Geology Rocks and Processes

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Igneous Rocks

** few pointers to remember**

  • Pyroxene = Augite
  • Amphibole = Hornblende
  • Olivine = green
  • Olivine and Pyroxene = Peridotite
  • measurement of silicity = 66 52 45
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Silicic Content

  • Ultramafic ---> pyroxene and olivine

 

  • 
  • Mafic ---> pyroxene and K. feldspar

 

  • Silic/ intermediate ---> Quartz, K.feldspar, Plagioclase, Mica, Amphibole
    • Silicic = more Quartz (more viscous)
    • Intermediate = less Quartz (more of the other minerals)
  • 
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Further Classification of Igneous Rocks

 

Silicic -------------------------------------------------------------------------------> Ultramafic

                           Increasing darkness, density, Ca, Fe, Mg

                 Decreasing viscosity, Si, Na, K

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Where Each Type can be Found

 

  • Silicic = continental
  • Intermediate = Island arc
  • Mafic = oceanic
  • Ultramafic = Mantle
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Fractional Crystalisation

fractional crystalisation = Soup of magma (all types of rock silicic --> ultrmafic)

                                        = makic minerals for crystals (high temperatures)

                                        = crystals fall to bottom (less dense)

                                        = leaves soup of magma more and more silic

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Random Point - Vocab

Stoping  = magma rising through lines of weakness

Fissure =  flood of basalt = spills out (very mafic = pressure to get to the top - as can flow)

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Sills and Dykes

Batholith ----> PLUTONIC ----> Intrusive

Dykes and Sills ----> HYPABYSSAL ----> Intrusive

Volcanoes -----> VOLCANIC ----> Extrusive

  • Dykes = discordent
  • 
  • Sills =  concordent
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Cone Dykes and Ring Cones

(http://science.jrank.org/article_images/science.jrank.org/ring-complex.1.jpg)

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Lavas

  • AA lava = thick and blocky(http://www.smate.wwu.edu/teched/geology/GeoHaz/vo-HA-impact/vo-HA-impact-08.JPG)
  • Pahoehoe = smooth ropey surface (http://t3.gstatic.com/images?q=tbn:ANd9GcTF3EThvfWOy5F6EfJlMYQwmMof52wR8GCXKGYG_DS-m7GgldkPYA)
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Pyroclastic Material

  • Ash (< 2mm)
  •  
  • Lapilli (2-64mm)
  • Bombs and blocks (>64)
    • bombs = ejected as liquid but solidify
    • blocks = always solid
      •  
        •  
          • bombs + blocks = agglomerates
          • 
  • gases ----> nueree aurdents
  • pyroclastic FLOW = on the ground
  • Pyroclastic FALL = in the air
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(http://www.cnsm.csulb.edu/departments/geology/people/bperry/IgneousRocksTour/BowensReactionSeriesDiagramS.jpg)

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