Spry A. Structures in Metamorphic Rocks: The structures of the metamorphic rocks are: (i) Slaty structure, (ii) Schistose structure, (iii) Gneissose structure, and (iv) Granulose structure. • Describe how metamorphic rocks are produced by the action of heat, pressure, and fluids on preexisting parent rocks over the course of time. Structure and Texture Anastasia Neni Metamorphic structure • Foliation; planar rock fabric (e.g. Cataclastic - Hornfelsic - Granoblastic - Schistose Cross Bedding. From examination of metamorphic rocks, it has been found that metamorphic minerals can be listed in a generalized sequence, known as thecrystalloblastic series, … -Favours appearance of new metamorphic phases: loss volume leads to mineral increasing density-Strain energy may overcome kinetic barriers to reactions-Deviatory stress affects the textures and structures, but not the equilibrium mineral assemblage-Pressure (s.l.) Miyashiro A. Classification of Metamorphic rocks based on texture/structures PHYLLITE -similar to slate, but slightly coarser phyllosilicate grains -grains can be seen in hand specimen, giving silk appearance to cleavage surfaces -often cleavage planes less perfectly planar than slates SLATE -strongly cleaved rock -cleavage planes are developed due to orientation of fine phyllosilicate grains e.g. It is generally by the texture that a geologist will first recognize whether a rock is igneous,will first recognize whether a rock is igneous, sedimentary, or metamorphic, before they get down tosedimentary, or metamorphic, before they get down to the business of identifying the rock or naming it.the business of identifying the rock or naming it. 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. • Recognize the different types of metamorphism, the processes that cause them, and the environments in which they occur. Evolotion of metamorphic belts. Oxford: Pergamon. “Blastic” or “blasto” is used as a suffix to represent the metamorphic rock equivalent to igneous texture… 2. • Magma forms from the melting of existing rocks. Muscovite… Grain shapes 2. Now customize the name of a clipboard to store your clips. The textures and structures of biogenic rocks are especially varied in the most common carbonate rocks—limestones and dolomites. Metamorphic. In many cases, the correlation of metamorphic isograds and their position in the structure implies a genetic relationship between the two. [This is a book that presents all the Those that are bounded by their own crystal faces are termed idioblastic. Help to identify the original rock type prior to metamorphism. • Texture – microscopic to small-scale mesoscopic features of the rock produced by: 1. Sedimentary ... Schistose texture (platy or needle-shaped minerals grow in response to differential stress. Furthermore, the texture of sedimentary rocks affects such derived properties of these rocks as porosity, permeability, bulk … For a limited time, find answers and explanations to over 1.2 million textbook exercises for FREE! Metamorphic rock textures • There are five basic metamorphic textures with typical rock types Basic rock texture Metamorphic rocks Name of foliation Slaty Slate and phyllite; slaty cleavage schistose schist schistosity gneissose gneiss gneissosity granoblastic marbles and quartzite ---- hornfelsic hornfels and skarn ---- 24. If you continue browsing the site, you agree to the use of cookies on this website. Over time, this collection should become more orderly and comprehensive, but don't hold your breath. – features that characterize handspecimen or larger masses of rock. Role of non government organizations in disaster management, Disaster Management System in India - Notes, No public clipboards found for this slide. If you continue browsing the site, you agree to the use of cookies on this website. 11 3. Metamorphic Rocks 2 Metamorphic rocks. Such features include folds, nappes, and faults with a wide variety of geometries. METAMORPHIC ROCKS Rocks that form from other pre-existing rock (sedimentary, igneous, or metamorphic) that have been changed from high temperature and/or high pressure – A free PowerPoint PPT presentation (displayed as a Flash slide show) on PowerShow.com - id: 67f87d-ZDczO Metamorphic rocks are often intimately related to large-scale (kilometres of tens of kilometres) structural features of Earth. All Time Show: Recommended. Examples include slate, gneiss, phyllite, and schist. Get step-by-step explanations, verified by experts. Journal of Petrology, 2, 277–311. burial, regional metamorphic rocks) – Slaty cleavage – Phyllitic – Schistose – Gneissose – Mylonitic • Non Foliation; equidimentional rock fabric (e.g. (1961). Introducing Textbook Solutions. There are textures during