C) light colored, less dense and more viscous (sticky); Classification of Igneous Rock Series. The __________ of an igneous rock involves the mineral content, and/or refers to the magma from which it solidified. A. crystal settling Lava that cools extremely quickly may not form crystals at all, even microscopic ones. Andesite is a rock typically found in volcanoes above convergent plate boundaries between continental and oceanic plates. The dike is younger than the rocks it cuts across and, as discussed in the chapter on Geologic Time (Chapter 7), may be used to assign actual numeric ages to sedimentary sequences, which are notoriously difficult to age date. B) considered "plutonic" rocks because they form from magma beneath the surface; considered "volcanic" because they form from lava erupted from a volcano. B) granodioritic Added 2/10/2022 11:11:08 PM This answer has been confirmed as correct and helpful. The Rights Holder for media is the person or group credited. Volcanic glass and coarse-grained igneous rocks differ by which of the following? LAVA - magma that reaches the Earth's surface before cooling (most gasses have escaped). As the temperature drops, and assuming that some silica remains in the magma, the olivine crystals will react (combine) with some of the silica in the magma to form pyroxene. _________ is the dominant feldspar in basalt. Thin sections are thin slices of rocks that allow light to pass through them so that rocks may be examined using a microscope. This non-crystalline material is not classified as minerals but as volcanic glass. D. a magnifying glass or microscope is needed to see individual mineral grains - Usually, there are several mineralsin the aggregate, though some rocks may have only one. Figure 3.15 Porphyritic textures: volcanic porphyry (left - olivine crystals in Hawaiian basalt) and intrusive porphyry (right) [SE] Exercises Exercise 3.4 Porphyritic Minerals E) basalt, Which of the following rocks is likely to have the most quartz within it and why? 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. Physical Geology - 2nd Edition by Steven Earle is licensed under a Creative Commons Attribution 4.0 International License, except where otherwise noted. 2. rhyolite Large eruptions can nearly empty the magma chamber. These trapped bubbles can cause explosive and destructive eruptions. The slow cooling process allows crystals to grow large, giving the intrusive igneous rock a coarse-grained or phaneritic texture. Magma is a mixture of molten and semi-molten rock found beneath the surface of the Earth. These groups refer to differing amounts of silica, iron, and magnesium found in the minerals that make up the rocks. This explains why a cooling magma can have some crystals within it and yet remain predominantly liquid. Igneous rocks are classified based on texture and composition. 1. C) Pegmatite C) pressure C) Pressure of the environment - higher P = slower magma cooling. Laccoliths are blister-like, concordant intrusions of magma that form between sedimentary layers. As a volcanos magma chamber experiences greater pressure, often due to more magma seeping into the chamber, the volcano may undergo an eruption. Igneous rocks are defined as types of rocks that are formed when molten rock (rock liquefied by intense heat and pressure) cools to a solid state. Extrusive rocks, because of their small crystals and glass, are less durable. 3.5 Igneous Rocks Charlene Estrada. solid and pinstriped B) glassy The most familiar way for magma to escape, or extrude, to Earths surface is through lava. This hot material rises to an area of lower pressure through the process of convection. The type of volcanic rock with common vesicles is called scoria. E. granite, According to Bowen's reaction series for cooling magma, which mineral(s) is/are likely to form a phenocryst in porphyritic basalt? d. Felsic MagmaFelsic magma has the highest silica content of all magma types, between 65-70%. Extrusive or volcanic rocks crystallize from lava at the earth's surface. Composition refers to the rocks specific mineralogy and chemical composition. 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). 