GEO 101 – Exam 3 Study Guide1. 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. Recrystallizationi. Same mineral – different size and shapeb. Phase changei. Same chemical compositionii. Different mineral (crystal structure)c. Neocrystallizationi. New mineralsd. Pressure solutioni. Minerals change shape1. Must have water + different pressuree. Plastic deformationi. Rock squeezed at high temperatures1. Grains change shape3. How do geologists classify metamorphic rocks? a. Parent rockb. Texturei. Size, shape, and arrangement of mineral grainsii. Two main textures: foliated and unfoliated1. Foliation forms by rotation and recrystallization of elongated minerals. Differential pressurea. Ex: stripes4. What causes foliation? Differential pressure5. What does metamorphic grade tell us? a. Reflect pressure and temperature conditions6. What do metamorphic facies and index minerals tell us? a. Metamorphic facies – a grouping of minerals created under specific conditionsb. Index minerals – form within specific temperature and pressure. Only 1 mineral 7. Where does metamorphism happen?a. Contact metamorphismi. Existing rock heated by intruding magmaii. Low-grade metamorphismiii. Auerole – concentric zone of metamorphism around an intrusionb. Regional metamorphismi. Associated with mountain building1. Middle of mountain = gneiss2. Edge of mountain = slatec. Burial metamorphismi. Very deeply buried sedimentd. Dynamic metamorphismi. 2 plates moving against each otherii. Fault zonese. Subduction zones8. What is the rock cycle?a. Any type of rock can be reformed into any other type of rock9. Define: epicenter, focus, faulta. Epicenter = surface of earth directly above focusb. Focus = actual spot in the earth where energy is releasedc. Fault = fracture/cracks along which movement has occurred. Release of energy10. Major types of faultsa. Dip-Slip Fault: Normali. Mid-ocean ridge and subduction zonesii. Hanging wall moves down relative to footwalliii. Stretching of Earth’s crustb. Dip-Slip Fault: Reversei. Hanging wall moves up relative to footwallii. Steep dip angle (60 degrees)iii. Compression of crustc. Dip-Slip Fault: Thrusti. Subduction zonesii. Hanging wall moves up relative to footwalliii. Gentle angle (< 30 degrees)iv. Compression of crustd. Dip-Slip Fault: Obliquei. Either stretching or compression1. Moves in 2 directions at onceii. Plus horizontal movemente. Strike-slip faultsi. Horizontal motion (shear)1. Transform plate boundaryii. Two types1. Right-lateral2. Left-lateral11. What is elastic rebound theory and what does it explain? a. How energy is stored and builds up and then is releasedb. Build up of strain, rupture, strain released12. What are driving forces that move rocks?a. Plate tectonicsb. Movement of magmac. Volcanic explosiond. Giant landslidese. Water pumping or injectionf. Underground nuclear bomb tests13. What are the kinds of movement/displacement that occur along a fault?a. Fault creepi. Release a little bit everydayii. Very littleb. Periodic energy releasei. Build up pressure and then let goii. Medium-sized earthquakesc. Store up energyi. Pressure released all at onceii. Huge earthquakes14. What is a foreshock and aftershock? Why do they happen?a. Foreshock – fault is starting to moveb. Aftershock – adjusting to new position15. What is earthquake triggering?a. More earthquakes outside aftershock area16. What are the types of seismic waves and their characteristics?a. Body Waves: P-Waves (primary waves arrive first)i. Compressional waveii. Can move through outer coreiii. Particle motion is parallel to the wave directionb. Body Waves: S-waves (secondary waves)i. Shear waveii. Particle motion is perpendicular to the waveiii. Never travel through the corec. Surface waves: Love wavesi. Move like a snake (side-to-side particle motion)ii. Motion decreases with depthd. Surface waves: Rayleigh Wavesi. Counter-clockwise elliptical particle motion1. Like an ocean movese. Creates most shaking during quake (causes most damage)17. How are earthquakes recorded, measured, and located?a. Seismograph – measures intensity, direction, and duration of earthquakeb. Seismograms – a record of ground motion as a function of timec. If you have 3 records, can triangulate location of epicenter of the earthquake18. Which earthquake magnitude is considered the most accurate? Why?a. Moment magnitude – most accurate because uses more data points19. What kinds of earthquakes happen at different plate boundaries?a. Divergent plate boundariesi. Shallowii. Normal faultb. Continental rift zonei. Shallow (cracking at surface)ii. Normal faultc. Convergent plate boundariesi. Wadati-Benioff zone1. 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 downii. Thrust and normal faultsd. Continental collision zonei. Shallowii. Thrust and reverse faulte. Transform plate boundaryi. Shallowii. Strike-slip faultf. Center of platei. Rareii. Not strong20. What are the hazards of an earthquake?a. Ground shaking damageb. Ground displacementc. Liquefactiond. Landslidese. Firesf. Tsunamisg. Disease21. Can earthquakes be predicted?a. Not reallyi. Can predict where, but not when22. What causes deformation? a. Stress23. What are the factors that determine the kind of deformation that will take place?i. Type of rockii. Temperature (more heat=more deformation)iii. Pressureiv. Rate of deformation24. Which geologic features are caused by deformation? What are their characteristics?a. Faultsi. Brittle deformationb. Jointsi. Natural cracks with no movementii. Tend to occur in groupsiii. Brittle deformationiv. Promotes chemical weatheringv. Veins – mineral precipitate in jointsc. Foldsi. Compressive stressii. Ductile deformation25. What information does a geologist get from a strike and dip?a. Measure the angle/orientation of the rocks26. What happens at each place where orogenies occur?a. A mountain building eventb. Mostly caused by convergent boundariesi. Subduction zonesc. Convergent-subductioni. Accreted terrains1. Scraped off terrain and smashed into continentd. Convergent mountain buildingi. Continental collision zonee. Divergent mountain buildingi.