GEL 001 Final Exam Study Guide PDF

GEL 001 Final Exam Study Guide Questions that you should be able to answer from the notes, images, and lecture What are tectonic plates composed of and how are they defined? ○ Geologic boundaries (earthquakes, volcanoes and seafloor features) ○ Rarely coincide with continental...

GEL 001 Final Exam Study Guide Questions that you should be able to answer from the notes, images, and lecture What are tectonic plates composed of and how are they defined? ○ Geologic boundaries (earthquakes, volcanoes and seafloor features) ○ Rarely coincide with continental boundaries ○ Constant motion, made of rock- tabular shape of slabs of earth's outer surface ○ Tectonics are large scale, slow motion movement and deformation ○ Lithosphere- crust and upper mantle ~100km down Cool and strong, rigid Plates consist of lithosphere ○ Asthenosphere- upper mantle down to 400-600 km, temperature change between lithosphere and asthenosphere Hot weak plastic (difference in strength) Moves by convection What is a divergent plate boundary? Where do they occur? What processes define them? ○ Marked by mid ocean ridges and continental rifts ○ Extensional stress ○ Seafloor spreading- new lithosphere is created Magma wells up and pours out onto seafloor Rift valley/axial rift ○ Plates pulled apart along axis, brittle crust breaks along ridges and faults Elongate ridges ○ Faults sub parallel to ridge axis Faults are planes of weakness within the body of rock along which abrupt movement occurs in response to tectonic stress. Fractures are planar cracks/fissures within a body of rock with no movement along the planar surface. Decompression melting Magma chambers Continued tectonic extension of plates border the mid ocean ridge. New ocean lithospheric rock gets split along faults and fractures and displaces on either side of mid ocean ridge, axial rift in the middle of mid oceanic ridge New lava solidifies, then is fractured by extensional stress and split by new lava welling up  Describe the process of seafloor spreading. ○ Magma wells up along fissures in mid ocean ridges in axial rift valleys, ○ Fissure eruptions (effusive) ○ Pillow basalt is formed and spreads laterally, continual eruptions melts the old lithosphere and continues spreading along sea floor ○ Asthenosphere moving passively What is some of the evidence that proves that seafloor spreading is real? ○ Observation and measurements of the seafloor ○ Dredging and drilling ○ Marine sediment thickness ○ Maps of earthquake distribution that correspond with mid ocean ridges ○ Heat flow - highest over mid ocean ridge, decreases away from ridge axis ○ Exploration of axial rifts with submersibles and remotely operated vehicles → which helps us understand hydrothermal vents and chemosynthesis How do continents break apart? ○ Ocean basins are born when a continent splits and separates into two divergent continents in a process called continental rifting ○ Upwelling (rising) asthenosphere beneath Africa pushes up the overlying lithosphere, stretching it and causing it to break along faults. Collapse of fault blocks creates a rift valley. ○ as lithosphere stretches and thins, the underlying asthenosphere rises even further, melts to form magma, and produces volcanism ○ Directly: divergent boundaries ○ Indirectly: continental rifting Why are there continents and ocean basins? ○ Oceanic crust is more dense than continental crust (more buoyant) and so the continental crust ‘floats’ higher than the oceanic crust ○ Both oceanic and continental ‘float’ above denser mantle, oceanic crust is iron rich and therefore ocean basins sink deeper into underlying mantle ○ Continental crust ‘floats’- like an iceberg  How do mountains form and why are most of them linear in extent? ○ Mountains form from continent-continent collision at collision zones ○ Ex. Himalayas (Mt. Everest) ○ Deformation and uplift What are the three types of convergent plate boundaries and how do they differ? ○ Continental-continental Collision zones Ex. Himalayas (Mt. Everest), European Alps Continental crust is not dense enough to submerge - no volcanism because there isn’t subduction happening Thrust faulting occurs- detachment of thick slivers of rock slowly creating mountains Compressional stress Thrust sheets move during earthquakes ○ Continental-oceanic Ex. Andes Mtns in South America, Cascades, Central America volcanic chain oceanic lithosphere dives beneath a continental part of a plate, lithospheric material is returned to the mantle → subduction Subducti ○ Oceanic-oceanic What types of physical features form along each of the boundaries? ○ Why are mountains elevated upward? How do rugged mountainous landscapes form? What are the various components of subduction zones? What happens to create collision zones? ○ Continental continent collision, no subductions because same density ○ No volcanism bc no subductions ○ Thrust faults causes mountain buildings- earthquakes ○ Continual uplift How do mountains influence the broader Earth system? ○ Creates mountains; himalayas have snow which melts into water which provides melt water to thousands or people ○ Earthquakes and volcanoes can be devastating ○ Influence on climatic zones What processes occur along transform plate boundaries? ○ Earthquakes - stick slip faults’ ○ Rebound theory ○ Primary forec is shear ○ What is the fault? ○ Planar weakness between two fault blocks - NOT tectonic plates, offsetting massive blocks of rock and surface features  ○ Causes rugtire triggering earthquakes San andreas fault What are mantle plumes and hot spots? Explain how hot spot trails form. How do seamounts and atolls form? What is the energy source for the movement of plates? What evidence do geologists use to determine ancient configurations of continents and ocean basins? What is an igneous rock and what are rocks composed of? How does the silica content of a magma influence the style of eruptions and the shape of volcanoes? How does the tectonic setting of volcanoes influence the amount of silica in a magma? How do volcanoes influence the Earth system? What is the elastic rebound theory of earthquakes? What is stick-slip behavior along faults and how does it relate to the earthquake cycle? What are the four types of seismic waves and how are they expressed during an earthquake? How do subduction zone earthquakes trigger tsunamis? What are some of the characteristics of tsunamis as they travel through the oceans? How do earthquake early warning systems work? Intro to Plate Tectonics Wegener continental drift exploration of oceans bathymetry mid-ocean ridges abyssal plains fracture zones deep-ocean trenches continental shelf, slope, rise coastal plain plate tectonics earthquake and volcano distribution lithosphere asthenosphere Divergent Plate Boundaries divergent plate boundary extensional stress seafloor spreading axial rift / rift valley magma vs. lava magma chamber faults fissure eruptions pillow basalt pelagic rain marine sediment heat flow hydrothermal vents chemosynthesis seafloor spreading rates age of the seafloor continental rifting East African Rift linear seas (e.g., Red Sea) origin of continental margins Convergent & Transform Tectonics oceanic vs. continental crust convergent plate boundary compressional stress deformation & uplift continental-oceanic convergence subduction / subduction zone creation of magma continental volcanic arc Cascadia subduction zone inclined zone of seismicity Ring of Fire oceanic-oceanic convergence volcanic island arc continental collision zones modern examples of convergent plate boundaries in the world transform plate boundaries continental transform faults shear stress fault oceanic transform faults & fracture zones Hot Spots mantle plume hot spot trails seamounts atolls Hawaiian-Emperor seamount chain what drives plate tectonics convection currents slab pull rates of plate motion plate tectonics and ancient continental positions Volcanism lava vs magma intrusive vs extrusive igneous environments volcanism vs plutonism role of silica effusive vs explosive eruptions viscosity volcanic gases low-silica magma shield volcanoes fissure eruptions basalt tectonic settings of low-silica volcanism intermediate to high-silica magma stratovolcanoes pyroclastic debris volcanic ash pumice pyroclastic fall pyroclastic flow andesite rhyolite volcanic tuff obsidian continental hot spots tectonic settings of high-silica volcanism volcanic impact on climate sulfur aerosols Earthquakes Loma Prieta earthquake, 1989 elastic rebound theory stick-slip behavior of faults earthquake cycle recurrence interval seismicity focus vs epicenter displacement (offset) faults fault trace (fault line) main quake vs. aftershocks seismic waves P waves S waves Love waves Rayleigh waves relative speeds of seismic waves tectonic settings of quakes focal depths of quakes earthquakes - mid-ocean ridges earthquakes - convergent margins inclined zone of seismicity “megathrust” earthquakes earthquakes – transform margins San Andreas fault zone 1857 Ft Tejon earthquake paleoseismology Hayward fault tsunami main events during 2011 Japanese quake & tsunami earthquake prediction vs forecasting earthquake early warning system earthquake safety from brochures