For igneous rock, the composition is divided into four groups: felsic, intermediate, mafic, and ultramafic. Glazner, A. F., Bartley, J. M., Coleman, D. S., Gray, W. & Taylor, R. Z. 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. One of the most spectacular types of pyroclastic deposit is an ignimbrite, which is the deposit of a ground-hugging pumiceous pyroclastic density current (a rapidly flowing hot suspension of pyroclasts in gas). Most of the mantle and crust are solid, so the presence of magma is crucial to understanding the geology and morphology of the mantle. Obsidian is a rock consisting of volcanic glass. It can be found in the Andes Mountains and in some island arcs (see. C) aphanitic A) Each vesicle was filled by a gas bubble when the lava was still mainly liquid. Legal. B. Extrusive igneous rocks have a fine-grained or aphanitic texture, in which the grains are too small to see with the unaided eye. 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. B. magma mixing 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). A rock that chiefly consists of pegmatitic texture is known as a pegmatite. Ultramafic refers to the extremely mafic rocks composed of mostly olivine and some pyroxene which have even more magnesium and iron and even less silica. Obsidian as a glassy rock shows an excellent example of conchoidal fracture similar to the mineral quartz (see Chapter 3). For igneous rock, the composition is divided into four groups: felsic, intermediate, mafic, and ultramafic. D. plate tectonics, Match the appropriate term associated with the production of magma to its best description. C. Amphibole - pyroxene - biotite - olivine if((replacementValue > 0) && (replacementValue < limit)). This creates magma in places where it originally maintained a solid structure. Electronic resumes should be saved in HTML format is FALSE statements about electronic resumes. D. Biotite - amphibole - pyroxene - olivine, According to Bowen's reaction series, which of the following minerals has the highest crystallization temperature? Magma Chamber In areas where temperature, pressure, and structural formation allow, magma can collect in magma chambers. Typical mafic rocks are gabbro (intrusive) and basalt (extrusive). Diorite is identifiable by its Dalmatian-like appearance of black hornblende and biotite and white plagioclase feldspar. If the fragments accumulate while still hot, the heat may deform the crystals and weld the mass together, forming a welded tuff. Its mean temperature ranges from 800o to 1000o Celsius (1472o to 1832o Fahrenheit). 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. 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. If the fragments accumulate while still hot, the heat may deform the crystals and weld the mass together, forming a welded tuff. Because felsic lavas are less mobile, it is less common than granite. B) basalt Figure 3.3.2 shows a zoned plagioclase under a microscope. Working mostly with basaltic magmas, he determined the order of crystallization of minerals as the temperature drops. 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. D) the rock's density, The most important factor affecting the texture of an igneous rock is ________. It is poor in silica, in the 40% or less range. C) number of ions 1. basaltic scoria Classification of Igneous Rock Series. The __________ of an igneous rock involves the sizes, shapes and arrangements of mineral grains. Some pumice is so full of vesicles that the density of the rock drops low enough that it will float. B. Si and O are the least abundant elements in the magma. C) basaltic, rhyolitic A. consist of very large grains of quartz, olivine and pyroxene in relatively large bodies of former sedimentary rock A) granite; gabbro. 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) . = 2 5/20 A) solid + gas Diorite is a coarse-crystalline intermediate intrusive igneous rock. 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. For example, it is not known what happens to the pre-existing country rock as the diapir intrudes. 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. A pluton is an intrusion of magma that wells up from below the surface. User: She worked really hard on the project. B) dark colored, more dense and less viscous (not sticky); This lava cools into basalt, a rock that is heavy and dark in color due to its higher iron and magnesium levels. Using Figure 3.3.8, predict what phenocrysts might be present where the magma cooled as far as line a in one case, and line b in another. B. an increase in heat (high temperature) 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. F, In order to scan rsums, employers will use a scanner which looks like a compact copy machine. One theory is the overriding rock gets shouldered aside, displaced by the increased volume of magma. Cooling history is also related to changes that can occur to the composition of igneous rocks. The results were studied under the microscope and by chemical analysis. Extrusive or volcanic rocks crystallize from lava at the earth's surface. These trapped bubbles can cause explosive and destructive eruptions. This heat makes magma a very fluid and dynamic substance, able to create new landforms and engage physical and chemical transformations in a variety of different environments. solid rock with a fine texture A. quartz and pyroxene 1. D. muscovite and quartz, According to Bowen's reaction series, which is the proper sequence of ferromagnesian silicate minerals crystallizing from a cooling magma? A. a decrease in the confining pressure (decompression) Because the earth was largely molten at its origin, magma may be considered the beginning of the rock cycle. E) rhyolite: extrusive rock that formed from cooling of relatively low silica magma Intrusive rocks, forming underground with larger, stronger crystals, are more likely to last. 4. porphyritic basalt Pegmatite is much coarser in grain size compared to most coarse-grained igneous rocks. E. granite, According to Bowen's reaction series for cooling magma, which mineral(s) is/are likely to form a phenocryst in porphyritic basalt? 1. K.C. B) Temperature of the environment - lower T = slower magma cooling. Lava that cools extremely quickly may not form crystals at all, even microscopic ones. -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. What is magma? 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. A. granite 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. crystal settling. Geothermal drilling projects discovered two magma sites on the Big Island of Hawaii, and one on Iceland. An igneous rock is any crystalline or glassy rock that forms from cooling of a magma. 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A. the rock has two or more distinctly different-size populations of mineral grains D. glassy and frothy texture 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. E. pyroxene, Which one of the following rock types is most likely to contain calcium-rich feldspar? A. Pyroxene - amphibole - olivine - biotite Decompression MeltingDecompression melting involves the upward movement of Earth's mostly-solid 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. Differences in temperature, pressure, and structural formations in the mantle and crust cause magma to form in different ways. 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. 2. granite and granodiorite D) gabbroic, granitic, The classification of igneous rocks is based on __________. Extrusive rocks, because of their small crystals and glass, are less durable. A) Basalt Granite is a good approximation for the continental crust, both in density and composition. How Magma Forms Earth is divided into three general layers. Classification of Igneous Rock Series. 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)! Types of MagmaAll magma contains gases and a mixture of simple elements. G. high silica, low iron and magnesium, aphanitic texture G. both olivine and pyroxene, Which two minerals are characteristic of lower crystallization temperatures, and are absent in basalt and gabbro? 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