GEOLOGY FOR CIVIL ENGINEERS Prepared by: NERISSA D. PAL, CE Instructor, CE Department (2nd Semester, A.Y. 2023-24) CHAPTER 3: PETROLOGY LESSON 1: INTRODUCTION GEOLOGY FOR CIVIL ENGINEERS 2 Lesson 1 Petrology - From Greek work ‘petra’ meaning rock and ‘logos’ meaning rock - A branch of geology that studies the origin, composition, distribution, and structure of rocks. GEOLOGY FOR CIVIL ENGINEERS 3 Lesson 1 Lithology - Specialization of petrology that focuses on macroscopic hand sample or outcrop scale description of rocks. GEOLOGY FOR CIVIL ENGINEERS 4 Lesson 1 Petrography - Specialty that deals with microscopic details or rocks. GEOLOGY FOR CIVIL ENGINEERS 5 Lesson 1 Petrogenesis - A branch of petrology dealing with the origin and formation or rocks (involves a combination of mineralogical, chemical, and field data). GEOLOGY FOR CIVIL ENGINEERS 6 Lesson 1 Branches of Petrology 1. Igneous Petrology - Focuses on the composition and texture of igneous rocks such as granite or basal. GEOLOGY FOR CIVIL ENGINEERS 7 Lesson 1 Branches of Petrology 2. Sedimentary Petrology - Focuses on the composition and texture of sedimentary rocks such as sandstone, shale, or limestone. GEOLOGY FOR CIVIL ENGINEERS 8 Lesson 1 Branches of Petrology 3. Metamorphic Petrology - Focuses on the composition and texture of metamorphic rocks such as slate, marble, gneiss, or schist. GEOLOGY FOR CIVIL ENGINEERS 9 Lesson 1 Branches of Petrology 4. Experimental Petrology - Employs high pressure, high temperature apparatus to investigate geochemistry and phase relations of natural or synthetic materials at elevated pressures and temperature. GEOLOGY FOR CIVIL ENGINEERS 10 Lesson 1 Methodology - Utilizes classical fields of mineralogy, petrology, optical mineralogy and chemical analyses to describe composition and texture of rocks. GEOLOGY FOR CIVIL ENGINEERS 11 Lesson 1 Methodology - Modern petrologist include principles of geochemistry and geophysics through studies of geochemical trends and cycles and use the thermodynamics data and experiments to better understand the origins of rocks. GEOLOGY FOR CIVIL ENGINEERS 12 CHAPTER 3: PETROLOGY LESSON 2: IGNEOUS PETROLOGY GEOLOGY FOR CIVIL ENGINEERS 13 - Any crystalline or glassy rock that forms from cooling of a magma. Conditions for Original Material - Very high temperature and at molten state. GEOLOGY FOR CIVIL ENGINEERS 14 Lesson 2 Igneous Rock 1. Igneous rocks are formed both from magma and lava. 2. Hot molten material occurring naturally below the Earth surface is called magma. 3. Magma erupted through volcanoes is called lava. 4. Magma is actually a hypothetical melt. 5. Lava is a material that has poured out occasionally from volcanoes in many regions of the world again and again. GEOLOGY FOR CIVIL ENGINEERS 15 Lesson 2 Composition: 6. Magma or lava from which igneous rocks are formed may not be entirely a pure melt; it may have a crystalline or solid fraction and also a gaseous fraction thoroughly mixed with it. 7. Solid and gaseous fractions form only a small part of the magma or lava, which are predominantly made up of liquid material igneous rock. GEOLOGY FOR CIVIL ENGINEERS 16 Lesson 2 Composition: Lesson 2 Difference in Molecular Concentration - Magma is rich in molecules of particular mineral; it has better chance to grow into big crystals which may be embedded in finegrained mass resulting from deficient components. GEOLOGY FOR CIVIL ENGINEERS 17 Lesson 2 Relative Insolubility - Crystal grains get enlarged whereas crystals of other soluble contents get mixed up again with magma. - Soluble contents make up the ground mass crystallizing toward the end. GEOLOGY FOR CIVIL ENGINEERS 