Earth Science Quarter 2 - Module 4: Metamorphism PDF

Earth Science Quarter 2 – Module 4: Metamorphism  What I Need to Know Most Essential Learning Competency: Describe the changes in mineral components and texture of rocks due to changes in pressure and temperature (metamorphism). This module was designed an...

Earth Science Quarter 2 – Module 4: Metamorphism  What I Need to Know Most Essential Learning Competency: Describe the changes in mineral components and texture of rocks due to changes in pressure and temperature (metamorphism). This module was designed and written with you in mind. It is here to help you master the concept on process of metamorphism accompanying the changes in rocks’ composition and texture. The scope of this module permits it to be used in many different learning situations. The language used recognizes the diverse vocabulary level of students. The lessons are arranged to follow the standard sequence of the course. The module discussions are evolving in the different factors affecting the process of metamorphism and its effect on the mineral and texture of the rocks. After going through this module, you are expected to: 1. identify the factors involved in the process of metamorphism; 2. differentiate the types of metamorphism; and 3. explain the effects of pressure and temperature on the composition and texture of the rocks undergoing metamorphism.  What I Know Directions. Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper. Note: If your answer to this pre-assessment is one hundred percent correct, you may skip and proceed to the next module. 1. What causes changes in the composition of a rock during the process of metamorphism? a. increase in pressure b. increase in temperature c. reaction with hydrothermal fluids d. All of these 2. Which of the following is the process exhibited by parallel alignment of mica in a metamorphic rock? a. bedding b. foliation c. metasomatism d. porphyroblasts 3. Which of the following sets is arranged in order of increasing metamorphic grade? a. shale - slate - schist b. phyllite - schist - slate c. schist - shale – gneiss d. phyllite - gneiss - schist 4. Which of the following statements about metamorphism of a limestone is false? a. with increasing metamorphism, foliation develops b. with increasing metamorphism, the amount of water decreases c. with increasing metamorphism, the calcite minerals form larger crystal. d. with increasing metamorphism, the grain size of the minerals gets smaller. 5. Which of the following is TRUE about contact metamorphism? a. It occurs within the continental crust. b. It takes place when the heat and shock waves from meteor or asteroid impact. c. Pressure has an important role in the transformation of rocks in contact metamorphism. d. It is prominent in areas where surrounding rocks are exposed to heat coming from magma intrusion. 6. Which of the following transformation is directly related to pressure in producing metamorphic rocks? a. formation of foliation b. change mineralogical in the rock c. increasing size of mineral crystals d. change in mineral composition of the rock 7. Which of the following metamorphic rocks would NOT come from mud rock? a. Gneiss b. Marble c. Schist d. Slate 8. What process contributes to metamorphism of oceanic crust at a spreading ridge? a. Dissolved minerals in the water confined within the rocks react with the heat and triggers chemical reaction. b. Minerals present in the ocean water percolates through the rocks and deposits the minerals within the rocks while replacing other minerals. c. Heat coming out from hydrothermal vents under the ocean heats up the rock and forms recrystallization of the original mineral content of the rock. d. Interaction of plates below the spreading oceanic crust creates horizontal movements and deform the rocks within leading to formations of foliations and cracks. 9. Rigel argued with his classmates that the rock he found in the campsite near the foot of Taal volcano was a metamorphic rock. Others claimed that it was igneous because it was found near a volcano so it must have been a volcanic rock, hence, an igneous rock. What features of the rock would have convinced Rigel that it was a metamorphic rock and not an igneous rock? a. The minerals in rocks are almost invisible to be seen. b. The rock contains bits of old shells of snails and wood. c. The surface of the rock has holes similar to a Swiss cheese. d. The rock contains interlocking and large crystals of minerals compared to minerals found in igneous rocks. 10. Diamonds are minerals made through the process similar to metamorphism which results into formation of very dense arrangement of carbon atoms. What type of metamorphism would create a diamond? i. Burial metamorphism ii. Contact metamorphism iii. Shock metamorphism iv. High-pressure metamorphism v. Hydrothermal metamorphism a. i and ii b. ii and v c. iii and iv d. iv and v 11. Which of the following metamorphic rocks may have come from a shale? a. gneiss b. phyllite c. schist d. all of the above 12. In which geographic area will there be a metamorphic rock with very distinct foliations? a. near magma intrusion b. at the core of the Himalayas c. in the mid-ocean ridge in the Atlantic Ocean d. in convergent boundaries where plates move towards each other 13. Low-grade metamorphism takes place at temperatures between about 200oC to 320oC, and relatively low pressure. Which metamorphic rock is created at this environmental setting? a. Gneiss b. Hornfels c. Schist d. Slate 14. How does the presence of a hot pluton contribute to metasomatism? I. The heat coming from pluton heats up the rock and triggers recrystallization of its original minerals II. A hot pluton heats the surrounding water, causing groundwater to circulate around the rocks. III. Magma within the pluton cooks up the minerals and destroy its original crystal arrangements. a. Only I is correct b. Only II is correct c. I and II are correct d. All are correct 15. How does metasomatism process occur? a. Recrystallization of minerals through contact metamorphism due to heat. b. Destruction of arrangement of original minerals by impact due to asteroid bombardment. c. Recrystallization and alignment of minerals through regional metamorphism due to heat and pressure. d. The dissolve minerals in the fluids react with rocks that the fluids penetrate causing changes in chemical and mineral compositions.  