A) The rock is crystalline, but mineral grains are of distinctly different sizes. A) Pressure of the environment - lower P = slower magma cooling. A) mafic - very fluid magma makes for passive (fluid) eruptions Magma is a mixture of molten and semi-molten rock found beneath the surface of the Earth. = 45/20 A. both quartz and muscovite Accessibility StatementFor more information contact us atinfo@libretexts.orgor check out our status page at https://status.libretexts.org. 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 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. 2. 3. rhyolitic pumice A magma chamber is a large underground reservoir of molten rock. Mafic magma also has high mean temperatures, between 1000o and 2000o Celsius (1832o and 3632o Fahrenheit), which contributes to its lower viscosity. The Henry Mountains of Utah are a famous topographic landform formed by this process. Therefore, most landforms and rock groups that owe their origin to igneous rocks are intrusive bodies. A) rate of cooling 3. Which of the following minerals crystallize early in Bowen's reaction series? seated magma in the magma chamber ascend s due to buoyancy or any tectonic activity and intrudes into the country rock (host rock) or it may come out at the surface and solidify. Magma that has cooled into a solid is called igneous rock. D) solid + crystal. The most abundant elements are oxygen and silicon, followed by aluminum, iron, calcium, sodium, magnesium, and potassium. The slow cooling process allows crystals to grow large, giving the intrusive igneous rock a coarse-grained or phaneritic texture. D) Each vesicle is filled by air and water. D. obsidian K.C. Rocks labeled as granite in laymen applications can be several other rocks, including syenite, tonalite, and monzonite. in, Chris Johnson, Matthew D. Affolter, Paul Inkenbrandt, & Cam Mosher, status page at https://status.libretexts.org. E) The presence or absence of volatiles (gases) - less gases = slower magma cooling. A sill is a concordant intrusion that runs parallel to the sedimentary layers in the country rock. As it falls to Earth, tephra includes rocks such as pumice. E) Both a. and c. There are three different types of . Granite commonly has large amounts of salmon pink potassium feldspar and white plagioclase crystals that have visible cleavage planes. As the liquid rock solidifies, it loses its heat to the surrounding crust. A magma chamber is a large underground reservoir of molten rock. Intermediate MagmaIntermediate magma has higher silica content (roughly 60%) than mafic magma. B) gabbroic, rhyolitic Decompression melting also occurs at mantle plumes, columns of hot rock that rise from Earths high-pressure core to its lower-pressure crust. 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. Each of these rocks are formed by physical changessuch as melting, cooling, eroding, compacting, or deforming that are part of the rock cycle. Cooling history is also related to changes that can occur to the composition of igneous rocks. 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. B) dark colored, more dense and less viscous (not sticky); Lava flows are typically finer grained than intrusive igneous rocks. What would happen if you replaced the ">=" operator in the test with ">" so that it reads 16/9 = Weegy: Whenever an individual stops drinking, the BAL will decrease slowly. The solid parts, called tephra, settle back to earth and cool into rocks with pyroclastic textures. Rock formed from large deposits of tephra fragments is called tuff. 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]. Rock formed from large deposits of tephra fragments is called tuff. This page titled 4.1: 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) . All rights reserved. In a porphyritic volcanic rock, which mineral grains are the last to crystallize? Gabbro is a coarse-grained mafic igneous rock, made with mainly mafic minerals like pyroxene and only minor plagioclase. The texture of an igneous rock (fine-grained vs coarse-grained) is dependent on the rate of cooling of the melt: slow cooling allows large crystals to form, fast cooling yields small crystals. Glazner, A. F., Bartley, J. M., Coleman, D. S., Gray, W. & Taylor, R. Z. 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? 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. gabbro a. The least-dense magma rises to the top. B. diorite B. basalt Extrusive igneous rocks have a fine-grained or aphanitic texture, in which the grains are too small to see with the unaided eye. The pool of magma in a magma chamber is layered. F) The presence or absence of volatiles (gases) - more gases = slower magma cooling. This section will focus on the common igneous bodies which are found in many places within the bedrock of Earth. B) granite; intrusive rock that formed from cooling of relatively high silica magma B. higher values of this require greater temperatures for melting Why? D. plate tectonics, Match the appropriate term associated with the production of magma to its best description. A) The glass is formed mostly when lava cools in a volcano whereas phaneritic rocks cool at the surface. 