18 Lesson 2 Change in Physico-chemical Conditions - Abrupt and discontinuous changes in textures result in formation of unequal crystal dimensions. - Magma crystallizing at great depths may produce well-defined large crystals. GEOLOGY FOR CIVIL ENGINEERS 19 Lesson 2 Change in Physico-chemical Conditions - When same magma moves upward, pressure and temperature acting on it is greatly reduced. - Crystallization in the upper levels of magma becomes very rapid resulting in fine-grained matrix containing the larger crystals formed earlier. GEOLOGY FOR CIVIL ENGINEERS 20 Lesson 2 Characteristics of Magma - Types of Magma are determined by chemical composition of the magma. GEOLOGY FOR CIVIL ENGINEERS 21 Lesson 2 Classification of Igneous Rocks - Igneous rocks are classified into two main categories: 1. Based on the proportion of silica as main constituent. 2. Based on the basis of solidification of magma. GEOLOGY FOR CIVIL ENGINEERS 22 Lesson 2 Classification Based on Silica - The content of silica (as 𝑆𝑖𝑂2 ) in igneous rocks varies from over 80% to about 40% in results in some. These were considered to be ‘salts’ of silicic acids. (Mohs Hardness Scale) GEOLOGY FOR CIVIL ENGINEERS 23 Lesson 2 1. Acidic Rocks - Igneous rocks having high percentage of silica (more than 2/3). - They are compositionally rich in silica, alumina and alkalis, but poor in calcium, magnesium and iron. GEOLOGY FOR CIVIL ENGINEERS 24 Lesson 2 1. Acidic Rocks - They are composed of quartz, alkali feldspar and muscovite mica-representing the late stage of crystallization of magma. - These rocks are light in color and weight. GEOLOGY FOR CIVIL ENGINEERS 25 Lesson 2 1. Acidic Rocks GEOLOGY FOR CIVIL ENGINEERS 26 Lesson 2 2. Basic Rocks - Igneous rocks which contain relatively low percentage of silica (generally less than 50%). - These rocks are dark in color and heavier than acidic rocks. GEOLOGY FOR CIVIL ENGINEERS 27 Lesson 2 2. Basic Rocks GEOLOGY FOR CIVIL ENGINEERS 28 a. Volcanic Rocks - Also called extrusive rocks - Formed on earth’s surface by cooling and crystallization of lava GEOLOGY FOR CIVIL ENGINEERS 29 Lesson 2 Classification on the Basis of Solidification of Magma Lesson 2 a. Volcanic Rocks - Grain size of crystals formed in these rocks is very fine, often microscopic - Cooling of lava may take place on the surface or even under waters of seas and oceans GEOLOGY FOR CIVIL ENGINEERS 30 Lesson 2 b. Plutonic Rocks - Also called intrusive rocks - Formed beneath the earth’s surface, generally 7 10 km deep - Coarse grained due to slow cooling rate GEOLOGY FOR CIVIL ENGINEERS 31 Lesson 2 b. Plutonic Rocks - These rocks get exposed on the surface of the earth as a result of erosion of the overlying strata Examples: Granites, Syenites, and Gabbros GEOLOGY FOR CIVIL ENGINEERS 32 Lesson 2 c. Hypabbysal Rocks - Formed at intermediate depths, generally up to 2 kms below the surface of the earth - Exhibit mixed characteristics of volcanic and plutonic rocks Examples: Porphyries of various compositions GEOLOGY FOR CIVIL ENGINEERS 33 Lesson 2 TEXTURE OF IGNEOUS ROCKS - Mutual relationship of different mineralogical component in a rock - Determined by the size, shape and arrangement of components within the body of the rock GEOLOGY FOR CIVIL ENGINEERS 34 Lesson 2 Factors affecting Texture: - Rate of cooling - Degree of crystallization - Fabric - Shape or form - Dimension - Granularity GEOLOGY FOR CIVIL ENGINEERS 35 Lesson 2 TYPES OF TEXTURE 1. Equigranular Texture - Majority of crystal components of rock are broadly equal in size. - Shown by granites and felsites GEOLOGY FOR CIVIL ENGINEERS 36 Lesson 2 TYPES OF TEXTURE 1. Equigranular