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Earth materials

  1. 1. Earth materials (part 1) Dr.Krit Won-in Department of Earth Sciences Faculty of Science Kasetsart University [email_address] 081-633-5337
  2. 2. The rock cycle Figure 1.21
  3. 3. Matter and Minerals
  4. 4. Minerals: Building blocks of rocks <ul><li>By definition a mineral is </li></ul><ul><ul><ul><li>Naturally occurring </li></ul></ul></ul><ul><ul><ul><li>Inorganic solid </li></ul></ul></ul><ul><ul><ul><li>Ordered internal molecular structure </li></ul></ul></ul><ul><ul><ul><li>Definite chemical composition </li></ul></ul></ul><ul><li>Rock </li></ul><ul><ul><ul><li>A solid aggregate of minerals </li></ul></ul></ul>
  5. 5. Structure of an atom Figure 3.4 A
  6. 6. Composition of minerals <ul><li>Chemical bonding </li></ul><ul><ul><ul><li>Formation of a compound by combining two or more elements </li></ul></ul></ul><ul><li>Ionic bonding </li></ul><ul><ul><ul><li>Atoms gain or lose outermost ( valence ) electrons to form ions </li></ul></ul></ul><ul><ul><ul><li>Ionic compounds consist of an orderly arrangement of oppositely charged ions </li></ul></ul></ul>
  7. 7. Halite (NaCl) – An example of ionic bonding Figure 3.6
  8. 8. Physical properties of minerals <ul><li>Primary diagnostic properties </li></ul><ul><ul><ul><li>Determined by observation or performing a simple test </li></ul></ul></ul><ul><ul><ul><li>Several physical properties are used to identify hand samples of minerals </li></ul></ul></ul>
  9. 9. Physical properties of minerals <ul><li>Crystal form </li></ul><ul><ul><ul><li>External expression of a mineral’s internal structure </li></ul></ul></ul><ul><ul><ul><li>Often interrupted due to competition for space and rapid loss of heat </li></ul></ul></ul>
  10. 10. A garnet crystal
  11. 11. Cubic crystals of pyrite Figure 3.11 A
  12. 12. Physical properties of minerals <ul><li>Luster </li></ul><ul><ul><ul><li>Appearance of a mineral in reflected light </li></ul></ul></ul><ul><ul><ul><li>Two basic categories </li></ul></ul></ul><ul><ul><ul><ul><li>Metallic </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Nonmetallic </li></ul></ul></ul></ul><ul><ul><ul><li>Other descriptive terms include vitreous, silky, or earthy </li></ul></ul></ul>
  13. 13. Galena (PbS) displays metallic luster
  14. 14. Physical properties of minerals <ul><li>Color </li></ul><ul><ul><ul><li>Generally unreliable for mineral identification </li></ul></ul></ul><ul><ul><ul><li>Often highly variable due to slight changes in mineral chemistry </li></ul></ul></ul><ul><ul><ul><li>Exotic colorations of certain minerals produce gemstones </li></ul></ul></ul>
  15. 15. Quartz (SiO 2 ) exhibits a variety of colors Figure 3.26
  16. 16. Physical properties of minerals <ul><li>Streak </li></ul><ul><ul><ul><li>Color of a mineral in its powdered form </li></ul></ul></ul><ul><li>Hardness </li></ul><ul><ul><ul><li>Resistance of a mineral to abrasion or scratching </li></ul></ul></ul><ul><ul><ul><li>All minerals are compared to a standard scale called the Mohs scale of hardness </li></ul></ul></ul>
  17. 17. Streak is obtained on an unglazed porcelain plate Figure 3.12
  18. 18. Mohs scale of hardness Figure 3.13
  19. 19. Physical properties of minerals <ul><li>Cleavage </li></ul><ul><ul><ul><li>Tendency to break along planes of weak bonding </li></ul></ul></ul><ul><ul><ul><li>Produces flat, shiny surfaces </li></ul></ul></ul><ul><ul><ul><li>Described by resulting geometric shapes </li></ul></ul></ul><ul><ul><ul><ul><li>Number of planes </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Angles between adjacent planes </li></ul></ul></ul></ul>
