The larger size gives the foliation a slighly shiny appearance. EARTH SCIENCE LAB Metamorphic Sample #1: Identify the Texture, Foliation, Composition, Parent Rock and Rock Type Metamorphic Rock Identification Chart FOLIATION COMPOSITION PARENT ROCK ROCK NAME TEXTURE Oslaty O mica Mudstone O phyllitic O quartz, mica, chlorite O Mudstone O Foliated Omica, quartz O Slate O schistose amphibole, plagioclase O Well foliated to nearly massive quartz monzonite gneiss, generally medium-grained and even textured but locally porphyritic and pegmatitic. Thick arrows pointing down and up. - Examples: quartzite derived from the metamorphism of sandstone, and marble derived from the metamorphism of limestone or dolostone. It can refer to green mica minerals, or metamorphic rocks that contain enough green mica to impart a green color. Exposure to these extreme conditions has altered the mineralogy, texture, and chemical composition of the rocks. Metamorphic Rock Specimens - Mineral In some cases, hornfels has visible crystals of minerals like biotite or andalusite. b. Hutton. Think of foliated rocks as something that is foiled. Non-foiliated - those having homogeneous or massive texture like marble. Created by unique combinations of minerals and metamorphic conditions, these rocks are classified by their chemical compositions. There are two basic types of metamorphic rocks. More technically, foliation is any penetrative planar fabric present in metamorphic rocks. Names given to rocks that are sold as building materials, especially for countertops, may not reflect the actual rock type. Where the object hits, pressures and temperatures become very high in a fraction of a second. On the other hand, any clay present in the original sandstone is likely to be converted to mica during metamorphism, and any such mica is likely to align with the directional pressure. It typically contains abundant quartz or feldspar minerals. Conglomerate is easily identifiable by the pebbles or larger clasts in a matrix of sand, silt, or clay. It is often referred to as "hard coal"; however, this is a layman's term and has little to do with the hardness of the rock. Silvery-gray, well foliated, micaceous quartz-pebble metaconglomerate and quartzite; apparent maximum thickness 700 feet. Volatiles may exsolve from the intruding melt and travel into the country rock, facilitating heating and carrying chemical constituents from the melt into the rock. Los Angeles Community College District: What Is a Foliated Metamorphic Rock? Heat is important in contact metamorphism, but pressure is not a key factor, so contact metamorphism produces non-foliated metamorphic rocks such as hornfels, marble, and quartzite. Place the thick arrows in the direction of maximum stress and the thin arrows in the direction of minimum stress. Texture is divided into two groups. Burial metamorphism occurs when sediments are buried deeply enough that the heat and pressure cause minerals to begin to recrystallize and new minerals to grow, but does not leave the rock with a foliated appearance. [2], The metaconglomerates of the Jack Hills of Western Australia are the source rocks for much of the detrital zircons that have been dated to be as old as 4.4 billion years.[3][4]. The layers form parallel to the direction of the shear, or perpendicular to the direction of higher pressure. Foliated metamorphic rocks exhibit layers or stripes caused by the elongation and alignment of minerals in the rock as it undergoes metamorphism. This is distinct from cleavage in minerals because mineral cleavage happens between atoms within a mineral, but rock cleavage happens between minerals. Materials in metamorphic rock (e.g., minerals, crystals, clasts) may exhibit orientations that are relatively random or preferred (aligned). However, a more complete name of each particular type of foliated metamorphic rock includes the main minerals that the rock comprises, such as biotite-garnet schist rather than just schist. One kind of foliation is called gneissic banding, which looks like bands of light and dark layers. It is foliated, crenulated, and fine-grained with a sparkly appearance. [http://commons.wikimedia.org/wiki/ File:Migmatite_in_Geopark_on_Albertov.JPG] Rich in talc, soapstones feel greasy, like soap. With wavy layering known as phyllitic foliation, these rocks often have a silky or satiny sheen, which is caused by the arrangement of very fine minerals that form as a result of the pressure applied during metamorphism. is another name for thermal metamorphism. Reading: Characteristics of Metamorphic Rocks | Geology - Lumen Learning Crenulation cleavage and oblique foliation are particular types of foliation. . Unlike slate and phyllite, which typically only form from mudrock, schist, and especially gneiss, can form from a variety of parent rocks, including mudrock, sandstone, conglomerate, and a range of both volcanic and intrusive igneous rocks. Foliation. GEOS 1111L: Physical Geology Lab Digital Rock & Mineral Kits French, B.M. In geology, cleavage refers to the tendency of a rock to break parallel to the alignment of the tiny mica minerals it is composed of. A special type of metamorphism takes place under these very high-pressure but relatively low-temperature conditions, producing an amphibole mineral known as glaucophane (Na2(Mg3Al2)Si8O22(OH)2). metaconglomerate - metamorphosed conglomerate ; marble - metamorphosed limestone ; hornfels - contact metamorphism of shale; very hard, like a brick ; . It is foliated, crenulated, and fine-grained with a sparkly appearance. Mariposite is a word that has been used in many ways. The resulting rock, which includes both metamorphosed and igneous material, is known as a migmatite (Figure 7.9). Chapter 5: Metamorphic Rocks Flashcards | Quizlet Marble and hornfels are metamorphic rock types that typically do not typically show observable foliation. It is produced by contact metamorphism. Contact metamorphic aureoles are typically quite small, from just a few centimeters around small dykes and sills, to as much as 100 m around a large stock. 