Lesson 1 Metamorphism This lesson contains activities and readings about one of the geologic activities that take place inside the Earth’s crust. You will learn basic concept and information about metamorphism through brief discussion on the process of metamorphism, the factors involved during the process and its connection to tectonic settings and environment where metamorphism occurs. In the activities, you are expected to use the knowledge and skills that you learned and gained from the previous modules in connection to the new set of skills and information that you will learn from this module. What’s In In the previous module you learned about the three processes that take place inside the Earth that influence the shape and structure of the Earth – the magmatism, volcanism and plutonism. In this module you will learn another important geologic process that also takes place inside the earth – the Metamorphism. Metamorphism is one of the geologic processes in which rocks change in the form, composition, and structure due to intense heat and pressure and sometimes with the introduction of chemically active fluids. While learning through this module, you can make concept connections between major geologic features such as tectonic features of Earth and endogenic processes that you learned previously with the processes that rocks undergo during metamorphism - how those geologic processes influence the changes that rocks undergo and form the so-called metamorphic rocks. Notes to the Teacher Hello dear teachers, this module may be used by learners with minimal supervision. The activities included are suitable for their level and capacity. As pre-requisite to this module, make sure that the learners had finished the previous modules on minerals, classification of rocks and endogenic processes such as magmatism, volcanism and plutonism. Thank you.  What’s New Activity 1 Geologic processesthat take place underneath the ground is very hard to decribe because we cannot directly observe what’s going on beneath us. Hence, to visualize the events that are taking place in the Earth’s crust, let us do this simulation activity. For this activity you may ask the help of your parents or siblings with you at home. You may use materials as alternatives if the ones given are not availabe at your house. Let’s start. Set-up 1 Materials for set up 1:  Raw egg white  A shallow pan (you may use plate as alternative)  Boiled water in a glass jar or bottle Procedures: 1. Separate yolk from the egg white (you will be using only the egg white) and pour it in a shallow pan. 2. Transfer your boiled water on a glass jar or a bottle and place it in the middle of the pan. 3. Observe the changes in the egg white. Questions: 1. What did you notice on the egg white near the glass jar with hot water? What do you think caused that change? 2. Did you observe any changes on the egg white far from the hot glass jar? How can you explain this observation? Set-up 2 Materials for set up 2:  Pieces of sticks taken from walis ting-ting with different lengths.  2 rulers (you may use any alternatives for the purpose) Procedures: 1. Drop the sticks onto an even surface and let them take different direction or orientation. 2. Using two rulers, placed on either side of the sticks, pull them toward the center while trapping the sticks in the middle. Questions: 1. The sticks represent the minerals present in the rocks. What changes did you observe on the sticks when you pulled the rulers together towards the middle? 2. In the activity, the rulers represent the tectonic forces that push rocks. What can you infer from this activity about the minerals in rocks when undergoing the same forces? 3. In this process, can you name the factor that is resposible to the changes that occurred? What is It The activity demonstrates how rocks respond to geologic factors such as heat and pressure forming metamorphic rocks through the process called metamorphism. The process of metamorphism takes place tens of kilometers below the surface where temperatures and pressures are high enough to transform rock without melting it. The increase in temperature and pressure and change of the chemical environment can change the mineral composition and crystalline textures of the rock while remaining solid all the while. The metamorphic rocks under these change conditions depends on the original rock chemistry, the exact pressures and temperature to which rocks are subjected and the amount of water available for chemical reaction. Factors Involved in the Process of Metamorphism 1. Temperature. It plays a crucial role in the process of metamorphism. The heat affects the rock’s chemical composition, mineralogy and texture. For instance, during burial metamorphism, at a depth of about 8 to 15 kilometers from the surface of the crust metamorphic reactions begin. The rocks adjust