupt, it must have a source of magma. Because mafic lava is more mobile, it is less common than basalt. C) Mafic is hard rock, felsic is soft rock. 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. The large crystals are called phenocrysts and the fine-grained matrix is called the groundmass or matrix. Thin sections are thick cuts of rocks that allow light and liquids to pass through them so that a microscope may be employed. C. Thin sections are thin slices of rocks that block light from passing through them so that rocks may be studied using a magnifying lens. Being that oxygen and silicon are the most abundant elements in magma, geologists define magma types in terms of their silica content, expressed as SiO2. 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. Laccoliths are blister-like, concordant intrusions of magma that form between sedimentary layers. A) Upon eruption, magma becomes "lava," the form of the magma that flows out of the volcano. Rhyolite is a fine-crystalline felsic extrusive rock. C) aphanitic 2. D) chemical composition of the magma or lava. If vesicular, pummus geothermal gradient Any interactives on this page can only be played while you are visiting our website. An intrusion can form features such as dikes and xenoliths. Parts of a volcano. Intermediate magma most commonly transforms into andesite due to the transfer of heat at convergent plate boundaries. D. andesite 7. obsidian, Which of the following is characteristic of pegmatites? Porphyritic texture indicates the magma body underwent a multi-stage cooling history, cooling slowly while deep under the surface and later rising to a shallower depth or the surface where it cooled more quickly. A) granite; gabbro. A) solid + gas Magma can also extrude into Earths atmosphere as part of a violent volcanic explosion. B) The rock has mineral grains that are glassy. D. ocean ridge volcanoes 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). Diorite is identifiable by its Dalmatian-like appearance of black hornblende and biotite and white plagioclase feldspar. The solid parts, called tephra, settle back to earth and cool into rocks with pyroclastic textures. A) pyroclastic Extrusive igneous rocks are _________, whereas intrusive igneous rocks are _________. But most magma remains molten or partly molten beneath Earths surface. B. The Henry Mountains of Utah are a famous topographic landform formed by this process. B. basalt User: 3/4 16/9 Weegy: 3/4 ? __________ is a volcanic rock that is extremely vesicular and glassy. A) Intrusive magma is cooler because it is well insulated by the surrounding rock. D. all of the above. A. phaneritic texture, relatively low silica content A. biotite Andesitic rocks are often found at continental volcanic arcs, such as the Andes Mountains in South America, after which they are named. Because of this, dikes are often vertical or at an angle relative to the pre-existing rock layers that they intersect. C) pressure A. intermediate silica, intermediate iron and magnesium, phaneritic texture A. Pyroxene - amphibole - olivine - biotite B) the rock's composition Mysterious MagmaMagma is usually studied as lava or igneous rock. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. B) crystal + lava Geothermal drilling projects discovered two magma sites on the Big Island of Hawaii, and one on Iceland. They have textures or mineralogy different than the surrounding material, and so are generally easy to spot. 4. glassy. User: Alcohol in excess of ___ proof Weegy: Buck is losing his civilized characteristics. 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. Of the common silicate minerals, olivine normally crystallizes first, at between 1200 and 1300C. User: She worked really hard on the project. Extrusive igneous rocks have a fine-grained or aphanitic texture, in which the grains are too small to see with the unaided eye. Common rock types within the intrusive category are granite and diorite. The fine-grained texture indicates the quickly cooling lava did not have time to grow large crystals. When volcanoes erupt explosively, vast amounts of lava, rock, ash, and gases are thrown into the atmosphere. Igneous rocks are common in the geologic record, but surprisingly, it is the intrusive rocks that are more common. The compositions of typical mafic, intermediate, and felsic magmas are shown in Figure 3.3.4. F. lower silica, high iron and magnesium, aphanitic texture Soon after that, all of the magma is used up and no further changes takes place. As a result, felsic magma also has the highest gas content and viscosity, and lowest mean temperatures, between 650o and 800o Celsius (1202o and 1472o Fahrenheit). Some pumice is so full of vesicles that the density of the rock drops low enough that it will float. 