10.2 Foliation and Rock Cleavage - University of Saskatchewan Geologic units in Harford county, Maryland - USGS Massive (non-foliated) structure. Pressures in the lower mantle start at 24 GPa (GigaPascals), and climb to 136 GPa at the core-mantle boundary, so the impact is like plunging the rock deep into the mantle and releasing it again within seconds. Thus, they are not always 'planar' in the strictest sense and may violate the rule of being perpendicular to the regional stress field, due to local influences. Regional metamorphism also takes place in this setting, and because of the extra heat associated with the magmatic activity, the geothermal gradient is typically steeper in these settings (between ~40 and 50 C/km). The specimen shown above is a "chlorite schist" because it contains a significant amount of chlorite. This will allow the heat to extend farther into the country rock, creating a larger aureole. Slate is a foliated metamorphic rock that is formed through the metamorphism of shale. Contact metamorphism can take place over a wide range of temperaturesfrom around 300 C to over 800 C. Block-in-matrix structures are observed in these exposures, including a large metaconglomerate block (10s m in diameter) found at . Figure 7.7 shows an example of this effect. Two features of shock metamorphism are shocked quartz, and shatter cones. (1998). Chapter 6 Sediments and Sedimentary Rocks, Chapter 21 Geological History of Western Canada, Next: 7.3 Plate Tectonics and Metamorphism, Creative Commons Attribution 4.0 International License. Foliation in geology refers to repetitive layering in metamorphic rocks. Chapter 6. Slate exhibits slaty foliation, which is also called cleavage. The outcome of prolonged dynamic metamorphism under these conditions is a rock called mylonite, in which crystals have been stretched into thin ribbons (Figure 6.34, right). Regional metamorphism refers to large-scale metamorphism, such as what happens to continental crust along convergent tectonic margins (where plates collide). Shale, slate, phyllite, schist, gneiss, partial melting Match each rock with its first-order metamorphic equivalent (the first rock it would turn into when metamorphosed). If the original limestone was pure calcite, then the marble will likely be white (as in Figure 7.10), but if it had various impurities, such as clay, silica, or magnesium, the marble could be marbled in appearance. Most foliation develops when new minerals are forced to grow perpendicular to the direction of greatest stress. Essentially, the minerals are randomly oriented. The stress that produced this pattern was greatest in the direction indicated by the black arrows, at a right angle to the orientation of the minerals. HyperPhysics*****Geophysics: Metaconglomerate: Non-foliated: Metamorphism of conglomerate: Metamorphic Rock . Solved EARTH SCIENCE LAB Metamorphic Sample #1: Identify the | Chegg.com Anthracite is the highest rank of coal. Alignment of tabular minerals in metamorphic rocks, igneous rocks and intrusive rocks may form a foliation. Chapter 8 Quiz Geology | Other Quiz - Quizizz . Introduction to Geology of the Oceans, 17a Introduction to Human Relationships with Earth Processes. The rock in the upper left of Figure 10.9 is foliated, and the microscopic structure of the same type of foliated rock is shown in the photograph beneath it. Usually, this is the result of some physical force and its effect on the growth of minerals. The surface of phyllite is typically lustrous and sometimes wrinkled. Determination of this information is not easily accomplished in this lab. When a rock is both heated and squeezed during metamorphism, and the temperature change is enough for new minerals to form from existing ones, there is a likelihood that the new minerals will be forced to grow with their long axes perpendicular to the direction of squeezing. In sheared zones, however, planar fabric within a rock may not be directly perpendicular to the principal stress direction due to rotation, mass transport, and shortening. Phyllite is similar to slate, but has typically been heated to a higher temperature; the micas have grown larger and are visible as a sheen on the surface. The rock also has a strong slaty foliation, which is horizontal in this view, and has developed because the rock was being squeezed during metamorphism. It often forms when carbonate rocks near a magma body are altered by contact metamorphism and metasomatism. Foliation, as it forms generally perpendicular to the direction of principal stress, records the direction of shortening. If a rock is both heated and squeezed during metamorphism, and the temperature change is enough for new minerals to form from existing ones, the new minerals can be forced to grow longer perpendicular to the direction of squeezing (Figure 10.7). Soapstones are another type of nonfoliated metamorphic rock. In gneiss, the minerals may have separated into bands of different colours. Metamorphism and Metamorphic Rocks, Chapter 17: Humans' Relationship to Earth Processes, Physical Geology, First University of Saskatchewan Edition, Next: 6.5 Metamorphic Facies and Index Minerals, Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License. In most cases, this is because they are not buried deeply, and the heat for the metamorphism comes from a body of magma that has moved into the upper part of the crust. The passage of this water through the oceanic crust at these temperatures promotes metamorphic reactions that change the original olivine and pyroxene minerals in the rock to chlorite ((Mg5Al)(AlSi3)O10(OH)8) and serpentine ((Mg,Fe)3Si2O5(OH)4). Following such a methodology allows eventual correlations in style, metamorphic grade, and intensity throughout a region, relationship to faults, shears, structures and mineral assemblages. Any rock type (sedimentary, igneous or other metamorphic) can be subjected any one or any combination of the referenced agents. METACONGLOMERATE The parent rock for metaconglomerate is the sedimentary rock . Foliated metamorphic rocks have a layered or banded appearance that is produced by exposure to heat and directed pressure. Introduction to Hydrology and Rivers, 11a. Schistose foliation is composed of larger minerals which are visible to the unaided eye.