to the new temperature causing its atoms and ions to recrystallize and form new arrangements thereby creating new mineral assemblages. During recrystallization, new crystals grow larger than the crystals in the original rock. For example, (see figure below) when sedimentary rock (mud rock) - shale become buried deeper and deeper, the clay minerals in the rock will begin to recrystallize and form new minerals, such as micas in slate – a metamorphic rock from shale. With additional burial, at greater depth, where temperature is higher, mineral micas begin to transform into a new mineral garnet in schist – another metamorphic rock with higher grade. The rate at which temperature increases with depth in the Earth’s crust is known as geothermal gradient which varies on plate tectonic settings like the thickness of the crust or whether the area is in the subduction zone between oceanic and continental or under the converging two continental crusts. Subduction zones, for instance, are characterized by low temperature metamorphism and the area at which collision takes place between two converging crustal plates is characterized by high temperature metamorphism. In a nutshell, the higher the temperature, the higher the metamorphism grade until such time when temperature is high enough to melt the rocks resulting to formation of magma. Sedimentary rock – Shale Metamorphic rock – Slate Metamorphic rock – Schist with clay minerals with mica minerals with garnet minerals 2. Pressure. Like temperature, it changes the composition, mineralogy, and texture of rocks. Pressure is different in various tectonic setting, similar to temperature. For instance, metamorphism in the subduction zone is characterized by high-pressure metamorphism. In contrast, collision zone between two continental crust is marked by moderate pressure metamorphism. There are two types of pressures known also as stresses that exert force to rocks causing changes. 1. The confining pressure or vertical stress, is the pressure or stress exerted on rock by the weight of overlying material such as in burial metamorphism. This type of pressure is the same in all directions and makes the rocks to fracture or deformed. 2. The directed or differential pressure imposed by a force in a particular direction. Differential pressure is dominant at convergent boundaries where plates move towards each other and collide thus exerting force and cause rocks to deform. Pressure causes rocks to form folds in a particular direction as directed by the pressure, thus directed pressure guides the shape and orientation of the new crystals formed as minerals recrystallize under the influence of both heat and pressure. This results in a textural change such that the minerals are elongated in the direction perpendicular to the directed stress and this contributes to the formation of foliation. Foliation is a set of flat or wavy parallel cleavage planes produced by deformation under directed pressures. In the figure below, the effect of compression due to pressure, aligned the minerals as they recrystallize during metamorphism. The diagram in the left represents the minerals in shale, a sedimentary rock with beddings in the direction shown. The diagram in the middle represents minerals in slate, a low-grade metamorphic rock from original rock shale, with the mica crystals orientated perpendicular to the direction of the pressure. The minerals in a higher- grade metamorphic rock schist, with very evident foliation, is represented by the diagram in the far right which shows larger bandings of minerals caused by even greater pressure.  Sedimentary rock – Shale Metamorphic rock – Slate Metamorphic rock – Schist with bedding plane with foliation with larger foliation The circulating mineral-laden fluids through rock bodies known as Hydrothermal fluids also play a role in the process of metamorphism. The dissolve minerals in the fluids react with rocks that the fluids penetrate causing changes in chemical and mineral compositions and sometimes completely replacing one mineral with another without changing the rocks textures. This type of metamorphism is known as metasomatism in which the alteration process is caused by fluids passing through the rock and catalyze chemical reactions. For example, when the heat of the intrusive igneous body heats up the groundwater containing dissolved minerals, convection of water forms flowing through the surrounding rocks and penetrating through them. Reactions occur among chemicals in the rocks and in the water resulting into significant change in the mineralogy of the rock. Example for this is the alteration of feldspars to clays, and deposition of quartz, calcite, and other minerals in fractures or cracks and other open spaces forming veins such as represented by the figure below. Calcite vein deposits in limestone rock Metamorphism caused by hydrothermal fluids also occurs in mid-ocean ridges where hot lava, coming out of the fissures, react with mineral-rich ocean water and cause serpentines to form through oxidation and hydration chemical reaction of peridotites- an olivine rich rocks at the base of the oceanic crust, this is known as Serpentinization process. Types of Metamorphism Metamorphic rocks are categorized on the basis of theory geologic origins. Foliated metamorphic rocks such as Gneiss and Schist were formed through Regional Metamorphism in which both high temperature and high pressure are imposed to large parts of the crust. Most regional metamorphism occurs within the continental crust. Although rocks can be metamorphosed at depth in most areas, deep below the mountains produced by collision