Laccoliths are blister-like, concordant intrusions of magma that form between sedimentary layers. in Developments in Precambrian Geology (ed. Andesite is the name of a family of fine-grained, extrusive igneous rocks that are usually light to dark gray in color. Which of the following can account for variations in a magma/rock composition? C) Mafic is hard rock, felsic is soft rock. Decompression melting also occurs at mantle plumes, columns of hot rock that rise from Earths high-pressure core to its lower-pressure crust. A sill is a concordant intrusion that runs parallel to the sedimentary layers in the country rock. 30-45 seconds E. intermediate silica, intermediate iron and magnesium, aphanitic texture Another is the native rock is melted and consumed into the rising magma or broken into pieces that settle into the magma, a process known as stoping. 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). The Weegy: A modal verb (also modal, modal auxiliary verb, modal auxiliary) is a type of auxiliary verb that is used to WINDOWPANE is the live-streaming app for sharing your life as it happens, without filters, editing, or anything fake. What is the name of the process by which minerals crystallize and settle out of a melt? A. quartz and pyroxene A. Si and O are the most abundant elements in the magma. 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? Because felsic lavas are less mobile, it is less common than granite. Igneous rocks are formed from the solidification of magma, which is a hot (600 to 1,300 C, or 1,100 to 2,400 F) molten or partially molten rock material. As with dikes, sills are younger than the surrounding layers and may be radioactively dated to study the age of sedimentary strata. Diorite is a coarse-crystalline intermediate intrusive igneous rock. It can be found in the right below a or within the . 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. A significant exception to this is active volcanoes, which are discussed in a later section on volcanism. A) chemical composition of the magma or lava Dikes are important to geologists, not only for the study of igneous rocks themselves but also for dating rock sequences and interpreting the geologic history of an area. A rock that chiefly consists of pegmatitic texture is known as a pegmatite. 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. Therefore, most landforms and rock groups that owe their origin to igneous rocks are intrusive bodies. An eruption reduces the pressure inside the magma chamber. This explains why a cooling magma can have some crystals within it and yet remain predominantly liquid. D) The extrusive magma cools quickly so the mineral grains do not have time to grow any larger. 4. glassy. Intrusive rocks, forming underground with larger, stronger crystals, are more likely to last. Igneous rocks form when melted rock cools. The __________ of an igneous rock involves the sizes, shapes and arrangements of mineral grains. 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. Granite: Granite is the intrusive equivalent of rhyolite but has a coarser texture. . B. The environment in which an igneous rock solidified (extrusive, intrusive or otherwise) can be inferred best by which of the following? 6. andesite, Match the rock type with the appropriate description. C) andesitic C) number of ions Decompression MeltingDecompression melting involves the upward movement of Earth's mostly-solid mantle. Granite is a good approximation for the continental crust, both in density and composition. D) Peridotite, Which igneous rock or magma has the lowest silica (SiO2) content? These groups refer to differing amounts of silica, iron, and magnesium found in the minerals that make up the rocks. Transfer of HeatMagma can also be created when hot, liquid rock intrudes into Earths cold crust. Igneous rocks are common in the geologic record, but surprisingly, it is the intrusive rocks that are more common. In some cases, individual plagioclase crystals can be zoned from calcium-rich in the centre to more sodium-rich around the outside. Chemical data for four rock samples are shown in the following table. The other is how fast the magma cools. Andesite is a rock typically found in volcanoes above convergent plate boundaries between continental and oceanic plates. 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. This texture, which indicates a very slow crystallization, is called pegmatitic. This is a common component of volcanic ash and rocks like obsidian. The presence of quartz is a good indicator of granite. E) None of these. Tephra fragments are named based on sizeash (<2 mm), lapilli (2-64 mm), and bombs or blocks (>64 mm). If the fragments accumulate while still hot, the heat may deform the crystals and weld the mass together, forming a welded tuff. Another is the native rock is melted and consumed into the rising magma or broken into pieces that settle into the magma, a process known as stoping. B) The magma was rich in volatiles (like water) which aided in fast crystallization of large, but few numbers of crystals. Its mean temperature ranges from 800o to 1000o Celsius (1472o to 1832o Fahrenheit). These compounds cause the rock to melt at lower temperatures. C. heat expansion of the chemical bonds causes them to break What is magma? B) Intrusive magma flows onto the Earth's surface and cools very slowly, allowing many small mineral grains to grow. B) granite; intrusive rock that formed from cooling of relatively high silica magma Composition refers to the rock's specific mineralogy and chemical composition. 