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). These eruptions eject lava violently into the air, which cools into dacite and rhyolite rock. Thick, viscous felsic magma can trap gas bubbles in a volcanos magma chamber. D) The rock contains broken fragments and is volcanic in origin. Diorite is identifiable by its Dalmatian-like appearance of black hornblende and biotite and white plagioclase feldspar. Stage 2 If that magma is then involved in a volcanic eruption, the rest of the liquid will cool quickly to form a porphyritic texture. The crystals that settle might either form an olivine-rich layer near the bottom of the magma chamber, or they might remelt because the lower part is likely to be hotter than the upper part (remember, from Chapter 1, that temperatures increase steadily with depth in Earth because of the geothermal gradient). C. assimilation Figure 4.1. 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. It is the source of all igneous rock. Types of MagmaAll magma contains gases and a mixture of simple elements. Chapter 6 Sediments and Sedimentary Rocks, Chapter 7 Metamorphism and Metamorphic Rocks, Chapter 21 Geological History of Western Canada, Chapter 22 The Origin of Earth and the Solar System, Creative Commons Attribution 4.0 International License. The Hawaiian Islands are a direct result of mafic magma eruptions. Name one advantage and one disadvantage of drug combination therapy. Most of the mantle and crust are solid, so the presence of magma is crucial to understanding the geology and morphology of the mantle. As a result of its higher viscosity and gas content, intermediate magma builds up pressure below the Earths surface before it can be released as lava. These groups refer to differing amounts of silica, iron, and magnesium found in the minerals that make up the rocks. Please select the best answer from the choices provided While normal geothermal sources average around 60 to 80Celsius (140 to 176 Fahrenheit), the magma wells steam reached a record-breaking temperature of 450 Celsius (842 Fahrenheit)! As long as more magma pools into a volcanos magma chamber, there is the possibility of an eruption and the volcano will remain active. Sills are another type of intrusive structure. Xenoliths are rock fragments broken from the magma chamber or conduit walls. 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). D. gabbro Rhyolite is commonly pink and will often have glassy quartz phenocrysts. B) the rock's composition Gabbro is a major component of the lower oceanic crust. if((replacementValue > 0) && (replacementValue < limit)). A) the magma heats up and ions in crystals break their bonds due to expansion and Si and O ion vibration B) When magma gets to the top of the volcano it releases gas found within the magma, and the lava that escapes the volcano has therefore lost those gases. E) basalt, Which of the following rocks is likely to have the most quartz within it and why? Normally, geothermal energy is created by pumping water into hot volcanic bedrock, creating steam that is then harnessed to generate electricity. 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. Typical intermediate rocks are diorite and andesite. D) the lava in the crystallizing magma chamber before eruption. 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. C) Mafic is hard rock, felsic is soft rock. Rhyolite refers to the volcanic and felsic igneous rocks and granite refer to intrusive and felsic igneous rocks. 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) . TRUE. Visible quartz and potassium feldspar grains are the main constituents in a. A. consist of very large grains of quartz, olivine and pyroxene in relatively large bodies of former sedimentary rock What are the other two, smaller percentage components of most magmas? A. peridotite D. andesite D) felsic - very sticky magma makes for explosive eruptions, Which one of the following rock types contains the greatest amount of quartz? Because felsic lavas are less mobile, it is less common than granite. Mafic magmas have 45% to 55% SiO2, about 25% total of FeO and MgO plus CaO, and about 5% Na2O + K2O. As a magma cools below 1300C, minerals start to crystallize within it. For the rock to be called porphyritic there has to be a significant difference in crystal size, where the larger crystals are at least 10 times larger than the average size of the smaller crystals. 2. porphyritic [Hint] 1. andesite This relates to the cooling history of the molten magma from which it came. This is a common component of volcanic ash and rocks like obsidian. Extrusive or volcanic rocks crystallize from lava at the earth's surface. Extrusive rocks, because of their small crystals and glass, are less durable. 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. Stage 3, Instead of having to know HTML code, most Web sites will have templates that make creating Web rsums easy. A significant exception to this is active volcanoes, which are discussed in a later section on volcanism. 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