Intrusive Igneous Rocks

Welcome to Poorna Pal's 'Earth Revealed' telecourse (Geol 101: Physical Geology; section #7695) at the Glendale Community College
  • Volcanic Rocks

Home | Quizzes  |  Module 1 | Module 2 | Module 3 | Module 4 | Module 5           05/05/15

 

Links to pages at this site

  

Links to Book's Website

  

Help available at this site

 

  • Home

  • Quizzes

  • Module 1

    Introduction

    Earth's Interior

    Earth's Oceans

  • Module 2

    Plate Tectonics

    Mountain Building

    Geological Structures

    Earthquakes

    Measuring Geologic Time

  • Module 3

    Evolution through Time

    Atoms, Elements and Minerals

    Volcanism and the Extrusive Rocks

    Intrusive Activity and the Igneous Rocks

    Weathering and Soil

    Mass Wasting

  • Module 4

    Sediments and Sedimentary Rocks

    Metamorphism and the Metamorphic Rocks

    Streams and Landscapes

    Underground Water

    Deserts and Wind Action

  • Module 5

    Glaciers

    Waves, Beaches and the Coasts

    Earth Resources

    Environmental Matters

  

 

Intrusive Activity, and the Origin of Igneous Rocks
 

  

 
     
   

  • Poorna's Outlines

Plutonic Rocks


Click on the title to access and download this MS word document
   
   
   
   
   
   
   
       
 

"Rock Cycle" ― a theoretical concept that relates tectonism, erosion, and the various rock forming processes to the common rock types ― plausibly began with the formation of granitic crust and granite, the most common plutonic rock is also what the "Rock Cycle" ends with.

Try the following links for interesting "Rock Cycle" presentations:

http://www.bbc.co.uk/education/rocks/rockcycle.shtml http://www.intel.com/education/unitplans/rockcycle/rock.htm

http://www.moorlandschool.co.uk/earth/rockcycle.htm

 
 
 
 
 
 
 
 
 
 
         
  How Igneous Rocks Form?

Visit the URL:
http://www.fi.edu/fellows/fellow1/
oct98/create/igneous.htm
for the animation of igneous rocks and for more information on the igneous rocks.

  

Plutonic Igneous Rocks

  • Igneous rocks are primary rocks in the rock cycle and form by solidifying from molten condition.

  • There are two kinds of igneous rocks: plutonic and volcanic.

  • Intrusive or plutonic rocks form from the slow cooling and solidification of magma.
   
   
   
   
   
   
   
   
   
 

  • These intrusive bodies can form either near-surface (volcanic necks or plugs, dikes and sills) or be deep-seated (plutons like stocks and batholiths).
 
 
         

  • The intrusive igneous rocks have phaneritic (or coarse grained) to porphyritic textures, compared to the porphyritic to aphinitic textures of extrusive igneous rocks.

  • Felsic (60-75% silica, with free quartz) composition dominates the intrusive or plutonic rocks (e.g., granites and granodiorites), compared to the mafic (with ~50% silica, no free quartz) basalts in the case of extrusive or volcanic rocks. Gabbro, the plutonic equivalent of basalt, is mafic and diorite, the plutonic equivalent of andesite, is of intermediate composition.

  • Granites and granitization complete the rock cycle as granite batholiths, the most common plutonics, often form in the core zones of folded mountain belts through the process of dynamothermal metamorphism. But then, note that the primordial crust too is likely to have been granitic.
     
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

The red and pink shaded regions in this geological map of California are intrusive igneous bodies. This map can be accessed at the California Geological Survey website http://www.consrv.ca.gov/cgs/information/geologic_
mapping/index.htm#Related%20Links.
These igneous intrusives form the bulk of the Sierra Nevada Ranges. Contrasted with these large batholiths are such more common though shallow or near-surface features as dikes and sills.

  
 
 
 
 
 
 
 
 
 
                 


Want to take a self-test on igneous rocks and processes? Try North Dakota State Universitys Geoscience website at the URL: http://www.ndsu.nodak.edu/instruct/schwert/geosci/g120/igneous.htm


To view the samples of different igneous rocks,
try the URL: http://www.dc.peachnet.edu/
~pgore/geology/geo101/igneous.htm


For a plutonic rocks exercise using Bowen's reaction series, try the URL: http://web.clas.ufl.edu/users/phiggins/BowensRSEx.html
 


Note: Rotating globe at the top left corner of this page is from http://adinet.net/Globe_HTML/frames/scientific/f2p3a7_78kb2.htm