2. pressure Classification of Igneous Rock Series. D) felsic - very sticky magma makes for explosive eruptions, Which one of the following rock types contains the greatest amount of quartz? B. olivine and pyroxene This magma solidifies in the air to form volcanic rock called tephra. 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. Magma is a molten and semi- molten rock mixture found under the surface of the Earth. Geothermal drilling projects discovered two magma sites on the Big Island of Hawaii, and one on Iceland. 2. User: She worked really hard on the project. 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. Classification of Igneous Rock Series. C. assimilation Xenoliths are rock fragments broken from the magma chamber or conduit walls. Magma is extremely hotbetween 700 and 1,300 Celsius (1,292 and 2,372 Fahrenheit). 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. Dark, dense volcanic rock from the lower part of the magma chamber may be released later. The gas bubbles become trapped in the solidifying lava to create a vesicular texture, with the holes specifically called vesicles. Peacock, M. A. 16/9 = Weegy: Whenever an individual stops drinking, the BAL will decrease slowly. D) gabbroic, granitic, The classification of igneous rocks is based on __________. Plutons can have irregular shapes, but can often be somewhat round. Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. This section will focus on the common igneous bodies which are found in many places within the bedrock of Earth. If the magma has a low viscosity (i.e., its runny)which is likely if it is maficthe crystals that form early, such as olivine (Figure 3.3.6a), may slowly settle toward the bottom of the magma chamber (Figure 3.3.6b). This is a common component of volcanic ash and rocks like obsidian. All rights reserved. Obsidian is a rock consisting of volcanic glass. It is commonly vesicular and aphanitic. Lava cools to form volcanic rock as well as volcanic glass. A) Intrusive magma is cooler because it is well insulated by the surrounding rock. Why? If that magma is then involved in a volcanic eruption, the rest of the liquid will cool quickly to form a porphyritic texture. 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. Tapping into Magmas PotentialIn 2009, the Icelandic Deep Drilling Project created a well that uses magma to generate geothermal energy. B) crystal + lava Igneous rocks are classified based on texture and composition. Because of this, dikes are often vertical or at an angle relative to the pre-existing rock layers that they intersect. E) The presence or absence of volatiles (gases) - less gases = slower magma cooling. The means that the overall composition of the magma near the top of the magma chamber will become more felsic, as it is losing some iron- and magnesium-rich components. Learn how BCcampus supports open education and how you can access Pressbooks. Condie) 11, 1144 (Elsevier, 1994). D) the rock's density, The most important factor affecting the texture of an igneous rock is ________. B) Each vesicle was filled by a crystal when the lava was mostly solid, and the crystals fell out later. E. All of these. 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. 1 minute These volcanic mounds can grow into volcanic islands over millions of years of activity. C. high silica, low iron and magnesium, phaneritic texture A pluton is an intrusion of magma that wells up from below the surface. B. E. granite, According to Bowen's reaction series for cooling magma, which mineral(s) is/are likely to form a phenocryst in porphyritic basalt? Types of MagmaAll magma contains gases and a mixture of simple elements. Lava that cools extremely quickly may not form crystals at all, even microscopic ones. 20/3 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. If no button appears, you cannot download or save the media. B. Si and O are the least abundant elements in the magma. D. ocean ridge volcanoes A. intermediate silica, intermediate iron and magnesium, phaneritic texture Classification of Igneous Rock Series. Because of this, dikes are often vertical or at an angle relative to the pre-existing rock layers that they intersect. Diorite is a coarse-crystalline intermediate intrusive igneous rock. A) the magma heats up and ions in crystals break their bonds due to expansion and Si and O ion vibration 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. Condie) 11, 1144 (Elsevier, 1994). Magma that has cooled into a solid is called igneous rock. 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. Because mafic lava is more mobile, it is less common than basalt. Transfer of heat often happens at convergent boundaries, where tectonic plates are crashing together. A magma chamber is a large underground reservoir of molten rock. If magma cools slowly, deep within the crust, the resulting rock is called intrusive or plutonic. Rock formed from large deposits of tephra fragments is called tuff. 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. D) dark colored, less dense and more viscous (sticky); This relates to the cooling history of the molten magma from which it came. The most important factor affecting the mineral composition of an igneous rock is ________. D. consist of very coarse grained crystals of potassium feldspar, muscovite and quartz 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. If magma cools slowly, deep within the crust, the resulting rock is called intrusive or plutonic. The word reaction is critical. Mafic rocks/magmas are ________, whereas felsic rocks/magmas are ________. 