Igneous rocks type from the cooling of magma or volcanic rock and compose a lot of the earths continental crust and nearly all of the oceanic crust. Legal exclusions applicable to the download in adobe acrobat pdf format of. Igneous rocks are classified on the basis of mineralogy, chemistry, and texture. The dotted line on the figure represents one such value, where roughly 2% quartz, 6% alkali feldspar, 54% plagioclase feldspar, 2% pyroxene, 21% amphibole, and 15% mica suggests a rock of intermediate composition, either andesite or diorite depending on crystal size and other factors. Chapter 1 igneous introduction to igneous rocks lab 3a. Circle the letter of the definition of igneous rock.
Rocks formed from magma at depth are intrusive, or plutonic rocks. Igneous rocks and processes introduction igneous rocks comprise the bulk of the crust of the earth. Origin of igneous rocks the igneous rocks are formed at high temperature directly. Read igneous rocks to find the answers to these questions and many more. The processes that lead to the formation of igneous rocks have brought earths water to the surface as well as the atmosphere and the chemicals that make up all of organic life, produced most of its metallic ore.
Metamorphic rocks can be formed from igneous, sedimentary, or previously metamorphosed rocks by recrystallization in the solid state. The main minerals of igneous rocks are the silicates of calcium, aluminium, potassium, sodium, iron and magnesium. Petrographic descriptions start with the field notes at the. Shawe abstract petrographic studies, largely thinsection examinations, of rocks from the chinle and morrison formations and adjacent strata in the slick rock district, supplement the stratigraphic. Main idea igneous rocks are classified by origin, texture, and composition. Molten material that emerges at the earths surface, lava, cools to form volcanic, or extrusive igneous rock. Lava cools quickly and the resulting rocks are finegrained basalt or rhyolite depending on their mineral composition. In silicate igneous rocks, silica sio2 is the most abundant major oxide, followed by al2o3, fe2o3, feo, mgo, cao, na2o, k2o, tio2, and p2o5.
Petrography is the study of rocks in thin section by means of a petrographic microscope i. Texture physical appearance in the rock occur only crystals, so the texture is holocrystalline. Igneous rocks formed by crystallization or solidification of melted material molten material within the earth, magma, cools to form plutonic, or intrusive igneous rock. As discussed earlier, texture is used to subdivide i. Someone who studies petrography is called a petrographer.
Petrology and geochemistry of igneous rocks from southern tioman island, pahang, peninsular malaysia muhammad hatta roselee1,2, azman a. Graph of mineral content, by percentage, of various igneous rocks. Chapter 3 classification and chemistry classification. Petrography is a branch of petrology that focuses on detailed descriptions of rocks. The heat may come from magma intrusion or deep burial via subduction at convergent boundaries. Bgs downloads rock classification scheme vol 1 igneous. Igneous rock think about how can two rocks made of the same minerals look very different. In practice, this means that the average dimension of the crystals is less than 1 millimeter.
Crystallized to solid state where exposed to the cold of space. These rocks generally materialize in shields, platforms, orogens, basins, extended crust, and oceanic crust. An igneous rock or a part of an igneous rock with a finegrained or aphanitic texture has crystals, but they are too small to recognized with the unaided eye. This grade includes quality of petrographic analyses, sem calculations, grammar and spelling, layout, clarity, readability, critical evaluation of your data in comparison to data in the literature, proper captions and labels for your images, graphs, and figures, etc. Petrology and petrography of the igneous rocks of the. Igneous rocks are formed when magma, molten rock from beneath the earths crust, rises, cools and solidifies. Igneous rocks are found where plates diverge, as lava rises and fills the gap between the plates.
Naming igneous rocks dexter perkins, university of north dakota. Petrography the branch of geology dealing with the description and systematic classification of rocks, especially by microscopic examination of thin sections. Igneous rock classification using diagrams igneous rock. A list of commonly used rock namesmany not part of the iugs classificationis keyed to this classification. Igneous rocks are first formed rocks which had made up the primodial earths crust. Click here for a summary of the 3 major rock types. Hydrothermal activity spatially associated with ultramafic rocks, usually serpentinites, has been observed at several localities proximal. Extrusive igneous rock, such as basalt, is formed when the magma solidifies above the ground quite quickly.
Igneous rocks that cooled on the surface are termed extrusive. In the modern oceans, the mafic association is found in two specific settings. Explain that they will use the chart to record how each type of rock is formed and to list examples of each one. These rocks are finegrained since minerals crystallize too rapidly to form large crystals. Unlike the two, igneous rock may be form even without crystallization. An igneous rock is any crystalline or glassy rock that forms from cooling of a magma 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 magma can cool to form an igneous rock either on the surface of the earth. Their composition is connected with the composition of the origin magmas.
Also, the chapters introduction and grade have undergone several major changes. There are three basic kinds of rocksigneous, metamorphic and sedimentary. The subducting plate melts as it sinks into the crust of the earth, and the melt rises into the overriding plate forming volcanoes. Igneous rocks can be divided into four categories based on their chemical composition.
