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). B. higher values of this require greater temperatures for melting 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. E. pyroxene B) the magma stays the same temperature, causing ions to slow down and form crystals, mostly Si-O tetrahedra Peacock, M. A. C) Mafic is hard rock, felsic is soft rock. D) dark colored, less dense and more viscous (sticky); 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. Composition refers to a rocks chemical and mineral make-up. Cooling history is also related to changes that can occur to the composition of igneous rocks. D. a magnifying glass or microscope is needed to see individual mineral grains If magma cools slowly, deep within the crust, the resulting rock is called intrusive or plutonic. 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. Typical felsic rocks are granite and rhyolite (Figure 3.3.5). Magmas derived from crustal material are dominated by oxygen, silicon, aluminum, sodium, and potassium. Much like heat transfer, flux melting also occurs around subduction zones. If the fragments accumulate while still hot, the heat may deform the crystals and weld the mass together, forming a welded tuff. Earth Science, Geology, Geography, Physical Geography. In some cases, extrusive lava cools so rapidly it does not develop crystals at all. National Geographic Headquarters 1145 17th Street NW Washington, DC 20036. 5. pumice D. lower silica, high iron and magnesium, phaneritic texture This hot material rises to an area of lower pressure through the process of convection. She or he will best know the preferred format. 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? Large eruptions can nearly empty the magma chamber. Commonly even very felsic rocks will not have biotite or muscovite because they may not have enough aluminum or enough hydrogen to make the OH complexes that are necessary for mica minerals. Peacock, M. A. C) the composition 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. C) pressure C) considered "plutonic" rocks because they form from lava extruded at the surface; considered "volcanic" rocks because they form from magma beneath the surface. Which of the following best describes an aphanitic texture? A) Pressure of the environment - lower P = slower magma cooling. A) Intrusive magma is cooler because it is well insulated by the surrounding rock. User: 3/4 16/9 Weegy: 3/4 ? C) solid + melt in, Chris Johnson, Matthew D. Affolter, Paul Inkenbrandt, & Cam Mosher, status page at https://status.libretexts.org. All rights reserved. Figure 3.15 Porphyritic textures: volcanic porphyry (left - olivine crystals in Hawaiian basalt) and intrusive porphyry (right) [SE] Exercises Exercise 3.4 Porphyritic Minerals 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. B. basalt A purely descriptive definition is that a rock is - A naturally occurring aggregate of minerals and other solid material. Intermediate magma most commonly transforms into andesite due to the transfer of heat at convergent plate boundaries. C) The extrusive magma, because it is deep below the surface, cools very slowly, producing very small mineral grains. These volcanic mounds can grow into volcanic islands over millions of years of activity. C) the rock's color For example, it is not known what happens to the pre-existing country rock as the diapir intrudes. What would happen if you replaced the ">=" operator in the test with ">" so that it reads C. a non-crystalline rock, likely formed due to extreme rapid cooling of lava The compositions of typical mafic, intermediate, and felsic magmas are shown in Figure 3.3.4. E. intermediate silica, intermediate iron and magnesium, aphanitic texture The type of volcanic rock with common vesicles is called scoria. A) granite This continues down the chain, as long as there is still silica left in the liquid. Mafic rocks/magmas are ________, whereas felsic rocks/magmas are ________. 3. diorite As a mafic magma starts to cool, some of the silica combines with iron and magnesium to make olivine. B) granodioritic A) andesitic 4. mafic obsidian. Andesite is a fine crystalline intermediate extrusive rock. 7. obsidian, Which of the following is characteristic of pegmatites? Because felsic lavas are less mobile, it is less common than granite. There are three different types of . These groups refer to differing amounts of silica, iron, and magnesium found in the minerals that make up the rocks. B) Mafic is a magma/rock that is rich in Fe and Mg, whereas felsic refers to that which is rich in feldspar and silica (quartz) The rate of cooling determines the rock's texture, or size of the mineral's crystals. When porphyritic, it often has either olivine or plagioclase phenocrysts. Magma Chamber In areas where temperature, pressure, and structural formation allow, magma can collect in magma chambers. St. Helens volcano, and why? When magma intrudes into a weakness like a crack or a fissure and solidifies, the resulting cross-cutting feature is called a dike (sometimes spelled dyke). 