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Ch03_outline - 9/30/10 Rocks: Materials of the...

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Unformatted text preview: 9/30/10 Rocks: Materials of the Solid Earth Chapter 3 2010 2 Rock cycle 3 4 1 9/30/10 The Geologic Cycle vs Rock Cycle 5 Sea ­Floor Spreading and Plate Boundaries 6 Rock cycle  Shows the interrelaG onships among the three rock types Earth as a system: the rock cycle • Sediment • LithificaGon • Sedimentary rock • Metamorphism 7 8 2 9/30/10 Rock cycle • Metamorphic rock • MelGng • Magma Rock cycle  Full cycle does not always take place due to "shortcuts" or interrupGons •  e.g., Sedimentary rock melts •  e.g., Igneous rock is metamorphosed •  e.g., Sedimentary rock is weathered •  e.g., Metamorphic rock weathers 9 Figure 3.2 10 Igneous rocks  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 Igneous rocks   CrystallizaGon of magma •  Ions are arranged into orderly paZerns •  Crystal size is determined by the rate of cooling NB: • Slow rate forms large crystals •  Fast rate forms microscopic crystals •  Called volcanic or extrusive rocks 11 •  Very fast rate forms glass 12 3 9/30/10 Igneous rocks  ClassificaGon is based on the rock's texture and mineral consGtuents •  Texture •  Size and arrangement of crystals •  Types •  Fine ­grained – fast rate of cooling •  Coarse ­grained – slow rate of cooling •  PorphyriGc (two crystal sizes) – two rates of cooling •  Glassy – very fast rate of cooling 13 Fine ­grained – fast rate of cooling : Basalt 4 Figure 3.5 A 14 Course ­grained igneous texture, slow rate of cooling: Granite PorphyriGc (two crystal sizes) – two rates of cooling Figure 3.5 B 15 Figure 3.5 D 16 4 9/30/10 Obsidian exhibits a glassy texture Igneous rocks  ClassificaGon is based on the rock's texture and mineral consGtuents •  Mineral composiGon •  Explained by Bowen's reacGon series which shows the order of mineral crystallizaGon •  Influenced by crystal seZling in the magma Figure 3.7 17 18 Rock type produced PeridoGte Magma evoluGon Basalt Gabbro Andesite Diorite Rhyolite Granite Figure 3.13 19 20 5 9/30/10 Igneous rocks  Naming igneous rocks •  GraniGc rocks •  Composed almost enGrely of light ­colored silicates  ­ quartz and feldspar •  Also referred to as felsic: feldspar and silica (quartz) •  High silica content (about 70 percent) Granite •  Common rock is granite 21 Figure 3.5 B 22 Igneous rocks  Naming igneous rocks •  BasalGc rocks •  Contain substanGal dark silicate minerals and calcium ­rich plagioclase feldspar •  Also referred to as mafic: magnesium and ferrum (iron) Basalt •  Common rock is basalt 23 24 6 9/30/10 Igneous rocks  Naming igneous rocks •  Other composiGonal groups • AndesiGc (or intermediate) • Ultramafic • Common rock is PeridoGte 25 Plutonic Rocks 26 Volcanic Rocks 27 El Capitan: The massive granite monolith. Yosemite 28 NP, CA 7 9/30/10 Summit of Half Dome, Yosemite NP, CA 29 The Bronze Horseman (Peter The Great Monument), St. Petersburg, Russia 30 Sedimentary rocks 31 Utah's Bryce Canyon National Park 32 8 9/30/10 DeposiEon of Sediment Sedimentary rocks  Form from sediment (weathered products)  About 75% of all rock outcrops on the conGnents 33 34 Sedimentary rocks  Used to reconstruct much of Earth's history •  Clues to past environments •  Provide informaGon about sediment transport •  Rocks oien contain fossils The White Chalk Cliffs, Sussex, England 35 36 9 9/30/10 Sedimentary rocks  Economic importance •  Coal •  Petroleum and natural gas •  Sources of iron and aluminum Figure 3.24 (top) 37 38 Figure 3.24 (boZom) Sedimentary rocks  Classifying sedimentary rocks •  Two groups based on the source of the material •  Detrital rocks •  Material is solid parGcles •  Classified by parGcle size • Common rocks include •  Shale (most abundant) •  Sandstone •  Conglomerate 39 40 10 9/30/10 Shale with plant fossils Sandstone Figure 3.19 (or 3.13 D ) Figure 3.18 (or 3.13 C) 41 42 Conglomerate Sedimentary rocks  Chemical rocks  Derived from material that was once in soluGon and precipitates to form sediment •  Directly precipitated as the result of physical processes, or •  Through life processes (biochemical origin) Figure 3.17 (or 3.13 A ) 43 44 11 9/30/10 Sedimentary rocks  Chemical rocks •  Common sedimentary Fossiliferous limestone rocks •  Limestone – the most abundant chemical rock 45 46 Limestone caves, Australia 47 France 48 12 9/30/10 France 49 France 50 Chert & Agat Rock salt 51 52 13 9/30/10 ClassificaEon of sedimentary rocks Sedimentary rocks  Sedimentary rocks are produced through lithificaGon •  Loose sediments are transformed into solid rock •  LithificaGon processes •  CompacGon •  CementaGon by •  Calcite •  Silica •  Iron Oxide 53 54 Figure 3.16 Sedimentary rocks  Features of sedimentary rocks •  Strata, or beds (most characterisGc) •  Bedding planes separate strata •  Fossils •  Traces or remains of prehistoric life •  Are the most important inclusions •  Help determine past environments •  Used as Gme indicators •  Used for matching rocks from different places 55 56 14 9/30/10 End of Ch. 3, part 1 57 15 ...
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This note was uploaded on 10/09/2010 for the course GEL sec 001 taught by Professor Delusinirina during the Spring '10 term at UC Davis.

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