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8.4: Activity 8C - Association of Magma Type with Tectonic Setting

  • Page ID
    14816
  • 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 (or type in) the latitude and longitude coordinates into the search bar.

    1. At Mid-Ocean Ridges (MORs), where oceanic plates are diverging, melt is generated by decompression and which causes partial melting of the mantle. What is the final composition of the melt produced here? Hint: think about the rock type that makes up the oceanic crust.

      1. ultramafic

      2. mafic

      3. intermediate

      4. felsic

    1. Type 19°28'19.7"N 155°35'31.9"W in the search bar on Google Earth and zoom out to an eye altitude of ~110 miles. This volcano is composed of:

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

      2. mafic rocks because a hotspot partially melted the oceanic crust

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

    1. ultramafic rocks because a hotspot partially melted the oceanic crust

    1. Type 41°24'38.4"N 122°11'42.6"W in the search bar in Google Earth. This volcano formed from an intermediate magma type, because:

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

      2. continental crust is subducting, causing magma to form

      3. a hot spot is partial melting the continental crust

      4. this is the result of a divergent plate boundary

    1. Type 36°40'41.6"N 108°50'17.2"W in the search bar in Google Earth. The dark colored rock that forms a straight line on the surface is most likely:

      1. a pluton of ultramafic rock

      2. a dike of ultramafic rock

      3. a sill of mafic rock

      4. a dike of mafic rock

    1. Type 37°44'39.19"N 119°31'59.05"W into the search bar in Google Earth and zoom out to an eye altitude of ~100 miles. The lighter colored rock that forms much of this area is most likely:

      1. a batholith of mafic rock

      2. a sill of mafic rock

      3. a batholith of felsic rock

      4. a sill of felsic rock