Plate Tectonics and the Rock Cycle

1. Plate Tectonics and the Rock Cycle Chapter 8

2. Earth Formed 4.6 billion years ago • Heavier elements sank (Fe) • Lighter elements floated above them (silica) • The elements/Minerals present when Earth formed are all we have to use! • Minerals = nonrenewable resource

3. Minerals Are Not Distributed Evenly on the Globe • Economic and political conflicts • California Gold Rush • Alaskan Gold Rush • Blood Diamonds • Earth contains a finite amount of mineral resources!

4. Layers of the Earth

6. Structure of the Earth

7. Three Geologic Cycles • Tectonic Cycle • Rock cycle • Soil Formation

8. Plate tectonics • Wegener, 1912: “Earth’s lithosphere is separated into plates that are in constant motion.” • Pangaea • Similar: • Rock formations & Fossil evidence • Plate types: Oceanic Plates & Continental Plates

13. Plate Tectonic Rules • Oceanic is denser than Continental plates so they sink. • O + O = subduction=trenches • O+ C= O subducts & get Mts & volcanoes • C+C = Mts (both upward) Hot spots = valcanoes island chains

14. Plate Tectonics-Types of Boundaries • Divergent plate boundary (mid ocean ridge-sea floor spreading) • Convergent plate boundary (trenches & volcanoes) • Transform fault plate boundary (San Andreas)

15. Which boundary is a transform fault boundary? (A) (B) (C)

16. What type of plate boundary?

17. Convection & Hot Spots • Radioactive decay of elements in Mantle and outer core generate heat • Magma well upward (convection currents) • Hot Spots

19. Earthquakes • Fault zone • Epicenter • Ring of Fire

22. Living in Areas of Seismic or Volcanic Activity • Run! (just kidding) • Richter Scale (exponential) • Building collapse at 5-5.9 • Concrete (static) buildings: Hatti: 7.0=200,000

25. Volcanoes • 2010 Iceland eruption • Cinders, ash, dust, rock, lava • Loss of life • Habitat destruction • Alter air quality

27. Mt St. Helen’s Eruption-1980

28. Rock Cycle Recycles Minerals & Elements

29. Minerals • Minerals • Elements or compounds of elements that occur naturally in Earth’s crust • ORES • Naturally formed aggregates of minerals

30. Mineral Distribution and Formation • Abundant minerals in crust • Aluminum and iron • Scarce minerals in crust • Copper, chromium, and molybdenum • Distributed unevenly across globe • If found in low abundance, mining is not profitable

33. Three Rock Types • Igneous (intrusive extrusive): obsidian, granitic basaltic • Fractures minerals ppt out  veins • Metamorphic (heat & pressure): slate, marble, anthracite • Sedimentary (from sediments): sandstone, mudstone, conglomerates

34. Weathering • The breakdown (P/C) • P: Water/wind/freeze-thaw/tree roots • C: Dissolving chemical elements (nutrients) • Feldspar clay & K+ • Lichens (weak acids) • Limestone (CaCO3) & H2CO3 • Anthropogenic Acid Rain via SOx, NOx emissions

38. Erosion • Transport by wind, water, ice • Gravity • Deposition • Humans exacerbate this: • Land use practices: deforestation, overgrazing • Construction/road building

40. Formation of Mineral Deposits • Result of natural processes • Magmatic concentration • As magma cools heavier elements (Fe and Mg) settle • Responsible for deposits of Fe, Cu, Ni, Cr • Hydrothermal processes • Sedimentation • Evaporation

41. (1) Discovering Mineral Deposits • geologists use a variety of instruments and measurements • Aerial or satellite photography • Aircraft and satellite instruments that measure Earth’s magnetic field • Seismographs • Sound Waves • Drill Core Samples • Combine this with knowledge of how minerals are formed

42. Minerals: A Non-renewable Resource