Metamorphism and metamorphic rocks metamorphism mineralogical, chemical, and physical changes that occur in solid rocks. Foliated metamorphic rocks such as gneiss, phyllite, schist, and slate have a layered or banded appearance that is produced by exposure to heat and directed pressure. Change is a result of pressure directed stress and heat solid state reaction no net change in chemistry ideally role of groundwater recrystallization of. The original amorphous material in the pdf planes is.
Foliated rocks produced by regional metamorphism these rocks have all been affected by pressure, to some degree, during regional metamorphism. Metamorphic rocks are former igneous, sedimentary or metamorphic rocks that have changed their texture and composition. Pdf microscopic techniques, such as polarising microscopy and scanning electron microscopy. General characteristics of metamorphic terrains springerlink. Depending on the location, metamorphism can occur on a local or regional scale. Summarize the progression of different rock types produced by regional metamorphism. Change is a result of pressure directed stress and heat solid state reaction no net change in chemistry ideally role of groundwater recrystallization of new minerals from old minerals. Metamorphic rocks metamorphic rocks are classified on the basis of texture and composition either mineralogical or chemical unlike igneous rocks, which have been plagued by a proliferation of local and specific names, metamorphic rock names are surprisingly simple and flexible may choose some prefixtype modifiers to attach. Grade of metamorphism metamorphic grade is a general term for describing the relative temperature and pressure conditions under which metamorphic rocks form. Notes on types and characteristics of rocks found on. Types of rocks and their properties pdf download geography.
Notes on types and characteristics of rocks found on the earths crust. When metamorphic rocks form, what main factors dictate the rock that will form. Metamorphism involves changes in mineral assemblage and rock texture and occurs in the solid state as a result of changes in temperature and pressure. Some of these minerals are included in the name of a metamorphic rock. Without careful examination by the geologist, and the recognition of the subtle changes in mineralogy and texture, much time and money can be wasted by drilling past the economic basement. Types of rocks igneous sedimentary rocks metamorphic. You can clearly see the deformation and features that are characteristic of an entire area. The earths crust is composed of rocks and on the basis of mode of formation, rocks are classified into three major types igneous rocks, sedimentary rocks and metamorphic rocks. Parent rock is the original, unaltered, unchanged rock.
Scheme for metamorphic rock identification scheme for sedimentary rock identification nonfoliated foliated. Contact metamorphism is due to a temperature rise in rocks adjacent to magmatic intrusions of local extent which penetrate relatively shallow and cold regions of the crust the majority of magmatic intrusions are of granitic composition. A pictorial guide to metamorphic rocks in the field. Because rocks are weak in the cleavage orientations, and so tend to break along. Learn vocabulary, terms, and more with flashcards, games, and other study tools. Metamorphic rocks are rocks which have had their form changed. Metamorphic rocks form by solidstate no melting transformation of preexisting rock by processes that take place beneath earths surface. Occurs at depths greater than where sedimentary rocks form. Under high temperature and pressure, the sediment becomes compacted. Knowledge of metamorphic processes and rocks is valuable, because metamorphic.
Types of rocks and their properties pdf download geography the earths crust is composed. Explain how different mineral resources both igneous and metamorphic form at plate boundaries. Metamorphic textures and mineralogy develop progressively over several hundreds of feetmeters of drilling. Pdf petrogenesis of metamorphic rocks, 8th edition. The process by which metamorphic rocks are produced is called metamorphism. Geology of the north cascades scenic metamorphic rocks. Gneisses may also be lineated, but must also show segregations of felsicmineralrich and darkmineralrich concentrations. Monometamorphism is a metamorphism resulting from one metamorphic event fig. Slightly changing the different elements that combine with silica greatly changes the mineral that results, or the characteristics of the mineral. Figure 3 classification scheme for metamorphic rocks. The newly developed composition difference between the shear surfaces and microlithons represents a new foliation feature layering, and is a type of metamorphic differentiation. Identify major minerals contained within a metamorphic rock. Metamorphic comes from the greek word meta and morph, meaning change in form.