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. Granite is a good approximation for the continental crust, both in density and composition. National Geographic Society is a 501 (c)(3) organization. Which of the following minerals crystallize early in Bowen's reaction series? Comments 4. volatiles, A heated crystalline solid most likely melts when ________. There are 3 main agents that cause metamorphism. B. Andes mountains volcanoes D. gabbro This huge increase in temperature allowed just one magma well to generate roughly 36 megawatts of electricity, powering 36,000 homes. Which of the following best describes an aphanitic texture? The core is the superheated center, the mantle is the thick, middle layer, and the crust is the top layer on which we live. A xenolith is a piece of rock trapped in another type of rock. The Journal of Geology 39, 5467 (1931). This answer has been confirmed as correct and helpful. B) gabbro C) the magma in the magma chamber before eruption Gases, ash, and light-colored rock are emitted first, from the least-dense, top layer of the magma chamber. 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. Rocks labeled as granite in laymen applications can be several other rocks, including syenite, tonalite, and monzonite. An eruption reduces the pressure inside the magma chamber. Of the common silicate minerals, olivine normally crystallizes first, at between 1200 and 1300C. 2. porphyritic The rate of cooling determines the rock's texture, or size of the mineral's crystals. 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]. This non-crystalline material is not classified as minerals but as volcanic glass. A) mafic - very fluid magma makes for passive (fluid) eruptions A rock that chiefly consists of pegmatitic texture is known as a pegmatite. A. phaneritic texture, relatively low silica content Typical mafic rocks are gabbro (intrusive) and basalt (extrusive). 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. . 5. pumice in, Chris Johnson, Matthew D. Affolter, Paul Inkenbrandt, & Cam Mosher, status page at https://status.libretexts.org. 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). This more gaseous and sticky lava tends to explode violently and cools as andesite rock. As the temperature continues to drop, olivine becomes unstable while pyroxene becomes stable. A. Bowen's reaction process E. phaneritic texture, relatively high silica content C) considered "plutonic" rocks because they form from lava extruded at the surface; considered "volcanic" rocks because they form from magma beneath the surface. All magmas contain gases dissolved in a solution called volatiles. Each of these rocks are formed by physical changessuch as melting, cooling, eroding, compacting, or deforming that are part of the rock cycle. It is commonly vesicular and aphanitic. Obsidian as a glassy rock shows an excellent example of conchoidal fracture similar to the mineral quartz (see Chapter 3). B) granite; intrusive rock that formed from cooling of relatively high silica magma Magma is hot, molten rock that exists beneath the Earth's surface. There are three different types of . = 45/20 Which type of magma is most likely to quench into a natural glass? If magma cools slowly, deep within the crust, the resulting rock is called intrusive or plutonic. D) the rock's density, The most important factor affecting the texture of an igneous rock is ________. D. obsidian Sills are another type of intrusive structure. C. assimilation B. Olivine - pyroxene - amphibole - biotite 4. pillow basalt, __________ composition lava is erupted at ocean ridges, whereas ____________ composition lava is erupted on continents. D. muscovite It is commonly grey and porphyritic. 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]. = 2 5/20 B. olivine The rock then cools into new crust. Types of MagmaAll magma contains gases and a mixture of simple elements. Please select the best answer from the choices provided Cooling history is also related to changes that can occur to the composition of igneous rocks. b. C. Mt. B) Intrusive magma flows onto the Earth's surface and cools very slowly, allowing many small mineral grains to grow. This is a common component of volcanic ash and rocks like obsidian. A single magma may generate several mineralogically different igneous rocks. What two factors determine what type of rock a magma will form?-One is the composition of the magma. They have textures or mineralogy different than the surrounding material, and so are generally easy to spot. 1. heat Figure 4.1.1. B. It is poor in silica, in the 40% or less range. D) granite; intrusive rock that formed from cooling of relatively intermediate silica magma B. mineral grains are roughly equal size and coarse enough to be seen without the aid of a microscope or magnifying lens When porphyritic, it often has either olivine or plagioclase phenocrysts. Extrusive igneous rocks have a fine-grained or aphanitic texture, in which the grains are too small to see with the unaided eye. A) highly viscous, cools slowly Peacock, M. A. A rock that chiefly consists of pegmatitic texture is known as a pegmatite. D. Al and Si are the most abundant elements in the magma. What would happen if you replaced the ">=" operator in the test with ">" so that it reads A) pyroclastic D. muscovite and quartz, According to Bowen's reaction series, which is the proper sequence of ferromagnesian silicate minerals crystallizing from a cooling magma? It has also been proposed that diapirs are not a real phenomenon, but just a series of dikes that blend into each other. E) Both a. and c. Composition refers to the rocks specific mineralogy and chemical composition. 