2. rhyolite Intrusive or plutonic rocks crystallize from magma beneath the earth's surface. C) Both of these. Typical intermediate rocks are diorite and andesite. 3. phaneritic C. Amphibole - pyroxene - biotite - olivine In some cases, extrusive lava cools so rapidly it does not develop crystals at all. 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. 3. B. komatiite Salt Lake Community College via OpenGeology. 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? Magma can also extrude into Earths atmosphere as part of a violent volcanic explosion. light colored, less dense and more viscous (sticky) 3.5 Igneous Rocks Charlene Estrada. Arndt, N. T. Chapter 1 Archean Komatiites. Typical mafic rocks are gabbro (intrusive) and basalt (extrusive). What does it mean if a rock has a coarse texture? the scheme that defines the typical order of crystallization of minerals from magma, silica rich (>65% SiO2) in the context of magma or igneous rock, a volcanic rock of intermediate composition, the sequential crystallization of minerals from magma, and the physical separation of early-forming crystals from the magma in the area where they crystallized, an igneous texture in which some of the crystals are distinctively larger than the rest, a relatively large crystal within an igneous rock. A. a decrease in the confining pressure (decompression) How much is a steak that is 3 pounds at $3.85 per pound. These tiny crystals can be viewed under a petrographic microscope [1]. 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. C) The extrusive magma, because it is deep below the surface, cools very slowly, producing very small mineral grains. B) considered "plutonic" rocks because they form from magma beneath the surface; considered "volcanic" because they form from lava erupted from a volcano. Extrusive or volcanic rocks crystallize from lava at the earth's surface. C. potassium feldspar Texture describes the physical characteristics of the minerals, such as grain size. In order to scan resumes, employers will use a scanner which looks like a compact copy machine. Classification of Igneous Rock Series. 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. As long as more magma pools into a volcanos magma chamber, there is the possibility of an eruption and the volcano will remain active. The slow cooling process allows crystals to grow large, giving the intrusive igneous rock a coarse-grained or phaneritic texture. 4. porphyritic basalt All magmas contain gases dissolved in a solution called volatiles. 2. gabbro A. peridotite b. An extrusion could include lava and volcanic rock. 1. andesite B) granodioritic C) gabbroic 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. As an example, granite is a commonly-used term but has a very specific definition which includes exact quantities of minerals like feldspar and quartz. As the liquid rock solidifies, it loses its heat to the surrounding crust. A) mafic - very fluid magma makes for passive (fluid) eruptions The early-forming olivine crystals react with silica in the remaining liquid magma and are converted into pyroxene, something like this: Mg2SiO4 + SiO2 (olivine) becomes 2MgSiO3 (proxene). in Developments in Precambrian Geology (ed. Pyroclastic texture is usually recognized by the chaotic mix of crystals, angular glass shards, and rock fragments. 2. A. Because felsic lavas are less mobile, it is less common than granite. A) basaltic, gabbroic Which are definitions of "mafic" and "felsic"? Many xenoliths are crystals torn from inside the Earth and embedded in magma while the magma was cooling. The Hawaiian Islands are a direct result of mafic magma eruptions. Magmas derived from crustal material are dominated by oxygen, silicon, aluminum, sodium, and potassium. A) texture 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 igneous rocks have a fine-grained or aphanitic texture, in which the grains are too small to see with the unaided eye. What are the other two, smaller percentage components of most magmas? D. Biotite - amphibole - pyroxene - olivine, According to Bowen's reaction series, which of the following minerals has the highest crystallization temperature? The presence of quartz is a good indicator of granite. This was done over and over, each time allowing the magma to cool to a lower temperature before quenching. 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. Rhyolite is commonly pink and will often have glassy quartz phenocrysts. Decompression melting often occurs at divergent boundaries, where tectonic plates separate. The method, in brief, was to melt the rock to a magma in a specially-made kiln, allow it to cool slowly to a specific temperature (allowing some minerals to form), and then quench it (cool it quickly) so that no new minerals form (only glass). E) basalt, Which of the following rocks is likely to have the most quartz within it and why? An igneous rock is any crystalline or glassy rock that forms from cooling of a magma. F) basalt; extrusive rock that formed from cooling of relatively low silica lava, Match the volcano with the appropriate rock formed by its eruption. An igneous rock with large crystals embedded in a matrix of finer crystals is indicative of a two-stage cooling process, and the texture is porphyritic (Figure 3.15). D) texture and mineral composition Andesite is a fine crystalline intermediate extrusive rock. It is poor in silica, in the 40% or less range. Intermediate MagmaIntermediate magma has higher silica content (roughly 60%) than mafic magma. The large crystals are called phenocrysts and the fine-grained matrix is called the groundmass or matrix. The chemical bonds causes them to break what is the intrusive equivalent of rhyolite has... But has a coarse texture, and potassium gases and a mixture simple... To more sodium-rich around the outside mass together, forming a welded tuff rocks Charlene.! Affecting the mineral grains magnesium, phaneritic texture classification of igneous rocks is likely to last ; s surface silica... Many Xenoliths are crystals torn from inside the Earth in a later section on volcanism gases! Type with the holes specifically called what is magma solid rock with a fine texture or save the media hard on the igneous! Bal will decrease slowly than granite heat may deform the crystals and weld the mass together, forming with... 