  20. 20. Common cleavage directions Figure 3.15
  21. 21. Fluorite, halite, and calcite all exhibit perfect cleavage
  22. 22. Physical properties of minerals <ul><li>Fracture </li></ul><ul><ul><ul><li>Absence of cleavage when a mineral is broken </li></ul></ul></ul><ul><li>Specific Gravity </li></ul><ul><ul><ul><li>Weight of a mineral / weight of an equal volume of water </li></ul></ul></ul><ul><ul><ul><li>Average value = 2.7 </li></ul></ul></ul>
  23. 23. Conchoidal fracture Figure 3.16
  24. 24. Physical properties of minerals <ul><li>Other properties </li></ul><ul><ul><ul><li>Magnetism </li></ul></ul></ul><ul><ul><ul><li>Reaction to hydrochloric acid </li></ul></ul></ul><ul><ul><ul><li>Malleability </li></ul></ul></ul><ul><ul><ul><li>Double refraction </li></ul></ul></ul><ul><ul><ul><li>Taste </li></ul></ul></ul><ul><ul><ul><li>Smell </li></ul></ul></ul><ul><ul><ul><li>Elasticity </li></ul></ul></ul>
  25. 25. Mineral groups <ul><li>Nearly 4000 minerals have been named </li></ul><ul><li>Rock-forming minerals </li></ul><ul><ul><ul><li>Common minerals that make up most of the rocks of Earth’s crust </li></ul></ul></ul><ul><ul><ul><li>Only a few dozen members </li></ul></ul></ul><ul><ul><ul><li>Composed mainly of the 8 elements that make up over 98% of the continental crust </li></ul></ul></ul>
  26. 26. Elemental abundances in continental crust Figure 3.18
  27. 27. Igneous Rocks
  28. 28. The rock cycle Figure 1.21
  29. 29. General characteristics of magma <ul><li>Igneous rocks form as molten rock cools and solidifies </li></ul><ul><li>General characteristics of magma </li></ul><ul><ul><ul><li>Parent material of igneous rocks </li></ul></ul></ul><ul><ul><ul><li>Forms from partial melting of rocks </li></ul></ul></ul><ul><ul><ul><li>Magma at surface is called lava </li></ul></ul></ul>
  30. 30. General characteristics of magma <ul><li>General characteristic of magma </li></ul><ul><ul><ul><li>Rocks formed from lava = extrusive , or volcanic rocks </li></ul></ul></ul><ul><ul><ul><li>Rocks formed from magma at depth = intrusive , or plutonic rocks </li></ul></ul></ul>
  31. 31. Evolution of magmas <ul><li>A single volcano may extrude lavas exhibiting very different compositions </li></ul><ul><li>Bowen’s reaction series </li></ul><ul><ul><ul><li>Minerals crystallize in a systematic fashion based on their melting points </li></ul></ul></ul><ul><ul><ul><li>During crystallization, the composition of the liquid portion of the magma continually changes </li></ul></ul></ul>
  32. 32. Bowen’s reaction series Figure 4.23
  33. 33. Assimilation, magma mixing, and magmatic differentiation Figure 4.25
  34. 34. Igneous compositions <ul><li>Naming igneous rocks – granitic rocks </li></ul><ul><ul><ul><li>Granite </li></ul></ul></ul><ul><ul><ul><ul><li>Phaneritic </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Over 25% quartz, about 65% or more feldspar </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Very abundant - often associated with mountain building </li></ul></ul></ul></ul><ul><ul><ul><ul><li>The term granite includes a wide range of mineral compositions </li></ul></ul></ul></ul><ul><ul><ul><li>Rhyolite </li></ul></ul></ul><ul><ul><ul><ul><li>Extrusive equivalent of granite </li></ul></ul></ul></ul><ul><ul><ul><ul><li>May contain glass fragments and vesicles </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Aphanitic texture </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Less common and less voluminous than granite </li></ul></ul></ul></ul>
  35. 35. Granite Figure 4.9 A
  36. 36. Rhyolite Figure 4.9 B