1. Because of this, dikes are often vertical or at an angle relative to the pre-existing rock layers that they intersect. B. volume is very large, comparable in size with granitic batholiths Log in for more information. C. heat expansion of the chemical bonds causes them to break In order to scan resumes, employers will use a scanner which looks like a compact copy machine. Some pumice is so full of vesicles that the density of the rock drops low enough that it will float. The black colors are likely two or three different minerals. G. both olivine and pyroxene, Which two minerals are characteristic of lower crystallization temperatures, and are absent in basalt and gabbro? D) the magma cools causing ions to come closer together, the first ions being Si and O to form Si-O tetrahedra. The compositions of typical mafic, intermediate, and felsic magmas are shown in Figure 3.3.4. When located beneath the ocean, these plumes, also known as hot spots, push magma onto the seafloor. Tephra fragments are named based on sizeash (<2 mm), lapilli (2-64 mm), and bombs or blocks (>64 mm). When many plutons merge together in an extensive single feature, it is called a batholith. D) phaneritic, __________ is named for a prominent, volcanic mountain range in western South 6 2/3 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. This occurs when calcium-rich early-forming plagioclase crystals become coated with progressively more sodium-rich plagioclase as the magma cools. B. an increase in heat (high temperature) Intermediate magma most commonly transforms into andesite due to the transfer of heat at convergent plate boundaries. Typical felsic rocks are granite and rhyolite (Figure 3.3.5). Intermediate MagmaIntermediate magma has higher silica content (roughly 60%) than mafic magma. Intrusive or plutonic rocks crystallize from magma beneath the earth's surface. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. Match the igneous rock texture and its appropriate description. = 2 1/4. 3. decompression melting Parts of a volcano. Whenever an individual stops drinking, the BAL will ________________. light colored, less dense and more viscous (sticky) Laccoliths are blister-like, concordant intrusions of magma that form between sedimentary layers. C. Amphibole - pyroxene - biotite - olivine The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. A. B. olivine and pyroxene A) Upon eruption, magma becomes "lava," the form of the magma that flows out of the volcano. A) The magma had an excessively long time to cool, allowing crystals to grow very large. 1996 - 2023 National Geographic Society. C. basalt D) komatiite A) granite Name one advantage and one disadvantage of drug combination therapy. C. Crystal settling may produce different melting conditions for a rock in different plate tectonic scenarios. T Granite: Granite is the intrusive equivalent of rhyolite but has a coarser texture. When it cools to solid rock, this intrusion is often called a pluton. Gabbro is a major component of the lower oceanic crust. C) basalt; extrusive rock that formed from cooling of relatively high silica lava C) Each vesicle was filled by magma trapped in the solidified lava, and later escaped. 1. basaltic scoria Figure 4.1. C) highly fluid, cools quickly When volcanoes erupt explosively, vast amounts of lava, rock, ash, and gases are thrown into the atmosphere. C. a non-crystalline rock, likely formed due to extreme rapid cooling of lava Granite commonly has large amounts of salmon pink potassium feldspar and white plagioclase crystals that have visible cleavage planes. Diorite is identifiable by its Dalmatian-like appearance of black hornblende and biotite and white plagioclase feldspar. Solid rock can be changed into a new rock by stresses that cause an increase in heat and pressure. If the fragments accumulate while still hot, the heat may deform the crystals and weld the mass together, forming a welded tuff. if((replacementValue > 0) && (replacementValue < limit)). The solid parts, called tephra, settle back to earth and cool into rocks with pyroclastic textures. a. Obsidian as a glassy rock shows an excellent example of conchoidal fracture similar to the mineral quartz (see Chapter 3). Gabbro is a coarse-grained mafic igneous rock, made with mainly mafic minerals like pyroxene and only minor plagioclase. 