Texture Granitic Texture - Either all coarse-grained or all medium-grained - Euhedral to subhedral outlines GEOLOGY FOR CIVIL ENGINEERS 37 Lesson 2 TYPES OF TEXTURE 1. Equigranular Texture Felsitic Texture - Micro granular and show perfect outlines - May be described as equiangular and panidiomorphic GEOLOGY FOR CIVIL ENGINEERS 38 Lesson 2 TYPES OF TEXTURE 1. Equigranular Texture Orthophyric Texture - Between granitic and felsitic textures - Individual grains are fine in size but microgranular GEOLOGY FOR CIVIL ENGINEERS 39 Lesson 2 TYPES OF TEXTURE 2. Inequigranular Texture - Majority of constituent minerals show marked difference in relative grain sized. - Classified as Porphyritic and Poiklitic textures. GEOLOGY FOR CIVIL ENGINEERS 40 Lesson 2 TYPES OF TEXTURE 2. Inequigranular Texture Porphyritic Texture - Large crystals set in finer-grained or glassy groundmass; larger crystals (phenocryst) forms earlier in crystallization sequence GEOLOGY FOR CIVIL ENGINEERS 41 Lesson 2 TYPES OF TEXTURE 2. Inequigranular Texture Poiklitic Texture - Large component crystals contain smaller crystals other than minerals within them. GEOLOGY FOR CIVIL ENGINEERS 42 Lesson 2 TYPES OF TEXTURE 3. Directive Texture - Indicate result of flow of magma during formation of rocks - Exhibit perfect or semi-perfect parallelism of crystals in the direction of magma flow GEOLOGY FOR CIVIL ENGINEERS 43 Lesson 2 TYPES OF TEXTURE 3. Directive Texture - Common examples are: Trachytic - Characteristic of certain feldspathic lavas recognized by parallel arrangement of feldspar crystals GEOLOGY FOR CIVIL ENGINEERS 44 Lesson 2 TYPES OF TEXTURE 3. Directive Texture - Common examples are: Trachytoid - Found in some syenites GEOLOGY FOR CIVIL ENGINEERS 45 Lesson 2 TYPES OF TEXTURE 4. Intergrowth Texture - Two or more minerals crystallize out simultaneously in a limited space resulting to mixed up or intergrown crystals - Intergrowth happens during formation of igneous rocks GEOLOGY FOR CIVIL ENGINEERS 46 Lesson 2 TYPES OF TEXTURE 4. Intergrowth Texture - Common examples are: Graphic Textures - Most obvious and regular in between quartz and feldspar crystals GEOLOGY FOR CIVIL ENGINEERS 47 Lesson 2 TYPES OF TEXTURE 4. Intergrowth Texture - Common examples are: Granophyric Textures - Intergrowth is irregular GEOLOGY FOR CIVIL ENGINEERS 48 Lesson 2 TYPES OF TEXTURE 5. Intergranular Texture - Crystals formed at earlier stages may get so arranged that polygonal or trigonal spaces are left in between them - The spaces are filled subsequently during rock formation by crystalline or glassy masses of other minerals GEOLOGY FOR CIVIL ENGINEERS 49 Lesson 2 TYPES OF TEXTURE 5. Intergranular Texture - Sometimes termed INTERSERTAL if material filling the space is GLASSY in nature. GEOLOGY FOR CIVIL ENGINEERS 50 Lesson 2 FORMS OF IGNEOUS ROCKS Factors affecting cooling of igneous rocks: - Structural disposition of host rock (country rock) Viscosity of magma or lava Composition of magma or lava Environment in which injection of magma or eruption of lava takes place GEOLOGY FOR CIVIL ENGINEERS 51 GEOLOGY FOR CIVIL ENGINEERS Lesson 2 FORMS OF IGNEOUS ROCKS 52 GEOLOGY FOR CIVIL ENGINEERS Lesson 2 FORMS OF IGNEOUS ROCKS 53 Lesson 2 FORMS OF IGNEOUS ROCKS Other factors involved: • DIFFUSION RATE – rate at which atoms or molecules can move through the liquid. • NUCLEATION RATE OF NEW CRYSTALS – rate at which enough of the chemical constituents can come together in one place without dissolving. GEOLOGY FOR CIVIL ENGINEERS 54 Lesson 2 FORMS OF IGNEOUS ROCKS Other factors involved: • GROWTH RATE OF CRYSTALS – the rate at which new constituents can arrive at the