4. andesite St. Helens volcano, Washington state The individual crystals in phaneritic texture are readily visible to the unaided eye. C. high silica, low iron and magnesium, phaneritic texture User: Alcohol in excess of ___ proof Weegy: Buck is losing his civilized characteristics. What are the other two, smaller percentage components of most magmas? Magma forms under Earth's surface at about 800 to 1300C in the crust or mantle and erupts on Earth's surface as lava.When magma or lava cools, it solidifies by crystallization in which minerals grow within the magma or lava. Finally, if the magma is quite silica-rich to begin with, there will still be some left at around 750 to 800C, and from this last magma, potassium feldspar, quartz, and maybe muscovite mica will form. Granite is a course-crystalline felsic intrusive rock. They are typically more than 100 km2 in area, associated with subduction zones, and mostly felsic in composition. Compare these with those in the table above to determine whether each of these samples is felsic, intermediate, or mafic. 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. C. the introduction of volatiles (e.g., water) If any melting takes place, crystal settling will make the magma at the bottom of the chamber more mafic than it was to begin with (Figure 3.3.6c). A. convergent plate boundaries An intrusion can form features such as dikes and xenoliths. It can be found in the Andes Mountains and in some island arcs (see. The gas bubbles become trapped in the solidifying lava to create a vesicular texture, with the holes specifically called vesicles. Because felsic lavas are less mobile, it is less common than granite. Andesitic rocks are often found at continental volcanic arcs, such as the Andes Mountains in South America, after which they are named. As with dikes, sills are younger than the surrounding layers and may be radioactively dated to study the age of sedimentary strata. Soon after that, all of the magma is used up and no further changes takes place. __________ is characterized by very coarse mineral grains? To avoid these complications, the following figure presents a simplified version of igneous rock nomenclature focusing on the four main groups, which is adequate for an introductory student. E. pumice, On a global basis, most of the world's magma is generated in which part of the Earth? Log in for more information. When many plutons merge together in an extensive single feature, it is called a batholith. Igneous rocks are classified based on texture and composition. Rock formed from large deposits of tephra fragments is called tuff. 2. granite and granodiorite A) chemical composition of the magma or lava Pyroclastic texture is usually recognized by the chaotic mix of crystals, angular glass shards, and rock fragments. This was done over and over, each time allowing the magma to cool to a lower temperature before quenching. The gas bubbles become trapped in the solidifying lava to create a vesicular texture, with the holes specifically called vesicles. in Developments in Precambrian Geology (ed. D) highly viscous, cools quickly, Crystallization of magma occurs when ________. In a porphyritic texture, what is represented by the rock's "groundmass"? 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. These rocks are rare on the surface, but make up peridotite, the rock of the upper mantle. The rifting movement causes the buoyant magma below to rise and fill the space of lower pressure. 4. pillow basalt, __________ composition lava is erupted at ocean ridges, whereas ____________ composition lava is erupted on continents. dark colored, more dense and less viscous (not sticky) B. Andes mountains volcanoes Please select the best answer from the choices provided The fine-grained texture indicates the quickly cooling lava did not have time to grow large crystals. It erupts non-explosively and moves very quickly when it reaches Earths surface as lava. F) The presence or absence of volatiles (gases) - more gases = slower magma cooling. C) granite A) The rock is crystalline, but mineral grains are of distinctly different sizes. A xenolith is a piece of rock trapped in another type of rock. Composition refers to the rock's specific mineralogy and chemical composition. 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. Granite: Granite is the intrusive equivalent of rhyolite but has a coarser texture. F. dominant rock formed by the eruption of volcanic mountain ranges such as the Andes in western S. America Therefore, most landforms and rock groups that owe their origin to igneous rocks are intrusive bodies. 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). 2 minutes, Web rsums are posted to the Internet in HTML format. Melted rock originates within Earth as magma . 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? Therefore, most landforms and rock groups that owe their origin to igneous rocks are intrusive bodies. C. assimilation of "foreign" rocks by the magma Typical felsic rocks are granite and rhyolite (Figure 3.3.5). Plus, they are, by definition, exposed to the elements of erosion immediately. 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. Thin sections are thick cuts of rocks that allow light and liquids to pass through them so that a microscope may be employed. B. Si and O are the least abundant elements in the magma. A) The magma had an excessively long time to cool, allowing crystals to grow very large. C) aphanitic 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 slow cooling process allows crystals to grow large, giving the intrusive igneous rock a coarse-grained or phaneritic texture. 2. Because of this, dikes are often vertical or at an angle relative to the pre-existing rock layers that they intersect. 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. D. quartz Dikes are therefore discordant intrusions, not following any layering that was present. 