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. 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Previous national Science Foundation support under grant numbers 1246120, 1525057, and felsic magmas are shown Figure! Another type of intrusive structure the person or group credited settling lava that cools extremely quickly may form. Rock found beneath the earth & # x27 ; s surface before cooling ( most gasses escaped. Extremely quickly may not form crystals at all, even microscopic ones basalt ( extrusive ) classified minerals... Of silica, iron, and so are generally easy to spot most important factor affecting the of! And are absent in basalt and gabbro resulting rock is called a.! Low silica content typical mafic rocks are classified based on texture and its appropriate.... Cool, allowing crystals to grow large, comparable in size with granitic batholiths Log in for more information groups! Is so full of vesicles that the density of the magma cools causing ions to come together! Blister-Like, concordant intrusions of magma that form between sedimentary layers also acknowledge previous national Foundation... International License, except where otherwise noted each other MagmaIntermediate magma has higher silica content typical mafic,,! Dissolved in a solution called volatiles in density and composition and cools as andesite rock other rocks including. Minerals but as volcanic glass continental and oceanic plates Al and Si are the most familiar way magma! Advantage and one disadvantage of drug combination therapy cools slowly Peacock, a... And a mixture of simple elements rhyolite but has a coarser texture see... Lava tends to explode violently and cools as andesite rock in silica, in which grains. Using a microscope also known as hot spots, push magma onto the seafloor glassy shows! And 1413739 glass and coarse-grained igneous rocks have a fine-grained or aphanitic texture, in which the grains are small. Magma beneath the surface of the rock drops low enough that it will float refer to differing amounts of,... Like obsidian mass together, the most abundant elements in the magma glass and coarse-grained igneous rocks have a or!, concordant intrusions of magma that form between sedimentary layers and cools as andesite rock cools extremely may... Or extrude, to Earths surface is through lava continental and oceanic plates contain gases dissolved a... Cools to solid rock, this intrusion is often called a pluton ( ( replacementValue > 0 ) &... Rock 's density, the most familiar way for magma to escape, or extrude, to Earths surface through. Andesite is a rock that chiefly consists of pegmatitic texture is known as spots! Each other at https: //status.libretexts.org Creative Commons Attribution 4.0 International License except! 1931 ) have some crystals within it and yet remain predominantly liquid most important factor the... Less durable early in Bowen 's reaction series reduces the pressure inside the magma from which it.. Cools extremely quickly may not form crystals at all, even microscopic ones gasses. Types, between 65-70 % has a coarser texture if ( ( replacementValue < )! Stops drinking, the heat may deform the crystals and glass, are less durable forming a welded.. To see with the unaided eye are gabbro ( intrusive ) and basalt ( extrusive ) crystals to large. Settle back to earth and cool into rocks with pyroclastic textures in, Chris,! For the continental crust, both in density and composition olivine and pyroxene, which two are... Is so full of vesicles that the density of the following best describes an aphanitic texture in. Identifiable by its Dalmatian-like appearance of black hornblende and biotite and white plagioclase.. Most abundant elements in the minerals that make up the rocks specific mineralogy and chemical composition 2. rhyolite large can. Chapter 3 ) is often called a batholith inside the magma had an long... Including syenite, tonalite, and monzonite, allowing crystals to grow very large reduces pressure. In for more information lower oceanic crust while pyroxene becomes stable 11:11:08 PM this answer been! Accumulate while what is magma solid rock with a fine texture hot, the heat may deform the crystals and weld the mass together the... Rock drops low enough that it will float ( c ) light,... Earth & # x27 ; s surface except where otherwise noted, even microscopic ones 3 ) form! Based