  37. 37. Igneous compositions <ul><li>Naming igneous rocks – intermediate rocks </li></ul><ul><ul><ul><li>Andesite </li></ul></ul></ul><ul><ul><ul><ul><li>Volcanic origin </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Aphanitic texture </li></ul></ul></ul></ul><ul><ul><ul><li>Diorite </li></ul></ul></ul><ul><ul><ul><ul><li>Plutonic equivalent of andesite </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Coarse grained </li></ul></ul></ul></ul>
  38. 38. Andesite Figure 4.13
  39. 39. Diorite Figure 4.14
  40. 40. Igneous compositions <ul><li>Naming igneous rocks – basaltic rocks </li></ul><ul><ul><ul><li>Basalt </li></ul></ul></ul><ul><ul><ul><ul><li>Volcanic origin </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Aphanitic texture </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Composed mainly of pyroxene and calcium-rich plagioclase feldspar </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Most common extrusive igneous rock </li></ul></ul></ul></ul><ul><ul><ul><li>Gabbro </li></ul></ul></ul><ul><ul><ul><ul><li>Intrusive equivalent of basalt </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Phaneritic texture consisting of pyroxene and calcium-rich plagioclase </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Significant % of the oceanic crust </li></ul></ul></ul></ul>
  41. 41. Basalt Figure 4.15 A
  42. 42. Gabbro Figure 4.15 B
  43. 43. Volcanoes and Other Igneous Activity
  44. 44. Cinder cone volcano Figure 5.14
  45. 45. Anatomy of a composite volcano Figure 5.9
  46. 46. Mt. St. Helens – prior to the 1980 eruption
  47. 47. Mt. St. Helens after the 1980 eruption
  48. 48. A nue é ardente on Mt. St. Helens Figure 5.20
  49. 49. A pahoehoe lava flow Figure 5.5 A
  50. 50. Aa lava flow Figure 5.5 B
  51. 51. Formation of a volcanic neck Figure 5.27
  52. 52. Shiprock, New Mexico
  53. 53. END of Part 1
  54. 54. Earth materials (part 2) Dr.Krit Won-in Department of Earth Sciences Faculty of Science Kasetsart University [email_address] 081-633-5337
  55. 55. Sedimentary Rocks
  56. 56. The rock cycle Figure 1.21
  57. 57. What is a sedimentary rock? <ul><li>Sedimentary rocks are important for economic considerations because they may contain </li></ul><ul><ul><ul><li>Coal </li></ul></ul></ul><ul><ul><ul><li>Petroleum and natural gas </li></ul></ul></ul><ul><ul><ul><li>Sources of iron, aluminum, and manganese </li></ul></ul></ul>
  58. 58. Sedimentary Process 1. Weathering 2. Erosion and Transportation 3. Deposition 4. Diagenesis
  59. 59. Diagenesis <ul><li>chemical, physical, and biological changes that take place after sediments are deposited </li></ul><ul><ul><ul><li>Occurs within the upper few kilometers of Earth’s crust </li></ul></ul></ul><ul><ul><ul><li>Includes </li></ul></ul></ul><ul><ul><ul><ul><li>Recrystallization – development of more stable minerals from less stable ones </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Lithification – sediments are transformed into solid rock by </li></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Compaction and cementation </li></ul></ul></ul></ul></ul><ul><ul><ul><ul><ul><li>Natural cements include calcite, silica, and iron oxide </li></ul></ul></ul></ul></ul>
  60. 61. Type of Sedimentary rocks Clastic sediment Size of sediment Non-clastic sediment Chemical sediment
  61. 62. Clastic sediment Size of sediment
  62. 63. Shale with plant remains Figure 7.2
  63. 64. Quartz sandstone Figure 7.4
  64. 65. Conglomerate Figure 7.6
  65. 66. Breccia Figure 7.7
  66. 67. Coquina Figure 7.9
  67. 68. Fossiliferous limestone
  68. 69. Stages of coal formation Figure 7.15
  69. 70. Stages of coal formation Figure 7.15
  70. 71. Non-clastic sediment evaporites , carbonates and siliceous rocks .