Types of rocks and their properties pdf download geography the earths crust is composed of rocks. Metamorphism and metamorphic rocks chapter questions. Each of these will be discussed in turn, then we will summarize how metamorphic rocks are classified. Metamorphic rocks pictures of foliated and nonfoliated types. Lightcolored dikes and sills of igneous rock cut the metamorphic rocks. It means a type of rock texture, not a composition. Physical geology metamorphic rocks flashcards quizlet. Metamorphic rocks are best identified when looking at the rock as you see them in nature. Understanding the average behavior and variability of heat production for these rock types are vitally important for. Throughout this lesson, students will explain the formation of metamorphic rocks as a result of. Experiments suggest that the time involved is tens of millions of years. Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means change in form.
Petrography of metamorphic rocks from the miller range, antarctica. Deep underground rocks are exposed to high pressures from the overlying layers of rocks and high temperatures from magma. Metamorphic textures consist of two main types, foliated and nonfoliated. Common mineral in highpressure lowtemperature metamorphosed basalts. Chemical, mineralogical and structural adjustments of solid rocks to physical and chemical changes at depths below the region of sedimentation. Describe the processes that act to form metamorphic rock. Mineral resources of igneous and metamorphic origin. This planar fabric is characteristic of many metamorphic rocks.
During metamorphism, new minerals grow at the expense of old minerals, andor the shape, size, and arrangement of grains in the rock may change. All chapters of part ii of the book have been rewritten. Under extreme metamorphic conditions, in which partial melting occurs, the mix of melt and. Objectives university of nairobi personal websites. Try and work out whether they are sedimentary, igneous or metamorphic. Similarly, those resulting from original igneous rocks are known as orthometamorphite say, formed from granite and granodiorite. Very low to lowgrade metamorphic rocks arkai, p, sassi, f p, and desmons, j.
Also, the chapters introduction and grade have undergone several major changes. Metamorphic rocks never melt if they did they would become igneous magma. Metamorphism occurs due to changes in temperature, pressure or chemistry. Where does water in hydrothermal chemically active fluids come from. Hasterok and webb, 2017, we combine the analysis of the two for this study. International listing of research groups working on metamorphic rocks and processes. Mineral resources of igneous and metamorphic origin learning outcomes 1. This is why we say that the changes are solid state. Gallery of photographs of highgrade metamorphic rocks. Several basic types of rock fabric are recognized in virtually all.
Metamorphic rocks can be formed from any type of older material. Studies of metamorphic rocks provide insights into the physical and chemical changes that take place deep within earth. A picture gallery of metamorphic rocks including amphibolite, gneiss, hornfels, marble, novaculite, phyllite, quartzite, schist, slate and soapstone. A rock or a rock complex may bear the effects of more than one metamorphic event e. These rocks are physically deformed and chemically changed due to. You should know all about sedimentary, igneous and metamorphic rocks, so have a look at these pictures and see if you can identify each specimen. As the rock crystallizes or recrystallizes under directed pressure, new crystals may grow in some preferred direction, sometimes. Texture in metamorphic rocks individual minerals may or may not be bounded by crystal faces. Feb 17, 2016 the banded rocks in the cliffs beyond the mountain hut were originally lavas and sediments formed in the sea. Metamorphic rock is the result of the transformation of a preexisting rock type, the protolith, in a process called metamorphism, which means change in form. Illustrate the time relations between metamorphic minerals and deformation. Gneiss nice is a rock of great variety with large mineral grains arranged in wide bands. Metamorphic rocks in thin section contents image scales widest frame width alsilicates other aluminous minerals amphiboles pyroxenes sheet silicates other metamorphic minerals 20x 6 mm 40x 3 mm 100x 1 mm 200x 0. Metamorphic rocks were once sedimentary, igneous, or another metamorphic rock.