surface of the growing crystal; depends greatly on diffusion rate or molecules of concern GEOLOGY FOR CIVIL ENGINEERS 55 Lesson 2 IMPORTANT IGNEOUS ROCKS 1. PLUTON GEOLOGY FOR CIVIL ENGINEERS 56 Lesson 2 IMPORTANT IGNEOUS ROCKS 2. BATHOLITHS GEOLOGY FOR CIVIL ENGINEERS 57 Lesson 2 IMPORTANT IGNEOUS ROCKS 3. DIKES GEOLOGY FOR CIVIL ENGINEERS 58 Lesson 2 IMPORTANT IGNEOUS ROCKS 4. SILLS GEOLOGY FOR CIVIL ENGINEERS 59 Lesson 2 IMPORTANT IGNEOUS ROCKS 5. LACOLITHS GEOLOGY FOR CIVIL ENGINEERS 60 Lesson 2 IMPORTANT IGNEOUS ROCKS 6. VOLCANIC NECKS GEOLOGY FOR CIVIL ENGINEERS 61 Lesson 2 MOST COMMON IGNEOUS ROCKS 1. GRANITE GEOLOGY FOR CIVIL ENGINEERS 62 Lesson 2 MOST COMMON IGNEOUS ROCKS 2. GABBRO GEOLOGY FOR CIVIL ENGINEERS 63 Lesson 2 MOST COMMON IGNEOUS ROCKS 3. BASALT GEOLOGY FOR CIVIL ENGINEERS 64 Lesson 2 MOST COMMON IGNEOUS ROCKS 4. DOLERITE GEOLOGY FOR CIVIL ENGINEERS 65 Lesson 2 MOST COMMON IGNEOUS ROCKS 5. DIORITE GEOLOGY FOR CIVIL ENGINEERS 66 CHAPTER 3: PETROLOGY LESSON 3: SEDIMENTARY ROCKS GEOLOGY FOR CIVIL ENGINEERS 67 - Are often deposited in layers, and frequently contain fossils. Lesson 3 Sedimentary Rocks - Are also called secondary rocks - Formed through the deposition and solidification of sediment, especially sediment transported by water (rivers, lakes, and oceans), ice (glaciers), and wind. GEOLOGY FOR CIVIL ENGINEERS 68 - Includes a wide variety of rocks formed by accumulation, compaction and consolidation of sediments. Lesson 3 Sedimentary Rocks - Sediments may be defined as particles produced from decay and weathering of pre-existing rocks or may be derived from remains of dead sea or land animals in suitable environments. GEOLOGY FOR CIVIL ENGINEERS 69 - Accumulation and compaction of these sediments commonly takes place under water or at least in the presence of water. GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Sedimentary Rocks 70 • The process of formation of sedimentary rocks is ever prevailing. Lesson 3 Formation • The sediments so produced are transported to the setting basins such as sea floors where they are deposited, get compacted and consolidated and finally transformed into a cohesive solid mass. That is a sedimentary rock. GEOLOGY FOR CIVIL ENGINEERS 71 • Some chemical processes especially evaporation and precipitation regularly operate on surface of water bodies containing dissolved salts and produce solids that settle down in those bodies. GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Formation 72 • Sedimentary rocks are broadly grouped into three classes on the basis of their mode of formation: Mechanically formed or Clastic Rocks; Organically formed Rocks and Chemically formed Rocks GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Formation 73 • The last two groups are considered as a single class and named as Non-Clastic Rocks and Clastic (Mechanically Formed) Rocks. Lesson 3 Formation • A series of well-defined steps are involved in the formation of clastic rocks. GEOLOGY FOR CIVIL ENGINEERS 74 Lesson 3 GEOLOGY FOR CIVIL ENGINEERS 75 Lesson 3 GEOLOGY FOR CIVIL ENGINEERS 76 Lesson 3 GEOLOGY FOR CIVIL ENGINEERS 77 Lesson 3 GEOLOGY FOR CIVIL ENGINEERS 78 Lesson 3 GEOLOGY FOR CIVIL ENGINEERS 79 Lesson 3 GEOLOGY FOR CIVIL ENGINEERS 80 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Classification of Sedimentary Rocks 81 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Classification of Sedimentary Rocks 82 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 83 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 84 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 85 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 86 