Binary and ternary phase diagram exercises jennifer m. Igneous rocks definition, classification and examples. Petrology and petrography of the igneous rocks of the. A list of commonly used rock namesmany not part of the iugs classificationis keyed to this classification. If the disk or file on which the information is delivered to you is corrupt or is. 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. Igneous rocks are first formed rocks which had made up the primodial earths crust. As you read about igneous rocks, fill in the detail boxes that explain the main idea in the graphic organizer below. The driving forces for metamorphism are changes in temperature,pressure,and composition of pore fluids. Igneous rocks that have mineral crystals easily seen with the unaided eye formed a.
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. Circle the letter of the definition of igneous rock. The heat may come from magma intrusion or deep burial via subduction at convergent boundaries. Invite volunteers to investigate the formation of igneous rocks. This reader emphasizes how all igneous rocks are formed and explores how the formation is related to igneous rock classification. Explain that they will use the chart to record how each type of rock is formed and to list examples of each one. Unlike the two, igneous rock may be form even without crystallization. Igneous rock identification introduction all igneous rocks were formed by the solidification of molten magma or lava.
Petrography of sedimentary rocks in the slick rock. Extrusive igneous rocks solidified at the earths surface, and therefore had a fast cooling history. Grain size and the proportion of grain sizes the texture is phaneritic equallycrystallized and crystals are medium 21mm. Igneous rocks can be divided into four categories based on their chemical composition. Igneous rocks are formed from the solidifying of liquid rock material. 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. Igneous rocks form from molten liquid called magma. Coleman, university of wisconsin, oshkosh and university of north carolina. Metamorphic rocks were formed through recrystallization, in anessentially solid. Igneous rock think about how can two rocks made of the same minerals look very different. Petrography is the study of rocks in thin section by means of a petrographic microscope i. All chapters of part ii of the book have been rewritten. Rocks formed from magma at depth are intrusive, or plutonic rocks.
In effect, the classification of the most important rocks is. Molten material that emerges at the earths surface, lava, cools to form volcanic, or extrusive igneous rock. I n t r o d u c t i o n petrography is the art of rock description. F767 2014 5521dc23 2012168 isbn 9781107027541 hdbacra k. Metamorphic rocks form when the buried rock is changed under high temperature and pressure. Igneous rock classification using diagrams igneous rock. Petrography is a branch of petrology that focuses on detailed descriptions of rocks. The igneous rocks of the stansbury mountains consist of several hypabyssal intrusions of intermediate and basic composition and four patches of extrusive s.
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. Igneous rocks are formed when magma, molten rock from beneath the earths crust, rises, cools and solidifies. This happens when magma seeps out on to the ocean bed, or. Molten rock that reaches the surface is called lava. Texture physical appearance in the rock occur only crystals, so the texture is holocrystalline. Introduction to igneous rocks an igneous rock is any crystalline or glassy rock that forms from cooling of a magma. 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. In silicate igneous rocks, silica sio2 is the most abundant major oxide, followed by al2o3, fe2o3, feo, mgo, cao, na2o, k2o, tio2, and p2o5. Explain to students that there are three types of rocksigneous, sedimentary, and metamorphic. Hydrothermal activity spatially associated with ultramafic rocks, usually serpentinites, has been observed at several localities proximal. In practice, this means that the average dimension of the crystals is less than 1 millimeter. Igneous rocks are found where plates diverge, as lava rises and fills the gap between the plates. 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. 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.
The rapid cooling does not give the crystals enough time to grow large. Bgs downloads rock classification scheme vol 1 igneous. 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. Lava cools quickly and the resulting rocks are finegrained basalt or rhyolite depending on their mineral composition. Billions of years ago, the earth was just a huge ball of burning gases. Chapter 3 classification and chemistry classification. 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 geochemistry of igneous rocks from southern. As discussed earlier, texture is used to subdivide i. This new edition of petrogenesis of metamorphic rocks has several completely revised chapters and all chapters have updated references and redrawn. In country rock surrounding a magma body, heats effect decreases with distance from the magma body. Their composition is connected with the composition of the origin magmas. The classification of rocks is based on the information acquired during the petrographic analysis. The mineral content and the textural relationships within the rock are described in detail.