Rocks that become metamorphic are so deep in the crust that they are very close to the mantle. Foliated metamorphic rocks form under directed pressure pressure that is not the same in all directions or shear stress forces acting parallel to each other, and having the result of smearing the rock. All the rocks described in this spread are foliated. Exposure to these extreme conditions has altered the mineralogy, texture, and chemical composition of the rocks. A process of change 1 metamorphic rock forms from a preexisting rock or protolith. Found in all rock types sedimentary, igneous, metamorphic. Rock cycle notes three types of rocks sedimentary igneous metamorphic sedimentary rocks sediment is produced through the process of weathering. Protolith original rock type before metamorphism metamorphism is typically indicated by change in mineral type, change in texture, or foliation. The original rock is subjected to heat with temperatures greater than 150 to 200c and pressure around 1500 bars, causing profound physical andor chemical change. Metamorphic rocks pictures of foliated and nonfoliated. They are formed when sedimentary and igneous rocks become changed by pressure and heat. Describe the processes that act to form igneous rock. This new edition of petrogenesis of metamorphic rocks has several completely revised chapters and all chapters.
Here, the lighter brown rocks in the upper part of the cliff are calcareous schists formed from impure limestones, and the dark rocks below are mainly metamorphosed. Hornfels is a finegrained metamorphic rock formed by the action of heat on clay rocks, known as contact metamorphism. This new edition of petrogenesis of metamorphic rocks has several completely revised chapters and all chapters have updated references and redrawn. With increasing grain size, foliated metamorphic rocks are termed slate, phyllite, schist and gneiss. Metamorphic rocks formed from parent sedimentary rocks are called parametamorphite e. The simplest planar features may be primary bedding akin to the layering in sedimentary rocks. Classification of metamorphic rocks is based on mineral assemblage, texture, protolith, and bulk chemical composition of the rock.
Metamorphic rock definition and limits including hydrothermally altered rock. Note the strong vertical fabric of the canyon wall. Buy atlas of metamorphic rocks and their textures on free shipping on qualified orders. Petrography of metamorphic rocks from the miller range. Appendix b classification of metamorphic and other compositegenesis rocks, including hydrothermally altered, impactmetamorphic, mylonitic, and cataclastic rocks, version 1. Dec 12, 20 metamorphism and metamorphic rocks ppt 1. Schist and phyllite rock types are preferentially veryfine to finegrained, showing a strong shape. Hornfels are heated when near heat source such as a sill, dike, or magma chamber. Relate common metamorphic rocks to different types of metamorphism. Products subcommission on the systematics of metamorphic. Large rocks are broken down very gradually and the smaller pieces are transported by wind, water, and ice. Metamorphic rocks metamorphic rocks rocks that have been subjected to either enough heat or pressure to cause the minerals in that rock to undergo solid state chemical changes. Parent rocks can be igneous, sedimentary or metamorphic rocks.
Thus coarse grained metamorphic rocks involve long times of metamorphism. Metamorphism and metamorphic rocks chapter questions 1. The presence of index minerals in metamorphic rocks allows geologists to assess the temperatures and pressures the parent rock encountered. Examples of metamorphic rocks include gneiss, slate, marble, schist, and quartzite. Recommendations by the iugs subcommission on the systematics of metamorphic rocks. Mechanical deformation and chemical recrystallization are the two processes that affect rock during metamorphism. Metamorphic rock metamorphic rocks are formed when preexisting rocks are exposed to extreme heat and pressure metamorphic rocks are found deep within earths crust, so there is a lot of rock on top pressing down. Metamorphic rocks are subdivided into foliated and nonfoliated varieties and are respectively classified according to grain size and composition. The most obvious features of metamorphic rocks are certain planar features that are often termed ssurfaces. Concise information about metamorphic processes, with excellent cartoon of mineral growth during compression. Any platy minerals they contain take on a preferred alignment known as foliation. Contact metamorphism occurs typically around intrusive igneous rocks as a result of the temperature increase caused by the intrusion of magma into cooler country rock. On the radiogenic heat production of metamorphic, igneous, and.
The original rock is subjected to heat temperatures greater than 150 to 200 c and pressure 100 megapascals 1,000 bar or more, causing profound physical or chemical change. Metamorphism and metamorphic rocks rocks created by heat, pressure andor chemically reactive fluids metamorphic rocks are produced from igneous rocks sedimentary rocks other metamorphic rocks 2. Changes occur in the solid state because melting doesn t occur. The area surrounding the intrusion where the contact metamorphism effects are present is called the metamorphic aureole.
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