4. mafic obsidian. Magma compositions vary, but will have eight main elements in different proportions. Batholiths and stocks are discordant intrusions that cut across and through surrounding country rock. D. plate tectonics, Match the appropriate term associated with the production of magma to its best description. D) highly viscous, cools quickly, Crystallization of magma occurs when ________. The cooling behaviour of intermediate magmas lie somewhere between those of mafic and felsic magmas. This mixture is usually made up of four parts: a hot liquid base, called the melt; minerals crystallized by the melt; solid rocks incorporated into the melt from the surrounding confines; and dissolved gases. The process by which the same magma may produce different composition igneous rocks. Granite is a good approximation for the continental crust, both in density and composition. B) amount of space available for crystals to fill In some cases, extrusive lava cools so rapidly it does not develop crystals at all. B) basaltic - very sticky magma makes for very passive (fluid) eruptions The processes by which a diapir intrudes into the surrounding native or country rock are not well understood and are the subject of ongoing geological inquiry [3]. E. All of these. 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. These differences in chemical composition are directly related to differences in gas content, temperature, and viscosity. The type of volcanic rock with common vesicles is called scoria. Diorite is a coarse-crystalline intermediate intrusive igneous rock. C) basaltic, rhyolitic 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. Composition refers to the rocks specific mineralogy and chemical composition. Its mean temperature ranges from 800o to 1000o Celsius (1472o to 1832o Fahrenheit). Granite commonly has large amounts of salmon pink potassium feldspar and white plagioclase crystals that have visible cleavage planes. The black colors are likely two or three different minerals. Dikes are therefore discordant intrusions, not following any layering that was present. Who was Bowen, and what is a reaction series? If the fragments accumulate while still hot, the heat may deform the crystals and weld the mass together, forming a welded tuff. F, During this stage of rsum review, employers use the rsum to guide interview questions: It is commonly vesicular and aphanitic. 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. Exercise 3.3 Determining rock types based on magma composition, The proportions of the main chemical components of felsic, intermediate, and mafic magmas are listed in the table below. Porphyritic texture indicates the magma body underwent a multi-stage cooling history, cooling slowly while deep under the surface and later rising to a shallower depth or the surface where it cooled more quickly. This process is known as fractional crystallization. 2. Transfer of HeatMagma can also be created when hot, liquid rock intrudes into Earths cold crust. A stock is a type of pluton with less surface exposure than a batholith and may represent a narrower neck of material emerging from the top of a batholith. Komatiite is a rare rock because volcanic material that comes directly from the mantle is not common, although some examples can be found in ancient Archean rocks [2]. This type of magma has a low gas content and low viscosity, or resistance to flow. Obsidian as a glassy rock shows an excellent example of conchoidal fracture similar to the mineral quartz (see Chapter 3). Thus, you can often figure out the relative order in which the minerals crystallized from the magma. G. high silica, low iron and magnesium, aphanitic texture E) basalt, Which of the following rocks is likely to have the most quartz within it and why? C) Pegmatite A. This relates to the cooling history of the molten magma from which it came. Plutons can include dikes and xenoliths. Gabbro is a coarse-grained mafic igneous rock, made with mainly mafic minerals like pyroxene and only minor plagioclase. E) The presence or absence of volatiles (gases) - less gases = slower magma cooling. = 2 5/20 This results in a higher gas content and viscosity. 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. As long as there is silica remaining and the rate of cooling is slow, this process continues down the discontinuous branch: olivine to pyroxene, pyroxene to amphibole, and (under the right conditions) amphibole to biotite. Text on this page is printable and can be used according to our Terms of Service. 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) . Ignimbrites may be loose deposits or solid rock, and they can bury entire landscapes. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. In either of these situations, the magma that has moved toward the surface is likely to cool much faster than it did within the magma chamber, and the rest of the rock will have a finer crystalline texture. solid and pinstriped Book: An Introduction to Geology (Johnson, Affolter, Inkenbrandt, and Mosher), { "4.01:_Classification_of_Igneous_Rocks" : "property get [Map MindTouch.Deki.Logic.ExtensionProcessorQueryProvider+<>c__DisplayClass228_0.
Ren Zhengfei Leadership Style,
Carrollton Elementary School Yearbooks,
What Does It Mean That The Ancient Of Days Takes His Seat In A Courtroom Setting,
Michael Myers Family Tree Explained,
Articles W