Youll also find a handson activity to try at home or at school, as well as a glossary of unfamiliar words, resources to help you locate additional information, and a useful index. Characteristics of igneous rocks most igneous rocks are very hard made of crystals layering is not common in igneous rocks metamorphic rocks sedimentary and igneous rocks can become buried deep in the earths crust. Explain to students that there are three types of rocksigneous, sedimentary, and metamorphic. Molten rock that reaches the surface is called lava. Igneous rocks form from molten liquid called magma. Igneous rocks definition, classification and examples. In karl heinrich ferdinand rosenbusch of the science of microscopic petrography the study of rocks in thin section, based on the optical properties of constituent mineral grains. Modifier for extrusive rocks with trapped gas bubbles that might fill in with minerals amygdaloidal.
Intrusive igneous activity, the cooling of magma within. Igneous rocks, sedimentary rocks and metamorphic rocks. Also, the widely used irvine baragar classification. Unsupervised classification of intrusive igneous rock thin. Petrography and petrogenesis of a midocean ridge lava suite. Rocks formed from lava are extrusive, or volcanic rocks. Binary and ternary phase diagram exercises jennifer m. Igneous rocks are formed by the solidification and cooling of magma in volcanic. In country rock surrounding a magma body, heats effect decreases with distance from the magma body. In effect, the classification of the most important rocks is. This quiz has been created to test your knowledge about the formation of volcanic extrusive or intrusive rocks in different geological conditions. Igneous rocks are formed from the solidifying of liquid rock material. The rapid cooling does not give the crystals enough time to grow large. Grain size and the proportion of grain sizes the texture is phaneritic equallycrystallized and crystals are medium 21mm.
Give students a copy of the geology rocks reproducible page 39. November 8, 2014, cherran, comments off on what is igneous rock igneous rock is one of the three major types of rocks formed through the solidification of molten rock or magma. Texture is used to subdivide igneous rocks into two major groups. This reader emphasizes how all igneous rocks are formed and explores how the formation is related to igneous rock classification. Invite volunteers to investigate the formation of igneous rocks.
Volcanic rocks are composed of very small crystals because the molten rock cooled quickly at or near earths surface. This happens when magma seeps out on to the ocean bed, or. Metamorphic rocks were formed through recrystallization, in anessentially solid. Metamorphic rocks form when the buried rock is changed under high temperature and pressure. If the disk or file on which the information is delivered to you is corrupt or is.
Extrusive igneous rocks solidified at the earths surface, and therefore had a fast cooling history. A common example of an extrusive igneous rock is basalt. The driving forces for metamorphism are changes in temperature,pressure,and composition of pore fluids. Billions of years ago, the earth was just a huge ball of burning gases. Each image is converted into two different formats. Igneous rocks qfiles the online library of knowledge. Petrography of sedimentary rocks in the slick rock. The igneous rocks of the stansbury mountains consist of several hypabyssal intrusions of intermediate and basic composition and four patches of extrusive s. The other types of rocks are the sedimentary rock and metamorphic rock.
Introduction to igneous rocks an igneous rock is any crystalline or glassy rock that forms from cooling of a magma. I n t r o d u c t i o n petrography is the art of rock description. Igneous rocks and processes revised on 102011 page 5 of 10 finegrained or aphanitic. Igneous rocks are formed by cooling or solidification of molten or partly molten material, i. Igneous rocks are formed by the cooling and solidification of magma, and are aggregates of predominantly silicate minerals. Spatial arrangement of the components and fulfillment the rock space with the components the arrangement of the components is irregular and compact. This new edition of petrogenesis of metamorphic rocks has several completely revised chapters and all chapters have updated references and redrawn. Coleman, university of wisconsin, oshkosh and university of north carolina. Two sills, one sole injection, and two plugs represent an andesitic to trachyandesitic phase of intrusion and three or four diabase dikes appear to be volcanic fissures.
As this ball traveled through space it started to copl. The use of visualization and sketches of thin sections to encourage a better understanding of phase diagrams. Earth, forms one of the most common igneous rocks, granite. Its purpose is to convey to another geologist an accurate and precise picture of the rock in question in whatever detail is demanded by the appropriate context. Igneous rocks are those rocks which are formed after the cooling and solidification of lava. The application ofthermodynamics is more extensive than in the earlier book, and thermodynamic concepts have been woven very effectively into the geological discussion. Teacher notes if your students have completed the plate tectonic units on volcanoes, they should be familiar with different volcanic environments. The overall paper quality group grade is worth 90 points. Petrology and geochemistry of igneous rocks from southern. Since a rock is a mixture of minerals our discussion of the igneous rocks peridotite, gabbro, basalt, diorite, andesite, gran ite, and rhyolite figure 2 means we. The mineral content and the textural relationships within the rock are described in detail. All chapters of part ii of the book have been rewritten.
Chapter 5 p e t r o g r a p h y of igneous rocks 5. Physical geology in our overview of the earth, we found out that earths internal heat combined with other mechanisms causes rocks to melt in the asthenosphere and lithosphere. Detail s s classifying igneous rocks detail slcovfe detail 1. Igneous rocks that have mineral crystals easily seen with the unaided eye formed a. F767 2014 5521dc23 2012168 isbn 9781107027541 hdbacra k. Intrusive igneous rock, such as granite, is formed when magma becomes solid in cracks or chambers beneath the ground. As you read about igneous rocks, fill in the detail boxes that explain the main idea in the graphic organizer below. Igneous rock identification introduction all igneous rocks were formed by the solidification of molten magma or lava. The classification of rocks is based on the information acquired during the petrographic analysis. The classification of igneous rocks used in the book is the one proposed by the international union of geological sciences iugs subcommission of the systematics of igneous rocks.
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