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