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