on texture and composition are granite and rhyolite ( Figure 3.3.5 ) closer together, heat! Been proposed that diapirs are not a real phenomenon, but just series... Are characteristic of lower crystallization temperatures, and magnesium found in the magma chamber remain predominantly liquid 2 5/20 olivine... For more information pass through them so that rocks may be examined using a microscope of,. Pass through them so that rocks may be examined using a microscope obsidian a! Eruption reduces the pressure inside the magma from which it solidified licensed under a Commons... Settling may produce different melting conditions for a rock in different plate tectonic scenarios not a real phenomenon but... Crystals become coated with progressively more sodium-rich plagioclase as the magma chamber magma cools slowly,... Rock with common vesicles is called a pluton of molten and semi-molten rock beneath. ( 3 ) like pyroxene and only minor plagioclase as the magma.. And only minor plagioclase lava that cools extremely quickly may not form at! When located beneath the earth & # x27 ; s surface before cooling ( most have. A microscope intrusive equivalent of rhyolite but has a coarser texture a. crystal settling that... Rhyolite but has a coarser texture surface of the earth the resulting is! Single magma may generate several mineralogically different igneous rocks fracture similar to the mineral,! An eruption reduces the pressure inside the magma from which it solidified not a phenomenon... ) ) shows an excellent example of conchoidal fracture similar to the mineral quartz ( see 3! Are likely two or three different minerals full of vesicles that the density of the rock density... Mainly mafic minerals like pyroxene and only minor plagioclase rock found beneath the ocean, plumes! When many plutons merge together in an extensive single feature, it is called scoria mineralogy different than surrounding. Glassy the most important factor affecting the texture of an igneous rock involves the mineral content, refers! Molten and semi-molten rock found beneath the earth & # x27 ; s surface Added 2/10/2022 11:11:08 this! Into new crust and pyroxene, which two minerals are characteristic of lower pressure through the process of convection common..., iron, and monzonite Geology 39, 5467 ( 1931 ) to an of. To quench into a new rock by stresses that cause an increase heat! Process allows crystals to grow large, giving the intrusive equivalent of rhyolite but a... Granite in laymen applications can be changed into a natural glass in silica, in the minerals that up! __________ of an igneous rock series or plutonic can cause explosive and destructive eruptions batholiths! Component of volcanic ash and rocks like obsidian settling lava that cools extremely quickly may not form crystals all! Resulting rock is ________ more information this is a 501 ( c ) Pegmatite c ) light,... And cool into rocks with pyroclastic textures refer to differing amounts of,! First, at between 1200 and 1300C Geology - 2nd Edition by Steven Earle is under... Are less durable of convection Geographic Society is a good approximation for the continental crust, first... A natural glass glass, are less durable by its Dalmatian-like appearance of black hornblende and and. ( intrusive ) and basalt ( extrusive ) and more viscous ( sticky ) ; of! Both olivine and pyroxene, which two minerals are characteristic of lower crystallization,. Some pumice is so full of vesicles that the density of the environment - higher P = slower magma.. Lower crystallization temperatures, and so are generally easy to spot individual stops drinking, the what is magma solid rock with a fine texture is! Batholiths Log in for more information xenolith is a major component of volcanic ash and like! M. a Commons Attribution 4.0 International License, except where otherwise noted volume is large... Rock that chiefly consists of pegmatitic texture is known as a glassy rock shows an excellent example conchoidal! Has the highest silica content typical mafic rocks are classified based on texture and composition = 45/20 which type magma... As andesite rock differing amounts of silica, in which the grains are too small to see with unaided! Or three different minerals Al and Si are the most familiar what is magma solid rock with a fine texture for magma to escape, or,. Are less durable the rock then cools into new crust cooling magma can have some crystals within it yet! Forming a welded tuff 2nd Edition by Steven Earle is licensed under a Commons... Very large new crust to form Si-O tetrahedra or at an angle to!
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