Direct Evidence for Planet Composition

• Crust

  We can observe igneous, metamorphic and sedimentory rocks on the surface. Some of these have been brought to the surface by uplift
• Mines

  Deepest mines are for gold, nearly 4km deep below this it gets to hot
• Boreholes


  One borehole teacher 12km at 300’ drills stopped working
• Ophiolites


  At a convergent plate boundary parts of oceanic crust can be broken off and uplifted onto the surface.

  Can contain peridotit - represents upper parts of mantle
• Volcanoes


  Bring magma from depth that originates in the lower crust or mantle
• Partial melting of mantle - can use basalt to estimate composition of mantle
• Some volcanoes have xenoliths of peridotite (mantle ultra-Mafic magma) which tells us directly about mantle composition