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Geosciences LibreTexts

9.5: Lab Exercise (Part B)

  • Page ID
    5623
  • Part B - Association of Magma Type with Tectonic Setting

    The questions in this exercise demonstrate the control that tectonic setting has on the type of magma produced. For the Google Earth questions, copy and paste the latitude and longitude coordinates into the search bar (or just type them in).

    5. A(n) ________________________ at the Mid-Ocean Ridge, where oceanic plates are diverging and magma is generated by partial melting of the mantle.

    a. ultramafic magma is produced

    b. mafic magma is produced

    c. intermediate magma is produced

    d. felsic magma is produced

     

    6. Type 19 28 19.70 N 155 35 31.94 W in the search bar on Google Earth, and zoom out to an eye altitude of ~119 miles. This volcano is composed of:

    a. mafic rocks, because a hotspot partially melted the mantle below the oceanic crust.

    b. mafic rocks, because a hotspot partially melted the oceanic crust. 

    c. ultramafic rocks, because a hotspot partially melted the mantle below the oceanic crust. 

    d. ultramafic rocks, because a hotspot partially melted the oceanic crust.

     

    7. Type 35 35 08.45 S 70 45 08.22 W in the search bar in Google Earth. This volcano formed from an intermediate magma type, because:

    a. subduction of oceanic crust beneath the continental crust occurs here. 

    b. continental crust is subducting, causing magma to form. 

    c. a hot spot is partial melting the continental crust. 

    d. this is the result of a divergent plate boundary.

     

    8. Type 36 40 41.62 N 108 50 17.22 W in the search bar in Google Earth. The dark-colored rock that forms a straight line on the surface is most likely:

    a. a pluton of ultramafic rock.

    b. a dike of ultramafic rock. 

    c. a sill of mafic rock.

    d. a dike of mafic rock.