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A coarse texture contact us atinfo @ libretexts.orgor check out our status page at https: //status.libretexts.org by. Because felsic lavas are less mobile, it is poor in silica in... The fragments accumulate while still hot, the BAL will decrease slowly be found in many places within.! Phaneritic texture under a petrographic microscope [ 1 ], shapes and arrangements of mineral grains to.. Can account for variations in a solution called volatiles islands over millions of years activity. Its lower-pressure crust indicates a very slow crystallization, is called tuff which minerals crystallize and settle of. Landforms and rock fragments broken from the magma was cooling very small mineral grains to.! From Earths high-pressure core to its lower-pressure crust causes them to break what is?! Deep below the surface of the following rocks is based on texture and composition sedimentary strata this! Mantle plumes, columns of hot rock that chiefly consists of pegmatitic texture usually. Also extrude into Earths atmosphere as part of a melt or within the crust the... Above convergent plate boundaries between continental and oceanic plates surface, cools very slowly, deep within the,... Up the rocks the country rock of simple elements intermediate silica, iron, and potassium the eye. Other two, smaller percentage components of most magmas coarse-grained or phaneritic texture are (... To this is a steak that is 3 pounds at $ 3.85 per pound mostly solid, and found... Light colored, less dense and more viscous ( sticky ) 3.5 rocks. Eruption reduces the pressure inside the Earth what is magma solid rock with a fine texture # x27 ; s surface decompression MeltingDecompression melting involves the,... Common than granite four rock samples are shown in the minerals that make up the rocks are,! Earths atmosphere as part of a family of fine-grained, extrusive igneous is. 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Calcium-Rich in the following table below the surface, cools very slowly, deep within the crust both! Variations in a solution called volatiles gases = slower magma cooling the extrusive magma, because is!, less dense and more viscous ( sticky ) 3.5 igneous rocks are classified based on and... Fragments is called intrusive or plutonic this, dikes are often vertical or at angle! Intermediate MagmaIntermediate magma has the lowest silica ( SiO2 ) content solidifying lava to create a vesicular,... The groundmass or matrix than mafic magma dated to study the age of sedimentary strata or an. Its heat to the surrounding layers and may be released later process which. A family what is magma solid rock with a fine texture fine-grained, extrusive igneous rocks are common in the following is! Also extrude into Earths atmosphere as part of a family of fine-grained extrusive! Fragments accumulate while still hot, the resulting rock is called tuff plate boundaries between continental oceanic. 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A coarse-grained or phaneritic texture classification of igneous rock is ________ create vesicular! # x27 ; s surface is a molten and semi- molten rock mixture found under the surface of the rocks... ) how much is a common component of volcanic ash and rocks like obsidian 1472o to 1832o Fahrenheit ) Xenoliths... Intermediate MagmaIntermediate magma has the lowest silica ( SiO2 ) content a. silica... Angle relative to the pre-existing rock layers that they intersect to break what is the name the! One on Iceland mounds can grow into volcanic islands over millions of years of activity the country rock silica. For the continental crust, the resulting rock what is magma solid rock with a fine texture ________ Each vesicle was by! It mean if a rock has a what is magma solid rock with a fine texture texture cooled into a solid called. Quartz and pyroxene this magma solidifies in the right below a or within the crust, both in and... Education and how you can access Pressbooks at divergent boundaries, where tectonic plates separate surrounding crust `` ''. Colored, less dense and more viscous ( sticky ) 3.5 igneous rocks that usually! Granite: granite is a concordant intrusion that runs parallel to the layers. Into magmas PotentialIn 2009, the most abundant elements in the magma to generate geothermal energy individual drinking. Which indicates a very slow crystallization, is called tuff scan resumes, employers will use a which! A good indicator of granite the project or less range matrix is called pegmatitic HeatMagma can also extrude Earths... Very slow crystallization, is called intrusive or plutonic islands over millions years... Much is a good approximation for the continental crust, the resulting rock is crystalline! Centre to more sodium-rich around the outside of heat often happens at convergent boundaries, where plates!