Es 14e lecture_ch03
- 1. © 2015 Pearson Education Ltd. Rocks: Materials of the Solid Earth Chapter 3 Lecture Jennifer Mangan James Madison University Earth Science Fourteenth Edition, Global Edition
- 2. © 2015 Pearson Education Ltd. • Shows the interrelationships among the three rock types • Earth as a system: the rock cycle – Magma • Crystallization – Igneous rock • Weathering, transportation, and deposition Rock Cycle
- 3. © 2015 Pearson Education Ltd. • Earth as a system: the rock cycle – Sediment • Lithification – Sedimentary rock • Metamorphism – Metamorphic rock • Melting – Magma Rock Cycle
- 4. © 2015 Pearson Education Ltd. • Earth as a system: the rock cycle – Full cycle does not always take place due to “shortcuts” or interruptions • e.g., Sedimentary rock melts • e.g., Igneous rock is metamorphosed • e.g., Sedimentary rock is weathered • e.g., Metamorphic rock weathers Rock Cycle
- 5. © 2015 Pearson Education Ltd. The Rock Cycle
- 6. © 2015 Pearson Education Ltd. • Form as magma cools and crystallizes – Rocks formed inside Earth are called plutonic or intrusive rocks – Rocks formed on the surface • Formed from lava (a material similar to magma, but without gas • Called volcanic or extrusive rocks Igneous Rocks
- 7. © 2015 Pearson Education Ltd. • Crystallization of magma – Ions are arranged into orderly patterns – Crystal size is determined by the rate of cooling • Slow rate forms large crystals • Fast rate forms microscopic crystals • Very fast rate forms glass Igneous Rocks
- 8. © 2015 Pearson Education Ltd. • Classification is based on the rock’s texture and mineral constituents – Texture • Size and arrangement of crystals Igneous Rocks
- 9. © 2015 Pearson Education Ltd. • Types of igneous textures – Fine-grained – fast rate of cooling – Coarse-grained – slow rate of cooling – Porphyritic (two crystal sizes) – two rates of cooling – Glassy – very fast rate of cooling – Vesicular – contains hole left by gas bubbles – Pyroclastic – fragmented; produced by consolidation of volcanic fragments Igneous Rocks
- 10. © 2015 Pearson Education Ltd. Fine-Grained Igneous Texture
- 11. © 2015 Pearson Education Ltd. Coarse-Grained Igneous Texture
- 12. © 2015 Pearson Education Ltd. Porphyritic Igneous Texture
- 13. © 2015 Pearson Education Ltd. Glassy Igneous Texture
- 14. © 2015 Pearson Education Ltd. Vesicular Igneous Texture
- 15. © 2015 Pearson Education Ltd. Pyroclastic Igneous Texture
- 16. © 2015 Pearson Education Ltd. • Classification is based on the rock’s texture and mineral constituents – Mineral composition • Explained by Bowen’s reaction series which shows the order of mineral crystallization • Influenced by crystal settling in the magma Igneous Rocks
- 17. © 2015 Pearson Education Ltd. Bowen’s Reaction Series
- 18. © 2015 Pearson Education Ltd. Classification of Igneous Rocks
- 19. © 2015 Pearson Education Ltd. • Naming igneous rocks – Granitic rocks • Composed almost entirely of light-colored silicates – quartz and feldspar • Also referred to as felsic: feldspar and silica (quartz) • High silica content (about 70 percent) • Common rock is granite Igneous Rocks
- 20. © 2015 Pearson Education Ltd. Granite and Granitic Rock
- 21. © 2015 Pearson Education Ltd. • Naming igneous rocks – Basaltic rocks • Contain substantial dark silicate minerals and calcium-rich plagioclase feldspar • Also referred to as mafic: magnesium and ferrum (iron) • Common rock is basalt Igneous Rocks
- 22. © 2015 Pearson Education Ltd. Basaltic Lava
- 23. © 2015 Pearson Education Ltd. • Naming igneous rocks – Other compositional groups • Andesitic (or intermediate) • Ultramafic Igneous Rocks
- 24. © 2015 Pearson Education Ltd. • Form from sediment (weathered products) • About 75 percent of all rock outcrops on the continents • Used to reconstruct much of Earth’s history – Clues to past environments – Provide information about sediment transport – Rocks often contain fossils Sedimentary Rocks
- 25. © 2015 Pearson Education Ltd. • Economic importance – Coal – Petroleum and natural gas – Sources of iron and aluminum Sedimentary Rocks
- 26. © 2015 Pearson Education Ltd. • Classifying sedimentary rocks – Two groups based on the source of the material • Detrital • Chemical Sedimentary Rocks
- 27. © 2015 Pearson Education Ltd. • Detrital rocks – Material is solid particles – Classified by particle size – Common rocks include • Shale (most abundant) • Sandstone • Conglomerate Sedimentary Rocks
- 28. © 2015 Pearson Education Ltd. Detrital Sedimentary Rocks
- 29. © 2015 Pearson Education Ltd. • Chemical sedimentary rocks – Derived from material that was once in solution and precipitates to form sediment • Directly precipitated as the result of physical processes, or • Through life processes (biochemical origin) Sedimentary Rocks
- 30. © 2015 Pearson Education Ltd. • Common chemical sedimentary rocks – Limestone – the most abundant chemical rock – Microcrystalline quartz (precipitated quartz) known as chert, flint, jasper, or agate – Evaporites such as rock salt or gypsum – Coal – compressed plant material Sedimentary Rocks
- 31. © 2015 Pearson Education Ltd. Chemical, Biochemical, and Organic Sedimentary Rocks
- 32. © 2015 Pearson Education Ltd. • Sedimentary rocks are produced through lithification – Loose sediments are transformed into solid rock – Lithification processes • Compaction • Cementation by – Calcite – Silica – Iron Oxide Sedimentary Rocks