of two continental crust is the area of greatest regional metamorphism. In general, the confining and directing pressures exerted by some tectonic forces unto to the rock formations cause new alignment of minerals (foliation) during recrystallization. Another type of metamorphism is the Contact Metamorphism which is prominent in areas where surrounding rocks are exposed to heat coming from magma intrusion within the layers of the rocks. Marble, quartzite and other granoblastic rocks with large visible crystals of minerals maybe formed through contact metamorphism. For example, when quartz-rich sedimentary rock come in contact with enough heat from the presence of ingenious intrusions to trigger recrystallization, all sedimentary structures are destroyed and quartz grains in the sandstone recrystallize to form an interlocking mosaic of crystals giving it a granoblastic texture. The resulting rock is white or pale grey in color known as metaquartzite. The size of the crystals is larger near to the contact with the igneous intrusion and smaller when further away from the contact where temperatures are not as high. The same things happen with limestone, the parent rock of marble. The heat coming from igneous intrusion destroys the calcite minerals including the fossils found in the limestone and form a marble with an interlocking mosaic of crystals. A limestone made of pure calcite minerals would transform into pure white marble. Other types of metamorphism include Shock Metamorphism which takes place when the heat and shock waves from meteor or asteroid impact transform rocks immediately around the impact site, examples of this is the transformation of mineral graphite into ultra-high-pressure polymorphs diamond and conversion of quartz minerals into coesite under high shock pressures. Burial Metamorphism occurs at lower temperature and pressure which transform sedimentary rocks that had undergone diagenesis into low grade metamorphic rocks through relatively low temperature and pressure. Partial alteration of the mineralogy and texture may occur while other sedimentary structures are usually preserved. In subduction zones, between two converging plates, High-pressure metamorphism occurs. Metamorphic rocks created through these processes are rarely found on the Earth surface as they were formed in such a great depth. Some metamorphic rocks formed through these types of metamorphism contains bits of microscopic diamonds, an indication that the rock was formed with great pressure. An example of rock made through this type of metamorphism is the eglcosite which has transformed with pressure greater than 28 kbar at a depth of approximately above 80 km. Questions: 1. At what depths in Earth do metamorphic rocks form? What happens if temperature and pressure get too high? 2. What texture is formed in the alignment of mineral crystals with a preferred orientation in a metamorphic? 3. How would you relate the grade of metamorphic rocks to the degree of temperature in which it is made? 4. Which metamorphic rock would you associate with high grade of regional metamorphism (phyllite, slate, schist, or gneiss)? Why? What’s More Activity A. Directions: Identify the geologic area and the respective type metamorphism that occur in the encircled portion in the illustration below. Write your answers in the table.  No. Geologic area Type of Metamorphism 1 2 3 4 5 6 B. Directions: Fill in the table below with the correct information about metamorphism. Most strategic Agent/factor Example of Type of Changes that geographic responsible for metamorphic metamorphism occurs in rocks location where it the change rock occurs (1) Alignment of (2) (3) (4) minerals perpendicular to force (5) (6) (7) (8) Hornfels (9) (10) (11) (12) Heat from impact of asteroid (13) (14) (15) (16) Subduction zone (17) (18) (19) (20) Burial metamorphism (21) (22) (23) (24) Hydrothermal fluids What have I Learned Directions: Complete the sentence below by writing the correct word/phrase. 1. Metamorphism is the alteration of rock’s _____________, _____________ and _____________. 2. Metamorphic rocks are formed when rocks are subjected to significant changes in _____________ and _____________. 3. Confining pressure is _____________, whereas directed pressure is _____________. 4. In the presence directed pressure, recrystallization may align minerals _____________ to the force/stress applied on the rocks.  5. _____________ metamorphism takes place where both high and temperatures are imposed over large parts of the crust and usually takes place in _____________ plate boundaries. 6. _____________ is the localized transformation or rocks near to igneous intrusions mainly as a result of high temperatures. 7. Other types of metamorphism are _____________, _____________, and _____________. 8. _____________ is created by alignment of minerals under directed pressure. 9. Granoblastic rocks are _____________ rocks composed mainly of crystals that grow in large size and distinct shapes. 10. Metasomatism occurs when the change in rock’s composition is due to interactions with _____________. What I can Do Semi-fieldwork Activity Go to your backyard, home, or school garden or in any place near and safe for you to collect some metamorphic rocks and bring them home. (make sure to clean them first and don’t forget to wash your hands) Make a table similar to the one below and make a log of the information about the rocks that you collected. Describe the Rock Classify the type of Write your inference about features of the Sample Picture the metamorphic rock how the rock samples metamorphic number sample undergone metamorphism. rock sample 1 2 3  Assessment Directions. Multiple Choice. Choose the letter of the best answer. Write the chosen letter on a separate sheet of paper. 