Igneous Rocks

Cards (22)

  • What makes up large parts of the continent and oceanic rocks?
    Igneous Rocks
  • The common rocks are igneous rocks
  • Igneous rocks indicate plate boundaries and hot spots.
  • What is a magma?
    A molten rock below the earth’s surface.
  • Magma solidifies into plutonic/intrusive igneous rock.
  • Magma erupts as either lava/pyroclastic materials. Pyroclastic materials and lava cool to form volcanic (extrusive) igneous rocks.
  • What is viscosity?
    Resistance to flow.
  • What controls viscosity?
    Primarily controlled by temperature and composition.
  • Higher temperature=lower viscosity. Lowe temperature=higher viscosity.
  • UMIF
    Ultramafic have the least silica and high Fe and Mg
    Mafic have less silica and Fe and Mg Rich
    Intermediate is between felsic and mafic
    Felsic is silica-rich and low in Fe and Mg
  • Low viscosity (mafic) is runny because of higher temperature and less silica content.
    High viscosity (felsic) is thick because of lower temperature and higher silica content.
  • Patrial melting is a magma that is less mafic than the parent rock.
  • Composition of a rock is ruled by the source area.
    Melting mantle = mafic magma
    melting crust = felsic/intermediate magma
  • Magma mixing = similar viscosities
  • Magma mingling = diff viscosities
  • Grain size determines the cooling speed of the rock.
  • Rocks that are fine-grained cooled fast. Rocks that are coarse-grained cooled slow.
  • Volcanic (extrusive) rocks are fine-grained with aphanitic texture.
  • Plutonic (intrusive) rocks are coarse-grained.
    Coarse-grained = phaneritic texture
    Extremely coarse pegmatitic texture
    Complex/non-uniform = porphyritic
    holes = vesicular
    ash = pyroclastic
    no grains = glassy
  • Welded tuff are formed when particles are buried before cooling down.
  • Non-welded tuff (rhyolitic tuff) forms when particles cooled before burying.
  • Plutons are bodies of igneous rocks which have intruded on country rock