sedimentation (primary - sedimentation), at the stage of diagenesis and subsequent changes (secondary - diagenetic and catagenetic). These can range from textures similar to the original protolith at low grades of metamorphism, to textures that are purely produced during metamorphism and leave the rock with little resemblance to the original protolith. Those that show none of their own crystal faces are termed xenoblastic. "Metamorphism takes place in a variety of geologic settings. [This paper presents the foundation for the recognition of metamorphic rocks in the various tectonic settings.] Texture of the sedimentary rock is the mutual arrangement of rock fragments, their orientation relative to each other, the bedding surface and the rock as a whole. Petrography - The branch of geology dealing with the description and systematic classification of rocks, especially by microscopic examination of thin sections. Change is a result of pressure (directed stress) and heat •Solid state reaction •No net change in chemistry (ideally – role of groundwater) •Recrystallization of … Metamorphic rocks and processes • Metamorphism comes from the Greek words “Meta” - change “Morphe” - form • Metamorphic rocks form by solid-state (no melting) transformation of preexisting rock by processes that take place beneath Earth’s surface. Textures and Structures of metamorphic rocks - Metamorphic Structures and Textures Structure features that characterize handspecimen or larger masses of. Non-foliated are formed as a result of tectonic movements or direct pressure which makes their formation highly dependent on their pre-existing conditions. petrogenetic principles of metamorphic rocks.] American Military University • INTRO INTO SCIN139, American Military University • ERSC181 B001, American Military University • SCIN 138 138, Chapter 11_Metamorphic Textures and Naming a Metamorphic Rock(1).ppt, Texas A&M University, Corpus Christi • GEOL 3326. These changes produce new minerals,new textures,and new structures with-in the rock body. Looks like you’ve clipped this slide to already. This is a somewhat haphazard collection of metamorphic textures and rocks seen in thin section, with some discussion of the processes thought to have made them. Intergrain relationships Almost all metamorphic structures are the result of deformation or metamorphic processes, except relict structures. Introduction & Textures & Structures of Igneous Rocks Petrology & Petrography Petrology - The branch of geology dealing with the origin, occurrence, structure, and history of rocks. Textures of this type are described as biomorphic or whole-shell. Grain sizes 3. Texture In metamorphic rocks individual minerals may or may not be bounded by crystal faces. Grain orientations 4. Metamorphic Fabric and Texture FABRIC: Refers to orientation of the crystallographic lattices of the minerals TEXTURE: Refers to mineral distributions or orientations within the rock, overall structure of the rock. Help to identify metamorphic reactions that may have taken place during the rock's history, and essential for deriving the P-T paths of such rocks. This preview shows page 1 - 7 out of 20 pages. (i) Slaty structure: The slaty structure is also called slaty cleavage. • Identify how the textures of metamorphic rocks … TEXTURE GRAIN medium Medium Fine Fine Fine coarse Scheme for Metamorphic Rock Identification MAP SYMBOL TYPE OF COMPOSITION METAMORPHISM COMMENTS Low-g rade metamorphism of shale Foliation surfaces shiny ... Microsoft PowerPoint - Metamorphic Rocks.ppt Author: Earth Science You can change your ad preferences anytime. causes textural readjustment…but not always deformation!! of igneous rocks Crystal development euhedral: grains bounded by its own perfect to near-perfect crystal growth faces subhedral: partly bound by its own growth faces, or growth faces only moderately well developed anhedral: irregular; little or no evidence for its own growth faces. When rocks are baked by heat of molten magma or squeezed by the movements of huge tectonic plates or by the pressure of overlying thick succession of rocks; They are altered or changed beyond their recognition ; i.e. Metamorphic textures and mineralogy develop progressively over several hundreds of feet/meters of drilling. Foliated metamorphic rocks have four distinguishable types of aligned textures and they normally have a banded or layered appearance. See our Privacy Policy and User Agreement for details. Metamorphic rocks are former igneous, sedimentary or metamorphic rocks that have changed their texture and composition. Slideshare uses cookies to improve functionality and performance, and to provide you with relevant advertising. 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