Rocks formed from lava are extrusive, or volcanic rocks. Read igneous rocks to find the answers to these questions and many more. Legal exclusions applicable to the download in adobe acrobat pdf format of. Igneous rocks and processes revised on 102011 page 5 of 10 finegrained or aphanitic. Extrusive igneous rock, such as basalt, is formed when the magma solidifies above the ground quite quickly. Volcanic rocks are composed of very small crystals because the molten rock cooled quickly at or near earths surface. Igneous rocks are those rocks which are formed after the cooling and solidification of lava. Igneous rocks formed by crystallization or solidification of melted material molten material within the earth, magma, cools to form plutonic, or intrusive igneous rock. The subducting plate melts as it sinks into the crust of the earth, and the melt rises into the overriding plate forming volcanoes.
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. As this ball traveled through space it started to copl. The main minerals of igneous rocks are the silicates of calcium, aluminium, potassium, sodium, iron and magnesium. Earth, forms one of the most common igneous rocks, granite. 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 are formed by the cooling and solidification of magma, and are aggregates of predominantly silicate minerals. 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. Chapter 5 p e t r o g r a p h y of igneous rocks 5. Unsupervised classification of intrusive igneous rock thin. This quiz has been created to test your knowledge about the formation of volcanic extrusive or intrusive rocks in different geological conditions.
Naming igneous rocks dexter perkins, university of north dakota. 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. Igneous rocks and processes introduction igneous rocks comprise the bulk of the crust of the earth. Igneous rocks are classified on the basis of mineralogy, chemistry, and texture. Igneous rocks are formed by the solidification and cooling of magma in volcanic. Igneous rocks that cooled on the surface are termed extrusive.
Main idea igneous rocks are classified by origin, texture, and composition. Also, the widely used irvine baragar classification. These rocks are finegrained since minerals crystallize too rapidly to form large crystals. Detail s s classifying igneous rocks detail slcovfe detail 1. The overall paper quality group grade is worth 90 points. Also, the chapters introduction and grade have undergone several major changes. Petrography and petrogenesis of a midocean ridge lava suite. Metamorphic rocks can be formed from igneous, sedimentary, or previously metamorphosed rocks by recrystallization in the solid state. Spatial arrangement of the components and fulfillment the rock space with the components the arrangement of the components is irregular and compact. Igneous rocks, sedimentary rocks and metamorphic rocks. The use of visualization and sketches of thin sections to encourage a better understanding of phase diagrams. Crystallized to solid state where exposed to the cold of space. The other types of rocks are the sedimentary rock and metamorphic rock. Give students a copy of the geology rocks reproducible page 39.
Chapter 1 igneous introduction to igneous rocks lab 3a. Texture is used to subdivide igneous rocks into two major groups. 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. Origin of igneous rocks the igneous rocks are formed at high temperature directly. 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.
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. Someone who studies petrography is called a petrographer. Petrography the branch of geology dealing with the description and systematic classification of rocks, especially by microscopic examination of thin sections. Petrographic descriptions start with the field notes at the. Igneous rocks are formed by cooling or solidification of molten or partly molten material, i. Petrology and geochemistry of igneous rocks from southern tioman island, pahang, peninsular malaysia muhammad hatta roselee1,2, azman a.
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. Intrusive igneous rock, such as granite, is formed when magma becomes solid in cracks or chambers beneath the ground. These rocks generally materialize in shields, platforms, orogens, basins, extended crust, and oceanic crust. 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. Each image is converted into two different formats. Click here for a summary of the 3 major rock types. Graph of mineral content, by percentage, of various igneous rocks.
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