GEO 101 Exam 3 Study Guide 1 How are diagenesis and metamorphism related to each other and what causes each a Diagensis is the way to metamorphism and explains what metamorphism is Pressure and temperature increase and change the rock 2 What kinds of changes occur during metamorphism a Recrystallization i Same mineral different size and shape b Phase change i Same chemical composition ii Different mineral crystal structure c Neocrystallization i New minerals d Pressure solution i Minerals change shape 1 Must have water different pressure e Plastic deformation i Rock squeezed at high temperatures 1 Grains change shape 3 How do geologists classify metamorphic rocks a Parent rock b Texture i Size shape and arrangement of mineral grains ii Two main textures foliated and unfoliated 1 Foliation forms by rotation and recrystallization of elongated minerals Differential pressure a Ex stripes 4 What causes foliation Differential pressure 5 What does metamorphic grade tell us a Reflect pressure and temperature conditions 6 What do metamorphic facies and index minerals tell us a Metamorphic facies a grouping of minerals created under specific conditions b Index minerals form within specific temperature and pressure Only 1 mineral 7 Where does metamorphism happen a Contact metamorphism i Existing rock heated by intruding magma ii Low grade metamorphism iii Auerole concentric zone of metamorphism around an intrusion b Regional metamorphism i Associated with mountain building 1 Middle of mountain gneiss 2 Edge of mountain slate c Burial metamorphism i Very deeply buried sediment d Dynamic metamorphism i 2 plates moving against each other ii Fault zones e Subduction zones 8 What is the rock cycle a Any type of rock can be reformed into any other type of rock 9 Define epicenter focus fault a Epicenter surface of earth directly above focus b Focus actual spot in the earth where energy is released c Fault fracture cracks along which movement has occurred Release of energy 10 Major types of faults a Dip Slip Fault Normal i Mid ocean ridge and subduction zones ii Hanging wall moves down relative to footwall iii Stretching of Earth s crust b Dip Slip Fault Reverse i Hanging wall moves up relative to footwall ii Steep dip angle 60 degrees iii Compression of crust c Dip Slip Fault Thrust i Subduction zones ii Hanging wall moves up relative to footwall iii Gentle angle 30 degrees iv Compression of crust d Dip Slip Fault Oblique i Either stretching or compression 1 Moves in 2 directions at once ii Plus horizontal movement e Strike slip faults i Horizontal motion shear 1 Transform plate boundary ii Two types 1 Right lateral 2 Left lateral 11 What is elastic rebound theory and what does it explain a How energy is stored and builds up and then is released b Build up of strain rupture strain released 12 What are driving forces that move rocks a Plate tectonics b Movement of magma c Volcanic explosion d Giant landslides e Water pumping or injection f Underground nuclear bomb tests 13 What are the kinds of movement displacement that occur along a fault a Fault creep i Release a little bit everyday ii Very little b Periodic energy release i Build up pressure and then let go ii Medium sized earthquakes c Store up energy i Pressure released all at once ii Huge earthquakes 14 What is a foreshock and aftershock Why do they happen a Foreshock fault is starting to move b Aftershock adjusting to new position 15 What is earthquake triggering a More earthquakes outside aftershock area 16 What are the types of seismic waves and their characteristics a Body Waves P Waves primary waves arrive first i Compressional wave ii Can move through outer core iii Particle motion is parallel to the wave direction b Body Waves S waves secondary waves i Shear wave ii Particle motion is perpendicular to the wave iii Never travel through the core c Surface waves Love waves i Move like a snake side to side particle motion ii Motion decreases with depth d Surface waves Rayleigh Waves i Counter clockwise elliptical particle motion 1 Like an ocean moves e Creates most shaking during quake causes most damage 17 How are earthquakes recorded measured and located a Seismograph measures intensity direction and duration of earthquake b Seismograms a record of ground motion as a function of time c If you have 3 records can triangulate location of epicenter of the earthquake 18 Which earthquake magnitude is considered the most accurate Why a Moment magnitude most accurate because uses more data points 19 What kinds of earthquakes happen at different plate boundaries a Divergent plate boundaries i Shallow ii Normal fault b Continental rift zone i Shallow cracking at surface ii Normal fault c Convergent plate boundaries i Wadati Benioff zone 1 Two plates coming together with shallow earthquakes Plate being brought down into earth and moves back and forth all the way down so there are intermediate and deep earthquakes all the way down ii Thrust and normal faults d Continental collision zone i Shallow ii Thrust and reverse fault e Transform plate boundary i Shallow ii Strike slip fault f Center of plate i Rare ii Not strong 20 What are the hazards of an earthquake a Ground shaking damage b Ground displacement c Liquefaction d Landslides e Fires f Tsunamis g Disease 21 Can earthquakes be predicted a Not really i Can predict where but not when 22 What causes deformation a Stress 23 What are the factors that determine the kind of deformation that will take place i Type of rock ii Temperature more heat more deformation iii Pressure iv Rate of deformation 24 Which geologic features are caused by deformation What are their characteristics a Faults i Brittle deformation b Joints i Natural cracks with no movement ii Tend to occur in groups iii Brittle deformation iv Promotes chemical weathering v Veins mineral precipitate in joints c Folds i Compressive stress ii Ductile deformation 25 What information does a geologist get from a strike and dip a Measure the angle orientation of the rocks 26 What happens at each place where orogenies occur a A mountain building event b Mostly caused by convergent boundaries i Subduction zones c Convergent subduction i Accreted terrains 1 Scraped off terrain and smashed into continent d Convergent mountain building i Continental collision zone e Divergent mountain building i Stretching ii Faulting iii Volcanoes 27 What does isostacy tell us about the earth s surface a Lithosphere floats on asthenosphere b Gravity pulls down