1. Which of the following statements about metamorphism of a shale is false? a. With increasing metamorphism, foliation develops b. With increasing metamorphism, the amount of water decreases c. With increasing metamorphism, the clay minerals breakdown to form micas d. With increasing metamorphism, the grain size of the minerals gets smaller 2. Which of the following has the correct set of major agents of metamorphism? a. Temperature and pressure b. Pressure and tectonic forces c. Temperature and mineral fluids d. Hydrothermal fluids and pressure 3. Which of the following correctly describes the major role of pressure in producing metamorphic rocks? a. Pressure leads to foliation in the rock b. Pressure decreases the size of mineral crystals c. Pressure leads to mineralogical changes in the rock. d. Pressure facilitates change in mineral composition of the rock. 4. What type of metamorphic rock will form if a mud rock experiences high-grade metamorphism? a. Gneiss b. Phyllite c. Schist d. Slate 5. Granite is an igneous rock that are formed through slow solidification of magma; accordingly, it does not change very much at lower metamorphic grades. Why is this so? a. Granite minerals are still stable at lower temperatures. b. Granite, like any other igneous rocks is geologically impossible to become a parent rock of metamorphic rock. c. Granite remains largely unchanged at lower metamorphic grades because its surrounding environment is constantly stable. d. All of the above. 6. What process contributes to metamorphism of oceanic crust at a spreading ridge? a. Dissolved minerals in the water confined within the rocks react with the heat and triggers chemical reaction. b. Heat coming out from hydrothermal vents under the ocean heats up the rock and forms recrystallization of the original mineral content of the rock. c. Minerals present in the ocean water percolates through the rocks and deposits the minerals within the rocks while replacing other minerals. d. Interaction of plates below the spreading oceanic crust creates horizontal movements and deform the rocks within leading to formations of foliations and cracks. 7. While walking, Daniel picked up a rock that have been washed up on the beach. Noticing that it has wavy bands of light and dark colored minerals, he claimed that the rock is a metamorphic rock. Which of the following inferences about its formation is the most correct? a. Pressure was the main agent in rock’s formation which aligned the minerals into new orientation. b. The rock was formed through high-pressure made by the impact of large body into the Earth’s surface. c. The minerals in the rocks were altered through recrystallization changing their size into large crystals. d. The bands in the rock was formed through deposition of minerals from the hot fluids that surround it during formation process. 8. Which of the following is the source of increase of temperature and pressure in regional metamorphism? a. Impact metamorphism b. Local intrusive heat source c. Increased rate of radioactive decay d. Increase in temperature with increasing depth of burial 9. Which of the following metamorphic rocks can NOT form from a shale? a. hornfels b. marble c. schist d. slate 10. On a local field trip, a group of students noticed that they are walking across a path made of rocks that starts from a shale into a slate and into a phyllite. What can you infer to the direction taken by the students in relation the grades of metamorphic rocks? a. It follows a decreasing metamorphic grade. b. It indicates an increasing metamorphic grade. c. It indicates an increasing degree of contact metamorphism. d. It shows an in decreasing degree to regional metamorphism. 11. In which geographic area will there be a highest potential for regional metamorphism? a. In the Philippine trench b. Near an igneous intrusion c. At the core of the Himalayas d. Mid-ocean ridge in the Atlantic Ocean 12. Which of the following does NOT belong to the group? a. Gneiss b. Hornfels c. Marble d. Quartzite 13. Blueschist metamorphism takes place within subduction zones. What is the temperature and pressure characteristics of this geological setting? a. Low temperature and pressure b. High temperature and pressure c. Low temperature and high pressure d. High temperature and low pressure 14. How does the presence of a hot pluton contribute to metasomatism? i. A hot pluton heats the surrounding water, causing groundwater to circulate around the rocks. ii. Magma within the pluton is the source of minerals that seep through the rocks and cause chemical exchange. iii. The heat coming from pluton heats up the rock and triggers recrystallization of its original minerals a. Only i is correct b. Only ii is correct c. i and ii are correct d. All are correct 15. The diagram below shows microscopic illustration of minerals of certain sedimentary rock (parent rock) which is subjected to high pressure and temperature underground forming a foliated metamorphic rock. High Pressure and temperature What type of metamorphism occurs in the given illustration? a. Burial metamorphism b. Contact metamorphism c. Regional metamorphism d. Shock metamorphism Additional Activities Directions: Using the important terms or vocabularies and concept from this module, create a concept map about the process of metamorphism. You may use computer in creating your concept map or draw it in a piece of typewriter paper. Once you are done, please submit your work to your teacher. Good luck!