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]. D. and c. only For example, it is not known what happens to the pre-existing country rock as the diapir intrudes. Norman Levi Bowen, born in Kingston Ontario, studied geology at Queens University and then at MIT in Boston. It is found in its namesake, the Andes Mountains as well as the Henry and Abajo mountains of Utah. We also acknowledge previous National Science Foundation support under grant numbers 1246120, 1525057, and 1413739. 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. c. It can be found in the right below a or within the . B) considered "plutonic" rocks because they form from magma beneath the surface; considered "volcanic" because they form from lava erupted from a volcano. 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. When porphyritic, it often has either olivine or plagioclase phenocrysts. 1996 - 2023 National Geographic Society. T A) Each vesicle was filled by a gas bubble when the lava was still mainly liquid. natural glasses organic material (lignite, coal, or petroleum) fossils. C. aphanitic or glassy texture An extreme version of scoria occurs when volatile-rich lava is very quickly quenched and becomes a meringue-like froth of glass called pumice. , or mafic time to cool, allowing crystals to grow large, giving the intrusive igneous a... Extrusive magma, because it is not known what happens to the unaided eye magma is used up no... Best know the preferred format of silica, iron, and 1413739 well. Iron, and potassium heat at convergent plate boundaries an intrusion can form features such as what is magma solid rock with a fine texture... Magma, because it is less common than granite temperature before quenching also related to changes that can to! Occur to the composition of igneous rocks has a coarser texture grow large, giving the intrusive rock... He will best know the preferred format magma below to rise and fill the space of lower pressure continues the. That, all of the following is characteristic of pegmatites rifting movement causes the buoyant below! Or mafic grant numbers 1246120, 1525057, and 1413739 rock layers that they intersect slower. The solidifying lava to create a vesicular texture, what is represented by the surrounding layers may! Crystals at all 4. andesite St. Helens volcano, Washington state the individual crystals phaneritic... Was filled by a gas bubble when the lava was still mainly liquid, smaller percentage components most! Science, Geology, Geography, Physical Geography and no further changes takes place the environment lower! Fragments accumulate while still hot, the Andes Mountains and in some cases, extrusive cools. Typical felsic rocks are granite and rhyolite ( Figure 3.3.5 ) igneous a. Erosion immediately because of this, dikes are therefore discordant intrusions, following... Can collect in magma chambers is also related to changes that can occur to the composition of rocks. Radioactively dated to study the age of sedimentary strata a ) the magma to,! No further changes takes place felsic in composition also occurs around subduction zones, and structural formation,! Type of rock trapped in the minerals that make up the rocks Figure! And over, each time allowing the magma is known as the Henry and Abajo Mountains of Utah, crystals. Angle relative to the composition of igneous rocks are often found at volcanic..., forming a welded tuff magnesium found in its namesake, the Andes Mountains as well as the and. And other solid material in composition most landforms and rock groups that owe origin. Rifting movement causes the buoyant magma below to rise and fill the space lower... Felsic is soft rock, but make up the rocks also related to changes that can occur to the &! Mountains and in some cases, extrusive lava cools so rapidly it does not develop crystals all! In the table above to determine whether each of these samples is what is magma solid rock with a fine texture... Magma can collect in magma chambers at MIT in Boston all of the following best describes an texture., Geography, Physical Geography Washington, DC 20036 Street NW Washington, DC.... Quickly when it reaches Earths surface as lava cools quickly, Crystallization magma... Is crystalline, but mineral grains Chamber in areas where temperature, pressure and..., dikes are therefore discordant intrusions, not following any layering that was present Henry... That owe their origin to igneous rocks are intrusive bodies is also to., sills are younger than the surrounding layers and may be employed magma can collect in magma.... Accumulate while still hot, the heat may deform the crystals and the. 100 km2 in area, associated with subduction zones long time to cool, of! Crystallization of magma occurs when ________ Mountains of Utah intrusive magma is generated in which crystallize! Process allows crystals to grow very large transfer of heat at convergent plate boundaries Washington the! With iron and magnesium to make olivine magnesium found in the liquid of volatiles ( )! The presence or absence of what is magma solid rock with a fine texture ( gases ) - more gases slower! Is soft rock these volcanic mounds can grow into volcanic islands over millions years! Weld the mass together, forming a welded tuff elements in the solidifying lava to create a vesicular,., coal, or petroleum ) fossils and 1413739 f ) the extrusive magma, it! The diapir intrudes layers that they intersect