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 87 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 88 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 89 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 90 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 91 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 92 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 93 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 94 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 95 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 96 GEOLOGY FOR CIVIL ENGINEERS Lesson 3 Important Sedimentary Rocks 97 CHAPTER 3: PETROLOGY LESSON 4: METAMORPHOUS PETROLOGY GEOLOGY FOR CIVIL ENGINEERS 98 Lesson 4 GEOLOGY FOR CIVIL ENGINEERS 99 Lesson 4 GEOLOGY FOR CIVIL ENGINEERS 100 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Process of Metamorphism 101 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Metamorphism Processes that work simultaneously: 102 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Metamorphism Processes that work simultaneously: 103 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Metamorphism Processes that work simultaneously: 104 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Metamorphism Processes that work simultaneously: 105 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Metamorphism Processes that work simultaneously: 106 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Group of Minerals Formed 107 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Group of Minerals Formed 108 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Mineralogical Composition 109 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Textures of Metamorphic Rocks 110 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Classification of Metamorphic Rocks 111 Lesson 4 GEOLOGY FOR CIVIL ENGINEERS 112 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Important Metamorphic Rocks 113 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Important Metamorphic Rocks 114 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Important Metamorphic Rocks 115 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Important Metamorphic Rocks 116 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Important Metamorphic Rocks 117 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Engineering Importance: 118 GEOLOGY FOR CIVIL ENGINEERS Lesson 4 Engineering Importance: 119 Lesson 4 GEOLOGY FOR CIVIL ENGINEERS 120 PLATE NO. 5: RESEARCH: Make a presentation on the different rock formations in Mindanao. GEOLOGY FOR CIVIL ENGINEERS 121 PLATE NO. 5: Here are guide questions to help you proceed with the presentation: a. What are the major rock formations available in Mindanao? b. What does the presence of these rock formations imply? GEOLOGY FOR CIVIL ENGINEERS 122 PLATE NO. 5: c. What are the rock formations available in Cotabato City? d. What are the limestones found in Mindanao GEOLOGY FOR CIVIL ENGINEERS 123 PLATE NO. 5: • You may use Canva or other platforms in making your presentation. • Make it beautiful and professional looking presentation. GEOLOGY FOR CIVIL ENGINEERS 124 PLATE NO. 5: • Provide the references at the end of your research. • Avoid plagiarism. Corresponding deductions will be applied. GEOLOGY FOR CIVIL ENGINEERS 125 PLATE NO. 5: • Since your creativity is graded, you can use any appropriate font, but the minimum size should be 12. • Don’t forget to use the plate format. GEOLOGY FOR CIVIL ENGINEERS 126 PLATE NO. 5: • Deadline of submission will be on Monday, 27 May 2024. GEOLOGY FOR CIVIL ENGINEERS 127
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