- 33. © 2015 Pearson Education Ltd. • Features of sedimentary rocks – Strata, or beds (most characteristic) – Bedding planes separate strata – Fossils • Traces or remains of prehistoric life • Are the most important inclusions • Help determine past environments • Used as time indicators • Used for matching rocks from different places Sedimentary Rocks
- 34. © 2015 Pearson Education Ltd. • “Changed form” rocks • Produced from preexisting – Igneous rocks – Sedimentary rocks – Other metamorphic rocks Metamorphic Rocks
- 35. © 2015 Pearson Education Ltd. • Metamorphism – Takes place where preexisting rock is subjected to temperatures and pressures unlike those in which it formed – Degrees of metamorphism • Exhibited by rock texture and mineralogy • Low-grade (e.g., shale becomes slate) • High-grade (obliteration of original features) Metamorphic Rocks
- 36. © 2015 Pearson Education Ltd. Metamorphic Grade
- 37. © 2015 Pearson Education Ltd. • Metamorphic settings – Contact, or thermal, metamorphism • Occurs near a body of magma • Changes are driven by a rise in temperature – Regional metamorphism • Directed pressures and high temperatures during mountain building • Produces the greatest volume of metamorphic rock Metamorphic Rocks
- 38. © 2015 Pearson Education Ltd. • Metamorphic agents – Heat – Pressure (stress) • Confining pressure – from burial • Differential stress – occurs during mountain building – Chemically active fluids • Mainly water and other volatiles • Promote recrystallization by enhancing ion migration Metamorphic Rocks
- 39. © 2015 Pearson Education Ltd. Confining Pressure and Differential Stress
- 40. © 2015 Pearson Education Ltd. • Metamorphic textures – Foliated texture • Minerals are in a parallel alignment • Minerals are perpendicular to the compressional force – Nonfoliated texture • Contain equidimensional crystals • Resembles a coarse-grained igneous rock Metamorphic Rocks
- 41. © 2015 Pearson Education Ltd. Development of Foliation due to Directed Pressure
- 42. © 2015 Pearson Education Ltd. • Common metamorphic rocks – Foliated rocks • Slate – Fine-grained – Splits easily • Schist – Strongly foliated – “Platy” – Types based on composition (e.g., mica schist) Metamorphic Rocks
- 43. © 2015 Pearson Education Ltd. Common Metamorphic Rocks
- 44. © 2015 Pearson Education Ltd. • Common metamorphic rocks – Foliated rocks • Gneiss – Strong segregation of silicate minerals – “Banded” texture – Nonfoliated rocks • Marble – Parent rock is limestone – Large, interlocking calcite crystals Metamorphic Rocks
- 45. © 2015 Pearson Education Ltd. • Common metamorphic rocks – Nonfoliated rocks • Marble – Used as a building stone – Variety of colors • Quartzite – Parent rock – quartz sandstone – Quartz grains are fused Metamorphic Rocks
- 46. © 2015 Pearson Education Ltd. • Metallic mineral resources – Gold, silver, copper, mercury, lead, etc. – Concentrations of desirable materials are produced by • Igneous processes • Metamorphic processes Resources from Rocks and Minerals
- 47. © 2015 Pearson Education Ltd. • Metallic mineral resources – Most important ore deposits are generated from hydrothermal (hot-water) solutions • Hot • Contain metal-rich fluids • Associated with cooling magma bodies Resources from Rocks and Minerals
- 48. © 2015 Pearson Education Ltd. Resources from Rocks and Minerals • Pegmatites – Result from crystallization in fluid-rich environment – Unusually large crystals
- 49. © 2015 Pearson Education Ltd. Resources from Rocks and Minerals • Types of deposits include – Vein deposits in fractures or bedding planes, and – Disseminated deposits which are distributed throughout the rock
- 50. © 2015 Pearson Education Ltd. Metallic Resources
- 51. © 2015 Pearson Education Ltd. • Nonmetallic mineral resources – Make use of the material’s • Nonmetallic elements • Physical or chemical properties – Two broad groups • Building materials (e.g., limestone, gypsum) • Industrial minerals (e.g., fluorite, corundum, sylvite) Resources from Rocks and Minerals
- 52. © 2015 Pearson Education Ltd. Energy Resources: Fossil Fuels • Coal – Burns energy stored by plants millions of years ago – Air pollution – Surface scarring
- 53. © 2015 Pearson Education Ltd. • Oil and Natural Gas – More than 60% of U.S.-consumed energy – Remains of marine plants and animals – Source rock – where oil and natural gas originate – Oil trap – geologic environment allowing oil and gas to accumulate Energy Resources: Fossil Fuels
- 54. © 2015 Pearson Education Ltd. • Oil trap – two basic features – Reservoir rock • Porous and permeable • Yields oil and gas in significant quantities – Cap rock • Impermeable • Keeps oil and gas from surface escape Energy Resources: Fossil Fuels
- 55. © 2015 Pearson Education Ltd. • Common oil and natural gas traps – Anticline – up-arched sedimentary strata – Fault trap – displaced strata – Salt dome – includes layers of rock salt – Stratigraphic (pinchout) trap – original sedimentation pattern Energy Resources: Fossil Fuels
- 56. © 2015 Pearson Education Ltd. Common Oil Traps
- 57. © 2015 Pearson Education Ltd. • Hydraulic Fracturing – “Fracking” – Shatters shale with significant gas and petroleum reserves – Pumping liquids into rock at very high pressure – Can include toxic chemicals Energy Resources: Fossil Fuels