Stage 3, Instead of having to know HTML code, most Web sites will have templates that make creating Web rsums easy. A) the magma heats up and ions in crystals break their bonds due to expansion and Si and O ion vibration Composition refers to a rocks chemical and mineral make-up. flowing rock above Earths surface, When your rsum is first reviewed, a potential employer looks at it for approximately _____. Salt Lake Community College via OpenGeology. __________ is a volcanic rock that is extremely vesicular and glassy. In comparison, one single wind turbine generates between 1 to 3 megawatts. B. mineral grains are roughly equal size and coarse enough to be seen without the aid of a microscope or magnifying lens St. Helens volcano, and why? These tiny crystals can be viewed under a petrographic microscope [1]. B) The rock has mineral grains that are glassy. All magmas contain gases dissolved in a solution called volatiles. Mafic magmas have 45% to 55% SiO2, about 25% total of FeO and MgO plus CaO, and about 5% Na2O + K2O. TRUE. These rocks are rare on the surface, but make up peridotite, the rock of the upper mantle. = 2 5/20 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. 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. In a porphyritic texture, what is represented by the rock's "groundmass"? Which are definitions of "mafic" and "felsic"? There are two reasons for this: one is that in the early analytical procedures, the results were always expressed that way, and the other is that all of these elements combine readily with oxygen to form oxides. A) highly viscous, cools slowly Basalt is a fine-grained mafic igneous rock. D. consist of very coarse grained crystals of potassium feldspar, muscovite and quartz This creates magma in places where it originally maintained a solid structure. 4. porphyritic basalt 4. glassy. C. high silica, low iron and magnesium, phaneritic texture solid rock with a fine texture cooled rock with large crystals molten rock below Earth's surface flowing rock above Earth's surface 1 See answer Advertisement Advertisement jjrudolf8 jjrudolf8 Answer: C. molten rock below Earth's surface. The most abundant elements are oxygen and silicon, followed by aluminum, iron, calcium, sodium, magnesium, and potassium. Felsic MagmaFelsic magma has the highest silica content of all magma types, between 65-70%. Decompression melting often occurs at divergent boundaries, where tectonic plates separate. 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) . The word reaction is critical. The rifting movement causes the buoyant magma below to rise and fill the space of lower pressure. This explains why a cooling magma can have some crystals within it and yet remain predominantly liquid. 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. Pyroclastic texture is usually recognized by the chaotic mix of crystals, angular glass shards, and rock fragments. 3. extrusive igneous rock A) the rock's texture Rock formed from large deposits of tephra fragments is called tuff. Rock formed from large deposits of tephra fragments is called tuff. 4. mafic obsidian. 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. Pyro, meaning fire, refers to the igneous source of the tephra and clastic refers to the rock fragments. 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. C. Crystal settling may produce different melting conditions for a rock in different plate tectonic scenarios. 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? Classification of Igneous Rock Series. A. consist of very large grains of quartz, olivine and pyroxene in relatively large bodies of former sedimentary rock A. a decrease in the confining pressure (decompression) All rights reserved. Composition refers to a rocks chemical and mineral make-up. 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. 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. Low viscosity means that mafic magma is the most fluid of magma types. This results in a higher gas content and viscosity. Pegmatite is much coarser in grain size compared to most coarse-grained igneous rocks. Solid rock can be changed into a new rock by stresses that cause an increase in heat and pressure. Extrusive igneous rocks have a fine-grained or aphanitic texture, in which the grains are too small to see with the unaided eye. 1. basaltic scoria Rhyolite is commonly pink and will often have glassy quartz phenocrysts. Glazner, A. F., Bartley, J. M., Coleman, D. S., Gray, W. & Taylor, R. Z. They have a mineral composition that is intermediate between granite and basalt. When porphyritic, it often has either olivine or plagioclase phenocrysts. A) andesitic It is commonly vesicular and aphanitic. Many xenoliths are crystals torn from inside the Earth and embedded in magma while the magma was cooling. This was done over and over, each time allowing the magma to cool to a lower temperature before quenching. 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. Basalt is one of the most common rocks in Earths crust as well as the volcanic islands created by hot spots. It can be found in the right below a or within the . Diorite is identifiable by its Dalmatian-like appearance of black hornblende and biotite and white plagioclase feldspar. Lava is molten rock flowing out of fissures or vents at volcanic centres (when cooled, they form rocks such as basalt, rhyolite, or obsidian). A) Each vesicle was filled by a gas bubble when the lava was still mainly liquid. Note that, unlike Figure 3.2.1, these compositions are expressed in terms of oxides (e.g., Al2O3 rather than just Al). What would happen if you replaced the ">=" operator in the test with ">" so that it reads Peacock, M. A. F, During this stage of rsum review, employers use the rsum to guide interview questions: 1. heat C. assimilation 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. D. extrusion The large crystals are called phenocrysts and the fine-grained matrix is called the groundmass or matrix. Magma is a mixture of molten and semi-molten rock found beneath the surface of the Earth. C. potassium feldspar These groups refer to differing amounts of silica, iron, and magnesium found in the minerals that make up the rocks. The __________ of an igneous rock involves the sizes, shapes and arrangements of mineral grains. Magmas derived from crustal material are dominated by oxygen, silicon, aluminum, sodium, and potassium. Peacock, M. A. 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. Granite commonly has large amounts of salmon pink potassium feldspar and white plagioclase crystals that have visible cleavage planes. G) All of these. B. basalt 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? C) Both of these. Classification of Igneous Rock Series. Dark, dense volcanic rock from the lower part of the magma chamber may be released later. Magma Escape Routes Magma leaves the confines of the upper mantle and crust in two major ways: as an intrusion or as an extrusion. (The values are similar to those shown in Figure 3.3.4.). B. magma mixing D) Both a. and c. C. basalt B) granodioritic Because felsic lavas are less mobile, it is less common than granite. a. Over millions of years, the magma in this subduction zone can create a series of active volcanoes known as a volcanic arc. C. heat expansion of the chemical bonds causes them to break A) Pressure of the environment - lower P = slower magma cooling. Peacock, M. A. Plus, they are, by definition, exposed to the elements of erosion immediately. -is what's meant by the phrase "The domesticated generations fell Weegy: A suffix is added to the end of a word to alter its meaning. 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. E. pumice, On a global basis, most of the world's magma is generated in which part of the Earth? This type of magma has a low gas content and low viscosity, or resistance to flow. -Sediments are solid fragments of inorganic or organic material that come from the weathering of rock and solid . This relates to the cooling history of the molten magma from which it came. B. olivine and pyroxene Magma is hot, molten rock that exists beneath the Earth's surface. This texture, which indicates a very slow crystallization, is called pegmatitic. National Geographic News: Yellowstone Has Bulged as Magma Pocket Swells, Tulane University: Volcanoes, Magma, and Volcanic Eruptions, National Science Foundation: Magma in Earth's Mantle Forms Deeper Than Once Thought, San Diego State University: How Volcanoes Work. Andesite is the name of a family of fine-grained, extrusive igneous rocks that are usually light to dark gray in color. The process by which the same igneous rock may produce different magma compositions upon melting. 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? G. high silica, low iron and magnesium, aphanitic texture The environment in which an igneous rock solidified (extrusive, intrusive or otherwise) can be inferred best by which of the following? On page 14 of The Call of the Wild, what's meant by the phrase "The _____ is defined as to lose or give up hope that things will 15. 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