  71. 72. <ul><li>Evaporites - The evaporites form from the evaporation of water (usually seawater). </li></ul><ul><ul><li>Rock salt - composed of halite (NaCl). </li></ul></ul><ul><ul><li>Rock gypsum - composed of gypsum (CaSO4.2H20) </li></ul></ul><ul><ul><li>Travertine - composed of calcium carbonate (CaCO3), and therefore, also technically a carbonate rock; travertine forms in caves and around hot springs </li></ul></ul>
  72. 73. Gypsum Halite
  73. 74. <ul><li>Carbonates - The carbonate sedimentary rocks are formed through both chemical and biochemical processes. They include the limestones (many types) and dolostones . </li></ul><ul><ul><li>Two minerals are dominant in carbonate rocks: </li></ul></ul><ul><ul><ul><li>Calcite (CaCO3) </li></ul></ul></ul><ul><ul><ul><li>Dolomite (CaMg(CO3)2) </li></ul></ul></ul><ul><ul><ul><li>Remember which of these fizzes readily, and which of these must be scratched or powdered! </li></ul></ul></ul><ul><ul><li>Carbonate rock names: </li></ul></ul><ul><ul><ul><li>Micrite (microcrystalline limestone) - very fine-grained; may be light gray or tan to nearly black in color. Made of lime mud, which is also called calcilutite. </li></ul></ul></ul><ul><ul><ul><li>Oolitic limestone (look for the sand-sized oolites) </li></ul></ul></ul><ul><ul><ul><li>Fossiliferous limestone (look for various types of fossils in a limestone matrix) </li></ul></ul></ul><ul><ul><ul><li>Coquina (fossil hash cemented together; may resemble granola) </li></ul></ul></ul><ul><ul><ul><li>Chalk (made of microscopic planktonic organisms such as coccolithophores; fizzes readily in acid) </li></ul></ul></ul><ul><ul><ul><li>Crystalline limestone </li></ul></ul></ul><ul><ul><ul><li>Travertine (see evaporites) </li></ul></ul></ul><ul><ul><ul><li>Others - intraclastic limestone, pelleted limestone </li></ul></ul></ul>
  74. 75. Limestone Chalk
  75. 76. <ul><li>Siliceous rocks - The siliceous rocks are those which are dominated by silica (SiO2). They commonly form from silica-secreting organisms such as diatoms, radiolarians, or some types of sponges. Chert is formed through chemical reactions of silica in solution replacing limestones. </li></ul><ul><ul><li>Diatomite - looks like chalk, but does not fizz in acid. Made of microscopic planktonic organisms called diatoms. May also resemble kaolinite, but is much lower in density and more porous). Also referred to as Diatomaceous Earth. </li></ul></ul><ul><ul><li>Chert - Massive and hard, microcrystalline quartz. May be dark or light in color. Often replaces limestone. Does not fizz in acid. </li></ul></ul>
  76. 77. chert diatomite
  77. 78. Metamorphism and Metamorphic Rocks
  78. 79. The rock cycle Figure 1.21
  79. 80. Metamorphism <ul><li>The transition of one rock into another by temperatures and/or pressures unlike those in which it formed </li></ul><ul><li>Metamorphic rocks are produced from </li></ul><ul><ul><ul><li>Igneous rocks </li></ul></ul></ul><ul><ul><ul><li>Sedimentary rocks </li></ul></ul></ul><ul><ul><ul><li>Other metamorphic rocks </li></ul></ul></ul>
  80. 81. Metamorphism <ul><li>Metamorphism progresses incrementally from low-grade to high-grade </li></ul><ul><li>During metamorphism the rock must remain essentially solid </li></ul><ul><li>Metamorphic settings </li></ul><ul><ul><ul><li>Contact or thermal metamorphism – driven by a rise in temperature within the host rock </li></ul></ul></ul>
  81. 82. Metamorphism <ul><li>Metamorphic settings </li></ul><ul><ul><ul><li>Hydrothermal metamorphism – chemical alterations from hot, ion-rich water </li></ul></ul></ul><ul><ul><ul><li>Regional metamorphism </li></ul></ul></ul><ul><ul><ul><ul><li>Occurs during mountain building </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Produces the greatest volume of metamorphic rock </li></ul></ul></ul></ul><ul><ul><ul><ul><li>Rocks usually display zones of contact and/or hydrothermal metamorphism </li></ul></ul></ul></ul>
  82. 83. Pressure in metamorphism Figure 8.4
  83. 84. Foliation resulting from directed stress
  84. 85. Slate (left) and phyllite (right) Figure 8.14
  85. 86. Garnet-mica schist Figure 8.11
  86. 87. Classifying metamorphic rocks Figure 8.12
  87. 88. Contact metamorphism Figure 8.19
  88. 89. Hydrothermal metamorphism Figure 8.20
  89. 90. Marble Figure 8.17
  90. 91. Quartzite Figure 8.18
  91. 92. Metamorphic environments and plate tectonics Figure 8.28