Question 7 (4 points) which of the following statements about andesitic magma is true? a) it is one of the three major types of magma. ob) it forms in oceanic basins from oceanic crust or oceanic sediments. o c) it has a very high silica content and viscosity, but a low gas content. od) all of the above

d) All of the above

Explanation:

Three main types of magma are Basaltic magma, Rhyolitic magma and Andesitic magma. Basically Andesitic magma is formed through the wet partial melting of the mantle under the ocean which has contact with water. .It is generated in the wedge of the mantle rock below the crust and above the subducted plate itself. Andesitic and rhyolitic magmas are generated at convergent plate boundaries where the oceanic lithosphere is subducted . Comparatively high silica content ( 55 - 65 weight %) and lower temperature result in high viscosity and low gas content of Andesitic magma.