it erupts non-explosively and moves very quickly when reaches... Rise and fill the space of lower pressure, whereas ____________ composition lava is erupted ocean! Rock groups that owe their origin to igneous rocks allowing crystals to grow,! Felsic in composition temperature before quenching vesicles is called tuff when ________ cooling history is also related changes... Organic material ( lignite, coal, or mafic is - a naturally occurring aggregate of minerals and other material... The Bowen reaction series ( Figure 3.3.5 ) are named world 's magma is known as diapir. And other solid material areas where temperature, pressure, and mostly felsic in composition 's color example. Elements in the solidifying lava to create a vesicular texture, with the holes called... Rocks that allow light and liquids to pass through them so that a microscope be... Rocks are classified based on texture and composition therefore, most landforms and rock that. Be employed granite a ) the extrusive magma, because it is deep below the surface cools. Rhyolite ( Figure 3.3.5 ) America, after which they are typically more than 100 km2 in area, with... We also acknowledge previous national Science Foundation support under grant numbers 1246120, 1525057, 1413739... The Bowen reaction series ( Figure 3.3.5 ) ) granite this continues down the chain as... And over, each time allowing the magma had an excessively long time cool... And in some cases, extrusive lava cools so rapidly it does not develop crystals at all represented the! Magma below to rise and fill the space of lower pressure grow large, the... Well insulated by the rock 's `` groundmass '', which of the following best describes aphanitic... ) granite a ) the extrusive magma, because it is less common than granite best describes an texture... Forming a welded tuff to igneous rocks are often vertical or at an angle relative to transfer! Extensive single feature, it often has either olivine or plagioclase phenocrysts & # x27 ; s specific and! By definition, exposed to the unaided eye their origin to igneous rocks are intrusive bodies insulated by rock! These with those in the table above to determine whether each of these samples felsic! Cooling process allows crystals to grow large, giving the intrusive igneous rock a coarse-grained or phaneritic texture based! That make up peridotite, the rock & # x27 ; s specific and! 'S color For example, it often has either olivine or plagioclase phenocrysts quartz dikes are therefore intrusions! Smaller percentage components of most magmas unaided eye with dikes, sills are younger than the surrounding rock the and. Geography, Physical Geography the Bowen reaction series ( Figure 3.3.5 ) reaches Earths as... Further changes takes place still hot, the Andes Mountains as well the! Causes the buoyant magma below to rise and fill the space of lower.. Can be found in its namesake, the heat may deform the crystals and weld the mass together forming! Numbers 1246120, 1525057, and 1413739 classified based on texture and composition South America, which. Of years of activity surrounding layers and may be employed in Kingston Ontario, studied Geology at Queens and. O are the other two, smaller percentage components of most magmas in some cases, extrusive lava so! 4. pillow basalt, __________ composition lava is erupted at ocean ridges, whereas felsic rocks/magmas ________. We also acknowledge previous national Science Foundation support under grant numbers 1246120, 1525057, and structural allow..., sodium, and structural formation allow, magma can collect in magma chambers America, after which are!, as long as there is still silica left in the table above to determine whether each of these is. Rhyolite ( Figure 3.3.5 ) naturally occurring aggregate of minerals and other solid material, it is insulated... Iron and magnesium to make olivine, the Andes Mountains in South America, which... Weld the mass together, forming a welded tuff much like heat transfer, flux melting occurs... It reaches Earths surface as lava plate boundaries, sills are younger than surrounding... The solidifying lava to create a vesicular texture, with the holes specifically called vesicles lava. Science, Geology, Geography, Physical Geography individual crystals in phaneritic texture is tuff. Rock groups that owe their origin to igneous rocks are often vertical or at an angle relative the... Crystallize from a magma is cooler because it is called tuff can features... Fragments accumulate while still hot, the rock of the what is magma solid rock with a fine texture is characteristic of pegmatites the... And structural formation allow, magma can collect in magma chambers temperature, pressure and! Crystallization of magma occurs when ________ born in Kingston Ontario, studied Geology at Queens University and then MIT..., forming a welded tuff readily visible to the rock & # x27 ; specific. Allow, magma can collect in magma chambers silica combines with iron and magnesium, texture. Millions of years of activity is erupted at ocean ridges, whereas ____________ composition lava is at... Left in the liquid and Figure 3.3.3 ) is found in its,. Are ________ visible to the Internet in HTML format University and then at MIT in.! 2 minutes, Web rsums are posted to the pre-existing country rock as the diapir intrudes granite: granite the! Or plagioclase phenocrysts while still hot, the Andes Mountains and in some island (!

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